目次

I． 本プロジェクトの意義と研究経過 ………………………………………………………………… 1
1． 本プロジェクトの背景と目的 …………………………………………………………………………

3

2． 本プロジェクトの課題への取り組み方 ………………………………………………………………

3

3． 運動時循環調整研究の拠点整備 ………………………………………………………………………

4

4． 研究組織および研究体制 ………………………………………………………………………………

5

5． プロジェクト達成目標と達成状況および優れた成果 ………………………………………………

7

II．本プロジェクトの研究成果の概要 ………………………………………………………………… 9
1． 運動特性との関連からみた運動時の血流再分配 …………………………………………………… 11
2． セントラルコマンドと反射性制御からみた運動時の循環調節機構 ……………………………… 13
3． 身体特性の相違と適応からみた循環調節 …………………………………………………………… 15
4． 運動時の循環応答からみた提案−エビデンスに基づく運動プログラムの構築に向けて− ………………………………………… 16

III．プロジェクトの個別課題における成果 …………………………………………………………… 19
1． 骨格筋への血流分配と筋からの血液還流 ……………………………………………加賀谷淳子

21

2． 運動時の内臓器官および脳の血流動態とその調節機構 ……………………………定本朋子

51

3． 運動時の筋交感神経活動からみた中枢指令および反射性制御の調節機構 ………斉藤満

65

Oxygenation Monitored by Near Infrared Spectroscopy …………Valentina Quaresima

71

4． Effects of Different Exercise Modalites on Skeletal Muscle and Prefrontal C o r t e x
5． Technical Developments of Multi-channel Near-infrared Devices for Studying O x y g e n a t i o n
and Hemodynamics in Brain Cortex and Skeletal Muscle ……………………Marco Ferrari81

6． 運動様式，運動強度，運動時間および筋代謝からみたモーターユニットの動員特性 ………………………………………………………………………………加茂美冬

89

7． 運動時の心拍出量の変化と各種血管への血中配分 …………………………奥山（清水）靜代

99

8． 有疾患者における運動および筋虚血に対する血流プロファイル−下肢閉塞性動脈硬化保有者における運動下肢血行動態の検討− ………………長田卓也 107

9． 運動時の呼吸循環系変化に対する中枢性・末梢性の神経調節 ……………………佐藤耕平 11110． 運動準備期のセントラルコマンドの働き ……………………………………………岩館

雅子 11911． 筋の酸素代謝特性と運動時循環応答との連関 ……………………………笹原（上田）千穂子 125
12． 運動時における一次運動野の酸素化動態 ……………………………………………澁谷

顕一 129

IV．プロジェクトの共同研究における成果 ……………………………………………………………137
共同研究1
Redistribution of blood flow during exercise; Critical exercise intensity for circulatory
and metabolic changes in response to knee extension exercise and its relationshipto blood flow to exercising limb ………………………………………………………………139
Atsuko Kagaya, Mitsuru Saito, Tomoko Sadamoto, Marco Ferrari,
Valentina Quaresima, Mifuyu Kamo, Takuya Osada, Shizuyo Shimizu-Okuyama,
Kohei Sato, Masako Iwadate, Fumiko Ohmori, and Valentina Cettolo
共同研究2Role of central command in the cerebral and renal blood flow responses during static
exercise ………………………………………………………………………………………153
Tomoko Sadamoto, Kohei Sato, Ai Hirasawa, Chihoko Ueda-Sasahara,
Kenichi Shibuya, Mitsuru Saito, Mifuyu Kamo, Sizuyo S h i m i z u -Okuyama,
Takuya Osada, and Atsuko Kagaya

V．研究業績一覧 …………………………………………………………………………………………165
VI．資料 …………………………………………………………………………………………………179

1． 研究成果別刷 ……………………………………………………………………………………………179
2． 学術フロンティア推進事業シンポジウム・研究成果報告会 ………………………………………441
3． 学術フロテンィアセミナー ……………………………………………………………………………504

I．本プロジェクトの意義と研究経過超音波法による心拍出量と身体各部位への動脈血流

1．本プロジェクトの背景と目的

分配，近赤外線分光法を用いた活動筋代謝と筋循環，「動く」ことは，人間存在の根幹をなすものである．

生化学的手法による血管内皮細胞由来の物質（NO，しかし，現代社会において，特に先進国と言われてエンドセリン）の分泌とその調節機構などの課題にいる国々では，日常的な身体活動の機会が減少し，焦点があてられてきた．しかし，神経性調節のうち，それが人々の心身に重大な影響を与えていることがセントラルコマンドの作用機序に関しては長い研究指摘されている．我が国においても，健康阻害が問史があるにもかかわらず，運動時の機序については題となっており，生活習慣病予防のための運動の推着手されたばかりである．また，血流分配に関して進が国の施策にも取り上げられているところである．

も，骨格筋や皮膚への循環に関しては多くの知見がこのような危機的状態は成人のみならず，子ども達あるものの，脳や腹部内臓への血流分配とその調節にも当てはまり，遊びや運動の減少が彼らの心身のについては，十分な解明がなされていない．さらに，健全な発達を阻害していると危惧されている．すな

血液のわち，すべての人々にとって，意図的な運動の実施

成果は極めて少ない．また，それらの成果も個別的が極めて重要になっているのが現状である．

であり，相互に補完し合って整合性を維持しようと循環を可能にする静脈還流に関する研究

このような背景を踏まえて，身体運動の推進が提する循環調節機序の統合的解明にはなっていなかっ唱され，国レベルの運動目標値が設定されているが，た．運動推進を考えるにあたってさらに重要な問題

すべてを網羅した明確な指針が示されているわけで点は，これらの循環調節機序が，運動様式，使用筋はない．その理由は，「動く」ことに対する身体適応群（局所的・全身的，使用部位），運動強度・運動頻のメカニズムとそれを根拠とした至適運動について，度・運動持続時間の様な運動特性別に明らかにされ必ずしも十分な科学的エビデンスが蓄積されているてこなかったことである．

とは言えないからである．なかでも，生命の安全性

このような研究の現状を踏まえて，本プロジェクに直結し，かつ多数の因子が複雑に作用する運動時

トでは，活動性だけでなく，生命の安全性に直結すの循環調節機序解明は，すべての人々の運動を推進

る運動時の循環調節に関する科学的エビデンスを，する前提として必要不可欠なことである．運動は心運動特性と関連させて蓄積し，それらを統合して得身に特異的な影響を与えるものであり，対象者の特られたエビデンスを基盤とし，健康・体力づくりの性に合わせた適切な運動でなければ効果がないだけための運動プログラムの構築に向けた提案を行うこ

でなく安全性も確保されないからである．

とを目指している．本プロジェクトで得た新知見は，運動に対する循環系の適応は極めて巧妙にできて学術的な貢献をすると同時に，国の重要かつ喫緊のいる．複雑な仕組みになっていることは，1 つの系が課題になっている国民の運動推進に対しても多大な破綻しても他の系が補償し，生命維持に必要な循環貢献ができると考えている．

システムを破綻させないような安全弁が用意されているということでもある．安静時につくられた循環2．本プロジェクトの課題への取り組み方

システムの安定性は，運動という外乱によって一旦はその整合性が破られる．そこで，運動開始と同時

課題解明に向けた本プロジェクトでの取り組み方に，運動を遂行するに必要な循環調節が行われ，同は図 I.1-1 に示した通りである．5 年間のプロジェク

時に生命を維持するための循環調節という 2 つの方向

ト研究期間の最初の 3 年間（2004 〜 2006 年度）は，の再調整がなされる．効果的な運動と同時に運動の運動時の循環調節に関する基礎的知見を集積し，そ安全性を考えなければならない所以である．しかし，

れを統合して循環調節の解明に貢献することを目指運動に対する循環系調整の機序はまだ全貌が明らかした．そのために，運動時の生体応答研究の基盤とにされていない．

なる運動単位の動員特性を明らかにするとともに，ヒトの運動時における循環調節機構に関する最近人を対象とした循環研究に必要な非侵襲的計測法の研究は，微小電極交感神経図法による神経性調節，（近赤外線分光法，超音波法など）の研究への適切な3

統合的分析

図 I.1-1 研究の課題の取り組み方

適用等を進めながら，1）運動時の血流再分配と 2）

知見をもとに，スポーツによる健康・体力づくりプ

循環系に対するセントラルコマンドを中心とした神

ログラムの構築に対して，循環調整の観点から提案

経性調節に焦点を当てた研究が遂行された．中心的を策定した．最終報告会（2009 年 2 月）ではこれま課題である「運動時の血流分配に関する研究」とでの成果とそれに基づく提案を，研究者だけでなく，「運動時のセントラルコマンドが循環に与える影響に一般の人々にも公開した．

関する研究」はプロジェクトメンバー全員が参加す

以上のように，本テーマに関して学術的な貢献をる共同研究として行われた．さらに，特化したテー

すること，それをもとに，運動プログラム構築にむ

マについては，個別に研究を実施し，プロジェクト

けた提案を行い，社会のニーズに応えることが本プ

全体で討議して統合するという研究体制をつくった．

ロジェクトの学術面でのねらいであった．

これらに関する成果は，2006 年 11 月の中間報告会で公表された．さらに，それらを統合した運動時の3．運動時循環調整研究の拠点整備

循環調節の機序については，2008 年 11 月の国際シンポジウムで報告し，この分野で精力的に新知見を文部科学省学術フロンティア推進事業は，私立大発表している海外の招待講演者や国内の研究者との学の大学院，研究所の中から，研究実績をあげ，将議論を展開して，本プロジェクトの学術的成果を確

来の研究発展が期待される卓越した研究組織を選定認した．

し，内外の研究機関との共同研究に必要な研究施設，

プロジェクト最後の 2 年間（2007 〜 2008 年度）

研究装置・設備の整備に対し，重点的かつ総合的支では，それまでの成果を様々な身体特性を持つ対象

援を行うものとされている．したがって，本プロジ者で検証することと，運動の継続が循環調節に与えェクトでは課題とする研究を推進して学術的貢献をる影響を横断的，縦断的に明らかにすることを中心

すると同時に，運動時の循環調節研究の拠点となる課題とした．そして，それまでに得られたすべてのようにハード・ソフト両面の研究環境の整備を行う

4

的なプロジェクトの推進を図った．

こともねらいの一つである．
本プロジェクトでは，初年度に脳の酸素動態を非

4.2

侵襲的・連続的に計測する近赤外線分光法や解像度

研究プロジェクトに参加する研究者・大学院生・ PD の状況が高く，画像分析が自動化した超音波測定装置を購入した．2 年目以降は既存の計測装置や運動負荷装置

本プロジェクトでは，各課題および共同研究課題

をシステム化して，ハード・ソフト面の整備が一段につき，研究者（1 〜 12 名）と，研究支援 PD スタッと進んだ．

フ（1 〜 2 名），本学および他大学の大学院生（1 〜 4

多様な因子によって調節されている循環調節につ名）の実験補助者を加えた研究チームを形成し，各いて，様々な様式・強度・持続時間の運動を用い，プロジェクトを遂行した．また人的支援の必要な課

異なる姿勢や環境の影響等を考慮しながら，性・年

題や医療施設で実施すべき課題では，必要に応じて，齢・身体特性の異なる対象者で検証するには多くの本学の教職員，他大学の研究者が参加した形で研究

研究者による共同研究が必要である．本プロジェクを実施した．学内の健康管理センター理学療法士 板トでは本研究所と他の研究機関との共同研究や本研

倉尚子氏との連携，学外では女子美術大学 石田良恵

究所を拠点として学内外の若手研究者が参加する研氏，お茶の水女子大学 水村真由美氏，独立行政法人

究プロジェクトを実施し，本分野の研究拠点形成を

理化学研究所 生体力学シミュレーション

目指した取り組みを行った．このような整備により，ユニット 小田俊明氏と連携した．さらに学内外の大プロジェクト終了後も研究実施主体である日本女子学院修士課程および博士課程（日本女子体育大学大体育大学の研究のさらなる研究活性化の中心となり，学院，お茶の水女子大学大学院，鹿屋体育大学大学

学内外の共同研究の拠点となるものである．

院）の学生が実験補助スタッフとして参加した．小

特別研究

人数であるが，高い活動力の研究者・大学院生・ PDが研究に参加する研究体制をとった．

4．研究組織および研究体制
4.1

研究組織と研究者の役割

4.3

研究チーム間の連携状況

平成 16 年度当初は 8 名の研究者と事務職員 1 名に本プロジェクトに参加する国内研究者の班員会議より，平成 17 年度からは，新たに基礎体力研究所助を平成 16 年度に 2 回，平成 17 〜 20 年度において年

手佐藤耕平氏（後に助教）が加わり 9 名の研究者とな

3 〜 4 回開催し，これまでに 14 回の班会議を開催しり，事務職員 1 名，研究支援 PD スタッフ 1 名（岩館た．班会議では，研究計画立案の問題点，各課題に雅子氏）を核とした研究組織を形成した．そして平関する研究成果報告会等を開催し，逐次研究の進捗

成 18 年 4 月に PD スタッフの異動があり〔岩館雅子

状況を確認し，相互に意見交換する場を設けた．こ氏から笹原（上田）千穂子氏へ〕，さらに平成 19 年の会は研究推進上の実務的意義もあるが，各研究者

10 月より澁谷顕一氏を新たな PD スタッフとして追の専門性を統合できるような議論の場として機能し加採用した．その後笹原（上田）千穂子氏が平成 20

た．循環調節にかかわる様々な因子を統合的に捉え

年 10 月に辞職したが，その後も引き続き研究メンバて，生理的機序を解明するという本プロジェクトのーとして課題の遂行にあたった．

趣旨を達成するために，極めて重要な位置を占めた．

したがって，表 I.4-1 に示したようなメンバーが本

イタリアの研究者の参加は 2 回であったが，討議課題

プロジェクトの研究組織である．6 名のメンバーは他

についてはあらかじめ電子メールで意見交換し，さ機関に属するが，機関相互の合意のもとで実施するらに随時連絡をとり，円滑な連携ができた．なお，通常の共同研究組織ではなく，研究者個人が日本女

平成 16 年度には国際シンポジウムを兼ねた班会議に

子体育大学附属基礎体力研究所の研究グループに参出席し，平成 17 年度にはイタリア研究グループの画するという組織形態をとった．研究代表者およびPD 研究者が約 2 週間基礎体力研究所に滞在し，国内各研究者のプロジェクト内での役割・責任は表 I.4-1

研究者を含む 13 名と連携した共同研究を実施した．

のとおりである．その役割分担は明確であり，効率

さらに平成 19 年度には国内メンバーが連携した共同

5

表 I.4-1 研究組織および研究体制
研究者氏名

所属・職名

プロジェクトでの研究課題

プロジェクトでの役割

加賀谷淳子

日本女子体育大学名誉教授

運動特性と骨格筋への血流分配への関
骨格筋への血流分配と筋から係解明，研究全体の統括と推進．平成の血液還流
16 〜 18 年度の研究代表者．

定本朋子

日本女子体育大学教授

非活動組織血流からみた運動時の循環
運動時の内臓器官および脳の調節の解明，研究の実施に関する統括
血流動態とその調節機構と推進．平成19〜20年度の研究代表者．

加茂美冬

日本女子体育大学准教授

運動様式，運動強度，運動時
筋疲労発現，運動特性，筋代謝との間および筋代謝からみたモー相互連関の解明
ターユニットの動員特性

奥山（清水）靜代

慶應義塾大学体育研究所
講師

運動時の心拍出量の変化と各 中心静脈と末梢循環のマッチングと種血管への血流分布
ミスマッチング佐藤

耕平

運動時の呼吸循環系変化に対日本女子体育大学附属基礎
呼吸循環応答にかかわる調節因子のする中枢性・末梢性の神経調
体力研究所助教
解明
節

斉藤

満

豊田工業大学教授

運動時の筋交感神経活動から自律神経による運動時循環調節メカ
みた中枢指令および反射性制ニズムの解明御の調節機構長田卓也

東京医科大学講師

有疾患者における運動および低体力者や有疾患者の循環調節メカ
筋虚血に対する血流調節プロニズムの解明と運動療法の基盤構築
ファイル

Marco Ferrari

University of L’Aquila（Italy）教授

脳循環・代謝測定用近赤外線研究装置の開発
分光法の開発Valentina
Quaresima

University of L’Aquila（Italy）教授

近赤外線分光法による運動時 脳への血流分配にかかわる調節機構の脳循環・代謝の変化
の解明

岩館

雅子

セントラルコマンドと循環応答の対学術フロンティア支援スタ 運動準備期のセントラルコマ
応関係の解明，各研究プロジェクト
ッフ，ポスドク研究員
ンドの働き実施のための補助や調整

笹原（上田）千穂子

学術フロンティア支援スタ
運動強度と筋の酸素代謝特性との関筋の酸素代謝特性と運動時循
ッフ，ポスドク研究員，東係を解明およびプロジェクト実施の環応答との連関
海学園大学講師
ための補助や調整

澁谷

筋出力調節時の左右半球間相互作用
学術フロンティア支援スタ 運動時における一次運動野のの解明およびプロジェクト実施のたッフ，ポスドク研究員
酸素化動態めの補助や調整顕一（平成 21 年 3 月 31 日付）

研究を約 3 ヵ月にわたり実施した．このように，本プら採用した．また研究支援スタッフとして学術フロ

ロジェクトでは，少人数の特性を活かした密な情報

ンティア PD 研究員〔岩館雅子氏は平成 17 年４月〜

交換と連携により，高い活動レベルを維持すること

19 年 3 月まで，笹原（上田）千穂子氏は平成 19 年 4ができた．

月〜 20 年 9 月まで，澁谷顕一氏は平成 19 年 10 月〜
平成 21 年 3 月まで〕を採用し，支援体制が整えられ

4.4

研究支援体制た．研究経費や実験補助者への謝金支払い，また研

学術フロンティア担当事務員として土井美由紀氏

究者間の連絡事項といった事務経理全般については，（派遣社員，週 4 日で 16 時間勤務）を平成 16 年度か

学術フロンティア担当事務員が行うこととした．一6

方，研究内容に直接かかわる事務作業については研

れらのエビデンスに基づいた健康・体力づくりのた究支援スタッフと PD 研究員が担当することにした．

めの運動プログラム構築に向けた提案ができた点で基礎体力研究所技術職員（平成 16 〜 17 年度大森あった．5.1 に示した達成目標に対応させると，公開

芙美子氏，平成 18 年度森山真由美氏，平成 19 〜 20

シンポジウム 3 回，国際シンポジウム 2 回，中間報告

年度平澤愛氏）が，実験装置の整備や実験補助者

会 1 回，年次研究成果報告書の刊行，学会発表 130

として，必要に応じて研究支援に加わった．また本

回，学術論文 84 篇，書籍 10 篇，その他の発表 4 回，

プロジェクト事務・経理の全体管理は，基礎体力研

その他の論文は 35 件と，すべての達成目標をクリア

究所事務長および本学の事務局が担当し，さらに経した．

理的なことに関しては学校法人二階堂学園法人本部公表された学会発表のなかで 2 演題が学会賞（アジ財務部が担当するという体制をとった．

アスポーツ医学会，日本体力医学会）を獲得した．
さらにプロジェクトメンバーの加賀谷淳子氏が平成
19 年に第 10 回秩父宮記念スポーツ医科学賞（功労賞）

5．プロジェクト達成目標と達成状況および優れた成果
5.1を受賞した．これらの受賞は，プロジェクトの研究
成果の質が評価されたこと，そして加賀谷氏を中心

プロジェクト達成目標とする共同研究者の業績と社会貢献が広く認知され評価されたことを示していた．

本プロジェクトの構想調書作成時に本プロジェク
トの達成すべき数値目標を次のようにした．平成 16

また，本プロジェクトにより，関連分野の研究者〜 18 年度には，運動時の循環調節の研究基礎を確立

および大学院生による活性化と研究拠点形成が実現

し，「学会発表 25 篇以上，レフリー付論文公表 10 篇

し，定着した．多数の大学院生や若手研究者が公開

以上，公開セミナー・シンポジウム 2 回，研究成果報

セミナー，シンポジウム，大学院生・若手研究者を告書の刊行 1 回，中間報告会（研究成果報告会）1 回」

育成するためのセミナー，国際シンポジウム，公開とした．平成 19 〜 20 年度には，応用的研究を展開

フォーラムに参加し，新たな共同研究や研究会の開し，エビデンスに基づく安全で効果的な運動のあり催も生まれた．特に 2 回の国際シンポジウムの開催方を提言することを目標として，「学会発表 20 篇以（平成 16 年度および 20 年度）では，世界的研究リー

上，レフリー付論文公表 10 篇以上，公開セミナー・

ダーでもある専門家を含むシンポジウムに多数の参シンポジウム 1 回，国際シンポジウム 1 回，最終研究加者があり，充実した情報交換と討論が行われた．

成果報告書の刊行 1 回，最終成果報告会 1 回」とした．

その成果の一部は国際誌の論争課題において見解を表明することになった（Kagaya et al. 2008）．この

5.2

優れた成果と特筆事項

ような活動に加え，実験データの提供や取材協力

本研究プロジェクトの目的は，「多数の因子が複雑（NHK ためしてガッテン，2005 年 10 月 15 日放映に作用する運動時の循環調節機構について，運動特「寝たきり予防！自転車エクササイズ」，毎日新聞東性と身体特性との関連から種々の循環動態を検討し，

京朝刊 2009 年 4 月 10 日，毎日新聞東京夕刊 2009 年

得られた成果を統合的に理解することにより，最終

4 月 11 日等），日本学術会議公開シンポジウム，市民

的には『安全で効果的な運動プログラムの構築に向公開講座，一般誌での解説記事，学会シンポジウム

けた提案』をすること」であった．5 年間にわたる本等での発表など，研究成果の社会還元が積極的に行

プロジェクトは，多くの成果をもたらせた．またそ

われた．

7

II．本プロジェクトの研究成果の概要

5 年間のプロジェクト成果を統合的に理解できるまいのに対して，椎骨動脈経路では運動による血圧おとめをするようにした．その統合的視点として，「運よび心拍出量の上昇に伴い血流量が増加することが動特性との関連からみた運動時の血流再分配」，「セ

明らかになった 7）．活動筋への動脈血流は筋収縮時にントラルコマンドと反射性制御からみた運動時の循は阻害され，筋の弛緩期に増加する．一方，活動筋

環調節機構」，「さまざまな対象者の身体特性からみからの静脈血の流出は筋活動期に加速され，筋弛緩

た運動時の循環適応」の 3 点とした．そして，最終的期には減速し，両者は，筋内圧の局所的変化によりに本プロジェクトの最終目標であるエビデンスに基相互に関連しているが，一義的ではない 4）．また，筋づく，「健康・体力づくり運動プログラムの構築に向の発揮張力が極めて低い場合であっても，ストレッ

けた提案・留意点」をまとめた．

チングのように筋線維が伸長すると，動脈側からの血流の逆行成分が増えて血流量は減少し，ストレッ
チング終了後には動脈側での加速，それに連動した

1．運動特性との関連からみた運動時の血流再分配

静脈側の流出増加が起こることがわかった 3）．
骨格筋の血流がどこまで増えるかについてはなお議

運動は，活動する骨格筋への血流量を増加させると論が続いている問題である．この課題に関する先行研

同時に，運動指令を出す脳，運動を支援する心臓や肺究は，主として代謝性の血管拡張能を調べたものが多への血液供給を適切に調節することが必要である．しかったが，酸素運搬系としての血流量の役割と考える

かし，血液を循環させる心臓の拍出能力には限界があと，運動中にどこまで増加するかが重要になる．本プること，生命維持に必要な調節が不可欠であることなロジェクトでは運動時最高値がどれくらいに達するか

どから，これらの臓器への血流調節だけでなく，活動を知る前提条件として，最高血流量に達する運動条件

筋以外の臓器や組織への血流再分配が必要となる．逆を明らかにしようとした．その結果，動的運動時筋弛

に言えば，運動時の各器官・組織への血流量変化は，緩期の血流量については，運動強度とテンポの増加に

それら調節の結果として起こったものである．したが伴って増加し，両者の組み合わせによって運動時血流って，それらを把握することは，その背後にある調節量が最高になるのではないかとの知見を得た 4）．また，機構を解明する有力な手がかりになる．一方，循環経

活動筋での血流増加は酸素需要に応えて酸素輸送を高路の動脈側と静脈側をつなぐ間に介在する骨格筋の活めるためであるが，閉塞性動脈硬化症保有者に多段階

動は，循環に対して物理的あるいは代謝性に干渉する．

負荷運動を実施した結果では，安静時には患側での血そのため，骨格筋の活動特性が循環応答を修飾する極流量が低いのに対して，運動時には患側の血流量が健めて大きな要因である．そこで，運動特性と関連させ側より増加して，虚血に伴う骨格筋酸素消費量を代償ながら，運動時の血流再分配を明らかにし，その背後する現象が見られた 6）．運動の物理的特性と代謝性特にある循環機構についてまとめた．

性の両面から，酸素供給系としての血流動態を捉えることが重要であることが示された．

1.1

骨格筋，脳，腹部内臓への血流分配運動に直接関与しない臓器である腹部内臓への血一般的に心拍出量は運動強度や活動筋量の増加に流量は，運動時に骨格筋へ血流を優先的に分配する

連動して変化するとされている．しかし，本プロジために減少するとされてきた．しかし，静的・動的ェクトでは，局所的な小筋群の運動の場合は，両者運動時の腎動脈と上腸間膜動脈の血流速度を調べるが必ずしも連動した変化を示さず，骨格筋の血流需と，腎動脈では血流速度減少が見られたが，上腸間要に対して末梢的な対応をすることもあることが示

膜動脈では顕著な変化は見られなかった．すなわち，された 5）（Shimizu and Kagaya 2004）．

運動時の腹部内臓器官への血流再分配は，一律の変運動指令を出す脳への血流再分配を，内頸動脈と化ではなく，本プロジェクトで調べた運動の範囲で

椎骨動脈の 2 つの経路から調べたところ，内頸動脈経は，消化器官血流量は腎動脈血流量のような著しい路では静的および動的運動時に動脈血圧および心拍減少がみられなかった 7）．

出量が著しく上昇しても，血流量の変化は見られな

11

図 II.1-1

1.2

血流変位点を基準とした運動強度と血流再配分

運動の時間経過に伴う循環・代謝応答の値に達する（Ohmori et al. 2006）．この時期には静変化

脈血流は安静時以下に減速し，動脈血流量が最高値に達し，筋の血管床への血液再充満が起こってから静的筋活動開始直後には筋内圧の上昇により，動静脈血流が安静レベルに復帰した 4）．

脈側からの流入が低下し，静脈側からの血液流出は加速される 4）．また，運動開始初期（約 30 秒程度）

運動後の筋の酸素化動態の回復の速さは運動中のの動的運動では，心拍出量の増加に先行して活動筋

筋の代謝を反映しているので，筋線維組成の異なるへの血流量が急速に増加するとされている．一方，深部と浅部において回復の速さ（T1/2）が異なるかど

運動開始初期の非活動肢の血流量変化をみると，強うかを検討したが有意な差は見られなかった 8）．

度依存で一過性の血流量の増加が見られ，それに続

1.3

いて強度依存の血流減少が起こった（Yoshizawa et

運動強度と血流再分配

al. 2008）．すなわち，筋収縮開始と同時に起こる動運動プログラムを考える上で，運動強度は極めて重静脈血流勾配の増加 4）等の作用によって，運動開始

要な運動条件である．本プロジェクトでは運動強度を初期から活動筋での血流増加が素早く起こるものの，

筋収縮強度と収縮頻度から検討した．筋収縮強度があ

全身性の血管収縮作用は高まらずに，この時期にはる強度を超えると筋交感神経の亢進が起こる（Saito

血流再分配は適切になされていないことが示唆されet al. 1986）ことが知られているが，その結果，強度る．非活動肢での血流量増加や，総末梢血管抵抗の変化に対する血圧上昇が顕著になる（Kagaya et al.

減少により血圧が低下することは 1）それを支持する

2001）．そこで，血圧上昇が高くなる負荷（血圧変移結果であると考えられる．

点負荷）を基準として強度をとらえ，本研究の血流再分配の成果をまとめた（図 II.1-1）．

律動的な運動が持続すると，活動筋での血管拡張により動脈血流量の増加が起こり，筋血液量が増加

活動筋への血流量が運動負荷強度の増加に伴って増する．そうなると，筋活動による静脈側の血液流出

加し，頭打ちになるかどうかは議論のあるところであが，続いて起こる動脈血流入量と密接な関係を保つ

る．本プロジェクトでは動的膝伸展運動・足底屈運動ようになることがわかっている ．

や間欠的な静的掌握運動において検討し，前者では頭4）運動が終了すると，静的筋活動後は急激な血流増打ちが観察され，後者では筋弛緩期血流が負荷の増加

加が起こり，運動後の血流は約 3 拍目の心周期で最高とともに増加するという結果を得た 1, 4）．動的・静的

12

ないことが示された．

運動ともに，運動後血流量に対する運動中血流量の比は，血圧変移点負荷とほぼ類似の負荷強度で急激に低下し，運動中の血流需要を満たす割合が低くなること

2. セントラルコマンドと反射性制御からが確認された 1）．また，強度が高くなると，運動持続

みた運動時の循環調節機構に伴う筋の電気活動漸増の割合が高くなり，筋疲労耐性の低い筋が動員されるようになることが示唆された

運動時の適切な血流再分配には，局所性調節に加えが，その強度は血圧変移点と類似であった 1）．筋の酸て，神経調節が必要である（図 II.2-1 参照）．運動は，素代謝をみると，運動中の活動肢筋酸素化動態が負荷

脳の運動中枢から出る運動指令がα運動神経を介して強度に対して低負荷とは異なる対応をする ようにな筋を収縮させることにより発現する．このような運動るのは，血圧変移点負荷よりやや低い負荷からであっ

指令と並行して延髄の循環中枢に情報が送られる．こた 4）．さらに，運動中の有酸素性エネルギー機構関与の高位中枢から循環中枢に入力される情報をセントラの度合いを，運動後の筋酸素動態（再酸素化時間 T1/2）

ルコマンドと呼び，運動開始に先行して起るフィード

からみると，強度に対して指数関数的な延長を示し，フォワード制御と考えられてきた．セントラルコマン

有意な延長を示すようになるのは血圧変移点よりさら

ドは運動に対する意思，頑張り，努力感といった主観に高い強度においてであった 8）．

的運動強度や筋疲労感覚を反映するといわれている．

1）

次に，運動中，活動筋での変化を中心に身体の様々

最近ではセントラルコマンドの概念が拡大され，筋収な変化を統合して感知する主観的筋疲労感覚（10 段階）

縮が伴わない運動想起や運動準備期に生じる循環反応

は，血圧変移点より低い負荷（38 ％ MVC）から急上

もセントラルコマンドに起因すると考えられている．

昇した．血圧変移点に対応する値は 4.0 であった 4）．

セントラルコマンドの発生回路と神経路および標的器

骨格筋への血流量が心臓の拍出量とどう対応する官は部分的なデータがあるのみである．特に人におけかをみると，局所的な運動（足底屈運動）では，活る標的器官については，心臓，皮膚血管，腎以外はあ動筋への動脈血流量が低負荷から増加を開始し始め

まり調べられてはいない．また，運動（筋活動）が発るが，心拍出量（中心循環）は中等度負荷にならな

現すると循環中枢に活動筋から反射性入力情報が伝えいと増加しなかった ．すなわち，低負荷では，心拍られる．これはフィードバック制御経路であり，活動出量の増加を伴わずに活動筋への血流再分配が起こ筋に生じる機械的変化および化学的（代謝性）変化をり，強度が高くなると心拍出量を増加させて骨格筋刺激として Group III，IV 求心性神経を介して循環中への血流再分配を行っていることが明らかになった．

枢に連絡する．それらを筋機械受容器反射と筋代謝受

また血圧が上昇するような強度の高い負荷では，脳

容器反射と呼ぶ．さらに常時血圧調節に働く圧受容器

への血液を供給する 1 つの経路である椎骨動脈の血流反射がある．このような運動時の循環調節に関わる神増加が見られた．それに対して，腹部内臓において経機構について，次のような新知見を得た．

5）は腎動脈での血流減少が確認された 7）．

2.1
1.4

運動時の循環に対する重力の影響

運動発現にかかわる神経調節

運動発現にかかわる脳神経系の働きを理解するた

本プロジェクトでは，循環系に対する重力の影響

めに，前頭前野の酸素化動態計測用の近赤外線分光を，活動体肢の位置を変化させて検討した 4）．掌握運計のセンサー，ホルダー，解析ソフトウェアの開発

動時の前腕を心臓より下にすると，筋活動中止期のをした 9）．それらを用いて，運動時の前頭前野の活性血流量が有意に変化し，上腕動脈では増加，静脈でを調べた結果，運動肢と同側半球の前頭前野が対側は減少を示した．近赤外線分光法の総ヘモグロビン

半球の前頭前野よりも高い活動があることを報告し，濃度変化からみた筋血液量は下垂で増加した．また，この活動が運動遂行に重要な役割を担うことを示唆し

重力負荷を一定にして，血液貯留状態を変えた下肢た 10）．運動指令を出す一次運動野の活動についても両の運動条件では，動脈静脈血流量には相違が見られ半球間で検討した結果，左右半球間が相互連絡をもち，ず，30 分程度では，貯留血液量レベルの差は影響し

対側一次運動野のみでは力発揮が不十分になる場合

13䐟 䝉䞁䝖䝷䝹䝁䝬䞁䝗䐣 ᅽཷᐜჾ
⑤
཯ᑕ
ᚠ⎔୰ᯡ

ᚰ⮚

Į 㐠ື⚄⤒

཯ᑕ
ồᚰ㊰
䐡

㦵᱁➽

*URXS ,,,䞉,9
ศ㓄
⬻

➽஺ឤ⚄
⤒άື
཰⦰స⏝

⭈⮚
ᣑᙇᅉᏊ

ෆ⮚

12
⾑⟶

⓶⭵
HWF

➽཰⦰
➽䝫䞁䝥

ᑡ

ከ
௦ㅰ
௦ㅰ⏘≀

㠀άື➽

䐢

䐠
ᣑᙇᅉᏊ
12

➽ᶵᲔཷᐜჾ
➽௦ㅰཷᐜჾ

⾑⟶άື➽

図 II.2-1 セントラルコマンドと反射性制御からみた運動時の循環調節機構
運動指令が脊髄を下降しα運動神経を興奮させて活動筋が収縮する．この時にセントラルコマンドが生じる（①）．運動が開始されると，活動筋には血流増加が起こる．この血流増加には代謝性血管拡張および血流依存性血管拡張（ずり応力による NO の増加が起因）が関与する（②）．運動強度が上がり活動筋の代謝が高まると，代謝産物が筋代謝受容器を刺激し（機械的刺激は筋機械受容器を刺激する），グループ III ・ IV 求心性神経を介した反射性入力を循環中枢へ送る（③）．その結果，非活動筋や腎のように運動に直接関与しない部位では，交感神経活動が優勢となり，血流が減少する．一方，活動筋
では代謝産物が交感神経活動の亢進を遮断するため〔神経伝達物質のノルエピネフリン（NE）が無効にされる（④）．これ
を機能的交感神経遮断と呼ぶ〕，血管拡張作用が優勢であり，血流増加が続く．このような活動筋と他の組織への心拍出量の血流分配を適正に保ち，一定の動脈血圧を常時維持するために圧受容器反射が働く（⑤）．

に，同側運動野の活性がそれを補完する役割を担うこ

1） 運動準備期・開始直前：運動準備期（約 1 分前かとが示唆された．さらに筋疲労時における対側半球のら）の大脳皮質運動野周辺の脳酸素動態と心拍数，

運動野の活動を，トップアスリートと一般人とで比較

血圧および前腕屈筋群の酸素動態を同時計測し，すると，アスリートは筋疲労時における活動が有意に

運動準備に関連した皮質活動と循環応答の対応性低いことから，トレーニングが一次運動野の活動を変を検討した．その結果，運動準備による大脳運動化させることが示唆された （Shibuya et al. 2008）．

野周辺の活性は心拍数および筋酸素化ヘモグロビ

運動指令に基づいて起こる運動単位の活動参加およびンの増加に対応することが示された（岩館と定本

放電間隔変化について検討した結果，一定筋力発揮時

2008）．随意運動と他動運動に伴う脳血流量を，には運動単位の放電間隔時間の延長が観察されること

内頸動脈経路（主に大脳皮質側頭葉，前頭葉，頭を報告した （Kamo et al. 2004）．

頂葉，島皮質へ潅流）と椎骨動脈経路（主に延髄，

11）

12）

小脳，後頭葉へ潅流）において比較した．その結

2.2

セントラルコマンドが働く標的器官

果，椎骨動脈経路においてのみ，随意運動開始前

セントラルコマンドは，先行研究で示されているの動作に先行する血管拡張がみられた．つまりセ心臓および皮膚組織に加えて，①運動前と運動中のントラルコマンドは椎骨動脈経路が潅流する脳部

椎骨動脈経路の脳血流量調節に働くこと，②筋疲労位にのみ働くことが示唆された 7）．同様の実験を，

時の活動筋と非活動筋の交感神経活動に働くこと，

腎動脈および上腸間膜動脈（主に消化器官へ血液③セントラルコマンドの働きはレジスタンストレーを送る）において行ったが，両動脈経路には予測

ニングで増大すること，④ヒトの腎血流量には働か制御に伴う変化は見られなかった 7）．

ないこと，という新しい知見が得られた（図 II.2-2）．
詳細は次のとおりである．

14

図 II.2-2 セントラルコマンドが働く標的器官2） 運動中について：一定負荷保持時の活動筋へ振2.3

反射性制御の働きと相互作用

動刺激（バイブレーション）を与え反射性張力

筋機械受容器反射は反射性に心拍数を上げること発揮により運動指令を低下させ，ひいてはセンが既に知られている．本プロジェクトでは，他動運

トラルコマンドも低下させるという実験条件を動（セントラルコマンドや代謝受容器反射を刺激し設定した．この実験条件により，セントラルコ

ない低負荷）で筋機械受容器反射の働きを調べた．

マンドが運動時の心拍数，動脈血圧，心拍出量，

その結果，脳，腎臓，消化器官といった血流量の調筋疲労感覚，前頭前野の酸素化動態，内頸動脈節には，低負荷では筋機械受容器反射が有意な作用

経路，椎骨動脈血経路，腎動脈の血流調節にもをもたないことが示唆された 7）．一方，筋代謝受容器低下をもたらすかどうかについて検討した．そ反射は，筋交感神経活動の亢進 15）（Saito et al. 2007）の結果，セントラルコマンド低下に伴う変化がおよび腎血流量の減少 7）といった顕著な作用をもたみられたのは，心拍数，平均血圧，筋疲労感覚

らすことが示された．また消化器官の血流には作用および椎骨動脈血流量のみであった．このことしないことも明らかとなった 7）．

から，椎骨動脈経路の血流量がセントラルコマ

筋代謝受容器反射は運動時の血圧を上昇させるが，ンドの影響を受けること，一方，動物とは異な圧受容器反射はその上昇を抑制する働きがあること

り，ヒトの腎動脈血流がセントラルコマンドのが知られている．本プロジェクトにより，代謝受容影響を受けないことが示唆された ．

器反射は圧受容器反射と競合関係にあるだけでなく，

2）

むしろ圧受容器反射の働きを助長する作用（反射の3） 筋疲労時：最大ハンドグリップ張力を疲労困憊

反応時間を早め，反応の大きさも上げる）をもつこまで維持すると筋交感神経活動が亢進する．ことが示された．これにより，筋疲労時や高強度運動の亢進が活動筋からの筋代謝受容器反射の機構

時のように代謝産物が蓄積され代謝受容器反射が働では説明できないため，筋疲労時における運動

く場合には，代謝受容器反射自体が血圧の監視機能

への意思・頑張り・努力感，すなわちセントラを高め循環破綻を防ぐ役割を果たしていることがわ

ルコマンドがこの筋交感神経活動の上昇をもたかった 15）（Ichinose et al. 2004）．

らすことが示された．この交感神経活動の亢進は，抗疲労の役割を担うと示唆された 15）（Saito

3．身体特性の相違と適応からみた循環調節

et al. 2007）．また筋疲労時にみられる筋交感神
経活動の亢進は，短期間（4 週間）の高強度レジ

身体活動・スポーツによる循環機能の向上策に必スタンストレーニングにより増大することも明

要な横断的研究および縦断的研究により，運動プロ

らかとなった （Saito et al. 2009）．

グラム作成上に有意義な結果を得た．以下に主な知15）見を述べる．
15

3.1

時の最大血流量も利き腕が高いことがわかった．テ

発育に伴う脳血流の変化について

加賀谷らによる先行研究（Muraoka et al. 2002）

ニス選手の利き腕による運動時血流量が非利き腕のでは，心筋の形態と機能についてその発達が調べら時よりも高くなるのは血管径の差によることも明られた．このような心拍出量の発達に加えて，未知なかになった 4）（Kagaya et al. in press）．このようにト部分であった脳循環の発達について検討した．特に，レーニングが筋量，血管形状，活動筋への血流量をどの程度の心拍出量が脳へ分配されるのか（脳血流増加させることが示された．

配分率）を，10 〜 22 歳の男女約 300 名について調べ

3.5

た．その結果，脳血流分配率は 10 歳で高く，その後トレーニングによる交感神経系の適応について徐々に低下し，15 歳でほぼ発育が終了し，成人値に達することが示された．また心機能が脳循環より先

成人男性の利き腕と非利き腕における掌握運動を行して発達するという新知見が得られた．さらに，維持した時にみられる筋交感神経活動を比較した結心機能と脳循環の後に筋力（握力）が著しく発達す果，トレーニング側と考えた利き腕運動時の筋交感る時期が出現することが示された 7）．

神経活動が非利き腕運動より高くなった．このことを，筋疲労に抗して運動を持続させるには，交感神

3.2 高齢者の心形態と血管形状の関連について

経活動を高いレベルに保つことが重要であること示

高齢者において心形態，筋厚および血管形状の変化

すものである 15）（斉藤ら 2006a, 2006b）．さらに，がどのような関連を保っているのかを検討した結果，実際に，片側の腕によるハンドクリップレジスタン

左室重量と大腿部筋体積との間には有意な正の相関関

ストレーニングを４週間行い，対照側と比較した結係が得られた．これまで，発育期の子どもでは，左室果，筋疲労時の筋交感神経活動が対照側の運動時よ重量-大腿部体積の間に密な関係のあることが示されりも高くなることが示された．またこの交感神経活ていたが，高齢者においても等しい関係性が認められ動の亢進は，活動筋からの反射性制御に起因するのたことは，身体運動による骨格筋量の保持が心臓の容ではなく，高位中枢からのセントラルコマンドの増量保持にも効果を与えるとの重要な知見を得た 5）．

強に起因することも示された．したがって，短期間のレジスタンストレーニングは，活動筋というより3.3

有疾患者における運動および虚血に対すも，運動への頑張り・努力感にかかわる高位中枢にる血流調節について適応をもたらせ，その結果，抗疲労の役割を果たす
交感神経活動の亢進をさせるという重要な知見を得

閉塞性動脈硬化症保有者は，下肢動脈血管の動脈た 15）（Saito et al. 2009）．

硬化による血行障害のために運動歩行時に間歇性跛
行を認める．しかしながら，疾病下肢運動中の血流上記知見の得られた研究課題は以下のとおりであり，学術雑誌に公表されていない個別課題は本報告書の個別課題

動態についての報告は少ない．本研究では，閉塞性研究成果に詳しくまとめられている．
1）「再分配」共同研究，2）「セントラルコマンド」共同研究，
3）
若手研究者受け入れ「ストレッチング」研究，4）加賀谷
担当個別課題，5）奥山（清水）担当個別課題，6）長田担当
個別課題，7）定本担当個別課題，8）笹原（上田）担当個別
課題，9）Ferrari 担当個別課題，10）Quaressima 担当個別課
題，11）澁谷担当個別課題，12）加茂担当個別課題，13）岩館担
当個別課題，14）佐藤担当個別課題，15）斉藤担当個別課題

動脈硬化症保有者の患側肢と健側肢において多段階
脚伸展運動時の下肢血行動態を比較検討した．その結果，運動時において，患側肢血流量が健側肢よりも顕著に増大することが確認され，末梢循環障害が安静時のみならず，運動中の骨格筋循環に大きな影響を及ぼすことが示唆された 6）．

3.4

テニス選手の利腕と非利腕の比較から

4．運動時の循環応答からみた提案−エビデンスに基づく運動プログラムの構築に向けて−

利き腕と非利き腕を各々トレーニング側，非トレ
ーニング側と捉えて，テニス選手の筋厚と血管形状，
上腕動脈血流量を比較した．その結果，利き腕の筋

運動プログラムは実施する運動特性と対象者の身厚と血管径が非利き腕よりも大きく，漸増負荷運動
16体特性を踏まえて作成する必要がある．本プロジェ

り，いずれも上肢で高くなることが既に知られていクトで得た知見をもとに次のような提案をする．

る．循環機能からみると，上肢の運動は，心臓との位置関係（重力作用）によって循環応答が変動する

4.1

運動様式についてことを考慮する必要がある．一方，心臓よりも低い
位置で運動することが一般的である下肢の運動は，

1）動的運動・静的運動

重力作用による血液貯留を避けるよう留意する必要

動的運動は心拍数や心拍出量を増加させ，血液循がある．

環を促進する運動様式といえる．また筋の収縮と弛緩がリズミカルに繰り返され（収縮期には静脈血が4）一側性の運動筋から流出し，筋弛緩期には動脈血の流入量が増加する反応をもたらす），活動筋の十分な血管拡張によ

循環促進に有効なサイクリングやウォーキングのり，運動時の血圧上昇が低く，生体への負担度が少ような両側性運動が運動プログラムの主体となってないという特徴をもつ．また軽強度による脚の動的いる．しかし，腕や脚の運動を片側だけで行った場

運動時（心拍数が 110 拍／分以下の強度）には，筋交合でも，運動を行わない対側や他の体肢（脚運動を感神経活動が安静時よりも低下することから，安静している時の腕など）の骨格筋血流量を一時的に変にするよりもゆっくり歩くほうがリラクゼーション

化させることから，一側性の運動も運動プログラム効果をもつと示唆される．一方，筋収縮が持続するとして活用できると考えられる．

静的運動は，心拍数や心拍出量の著しい上昇はみら
5）その他の運動や運動想起

れないが，活動筋での血液の流入・流出が制限されるため，動脈血圧を上昇させやすい運動様式となる．

ストレッチングのように筋の長さを変える運動も，

特に強度が高くなると，心臓や血管系への負担も大筋内循環を促進させることから，ウォーミングアッ

きくなりやすい．このような動的運動と静的運動のプやクーリングダウンに用いるだけでなく，要介護

特徴を理解した運動プログラムの作成が必要である．

者や病床にある患者の筋循環の促進を目的とした運動プログラムとしても活用できる．

2）大筋群運動（全身的運動）・小筋群運動（局所的運動）

運動の準備・想起（イメージ）は，運動野皮質関

大筋群を用いた全身的運動による持久性運動は呼吸連領域の脳活性，心拍数，活動筋の酸素化動態，脳循環機能の維持向上のために有効であり，既に運動処

血流量（椎骨動脈経路）を上昇させたことから，随方で広く活用されている．本プロジェクトでは，掌握

意的に運動を準備し運動遂行のイメージをもつこと

運動のような小筋群の局所的運動であっても，活動筋

は，運動開始後の循環調節および動作をスムーズにのみならず非活動筋への血流量を増加させ，循環機能させる手段となる．

を活性化させることが示されている．運動強度が高く4.2なると，脳血流増加の頭打ち，腎血流の減少，筋交感

運動強度の選定について

神経活動の亢進をもたらすことになる．また高強度負運動プログラムの作成において，適切な運動強度

荷の掌握運動レジスタンストレーニングが運動時の頑を選択することは重要課題である．全身運動におけ

張り・努力感にかかわる中枢指令（セントラルコマン

る強度設定指標は確立されているが，局所運動につド）を増強させる効果をもつことも示されている．しいては未だ確立されてはいない．本プロジェクトのたがって，対象者の特性を考慮した適切な運動様式や結果から，次の二つの強度選定指標を提案する．

運動強度を選択することにより，小筋群の局所的運動
も循環機能の活性に有効な手段となる．

1）負荷増加に対して血圧上昇が顕著になる「血圧変移点」を指標とする．

3）上肢の運動・下肢の運動「血圧変移点」を調べると（図 II.1-1），随意最大筋

上肢の運動と下肢の運動では，一定の酸素摂取量

力（MVC）の 30 〜 50 ％の運動強度に分布する．こに対する動脈血圧，心拍数，毎分換気量などが異なの血圧変移点の出現付近の負荷強度から，血液供給17

が不足し，筋交感神経活動の亢進も起こる．そして，

させ，ひいては運動終了後低血圧を招く場合もあ

腎動脈および内頸動脈血流量の減少や頭打ちがみらる．そのため，軽い運動（クーリングダウン）をれる．なお，血圧変移点を超えて 50 〜 70 ％ MVC ま

運動終了後にも行い，筋ポンプ作用により静脈還で上がると，活動筋代謝は有酸素系から無酸素系へ流の急激な低下を予防する必要がある．

とシフトし，活動筋中には代謝産物・局所性ホルモ
2）対象者の身体特性の観点からンが蓄積されることになる．

①発育期の子どもにおける循環機能の発達：心機能および脳循環が著しく発達する時期は，心機能

2）主観的筋疲労感覚を指標として活用する．
筋疲労感覚は筋交感神経活動を反映する指標であ（推定心拍出量）が 10 〜 12 歳頃であり，脳循環り，血圧変移点負荷に相当する筋疲労感覚は「4」で（頸動脈血管内径）が 12 〜 15 歳である（男女差があり，これは「疲れた」と「かなり疲れた」の中間ある）．したがって，このような心臓および血管機の感覚である．この指標は誰もが容易に活用できる能が発達する時期を考慮した運動のプログラムがことから，単独で，あるいは他の強度指標と併用し発育期には必要である．

て用いることを提案する．また，運動実施時には常②高齢者における筋量の保持：高齢者の心臓の形態にモニターすることを推奨する．

（左室重量）は大腿部筋体積と密接に相関することが示された．このことから，高齢者においても骨4.3

運動実施にあたっての留意点

格筋量の保持が心機能の保持に有効であるといえ，高齢者も筋量の維持に結びつく運動プログラムが本プロジェクトの成果に関連する運動実施上の留必要である．

意点をまとめた．

③末梢循環系有疾患者の運動：閉塞性動脈硬化症保1）運動時間の観点から

有者は筋虚血を代償するために著しい血流量増加①運動開始前：運動への準備やイメージをもつことが生じる．しかし，運動時の心拍出量の増大にはは運動開始後の循環調節および動作をスムーズに限界があることを考えると，健常人よりも運動時させる有効な手段となる．

の血流および血圧調節が難しい．このことを踏まえたプログラム作成が必要である．

②運動開始時：運動に適した循環システムを再調整するには，運動開始後約 30 秒間は必要である．こ

3）呼吸法との関連についての調整がうまく運ばないと，血圧が低下することもある．したがって，運動開始時の急激な負荷上

短時間の高強度レジスタンス運動時の脳血流応答

昇を避け，ゆっくりと徐々に運動強度を上げるよから，息こらえは脳血流減少を，過呼吸は運動終了

うにする．

後の著しい血流増加（オーバーシュート）をもたらせることから，運動時の呼吸をコントロールするこ③運動終了前（疲労時）：運動持続時間とともに活動とに留意する必要がある．

筋の疲労が始まる．筋疲労に抗して「頑張り・努
力感」を働かせると，交感神経活動を介した力の4）運動時の姿勢（重力作用）について維持が可能となる．しかし，運動経験の少ない人
や低体力者の人は，無理のない時点で運動を終了

活動筋と心臓との位置関係によって生じる重力作させるようにする．その判断基準には主観的運動

用が循環応答を大きく変動させることに留意する必強度や筋疲労感覚を用いる（図 II.1-1 参照）．

要がある．活動筋が心臓よりも高い位置にある場合④運動終了直後：運動終了とともに，身体の各部位

は，筋への動脈血流量が低下し筋から流出する静脈の調節機能は運動前のレベルに戻ろうとする．し血流量が増加し，運動遂行には不利なことが多い

かし，活動筋では運動時に生じた血管拡張物質が（上肢の運動・下肢の運動参照）．

洗い出されるまで，血流増加が続くことになる．
この運動後の著しい血流増加が静脈還流量を低下

18

III．プロジェクトの個別課題における成果

1

骨格筋への血流分配と筋からの血液還流
加賀谷淳子 1）

Distribution of blood flow to and outflow from skeletal muscles
Atsuko Kagaya■本課題の共同研究者
大森芙美子 1, 5），奥山（清水）静代 2），村岡 慈歩 3），吉澤 睦子 4），熊谷 真奈 4），森
鈴木早紀子 6），水村真由美 7），佐藤 耕平 2），浜岡 隆文 8），小田 俊明 9）

曜生 6），

日本女子体育大学基礎体力研究所，2）慶應義塾大学体育研究所，3）明星大学人文学部，4）日本女子体育大学大学
院スポーツ科学研究科，5）鹿屋体育大学大学院体育学研究科，6）お茶の水女子大学大学院人間文化研究科，7）お茶の水女子大学文教育学部，8）鹿屋体育大学体育学部，9）理化学研究所
1）

1.1

研究の背景と目的

1.2

Venous and arterial blood flow velocity during static handgrip exercise at varying intensities
with the forearm below heart level.
Atsuko Kagaya, Shizuyo Okuyama, Fumiko Ohmori, Yoshiho Muraoka, and Mutsuko Yoshizawa

1.3

前腕の律動的運動中の動静脈血流バランス
加賀谷淳子，清水 靜代，大森芙美子，熊谷 真奈，吉澤 睦子

1.4

受動的ストレッチングが循環・筋酸素動態に与える影響
1.4.1 受動的ストレッチングによる末梢動脈と静脈の血流変化
加賀谷淳子，奥山（清水）靜代，大森芙美子，村岡慈歩，水村真由美，森曜生，鈴木早紀子

1.4.2 受動的下腿ストレッチングによる膝窩動脈血流速度の変化−血流の順行成分と逆行成分からの検討−
大森芙美子，村岡慈歩，奥山（清水）靜代，森曜生，鈴木早紀子，水村真由美，加賀谷淳子

1.4.3 受動的ストレッチング中の拮抗筋および協働筋における筋血液量と筋形状の関係
村岡 慈歩，鈴木早紀子，森曜生，大森芙美子，奥山（清水）靜代，水村真由美，加賀谷淳子

1.4.4 受動的ストレッチング時における下腿協働筋間への血流分配の相違
森

曜生，村岡

慈歩，奥山（清水）靜代，大森芙美子，鈴木早紀子，水村真由美，加賀谷淳子

1.4.5 最大位までの多段階ストレッチングが筋の循環に与える影響
大森芙美子，奥山（清水）靜代，村岡慈歩，森曜生，鈴木早紀子，水村真由美，加賀谷淳子

1.4.6 ストレッチングが筋血管容量に及ぼす影響（preliminary report）
小田 俊明，大森芙美子，森曜生，村岡 慈歩，奥山（清水）靜代，水村真由美，加賀谷淳子

1.5． Transient increase in femoral arterial blood flow to the contralateral non-exercising limb during one-legged exercise
Mutsuko Yoshizawa, Shizuyo Shimizu-Okuyama and Atsuko Kagaya
1.6． Influence of combination of contraction intensity and frequency on attaining peak blood flow
during exhaustive dynamic plantar flexion
Fumiko Ohmori, Takafumi Hamaoka, Shizuyo Okuyama, and Atsuko Kagaya
1.7． 静的掌握運動時の主観的筋疲労感覚と血圧急上昇負荷との関係
大森芙美子，清水 靜代，村岡 慈歩，佐藤 耕平，加賀谷淳子
1.8． Blood flow and arterial vessel diameter change during graded handgrip exercise in dominant
and non-dominant forearms of tennis players
Atsuko Kagaya, Fumiko Ohmori, Shizuyo Okuyama, Yoshiho Muraoka, and Kohei Sato
1.9． 運動時の末梢循環に対する重力の影響
加賀谷淳子，奥山 靜代，大森芙美子，佐藤 耕平，村岡 慈歩，森曜生

1.9.1 上肢垂下状態における掌握運動時の動静脈血流変化と酸素動態
1.9.2 足底屈運動時の血液供給と酸素動態に対する血液プーリングの影響
1.10 まとめ
1.10.1 時間経過に伴う骨格筋への血流調節
1.10.2 運動強度と血流再分配
1.10.3 活動筋血流量に効果的なトレーニング条件

1.1 研究の背景と目的

筋活動による静脈内の血液減少が，運動時の血流

during one-legged exercise

量増加に関与する要因となるとの報告はいくつかな

5． Influence of combination of contraction inten-

されている．Magder（1995）は動物で，また，

sity and frequency on attaining peak blood

Leyk et al.（1994）や Tschakovsky et al.（1995），

flow during exhaustive dynamic plantar flexion

Tschakovsky and Hughson（2000）は，ヒトにおい6． 静的掌握運動時の主観的筋疲労感覚と血圧急上昇て活動筋の位置変化や静脈閉塞等を行って静脈側に血負荷との関係液が貯留する時には動脈側からの血液の流入は制限さ

7． Blood flow and arterial vessel diameter change

れるとし，血液循環の促進に対して，静脈内血液を空during graded handgrip exercise in dominantにして動静脈の圧勾配を高くすることの重要性を指摘

and non-dominant forearms of tennis players

した．そして，Shiotani et al.（2002）は，筋活動に

8． 運動時の末梢循環に対する重力の影響

伴う静脈圧の低下は座位での下肢血流量を少なくとも8.1 上肢垂下状態における掌握運動時の動静脈血3 倍に増加させるとしている．しかし，筋ポンプ作用

流変化と酸素動態は動脈側の血管拡張作用には貢献しないとする報告も

8.2 足底屈運動時の血液供給と酸素動態に対する見られる（Hamann et al. 2003; Valic et al. 2005）．

血液プーリングの影響

Hamann et al.（2003）は，アデノシン注入により最● 文

大血管拡張を生じさせて筋活動を行っても血流はさら献Hamann JJ, Valic J, Buckwalter JB : Muscle pumpdoes not enhance blood flow in exercising skeletal. muscle. J Appl Physiol, 94: 6-10, 2003.
Kagaya A, Shimizu S, Ohmori F, Kumagai M, Muraoka
Y, Yoshizawa M : Blood flow balance between
arterial inflow to and venous outflow from theexercising muscles. The 55th Annual Meeting ofJapan Society of Physical Education, Health andSports Sciences. Nagano, 2004 (in Japanese).
Leyk D, EBfeld D, Hoffmann U, Wunderlich HG,
Baum K, Stegemann J : Postural effect on cardiac
output, oxygen uptake and lactate during cycle
exercise of varying intensity. Eur J Appl Physiol,
68: 30-35, 1994.
Magder S : Venous mechanics of contracting gastrocnemius muscle and the muscle pump theory. J
Appl Physiol, 79: 1930-1935, 1995.
Shiotani I, Sato H, Sato H, Yokoyama H, Ohnishi Y,
Hishida E, Kinjo K, Nakatani D, Kuzuya T, Hori M: Muscle pump-dependent self-perfusion mechanism in legs in normal subjects and patients withheart failure. J Appl Physiol, 92: 1647-1654,
2002.
Tschakovsky ME, Shoemaker JK, Hughson RL : Beatby-beat forearm blood flow with Doppler ultrasound and strain-gauge plethysmography. J Appl
Physiol, 79: 713-719, 1995.
Tschakovsky ME, Hughson RL : Venous emptying
mediates a transient vasodilation in the humanforearm. Am J Physiol Heart Circ Physiol, 279:
H1007-H1014, 2000.

に増加しなかったことを根拠にあげている．しかし，ヒトを対象としたこれまでの研究では，静脈血流量を直接測定して検討しておらず，動脈血流量や筋内の血液量の変化（Kagaya et al. 1999; 市之瀬ら 1999）から推定されていることが多かった．
本研究では，筋が張力を発揮する筋活動や筋が主として形状を変える運動を取り上げて，運動時の動静脈
血流バランスを中心に，骨格筋血流調節を運動特性との関係で明らかにすることを目的としている．そして，動静脈血流バランス，活動筋への最高血流量や骨格筋血流に対するトレーニング効果を運動条件と関連させて明らかにしようとした．
本課題に関連して行った研究は以下の通りである．
1． Venous and arterial blood flow velocity during
static handgrip exercise at varying intensities
with the forearm below heart level.
2． 前腕の律動的運動中の動静脈血流バランス
3． 受動的ストレッチングが循環・筋酸素動態に与える影響
4． Transient increase in femoral arterial bloodflow to the contralateral non-exercising limb
23

1.2 Venous and arterial blood flow velocity during static
handgrip exercise at varying intensities with the forearm below heart level
Atsuko Kagaya, Shizuyo Shimizu-Okuyama, Fumiko Ohmori,
Yoshiho Muraoka, and Mutsuko Yoshizawa

Abstract
The purpose of this study was to clarify the effect of contraction intensity on venous blood flow during short-term static muscle contraction and to test the hypothesis that the increase in venous flow
accelerates arterial inflow in human subjects. Eight females performed 5-s handgrip contraction at
10%, 30%, 50% and 70% maximal voluntary contraction (MVC), with the forearm below heart level.
Brachial venous blood flow velocity (Doppler ultrasound method) was accelerated at the onset of
handgrip, and thereafter decreased to baseline during static phase of exercise. Further decrease invenous flow velocity was observed after cessation of handgrip contraction. The initial acceleration ofvenous flow was intensity-dependent (P<0.01). In contrast, the brachial arterial blood flow velocity wassignificantly reduced during exercise compared to baseline values, followed by intensity-dependentenhancement of post-exercise blood flow. Oxy-Hb concentration in forearm flexor muscles (NIR) was
greatly decreased at higher intensities of 50% and 70% MVC. A significant relationship (P<0.01) was
obtained between brachial venous velocity at the onset of exercise and post-exercise arterial velocity.
In conclusion, muscle pump is effective at the onset of muscle contraction to induce intensity-dependent acceleration of venous outflow in humans and contributes to increase in arterial blood flow immediately after contraction of short duration intensity, whereas other circulatory parameters increased
linearly.

tary contraction (MVC). Five trials were per-● Purpose

The purpose of this study was to clarify theformed for identical intensity, with the order ofeffect of contraction intensity on venous bloodthe intensity at random. All the experiments were

flow during short term static muscle contraction

conducted in a room where the temperature andwith the forearm below heart level and to test therelative humidity were regulated at 26 ℃ andhypothesis that an increase in venous flow accel-

60%, respectively.
Blood flow velocity was measured using

erates arterial inflow in human subjects.

Doppler ultrasound method (HP 8500, USA) in
brachial artery and brachial vein at approximately● Methods

Eight females participated in this study as sub-

3 cm proximal from the level of elbow joint, andjects (25.5 ± 2.2 years old), after providing theirat a place where the clear vessel image waswritten informed consents. Five-second static

obtained. The pulsed wave transducer with anhandgrip exercise was performed by dominantoperating frequency of 7.5 MHz and sound beamhands in upright sitting position with the forearm

angle relative to the flow direction was 60 °.

below heart level. Four exercise intensities were

Blood pressure was measured (Finapres, Ohmeda,

used; 10%, 30%, 50% and 70% of maximal volun-USA), muscle oxygenation was measured using24

near-infrared spectroscopy (NIRS) (Niro 300,
Hamamatsu Photo, Japan) on the flexor andextensor muscles of the right forearm. The distance between two optodes was 3cm.
Two-way ANOVA (intensity × phase) was usedfollowed by Turkey’s post hoc comparison whensignificant difference was obtained. A p value ofless than 0.05 was considered statistically significant.

● Results and Discussion

During baseline, venous blood flow velocity wasFig. III.1.2-1 Comparison of venous flow velocity
among exercise phases and exercise intensities. **; P <significantly (P < 0.01) slower below heart level
than that at heart level, whereas arterial blood flow

0.01 among exercise phases, $$; P< 0.01 among exercise intensities at the onset, #: P < 0.05 vs 10% MVC.

velocity tended to be higher but not significant.
During handgrip contraction, the arterial flow
velocity was significantly lower (P < 0.01) com-

became significantly lower with exercise intensity.

pared to baseline value. However, no significant

The results obtained in this study suggested thatdifference was obtained among blood flow veloci-the blood was expelled when the muscle tension

ties of 4 different intensities. In contrast, post-

was developing, concomitant with the deforma-

exercise arterial blood flow increased significantly

tion of muscle fibers (shortening) and showed that

(P < 0.01) with increasing exercise intensities. It

the increasing contraction force made the outflow

increased from 37.7 (± 2.8) cm/s at 10%MVC tovelocity higher on venous side and impede the57.9 (± 2.9) cm/s at 50%MVC, and 59.5 (± 3.9)

blood flow inflow on arterial side. When muscle

cm/s at 70%MVC.

was relaxing, arterial blood flow velocity

Venous blood flow velocity increased markedly

increased dramatically provably due to increased

just before or upon initiation of tension develop-

arterial-venous pressure gradient (Shiotani et al.

ment. Durations of the venous acceleration did

1996) and metabolic vasodilation (Tschakovsky et

not differ among 4 intensities, which indicatedal. 1996). Thus muscle pump contributes to thethat venous blood flow was accelerated only dur-increase in venous outflow at the onset of muscle

ing concentric phase of the muscle action, despite

contraction to empty blood vessel within the mus-of contraction force. However, the magnitude ofcle and enhances arterial inflow during relxation

acceleration increased with increasing exercise

phase of the exercise．

intensity (Fig. III.1.2-1) and was negatively corre● References

lated with average arterial blood flow velocity

Shiotani I, Sato H, Sato H, Yokoyama H, Ohnishi Y,
Hishida E, Kinjo K, Nakatani D, Kuzuya T, Hori M: Muscle pump-dependent self-perfusion mechanism in legs in normal subjects and patients withheart failure. J Appl Physiol, 92: 1647-1654,
1996.
Tschakovsky ME, Shoemaker JK, Hughson RL :Vasodilation and muscle pump contribution to
immediate exercise hyperemia. Am J Physiol
Heart Circ Physiol, 271: H1697-H1701, 1996.

during handgrip exercise (r= − 0.478, P < 0.01),
whereas positively correlated with that immediately after exercise (r=0.589, P < 0.01).
Systolic, diastolic and mean blood pressure(SBP, DBP, MBP) were significantly elevated at
the end of exercise at 50% and 70% MVC. The
oxy-Hb and total Hb at the end of handgrip

25

1.3

前腕の律動的運動中の動静脈血流バランス

加賀谷淳子，奥山（清水）靜代，大森芙美子，熊谷

真奈，吉澤

睦子

An increase in venous outflow from exercising limb enhances arterial
inflow during rhythmic exercise
Abstract
The aim of this study was to test the hypothesis that an increase in venous outflow due to muscle
contraction enhances arterial inflow during exercise. Seven female subjects (aged 25.5 ± 2.4yrs) performed 60-s rhythmic handgrip in a sitting position with the forearm below heart level, following 2minute rest with the forearm at heart level and 2-minute below heart level. The exercise consisted of
2-second handgrip (C) at 50%MVC, performed at 2-second interval (R). Arterial and venous blood flow
velocities and minute flow volume were measured by Doppler and M-mode ultrasound method(HP8500). Muscle oxygenation was measured using near-infrared spectroscopy in radial and ulnar flexor muscles. Blood pressure was recorded on a finger by Finapres. Upon initiation of handgrip, thevenous blood velocity was immediately and significantly accelerated from 6.48 ± 0.71 at baseline to
18.98 ± 3.21 cm・sec-1, with no further increase through the entire period of exercise. Blood volume,
during the first 16-20 seconds, decreased significantly in radial muscles. Thereafter, it gradually
increased analogous to vascular conductance. When exercise was continued further, arterial inflow,
venous outflow, and blood volume during C- and R-phases significantly increased. Significant relationships were observed between venous outflow during C- or R-phases and arterial inflow during successive R- and C-phases during the later period of exercise but not at the beginning of exercise. In conclusion, the augmented venous outflow due to muscle pump will increase arterial inflow when exerciseinduced vasodilatation increases muscle blood volume. Key words: muscle pump, muscle blood volume, exercise duration● 目と筋酸素動態（近赤外線分光法； NIRO300）の測定的を行った．筋酸素動態は，前腕屈筋群の撓側と尺側筋活動による静脈内の血液量減少が，運動時の動の 2 カ所とした．

脈血流量増加の要因となるか否かについて，いくつか報告がなされているが，結果は一貫していない．

● 結果および考察

本研究は，これまでヒトの運動時に実測されることの少なかった筋からの静脈血流量を実測し，静脈血

上腕動静脈血流速度は，筋活動期には静脈側が加流量の増加が，動脈血流増加を促進するか否かを明速し，活動休止期には動脈側が加速し，筋活動期とらかにすることを目的とした．

休止期の血流速度の間には，動静脈とも，また，活動回数にかかわらず，有意差がみられた．

● 方

運動の時間経過に伴う活動期の静脈血流速度（Fig.

法

成人女性 7 名を被験者として，律動的掌握運動（活III.1.3-1）には有意な変化が見られず，筋活動による動 2 秒，活動中止 2 秒）を 1 分間行わせた．姿勢は，血流は一定の高値を維持した．それに対して，筋活座位とし，活動体肢の前腕を心臓レベルより下位に

動間の静脈血流速度には，時間経過に伴う有意な変位置させた．実験中，上腕静脈と上腕動脈の血流速化（P ＜ 0.05）が見られた．最初の１回の筋活動に度を超音波 Doppler 法（HP8500）で，血流量を超音より静脈血流速度は安静時より有意に低下した後，

波 M モード法で測定した．さらに，血圧（Finapres）

徐々に増加し，24 秒で１回めより有意に高くなった．

26

Fig. III.1.3-1 Venous blood flow velocity changes during rhythmic hand grip.

上腕動脈と静脈の血流速度を比較すると，運動開るので，動脈側からの血流量が増えないと，筋ポン始と共に静脈血流速度は一気に加速され，中止期のプ作用は有効にならないために，この時期にはむし

動脈血流速度は徐々に加速されるが，活動中の動脈

ろ，動脈血の流入量が静脈血流量を規定すると考えと活動中止期の静脈血流速度は一旦低下した後，安られる．それに対して，筋活動の持続に伴って血管静時以上に増加するのに 12 〜 24 秒を要しているこ

拡張が起こり，筋血液量が増加するようになると筋とがわかった．また，時間経過に伴う血流速度の変ポンプ作用による静脈血流量の増加が動脈血流入を化は動静脈とも，活動期よりも，活動中止期に顕著促進すると考えられる．
これまで，筋ポンプ作用は動脈側の血管拡張作用であることが示された．
近赤外線分光法で得た筋血液量は開始初期に低下に貢献するか否かの観点で議論がすすめられてきたした後に増加した（掌握運動 2 回まで）．運動時全体

が（Hamann et al. 2003; Valic et al. 2005），本研究における動脈と静脈の血流量の間には有意な相関関の結果は，少なくとも血管拡張が起こって，筋血管係が得られたが，開始初期約 20 秒までと，それ以後床が拡大する時期には，筋からの静脈血流出増加が，では循環応答が異なるので両時期に分けて両者の関動脈血流入を促進することが明らかになった．

係を調べた．
● 文

その結果，運動開始時には運動中止期の動脈血流

献Hamann JJ, Valic J, Buckwalter JB : Muscle pumpdoes not enhance blood flow in exercising skeletal
muscle. J Appl Physiol, 94: 6-10, 2003.
Valic Z, Buckwalter JB, Clifford PS : Muscle bloodflow response to contraction: influence of venous
pressure. J Appl Physiol, 98: 72-76, 2005.

量と次の活動期の静脈血流量の間，運動後半には，筋活動による静脈血流量の増加とそれに続く筋活動
中止期の動脈血流量の間に有意な相関関係が得られた．したがって，運動開始による筋内血流の静脈への流出は，筋内血液量を減少させ（筋血液量の減少）

27

1.4

受動的ストレッチングが循環・筋酸素動態に与える影響

加賀谷淳子，村岡 慈歩，奥山（清水）靜代，大森芙美子，森鈴木早紀子，水村真由美，小田 俊明

曜生，

Effects of passive streching on circulation and muscle oxygenationの血流変化

筋が張力を発揮しないで，筋線維が伸長・短縮するというように筋の形状を変えた場合，それに付随

1.4.2 受動的下腿ストレッチングによる膝窩動脈血

して筋内血管床の位置変化や血管の伸長・短縮を起流速度の変化−血流の順行成分と逆行成分かこす．本プロジェクトでは，下腿筋のストレッチン

らの検討−
1.4.3 受動的ストレッチング中の拮抗筋および協働

グをモデルとして，以下の課題について知見を得た．

筋における筋血液量と筋形状の関係

ストレッチングを取り上げた理由は，1）筋循環に影

1.4.4 受動的ストレッチング時における下腿協働筋

響する因子の一つである筋の形状変化から循環変化

間への血流分配の相違を明らかにすることと，2）ストレッチングは運動現

1.4.5 最大位までの多段階ストレッチングが筋の循場で実際によく行われている運動であり，その循環環に与える影響

への影響を明らかにするためであった．

1.4.6 ストレッチングが筋血管容量に及ぼす影響
1.4.1 受動的ストレッチングによる末梢動脈と静脈

1.4.1

受動的ストレッチングによる末梢動脈と静脈の血流変化

加賀谷淳子，奥山（清水）靜代，大森芙美子，村岡
森曜生，鈴木早紀子

慈歩，水村真由美，Regional blood flow changes in artery and vein during passive streching
Abstract
The purpose of this study was to test the hypothesis that stretching stimulates muscle circulation andalso causes mechano-receptor mediated vasoconstriction. Blood flow in popliteal artery and vein were
measured (ultrasound method) during passive stretching of the calf muscles with the angle of ankle
joint kept at the maximally stretched position without pain. When calf muscle was stretched, bloodflow velocity in the popliteal artery tended to decrease, whereas it deceased in brachial artery. Whenstretched muscle was restored to baseline position, the popliteal arterial velocity significantly
increased, followed by an increase in venous blood velocity in 10-15 s. The results suggested that themuscle fiber stretching reduced blood flow to the muscles due to mechano-receptor mediated vasoconstriction and mechanically narrowing vessel diameter. However, immediately after stretching, theblood flow in the artery was accelerated and it pushed out blood in the venous side, resulting inincrease in venous blood flow velocity.
28

● 目

脈血流速度（超音波 Doppler 法，Vivid7pro,

的HP8500）であった．

ストレッチングによる筋線維の伸長（Kagaya andMuroka 2005; 横澤ら 2002）は，血管径の短縮や筋● 結果および考察

機械受容器反射を起こし，動静脈血流を修飾すると考えられる（Fisher et al. 2005; Poole et al. 1997;

ST 中の膝窩動脈血流速度は減少傾向を，静脈血流Supinski et al. 1986）．しかし，ストレッチングによ速度は開始初期に増加傾向を示したがいずれも統計る当該筋への動脈血流量や当該筋からの静脈血流量的に有意ではなかった（Fig. III.1.4.1-1）．ST 終了の変化は明らかにされていない．本研究は受動的下

10 秒から動脈血流速度は有意に増加し，それに遅れ腿ストレッチング（ST）によって，膝窩動脈血流速て回復 10 〜 15 秒で静脈血流速度の有意な増加がみ

度が減少し，膝窩静脈からの血液流出が促進されるられた．上腕動脈では，開始直後に有意な速度減少

か否か，ストレッチング中止後に血流加速が起こるが起こり，上腕静脈血流速度も低下傾向を示したか否かを明らかにすることを目的とした．さらに，（Fig. III.1.4.1-2)．しかし，ストレッチング中，血圧

筋機械受容器反射による血管収縮作用を上腕血管にには有意な変化は見られなかった．
ST 中，当該筋より近位で測定された動脈血流速度

おける動静脈血流速度変化から検討することとした．

は，ストレッチング中低下傾向を示し，ストレッチ● 方

ング終了により有意な増加を示した．静脈血流速度法

被験者は健康な成人女性 10 名（年齢 21.6 ± 0.8 歳）の変化が遅れて起こることは，動脈血依存の変化でとし，仰臥位で，膝関節角度を 180 °に伸展した状態あると考えられる．このような変化が見られた第 1 ので，痛みを伴わない最大角度まで足関節を背屈させ要因は，ストレッチングによる筋形状変化に伴う血てストレッチングを行わせた．実験では，4 分間の安管径の短縮と終了による拡大と考えられる．第２の静状態を保った後，15 秒で他動的に規定角度（痛み

要因は，上腕血管でストレッチング開始初期に血流を伴わない最大角度）まで背屈して，1 分間保持し，速度減少が観察されたことから，開始初期には機械

その後，15 秒間で安静角度に復帰させた．回復期の受容器反射も作用していたと考えられる（Welsh

測定は 2 分とした．循環系，特に静脈血流への呼吸運

and Segal 1996)．それにもかかわらず，ストレッチ

動の影響をコントロールするため，安静 2 分め経過後ング中の当該筋で，有意な血流速度低下が見られなから，回復期まで，吸息 1 秒・呼息 4 秒の呼吸を行わかったのは，ストレッチングに関与する下腿の各筋せた．測定項目は，膝窩動静脈血流速度と上腕動静群の循環応答が一様ではなかったことによると考え

Fig. III.1.4.1-1 Arterial and venous blood flow velocity in popleteal vessels. ○: artery, ■: vein.

29

Fig. III.1.4.1-2 Blood flow velocity in brachial artery (upper) and vein (lower). **;P<0.01 vs baseline

Health Sci, 3: 171-180, 2005.
Poole DC, Musch TI, Kindig, CA : In vivo microvascular structural and functional consequences ofmuscle length changes. Am J Physiol Heart Circ
Physiol, 272: H2107-H2114, 1997.
Supinski GS, Bark H, Guanciale A, Kelsen SG : Effectof alterarions in muscle fiber length on diaphram
blood flow. J Appl Physiol, 60: 1789-1796, 1986.
Welsh DG, Segal S : Muscle length directs sympathetic
nerve activity and vasomotor tone in resistancevessels of hamster rectactor. Circ Res, 79: 551559, 1996.
横澤仁美, 村岡慈歩, 清水靜代, 加賀谷淳子 : 静的ストレッチング中の筋束長の変化と筋酸素動態. 脈管学, 42
Suppl: 25-28, 2002.

られ，この点に関しては，血液量の変化から確認している．結論として，ストレッチングにより当該筋への血流，当該筋からの血流は動静脈とも修飾されるが，それは血管形状の物理的変化と筋機械受容器
反射によると考えられる．

● 文

献Fisher JP, Bell MPD, White MJ : Cardiovascularresponses to human calf muscle stretch during
varying levels of muscle metaboreflex activation.
Exp Physiol, 90: 773-7781, 2005.
Kagaya A, Muraoka Y : Muscle architecture and its
relationship to muscle circulation. Int J Sport30

1.4.2受動的下腿ストレッチングによる膝窩動脈血流速度の変化−血流の順行成分と逆行成分からの検討−

大森芙美子，村岡慈歩，奥山（清水）靜代，森
水村真由美，加賀谷淳子

曜生，鈴木早紀子，

Blood flow velocity changes in popliteal artery due to passive strechingof calf muscle
Abstract
The flow pattern of antegrade and retrograde (Doppler ultrasound method) was studied in popliteal
artery during calf muscle passive stretching in 10 female subjects. During stretching at anatomical
position of the ankle joint, no significant changes were observed in mean blood flow velocity, antegrade and retrograde velocity. At maximal confortably streched position (CP), the retrograde diastolic
flow was significantly accelerated, whereas the antegrade systolic flow and mean blood velocity did
not change. Vascular resistance index increased during diastole at CP position (P < 0.05). The results
suggest that the reduced diameter of the vessels in the stretched muscles increased vascular resistanceduring diastole and increased the retrograde diastolic flow.

● 目

的

● 方

法

動脈血流には中枢から末梢へ流れる順行（ante-

成人女性 10 名を被験者とし，仰臥位での受動的ス

grade）成分とその逆に末梢から中枢に戻る逆行

トレッチングを行わせた．ストレッチング角度には，（retrograde）成分がある（Green et al. 2005）．これ

足関節角度 120 °から解剖学的正位（AP）まで 30 °までの報告では，antegrade と retrograde 速度は，

背屈させる AP と足関節角度 120 °から快適最大角度

血管壁への刺激や血管拡張物質の放出などによって（痛みを感じる角度から 3 °減じた）まで背屈させる

影響を受けること，また retrograde 速度は，pulse-

CP の 2 種類を用いた．安静 4 分の後，15 秒で各角度

wave 反射または筋収縮における血管圧迫などの抵抗

まで背屈させ，1 分間角度保持し，その後，15 秒でのどちらかに起因し（Hoelting et al. 2001)，血管抵

底屈し，ベースラインに復帰させた．測定項目は，抗の増加に反して動脈流入が増加したときに加速す

膝窩動脈血流速度と血圧であった．膝窩動脈速度は，ることが報告されている．一方，筋線維の伸長は筋

平均血流速度，antegrade 速度および retrograde 速内血管の地理的位置を変化させ，筋のサルコメアの度を計測した．

伸長は血管径を縮小させる（Poole et al. 1997）こと● 結果および考察が知られている．したがって，ストレッチングのように筋線維長が伸長すると，当該筋内の血管が引き伸長度の異なる 2 種の角度のストレッチングにおけ伸ばされ，循環に影響を与えると考えられる．すなる動脈血流速度（Fig. III.1.4.2-1）の中で，平均血流

わち，血管径の短縮は血管抵抗を増加させ，当該筋速度は一定角度保持中，CP で低い値を示したが，有へ流入する血流の速度成分を変えると考えられる．

意な変化ではなかった．また，antegrade 速度も一定

そこで本研究は，ストレッチングを行わせて，筋束

角度保持中に有意な変化はみられなかった，しかし，長の伸長に伴い当該筋へ血液を供給している血管のretrograde 速度は，CP 角度において，安静時より有速度成分に retrograde 成分が増えるか否かを明らか

意に速くなった．また，平均血流速度と antegradeにすることを目的とした．

速度では，角度間の血流速度に差が見られないが，
31

Fig. III.1.4.2-1 Antegrade systolic (upper panel) and retrograde diastolic (lower panel) blood flow during passive
stretching. Passive stretching ｓ at two positions were performed.
○; anatomical position, ●; maximal comfortable position.

retrograde 速度では，AP 角度より，CP 角度で有意● 文献Green DJ, Bilsborough W, Naylor LH, Reed C, Wright
J, O’Driscoll G, Walsh JH : Comparison of forearm blood flow responses to incremental handgrip
and cycle ergometer exercise: relative contribution of nitric oxide. J Physiol, 562: 617-628, 2005.
Hoelting BD, Scheuermann BW, Barstow TJ : Effect ofcontraction frequency on leg blood flow during
knee extension exercise in humans. J Appl
Physiol, 91: 671-679, 2001.
Poole DC, Musch TI, Kindig CA : In vivo microvascular structural and functional consequences ofmuscle length changes. Am J Physiol, 272:
H2107-H2114, 1997.

に高かった（P ＜ 0.05）．一定角度保持中の血圧には有意な変化がなく，血管抵抗指数も心臓の収縮期には有意な変化が見られなかった。しかし，拡張期には増大し，それは CP 角度で有意に高かった（P ＜0.05）．したがって，筋束長の伸長度が高い CP 角度
では，ストレッチによって当該筋内の血管の伸長と血管径の短縮が顕著になり，血管抵抗が増加したことにより，血流の逆行成分が多くなったと考えられ
る．

32

1.4.3村岡

受動的ストレッチング中の拮抗筋および協働筋における筋血液量と筋形状の関係

慈歩，鈴木早紀子，森曜生，大森芙美子，奥山（清水）靜代，
水村真由美，加賀谷淳子

Relationship between blood volume and muscle structure in calf synergist and antagonist muscles during passive streching
Abstract
Changes in muscle structure in calf synergist and antagonist muscles were studied during passive
stretching in 10 female subjects. Fascicle lengths of gastrocnemius medialis (MG) and soleus (SOL)muscles were lengthened, whereas shortened in tibialis anterior (TA) muscles. Percent increase in fascicle length was greater in MG than in SOL. These changes in fascicle length were closely related tomuscle blood volume (total Hb) changes estimated by near-infrared spectroscopy, irrespective of synergist or antagonist muscles● 目

ST 中の筋血液量は，MG では減少し，SOL と TA では

的ストレッチング（ST）中には筋線維と筋内血管の位増加した．MG と TA において，筋束長の伸長に伴い筋置関係が変化し，それにより筋内循環の変化が生じる

血液量が減少する傾向が見られ，SOL においては，こことが報告されている．また，関節角度変化による筋れらと相反する傾向が見られた．

線維長変化は筋によって異なるため，ST による筋線維

足関節底屈筋群について，一定関節角度の ST を行っ

長変化がもたらす筋内循環への影響は，協働筋間におた結果，MG と SOL は協働筋であるにもかかわらず異いても異なると考えられる．また ST の当該筋に拮抗す

なる筋血液動態を示した．SOL の筋血液量が ST 中に減る筋は受動的に短縮されるが，それによる筋内循環へ少した理由については，MG と SOL の筋内血管の配置の影響については明らかにされていない．そこで本研に差異が見られる可能性が考えられる．また，膝関節

究は，受動的 ST 中の筋形状と筋血液量変化との関係を屈曲位で足関節背屈を行うとより SOL を ST すること

協働筋（腓腹筋内側頭： MG，ヒラメ筋： SOL）と拮抗ができるが，本プロトコルでは膝関節完全伸展位で行筋（前脛骨筋： TA）で明らかにすることを目的とした．

ったため，MG に比較して SOL の ST は十分ではなかった可能性もある．一方，拮抗筋である TA は，足背屈● 方方向の ST 中は MG と逆に筋束が短縮し，筋血液量が増法

10 名の成人女性に仰臥位・膝関節完全伸展位にて足加した．つまり，筋束長の変化と筋血液量変化の関係

背屈による ST を行わせた．足関節角度 120 °で 4 分間

については，MG と TA は同様の傾向を示した．従って，の安静時測定を行い，引き続き 15 秒で関節角度を 2 種

受動的 ST 中は，拮抗筋においても，筋束長と筋血液量類の一定値（解剖学的正位，快適最大角度；痛みを感の関係は類似し，筋束長の短縮・伸長により血流量はじる最初の角度から 3 °底屈した角度）まで変化させ，増加・減少することが明らかになった．

60 秒間保持した後，15 秒で 120 °に戻した．安静時から連続的に各筋の血液量（総 Hb 濃度；近赤外線分光法）を計測した．同様のプロトコルを用いて，筋形状（筋束長と羽状角；超音波 B モード法）を計測した．
● 結果および考察

ST 中の SOL と MG の筋束長は伸長し，TA は短縮しFig. III.1.4.3-1 Fascicle length (left) and angle (right) ofMG (○), SOL (■), and TA (△) during passive stretching.
AP; anatomical position, CP; Maximal comfortable
stretching without pain. *P < 0.001 vs rest.

た（Fig. III.1.4.3-1）．筋束変化率は MG が有意に大きく（73 ％），続いて SOL（30 ％），TA（19 ％）の順であった．MG と SOL の羽状角減少率は同程度であった．

33

1.4.4 受動的ストレッチング時における下腿協働筋間への血流分配の相違
森

曜生，村岡

慈歩，奥山（清水）靜代，大森芙美子，鈴木早紀子，
水村真由美，加賀谷淳子

Heterogeneity of blood flow re-distribution during passive streching incalf muscles
Abstract
Purpose of this study was to clarify the heterogeneity of blood flow re-distribution during passive
stretching in calf muscles. Ten female subjects were studied for muscle oxygenation in gastrocnemius
medialis (MG) and solues (SOL) muscles using near-infrared spectroscopy. Angle of ankle joint was
passively changed from resting position (120 °) to anatomical position (AP; 90 °) or maximal comfortable position without pain (CP). In MG, blood volume, oxygenated Hb and deoxygenated Hbdecreased during stretching. In contrast, they increased in SOL muscles. The possible reasons to
explain this different response include the difference in the ratio of fascicle lengthening and anatomical heterogeneity in vessel distribution among muscle fibers.

● 目

依存して起こったと考えられる．1.4.1 で報告されたよ

的ストレッチング（ST）中に筋血管床血流量は減少す

うに膝窩動脈血流速度は ST 中に変化しなかったが，そるとされている．その要因には主に筋線維と平行に走れは SOL のように血液量が増加した筋もあったためと行する血管が伸長し，血管径が縮小することが考えら考えられる．MG と SOL で血液量の変化が異なった要れるが，筋線維の走行と血管網との関係がストレッチ

因の 1 つに筋束長の伸長率があげられる（1.4.3）．

ングに関与する協働筋群において同じかどうかは明ら

SOL の伸長率が MG よりも低かったことは，当該筋のかでない．それらの関係が異なるとすると，ストレッ

血管の伸長・血管径の縮小・血管抵抗変化が MG より

チングによる筋血液量の変化も異なると考えられる．

も SOL で相対的に小さかった可能性を示唆しており，

本研究は，ST による血液量の変化が下腿協働筋群間でその結果 SOL への血液流入量が増加したとも考えられ異なるかどうかを明らかにすることを目的とした．

る．また，筋線維と血管の走行方向との関係のような構造的な違いも，もう一つの可能性としてあげられる．

● 方

結論として，ST 中の下腿協働筋群間では筋血液量の応法

被験者およびストレッチングの方法は 1.4.1 と同様答に相違があり，減少するだけでなく増加する筋も見である．安静 2 分後からは血液循環への影響をコントられたことは下腿上位動脈の血流速度を必ずしも減少

ロールするため，吸息 1 秒・呼息 4 秒の呼吸を ST 終

させない要因になると考えられる．

了まで行わせた．ST には解剖学的正位（AP）と快適最大角度（CP）の 2 種類を用い，腓腹筋内側頭（MG）とヒラメ筋（SOL）の筋束長（超音波 B モード法），
酸素化（OxyHb）・脱酸素化（DeoxyHb）・総ヘモグ
ロビン（TotalHb）濃度（近赤外分光法），電気的筋活動（表面筋電図法）を測定した．
● 結果および考察

筋の平均活動電位は ST 中に有意な変化をしなかった．TotalHb は，MG では CP で減少し，SOL では両角度で増加した（Fig. III.1.4.4-1）．OxyHb ・ DeoxyHbの増減は TotalHb の増減と一致した．筋束長の伸長率
は AP よりも CP で，また両角度において SOL よりもFig. III.1.4.4-1 Blood volume (total Hb) changes ingastrocnemius medialis (MG) and soleus (SOL) muscles
during passive stretching.

MG で高かった．ST 中に筋の電気的な活動は変化しな
かったので，OxyHb と DeoxyHb の変化は TotalHb に34

1.4.5

最大位までの多段階ストレッチングが筋の循環に与える影響

大森芙美子，奥山（清水）靜代，村岡 慈歩，森水村真由美，加賀谷淳子

曜生，鈴木早紀子，

Effect of maximal passive streching on muscle circulation

Abstract
Muscle blood volume and popliteal artery blood flow were determined during progressively increasing stretching calf muscles to find the extent of stretching to induce changes in muscle oxygenationand circulation in ten female subjects. Muscle blood volume (total Hb measured by NIRS) began toincrease at 40% maximal stretched position in soleus muscles and to decrease at 80% max in medial
gastrocnemius muscle. The latter corresponded to the ankle position of maximal comfortable stretching. However, no significant changes were obtained in popliteal arterial blood flow. These results suggest that submaximal muscle stretching larger than 40% could stimulate circulation within the muscles.

● 目的● 結果および考察

ストレッチング（ST）によって筋内血液量は減少

THb は，MG において 80 ％ max（52 °底屈）からする（横澤ら 2002）が，一定角度を保持した場合に角度増加と共に減少した（p ＜ 0.05）（Fig. III.1.4.5-は上位血管の血流量低下はみられない（1.4.1）．そこ

1）．この角度は，痛みを伴わない最大角度（71.1 ±で，本研究では段階的に最大位まで伸長させる ST に

1.5）に近似していた．しかし，SOL では 40 ％ max

おいて，1）下腿の血液量変化を生ずるストレッチン（26 °底屈）から角度増加ともに増加し（p ＜ 0.05），

グ角度，2）上位血管の血流動態と下位筋群での血液協働筋であっても筋群間で応答は異なることが明ら

量との関係を明らかにすることを目的とした．

かになった．上位血管である膝窩動脈血流速度は，角度増加と共に減少傾向を示したが最大位まで有意● 方法

な変化はみられなかった．以上のことから，1）下腿健康な成人女性 10 名に仰臥位で最大角度（max）

協働筋群間では 40 ％ max 以降で筋血液量応答に相違の 10，30，40，60，80，100 ％のストレッチングがみられる，2）下腿協働筋群間で血液量が増加するを漸増的に行わせ，各角度 30 秒間維持させた．測定筋と減少する筋があることから，上位血管である膝項目は，腓腹筋内側頭（MG）とヒラメ筋（SOL）の窩動脈血流速度では有意な変化がみられないことが酸素化（O2Hb）・脱酸素化（HHb）・総ヘモグロビン

明らかとなった．

（THb）濃度（近赤外分光法）と膝窩動脈血流速度（超音波法）とした．

Fig. III.1.4.5-1 Blood volume changes (Total Hb, NIRS) during incremental passive stretching of calf muscles inmedial gastrocnemius (MG) and solues (SOL) muscles. *, **; P < 0.05, P < 0.01 vs. baseline (0).
35

1.4.6 ストレッチングが筋血管容量に及ぼす影響（preliminary report）
小田俊明，大森芙美子，森曜生，村岡 慈歩，奥山（清水）靜代，
水村真由美，加賀谷淳子

The effect of muscle streching on vessel capacity in muscle
Abstract
The effect of muscle fiber stretching on blood vessel shape was preliminary investigated using MR
fresh blood imaging sequence. The image acquisitions with ECG gating were performed during resting,stretching to maximal comfort level without pain, and recovering phases. By modifying inversion timeof imaging, each image of artery and vein was separately measured. The index of vein volume wasdecreased up to 0.75 by stretching. Then, the decreased index was gradually returned to the baseline
after stretching. Additional analyses in detail are currently developing.

● 目

対側のコントロール肢も同時に撮像した．心電図同的ストレッチングによる筋線維の形状的変化が筋内期を用い，下腿横断面画像を echo time 80 ms, rep-

循環に与える影響に関して，これまでいくつかの知

etition time 2220 ms, スライス厚 5 mm で計測した．

見が報告されているが，筋線維の形状的変化が筋内

撮影パラメータである Inversion time を動脈撮像用の血管形状をどのように変えるかについて明確に示と静脈撮像用に調整することで，心電図 R 波からのした研究は人では見あたらない．これまでの我々の画像取得までの時間を制御し動脈と静脈の画像を分研究では，筋線維長が伸長する協働筋群間において，離して計測することとした．

筋血液量が相反する方向に変化するという結果も得● 結果および考察られているが，ストレッチングによる筋線維の形状変化の相違が各筋の血管形状を異なる方向に変えて

Fig. III.1.4.6-1 に Flesh Blood Image 法による末いるか否かは明らかではない．そこで本研究では，

梢血管の撮像写真を示す．これは，安静時と（左）MR を用いて，Flesh Blood Imaging 法（FBI 法）にとストレッチング中（中）と回復時（右）の画像変より，ストレッチング中の末梢血管像を取得し，筋化の例を示したものである．どの図においても右が血管容量の変化を明らかにすることを目的とした．

コントロール肢である．ストレッチングによって血管形状が変化し，ストレッチング終了によって安静● 方時に戻ることが観察される．右側の静脈血 index 変化法

被験者は健康な女性 5 名であった．東芝メディカルをみると，ストレッチング中に減少することが示さ

システムズ株式会社製 EXELARTE を使用し，Flesh

れた．ストレッチングによる筋線維の形状的変化がBlood Imaging 法を用いて下腿の血管画像を取得し下腿のストレッチングに関与する協働筋の各筋におた．被験者は MRI のガントリー内で仰臥位をとり，

いて血管形状をどのように変化させるはまだ明らか安静状態で撮像を行った後，最大快適ストレッチンにされていないので，今後はこの方法を用い，各筋

グ角度で足関節底屈によるストレッチングを行った．

別に検討していく必要がある．

At restDuring Stretching

RecoveryFig. III.1.4.6-1 The left figures demonstrate the examples of blood vein images over threshold, which wereacquired by flesh blood imaging sequence and were conducted by maximal intensity projection. As shown in rightgraph, the vein area was decreased up to 0.75 by stretching with maximal comfort level without pain. Then, thedecreased area was gradually returned to the baseline after stretching.

36

1.5 Transient increase in femoral arterial blood flow to thecontralateral non-exercising limb during one-legged
exercise
Mutsuko Yoshizawa, Shizuyo Shimizu-Okuyama, and Atsuko Kagaya
Abstract
We studied the effect of exercise intensity and duration on blood flow to the non-exercising leg during one-legged dynamic knee extension. Femoral arterial blood flow (FBF) to the non-exercising leg,blood pressure (BP), and heart rate (HR) were monitored during one-legged dynamic knee extension
exercise at 15, 30, and 45% maximal voluntary contraction (MVC) in seven healthy females. There wasan interaction between exercise intensity and duration for FBF and FVC (P < 0.01). During the initial
phase of contralateral leg exercise at all intensities, FBF and femoral vascular conductance (FVC) of
nonexercising leg increased, and the increase was larger at higher intensities (P < 0.01). After initial
vasodilatation, FBF and FVC decreased to baseline, which suggests the vasoconstriction. However,FBF and FVC gradually increased during exercise at 15% MVC. We conclude that transient vasodilatation at the onset of exercise is followed by gradual change to vasoconstriction in non-exercising limb
during dynamic one-legged exercise and these changes are exercise intensity- and duration-dependent.

females. The right leg maximal voluntary contrac-● Purpose

Recent findings regarding blood flow to nonwork-

tion (MVC) of knee extension was assessed by an

ing limbs are controversial. Several studies indicate“Action meter device” (VINE, Tokyo, Japan). On

that blood flow to the inactive forearm increases dur-

separate days, the subjects performed one-legged

ing leg cycling exercise (Ahlborg et al. 1975; Kagaya

dynamic knee-extension exercise of the right leg

and Homma 1997; Tanaka et al. 2006; Taylor etin the upright position with the knee joint angle

al.1989). In contrast, Green et al. (2002a, b, c) foundextended from 90 °to 120 °(180 °= full exten-

that leg cycling exercise at least at a low intensitysion). The exercise comprised contraction anddecreases blood flow in the inactive forearm.

relaxation for 1 s each, as indicated by a metro-

The purpose of this study, therefore, was tonome. The exercise intensities corresponded todetermine the effect of exercise intensity, duration

15, 30, and 45% of the MVC. Following a 10-minof leg exercise, and the interaction between theserest period, the subjects performed the knee

two variables on the blood flow in the contralateralextension exercise at a given load until exhaus-leg during dynamic knee extension exercises. The

tion. However, the activity was stopped after 15

time course of changes in the blood flow to themin if the subjects could continue to exercise. B-

femoral artery of the non-exercising contralateralmode ultrasound sonography was used to meas-

leg was studied during one-legged knee extension

ure the diameter of the artery and Doppler-mode

exercise conducted at various intensities and con-

was used to measure blood flow velocity (HPtinued to exhaustion.

8500-GP, Hewlett-Packard, USA). A 7.5 mHz linear array transducer was placed on the skin overthe femoral artery. Blood flow was obtained every● Methods

15 s for 90 s during exercise and at exhaustion.

The subjects in this study were seven healthy37

Fig. III.1.5-1 Femoral arterial blood flow to non-exercising leg during contralateral knee extension exercise at 15%,30% and 45% MVC.

thereafter decreased with time.

Heart rate (ECG) and blood pressure (BP)(Finapres model 2300, Ohmeda, USA) were meas-

These results suggested that the vasodilatory

ured on beat-by-beat basis throughout the experi-

response occurred in the non-exercising leg dur-ment.

ing the initial phase of exercise, and the magnitude of increase in blood flow was exercise-inten-● Results and discussion

sity dependent. Interestingly, it took 30-45 s to

At 15 s, FBF increased at all the intensities, andinduce vasoconstriction in non-exercising regions.

the changes in blood flow reached a maximum at

The mechanism to induce this biphasic response

45% MVC. FBF remained elevated until 45 s (30%of blood flow should be studied further.

MVC) and 60 s (45% MVC), and thereafter it● References

decreased toward the baseline, whereas at 15%

Ahlborg G, Hagenfeldt L, Wahren J : Substrate utilization by the inactive leg during one-leg or arm exercise. J Appl Physiol, 39: 718-723, 1975.
Green D, Cheetham C, Mavaddat L, Watts K, Best M,
Taylor R, O’Driscoll G : Effect of lower limb exercise on forearm vascular function: contribution of
nitric oxide. Am J Physiol, 283: H899-H907,
2002a.
Green D, Cheetham C, Reed C, Dembo L, O’Driscoll G: Assessment of brachial artery blood flow acrossthe cardiac cycle: retrograde flows during cycle
ergometry. J Appl Physiol, 93: 361-368, 2002b.
Green D, Cheetham C, Henderson C, Weerasooriya R,
O’Driscoll G : Effect of cardiac pacing on forearm
vascular responses and nitric oxide function. Am J
Physiol, 283: H1354-H1360, 2002c.
Kagaya A, Homma S : Dynamic leg exercise accelerates
blood flow in the inactive forearm. Adv Exerc
Sports Physiol, 3: 29-34, 1997.
Taylor JA, Joyner MJ, Chase PB, Seals DR : Differential
control of forearm and calf vascular resistance during one-leg exercise. J Appl Physiol, 67: 17911800, 1989.
Tanaka H, Shimizu S, Ohmori F, Muraoka Y, Kumagai
M, Yoshizawa M, Kagaya A : Increases in bloodflow and shear stress to nonworking limbs during
incremental exercise. Med Sci Sports Exerc, 38: 8185, 2006.

MVC, the FBF returned to the resting level after
initial increase and increased again at the end of
exercise (Fig. III.1.5-1). Interaction was observed
between the exercise intensity and duration (P <0.01). An increase in the MBP was observed after
30 s of exercise at 15% (P < 0.01) and 30% MVC(P < 0.01), whereas it was observed after 45 s of
exercise at 45% MVC (P < 0.01) The HR increased
immediately at the onset of exercise and continued to increase throughout exercise. Femoral vascular conductance (FVC) increased at the onset ofthe exercise at all intensities (P < 0.01). Thechange in FVC was the highest at 45% MVC. At
15% MVC, the FVC increased again after having
being reduced to the resting level, and high FVC
values were observed at the end of exercise. At
30 and 45% MVC, FVC remained elevated until
30 s (30% MVC) and 60 s (45% MVC), and it38

1.6 Influence of combination of contraction intensity andfrequency on attaining peak blood flow during exhaustive dynamic plantar flexion
Fumiko Ohmori, Takafumi Hamaoka, Shizuyo Shimizu-Okuyama,
and Atsuko Kagaya
Abstract
We aimed to elucidate the effects of the contraction intensity and frequency on peak blood flow
(BFpeak) during exhaustive dynamic plantar flexion exercise (EDPFEx) and to identify the conditions
required for attaining BFpeak during EDPFEx. Seven women performed EDPFEx at intensities of 15%,30%, 50%, and 70% of the maximal voluntary contraction (MVC) with 1-s contractions. EDPFEx was performed at 4 different intervals (10%, 30%, 50%, and 70% of the time required to attain BFpeak after asingle contraction). The mean blood velocity and the vessel diameter of the popliteal artery were measured using Doppler and B-mode ultrasound. Beat-by-beat popliteal artery blood flow was calculated asfollows: the flow integral × heart rate × area of the vessel. BFpeak immediately before and after the endof EDPFEx significantly changed with altering intervals and intensities. The BFpeak was obtained neither
at the highest total work amount (30% MVC with 10% interval) nor at the highest work rate (70% MVC
with 10% interval) but at 50% MVC with 10% interval (p < 0.05) both immediately before (618 ± 83
ml/min) and after (1246 ± 108 ml/min) the end of EDPFEx. This indicated that the combination of exercise intensity and frequency used in this study exerted a greater influence on the BFpeak during and after
EDPFEx than those exerted individually by the total work amount and work rate per se.

during dynamic exercise (Ohmori et al. 2007).

● Purpose

The blood flow to an active muscle changes

Therefore, this study aimed to elucidate thedepending on the exercise intensity, interval

effects of exercise intensity and interval, as deter-

between contractions, contraction-to-relaxation

mined by the blood flow response after a single

duty cycle, etc. Blood flow markedly increases

contraction, on the peak blood flow during

during the relaxation phase of dynamic exercise,exhaustive dynamic plantar flexion exercise.

whereas it remains at a lower level during the

Further, it aimed to determine the conditions

contraction period. Corcondilas et al. (1964)

required for attaining peak blood flow during

reported that the increase in the blood flow dif-

dynamic plantar flexion exercise.

fered when the second contraction was performed● Methods

4 seconds and 10 seconds after a single contraction. An earlier study on contraction-to-relaxation

A total of 7 physically active women (age: 21.9

duty cycle indicated that the blood flow to an± 0.7 years old) participated in the study after

active muscle during dynamic exercise reflected

providing informed consent. In a supine position,

the influence of the alteration in the duration ofeach subject placed her respective right foot for

the relaxation phase, rather than the effect of

0.5 s on the pedal of the ergometer with the ankle

altering the duration of contraction phaseand knee joints at 90 °and 180 °, respectively. The(Hoelting et al. 2001). Therefore, the relaxationloads applied were adjusted to 15%, 30%, 50%,

interval between successive contractions may be

and 70% of the maximal voluntary contraction

a causal factor that determines the blood flow(MVC). The subjects continued plantar flexions
until exhaustion or for a maximum of 10 min.
39

blood flow both immediately before and after theend of exercise. The highest blood flow values
was obtained at the 50% MVC with 10% interval(p < 0.05) both immediately before (618 ± 83
ml/min) and after (1246 ± 108 ml/min) the end of
exercise. A significant major effect on the mean
blood pressure immediately after the end of exercise was observed among the 4 different frequencies and intensities.
In general, the increase in blood flow is influenced
by the work rate and the total amount of work load,
specifically after the end of exercise achieved(Gonzales et al. 2007; Osada and Rådegran 2002;
Saltin et al. 1998). However, our results indicatedthat the peak blood flow was not always obtained
during exercise at higher work load and work rate
andthat the combination of exercise intensityand frequency has a greater influence on the peakFig. III.1.6-1 Peak blood flow immediately before (A)and after (B) the end of exhaustive exercise at 4 frequencies and intensities. * P < 0.05 (significant difference among intervals).

blood flow than that of either the total work
amount or the work rate individually. The highest
blood flow in this study was obtained at the intensity of 50% MVC and repeated at such a shortinterval as 10% of the time required to attain peak

In the first experiment, we measured theblood flow.

popliteal artery blood flow after a single contraction during plantar flexion exercise to determine● References

when peak blood flow was achieved. In the sec-

Corcondilas A, Koroxenidis GT, Shepherd JT : Effect ofa brief contraction of forearm muscle on forearm
blood flow. J Appl Physiol, 19: 142-146, 1964.
Gonzales JU, Thompson BC, Thistlethwaite JR, Harper
AJ, Scheuermann BW : Forearm blood flow follows
work rate during submaximal dynamic forearm
exercise independent of sex. J Appl Physiol, 103:
1950-1957, 2007.
Hoelting BD, Scheuermann BW, Barstow T : Effect ofcontraction frequency on leg blood flow during
knee extension exercise in humans. J Appl Physiol,
91: 671-679, 2001.
Ohmori F, Shimizu S, Kagaya A : Exercise-induced
blood flow in relation to muscle relaxation period.
Dyn Med, 6: 5, 2007.
Osada T, Råegran G : Femoral artery inflow in relation
to external and total work rate at different knee
extensor contraction rates. J Appl Physiol, 92:
1325-1330, 2002.
Rådegran G, Saltin B : Muscle blood flow at onset ofdynamic exercise in humans. Am J Physiol, 274:H314-H322, 1998.
Saltin B, R å egran G, Koskoulou MD, Roach RC :Skeletal muscle blood flow in humans and its regulation during exercise. Acta Physiol Scand, 162:
421-436, 1998.

ond experiment, dynamic plantar flexion until
exhaustion was performed at 4 different intervals;
these intervals were determined based on the
results of the first experiment. They corresponded
to 10% (10%I), 30% (30%I), 50% (50%I), and 70%(70%I) of the time required to attain peak blood
flow. The blood velocity and the vessel diameterof the popliteal artery (Doppler and B-mode ultrasound method, HP8500GP, Hewlett-Packard
Company, USA) and the blood pressure (Finapres,Ohmeda, USA) were measured.
● Results and Discussion

The peak blood flow values immediately before
and after the end of exercise until exhaustion are
shown in Fig. III.1.6-1A and III.1.6-1B, respectively. Significant interaction was detected among 4
different frequencies and intensities for peak

40

1.7

静的掌握運動時の主観的筋疲労感覚と血圧急上昇負荷との関係

大森芙美子，奥山（清水）靜代， 村岡慈歩，佐藤耕平，加賀谷淳子

Muscle fatigue sensation and critical blood pressure elevation during
graded static handgrip exercise
Abstract
The purpose of this study was to clarify the changes in circulatory responses to graded handgrip
exercise and its relationship to muscle oxygenation and muscle fatigue sensation in tennis players.
Dominant hands of 10 tennis players were studied. Muscle oxygenation (NIRS), subjective muscle
fatigue sensation, blood pressure (Finapres), brachial arterial blood flow velocity (Doppler ultrasoundmethod) and vessel diameter (2-D ultrasonography) were determined during the muscle contraction
and the relaxation phases of 30-s graded handgrip exercise. During this exercise, muscle oxygenation(NIRS), subjective muscle fatigue sensation, and blood pressure and blood flow increased linearly
related to exercise load at lower intensities, and the former 3 parameters deviated from the initial linear relationship at higher intensities, whereas the blood flow continued to increase linearly. Criticalload for blood pressure was significantly higher than that for muscle fatigue sensation, and did not differ from that for muscle oxygenation deviation.

● 目

器用超音波診断装置 VIVID7 pro），前腕屈筋群の組

的

局所的運動時の血圧応答は，低い負荷では負荷増

織酸素飽和度（浜松ホトニクス：酸素モニター加に対して直線的に上昇し，ある負荷以上の高い負NIRO200）であった．また，Saito et al.（1989）に荷になると急上昇する（Kagaya et al. 2001）．そのよる主観的筋疲労感覚を各負荷終了後に報告させた．

ような変化は筋酸素動態についても確認されている

この感覚は「0 ：疲れがない」から「9 ：疲れの限界（Grassi et al. 1999）．本研究では，静的掌握運動のである」まで 10 段階になっている．

負荷増加に対して，1）主観的筋疲労感覚が急上昇す● 結果および考察

る負荷が存在するか否か，2）筋疲労感覚が急上昇するとすれば，その負荷と血圧急上昇の発現や筋酸素血圧および主観的筋疲労感覚は運動負荷の増加に動態が顕著に変化する負荷との順序性を明らかにす

対して非直線的上昇を示した．それに対して，前腕ることを目的としている．

屈筋群（RAD, ＵＬ）の酸素化指標は非直線的な低下を示した．3 種のパラメータが負荷に対して非直線的● 方に急増あるいは急減する変移点負荷を Fig. III.1.7-1

法

被験者は大学のテニス部に所属して活動しているに示した．前腕屈筋群の尺側および橈側の筋酸素動

女子テニス選手 10 名（平均年齢 20.1 ± 1.0 歳）であ

態変移点負荷は，主観的筋疲労感覚とは有意差が見った．運動は，仰臥位の静的掌握運動であり仰臥位られなかったが，血圧急上昇負荷（右： 14 ± 1kgw，でハンドエルゴメータを用いて 30 秒間の静的掌握運

左： 13 ± 1kgw)は筋疲労感覚急上昇負荷（右： 11 ±動を，負荷を漸増して疲労するまで繰り返した．第1kgw，左:9 ± 1kgw）よりも高い値（右： p ＜ 0.05，

一負荷は 2kg とし，30 秒の休息を挟んで 2kg ずつ負

左： p ＝ 0.051）を示した．血圧変移点負荷に相当す

荷を漸増した．測定項目は，仰臥安静および運動時

る筋疲労感覚は 4.0 ± 0.6 であった．これらのパラメの血圧（オメダ： Finapres），上腕動脈血流量（循環ータに対して，上腕動脈血流量は，左右共に筋活動41

Homma 1997）．需要に対して供給がどの程度満たされるかの指標として筋活動時中止後の血流に対する
筋活動時血流の割合を求めると，それは負荷強度に対して指数関数的に低下した．すなわち，負荷増加に対する血流需要が低下し，それが筋酸素飽和度の低下，筋疲労感覚の急上昇を起こし，それに続いて血圧の上昇が起こったと考えられる．以上の結果は，負荷強度の選定に血圧変移点負荷を用いる生理的意
義を示唆するものである．

● 文

献Grassi B, Quaresima V, Marconi C, Ferrari M,
Cerretelli P : Blood lactate accumulation and muscle deoxygenation during incremental exercise. J
Appl Physiol, 87: 348-55. 1999.
Kagaya A, Homma S : Brachial arterial blood flow
during static handgrip exercise of short duration
at varying intensities studied by a Doppler ultrasound method. Acta Physiol Scand, 160: 257-265,
1997.
Kagaya A, Muraoka Y, Matsuda M, Kuno S, Shimizu S,
Yamamoto Y, Kera N, Kimura Y : Forearm work
capacity in association with age and daily physical activity in elderly women. The 4th symposiumof “Inactivity (prolonged bed-rest), Health andAging”. Seigakuin University Press, pp. 61-66,
2001.
Ohmori F, Shimizu S, Muraoka Y, Kuno S, Matsuda
M, Kagaya A : Blood flow during graded, submaximal static handgrip exercise at different intensities in elderly and young women. Int J Sports
Health Sci, 4: 480-488, 2006.
Saito M, Mano T, Iwase S : Sympathetic nerve activity
related to local fatigue sensation during static
contraction. J Appl Physiol, 67: 980-984, 1989.

Fig. III.1.7-1 Critical loads for muscle oxygenation,muscle fatigue sensation and blood pressure.

時・活動中止期ともに，負荷増加に対して直線的増加を示している．しかし，筋活動中止期（筋内圧の除去）時の血流量に対する筋活動中の血流量の割合
は，左右共に非直線的に低下した．
負荷増加に対する各パラメータ応答の関係には左右の相違は認められなかった．すなわち，主観的筋
疲労感覚，筋酸素動態および血圧は非直線的変化を示すのに対して，活動肢への血流量は直線関係を保って増加した．しかし，運動中の血流量は，筋活動による機械的血管圧迫による血流制限が起こり，組織の血流需要を満たすものではない（Kagaya and42

1.8 Blood flow and arterial vessel diameter change during
graded handgrip exercise in dominant and non-dominant forearms of tennis players
Atsuko Kagaya, Fumiko Ohmori, Shizuyo Shimizu-Okuyama,
Yoshiho Muraoka, and Kohei Sato
Abstract
The training effect on exercise-induced maximal blood flow is still unclear. The purpose of this study
was to clarify the difference of exercise-induced blood flow, blood flow velocity and vessel diameter ofbrachial artery in dominant and non-dominant forearms of tennis players during graded handgrip exercise. Ten female tennis players aged 20.1 ± 0.1 yrs. (mean ± SD) performed 30-s static handgrip exercise
in a supine position with either the dominant or non-dominant hand by increasing load at 30-s intervals
until exhaustion. Brachial arterial blood flow velocity (Doppler ultrasound method) did not differ between
both limbs, whereas the vessel diameter (2-D method) was significantly larger in the dominant limb during
diastole both at baseline (P < 0.01) and after exercise (P < 0.05), but no difference was found during systole. As a result, the blood flow was significantly higher (P < 0.05) in the dominant limb during post-exercise condition. Muscle thickness of the forearm muscles and maximal handgrip strength were significantly
higher in the dominant limb. Thus, the effect of training on exercise-induced blood flow specific to thedominant limb was confirmed during post-exercise due to the enlarged vessel diameter during diastole ofcardiac cycle. The dimensional change in the vasculature specific to the dominant side will be included in
the training effects associated with the dimensional muscular changes in the dominant forearm.
either the dominant (right side) or non-dominant● Purpose

Despite that structural adaptation of vasculature

hand on different days. The static handgrip exercise

has been reported at baseline, a training effect on

was repeated at 30-s intervals with increasing loadvascular dimension during exercise remains to be

by 2 kgw until exhaustion. Brachial arterial bloodstudied. The purpose of this study was to clarify

flow velocity (V) and diameter (D) were obtained

the effects of training on blood flow and structure

continuously using ultrasound Doppler and 2-Dof the conduit artery during static exercise (muscle

methods (GE, Vivid7 Pro), each at diastole (Dd) andaction). For this purpose, the blood flow velocity

systole (Ds). Brachial arterial blood flow was calcu-

and vessel diameter of the brachial artery werelated as V* π(D/2)2 (D = 2Dd/3 + Ds/3). Blood pres-determined in dominant and non-dominant fore-

sure (BP; Ohmeda, Finapres 2300) and maximal vol-arms of tennis players during and after each load

untary contraction (MVC) of forearm muscles, andof graded handgrip exercise.

radial and ulnar forearm flexor muscle thickness
were measured (Aloka, SSD1000).

● Methods● Results and Discussion

Subjects; Ten female tennis players aged 20.1 ±
0.1 (mean ± SD) years old participated in the study.

Muscle thickness of Rad and UL, MVC, highest

They were recruited from the collegiate tennis team,load attained by each subject and total work index

which won 4th place in the national inter-collegiate

performed until exhaustion were significantly high-tennis tournament that year. Following 3-minuteer in the dominant limb.

baseline measurements, the subject performed 30-s

The blood flow velocity during exercise andstatic handgrip exercise in a supine position withimmediately after exercise increased significantly
43

icantly between limbs, whereas the diameter during diastole was larger in the dominant limb. The
latter finding is consistent with the study of
Huonker et al. (2003), who studied thoracic,
abdominal, subclavian and common femoral arteries in trained athletes including professional tennis
players, but not with the study of SchmidtTrucksäss et al. (2000). The discrepancy might bedue to the difference of subjects compared in therespective studies. The possible mechanism to
explain an increased blood flow with training
involves structural remodeling of the vasculature(Miyachi et al. 1998). Other underlying mechanisms
for the increased blood flow with training will
Fig. III.1.8-1 Diastolic (a), systolic (b) vessel diameterand brachial arterial blood flow (c) at baseline, dur-

include a change in vasoactivity because of aning, and after exercise at the highest loads in dominant（■) and non-dominant（□）limbs. *, ** P <0.05, P < 0.001 between limbs.

(Allen et al. 2003; Clarkson et al. 1999). The contri-

increased flow-mediated dilation after training

bution of NO to the effect of exercise training on
vascular responses in human subjects remains(P < 0.01) with loads both in dominant and non-undecided (Green et al. 1996).

dominant limbs, though no significant difference invelocity was found between both limbs. The dias-● References

tolic and systolic vessel diameters, during exercise

Allen JD, Geaghan JP, Greenway F, Welsche A : Timecourse of improved flow-mediated dilation after
short-term exercise training. Med Sci Sports
Exerc, 35: 847-853, 2003.
Clarkson P, Montgomery HE, Mullen MJ, Donald AE,
Powe AJ, Bull T, Jubb M, World M, Deanfield JE :Exercise training enhances endothelial function inyoung men. J Am Coll Cardiol, 33: 1379-1385,
1999.
Green DJ, Fowler DT, O’Driscoll JG, Blanksby BA,
Taylor RR : Endothelium-derived nitric oxide
activity in forearm vessels of tennis players. J
Appl Physiol, 81: 943-948, 1996.
Huonker M, Schmid A, Schmidt-Trucksäss A,
Grathwohl D, Keul J : Size and blood flow of central and peripheral arteries in highly trained ablebodied and disabled athletes. J Appl Physiol, 95:
685-691, 2003.
Miyachi M, Iemitsu M, Okutsu M, Onodera S : Effects
of endurance training on the size and blood flowof the arterial conductance vessels in humans.
Acta Physiol Scand, 163: 13-16, 1998.
Schmidt-Trucksäss A, Schmid A, Brunner C, Scherer
N, Zäch G, Keul J, Huonker M : Arterial properties of the carotid and femoral artery inendurance-trained and paraplegic subjects. J Appl
Physiol, 89: 1956-1963, 2000.
Sinoway LI, Musch TI, Minotti JR, Zelis R : Enhanced
maximal metabolic vasodilatation in the dominantforearms of tennis players. J Appl Physiol, 61:
673-678, 1986.

and immediate post-exercise, gradually increased
with time and increasing loads. The diastolic diameters were significantly larger in the dominant limb
at baseline (dominant; 3.4 ± 0.1, non-dominant;
3.0 ± 0.1 mm) and after exercise at the highest
load (dominant; 3.5 ± 0.1, non-dominant; 3.2 ± 0.1mm) (Fig. III.1.8-1). In contrast, systolic diameter
did not differ either during exercise or post-exercise between both limbs. The brachial arterial
blood flow in both limbs increased linearly related
to exercise load both during (P < 0.01) exercise andpost-exercise (P < 0.01). Interaction was significant(P < 0.05) and higher post-exercise blood flow was
obtained in the dominant limb after exercise at thehighest load (P < 0.05).
The first finding of this study was that the trained
forearm showed higher exercise-induced bloodflow increase during post-exercise phase, (or relaxation phase of dynamic exercise). Our second finding was that the luminal vessel diameter of thebrachial artery during systole did not change signif44

1.9

運動時の末梢循環に対する重力の影響

加賀谷淳子，奥山（清水）靜代，大森芙美子，佐藤村岡 慈歩，森曜生

耕平，

Effects of gravity on peripheral circulation during exercise
地球上では，重力の影響を受けて血液循環が変化する．

ングは動静脈バランスにも依存するので，静脈血流量にその結果，活動体肢と心臓との相対的位置関係が，骨格変化があると，筋の酸素ダイナミクスにも影響を及ぼす

筋への酸素供給を行う動脈側血流を修飾して，筋の酸素可能性がある．しかし，運動時の静脈血流量の変化と血供給−消費バランスを変えると考えられる．実際，上肢を液プーリングおよびその動脈側への影響については，こ挙上・垂下して，心臓との相対的位置関係を変えたとき，れまで明らかにされていない．

挙上時には，垂下時に比較して上腕動脈血流量が減少し，本研究は，活動体肢位置を心臓より下に位置させて，酸素化ヘモグロビン濃度の低下，脱酸素化ヘモグロビン

血液プーリングが起こるような状態で動的運動を行わせ，濃度の上昇度は大きくなった（加賀谷ら 2001）．体肢がそれが活動筋の血流変化と酸素ダイナミクスに与える影

心臓より下に位置する場合は，重力の影響により筋血管響を明らかにすることを目的としている．特に静脈血流

床での血液プーリング（貯留）が起こる（加賀谷ら 2001）．

量の変化に着目して活動体肢を心臓レベルにおいて運動

それは，動脈血流入にも影響を及ぼす（Tschakovsky

した時の変化と比較検討した．

and Hughson, 2000）と考えられる．一方，血液プーリ

1.9.1

上肢垂下状態における掌握運動時の動静脈血流変化と酸素動態
加賀谷淳子，奥山（清水）靜代，大森芙美子，吉澤
熊谷 真奈

睦子，

Venous and arterial blood flow, and muscle oxygenation during handgrip exercise with the arm below heart level
Abstract
The purpose of this study was to test the hypothesis that venous return from exercising muscles wasenhanced under the condition that it was placed below heart level. Thirteen young females performed
rhythmic handgrip exercise with the forearm at heart level or below heart level. Brachial venous bloodflow was significantly larger with the forearm at heart level than that below heart level at the beginning of exercise. In contrast, the brachial arterial blood flow was higher with the forearm below heartlevel. The blood volume (THb) estimated by NIRS increased gradually with exercise duration and theincrease was significant during exercise below heart level. These results suggested that the venous outflow and arterial inflow during the rhythmic handgrip became out of balance toward the arterial
inflow, due to an increase in vascular bed and blood pooling in the muscle.
● 目

心臓レベルに置くよりも，心臓より下においた場合

的の方が運動による変化が大きく，それが動脈血流に本研究は，活動筋からの静脈還流は，活動体肢を45

Fig. III.1.9.1-1 Venous (upper) and arterial (lower) blood flow changes during the contraction (left) and relaxation(right) phases of handgrip exercise. Handgrip exercises were performed with the forearm at heart level (at H) or
below heart level (below H).

も影響するとの仮説を検証しようとした．その目的

ベル運動時では時間経過に伴って静脈血流量は徐々のため，上肢を下垂した状態で行う律動的掌握運動に増加するが，心臓レベル以下での運動時には増加

時の循環・酸素代謝変化を，心臓レベルでの運動時しなかった．また，NIRS によって得られた O 2Hb，と比較した．

HHb，THb はいずれも開始初期に一旦減少し，その後，O 2Hb は漸減，HHb と THb は漸増した．次に，● 方法

心臓レベルでのベースライン値を基準として，血流若年女性 13 名を被験者として，心臓レベル（6 名）

量の変化分を筋活動期と活動中止期に分けて体肢のと心臓より下位（7 名）に体肢をおいて，椅座位で，位置間で比較すると，Fig. III.1.9.1-1 のようになっ

律動的掌握運動（50 ％ MVC 強度，1 分間，活動・休た．静脈血流量は，心臓レベル以下の運動の方が有止各 2 秒）を行わせた．測定項目は，上腕動静脈の血意に低く，それは，筋活動開始初期の筋活動中止期

流速度（超音波 Doppler 法），血流量（M-mode 法），

において認められた．それに対して動脈血流量は，

血圧（Finapres）および近赤外線分光法（NIRO300）

筋活動中止期に心臓レベル以下の運動時の方が有意による前腕屈筋群の酸素化ヘモグロビン（O 2 Hb），に高くなった．このような，動静脈血流量のバラン

脱 酸 素 化 ヘ モ グ ロ ビ ン （ H H b ）， 総 ヘ モ グ ロ ビ ン

スの変化は，心臓レベル以下で行われている活動体（THb）濃度であった．

肢への血液プーリングを促進する結果になった．このことは，血液量（THb）の増加にも反映されてお● 結果および考察

り，運動に伴う血管拡張により，筋内血管床が増大したこと，筋からの流出血液量の減少が血液プーリ

律動的掌握運動を，心臓レベルと心臓以下のレベングをより大きくしたことを示唆している．

ルで実施した時の血流量（M-mode 法）は，心臓レ

46

1.9.2 足底屈運動時の血液供給と酸素動態に対する血液プーリングの影響
加賀谷淳子，奥山（清水）靜代，大森芙美子，佐藤村岡 慈歩，森曜生

耕平，

Effect of blood pooling on blood supply and oxygenation during plantar
flexion exercise
Abstract
Arterial and venous blood flow responses to rhythmic plantar flexion exercise were compared before
and after 30-min upright sitting rest to determine the effect of pooling. Eight female subjects participated in this study. During 30-min upright rest, the blood volume (total Hb) in the calf muscles estimatedby near-infrared spectroscopy increased significantly, suggesting blood pooling in the calf muscles.
Either venous or arterial blood flow change did not differ significantly before and after pooling.
Further study should be conducted to clarify the effect of pooling on venous and arterial blood flowchanges during exercise.

● 目

その点からも前腕の運動は静脈貯留・筋ポンプ作用

的運動時の動脈血流入に対して，活動筋からの血液の影響の可能性が小さい．そこで，本実験では，活流出（静脈血流）が規定因子になるか否かに関して，

動体肢をさらに低い位置に置くことができ，筋量も上肢を下垂した実験モデルで検討したが，上肢では多い下腿の運動を対象として検討した．本実験では，心臓と活動体肢との高低差が小さい．また，筋ポン

血液貯留の影響が顕著になるよう下肢下垂状態を 30

プ作用は血液貯留量と関連しているとされており，分保持した．このような血液プーリングが起こるよ

Fig. III.1.9.2-1 The muscle oxygenation changes during upright sitting rest and during dynamic plantar flexion
exercise before and after 30-min upright rest. ◇ : O2Hb.

47

°)
(1
50
B
as
el
in
e
Fig. III.1.9.2-2 Venous (□) and arterial (■) blood flow in popliteal vessels during upright sitting rest and duringrhythmic plantar flexion exercise. Significant difference was found between arterial blood flow and venous blood
flow, whereas no significant difference was found those parameters between 1st and 2nd bout of exercise.

うな実験条件を設定し，運動時の動静脈血流バラン

O2Hb，HHb，THb の変化を高強度運動の例で示しスがプーリング前後で異なるか否かを明らかにするたものである．30 分間の椅座位姿勢保持によって，ことを目的とした．

MG の THb が増加し，血液プーリングが確認された．
律動的足底屈運動時の膝窩動静脈血流量は，高強● 方法

度・低強度運動共に，プーリング前に比べてプーリ

若年女性 8 名を対象に，椅座位で安静状態を保った

ング後はやや低い値を示したが，統計的に有意な変後，60 秒間の律動的（活動 2 秒，休止 2 秒）な足底化ではなかった（III.1.9.2-2）．逆に筋酸素動態の変屈運動を行わせた．引き続き，30 分間の椅座位安静

化は，プーリング後やや大きかったが統計的に有意を保持して血液プーリングを行った後，最初と同様ではなかった．

の足底屈運動を実施した．運動の強度は，あらかじ● 文

め漸増負荷運動によって得られた負荷−血圧関係式か献加賀谷淳子, 清水静代, 東香寿美 : 上肢位置変化に伴う掌握運動中の血流量と筋酸素動態の変化. 第 9 回日本運動生理学会, 2001.
Tschakovsky ME, Hughson RL : Venous emptying
mediates a transient vasodilation in the humanforearm. Am J Physiol, 279: H1007-H1014, 2000.

ら，血圧が急上昇する負荷を求め，その＋ 20%（高負荷）と− 20%（低負荷）に相当する負荷を用いた．
測定項目は，腓腹筋内側頭（MG）の筋酸素動態（近赤外線分光法，NIRO200），膝窩動脈血流速度（超音波ドップラー法，Vivid7pro）であった．

● 結果および考察

Fig. III.1.9.2-2 は安静状態から実験終了までの48

1.10 まとめ本研究で明らかになった結果を，運動特性（特に，により動脈血流量の増加が起こり，筋血液量が増加

運動持続時間，運動強度）と関連させてまとめるとする．そうなると，筋活動による静脈側の血液流出

以下のようになる．

は，続いて起こる動脈血流入量と密接な関係を保つ
ようになることがわかったが，運動が終了すると，1.10.1

時間経過に伴う骨格筋への血流調節

急激な動脈血流増加が起こり，運動後の血流は約 3 拍

本研究の結果から筋活動の開始時には筋ポンプ作

目の心周期で最高値に達する（Ohmori et al. 2006）．

用により静脈血の流出が起こり，動脈血流入は開始

この時期には静脈血流は安静時以下に減速し，静脈初期に一旦抑制されるものの，続いて起こる活動筋

血流が安静レベルに復帰したのは，動脈血流量が最の血管拡張によって血流量が増加した（Fig. III.1.10-

高値に達し，筋の血管床への血液再充満が起こって

1）．一方，運動開始初期の非活動肢の血流量変化をからであった．

みると，強度依存で一過性の血流量の増加が見られ，

このように運動開始時や運動終了直後のように身それに続いて強度依存の血流減少が起こった

体が劇的に変化する状況においては，局所的運動の（Yoshizawa et al. 2008）．すなわち，筋収縮開始と開始や中止に対する局所的対応と循環システム維持

同時に起こる動静脈血流勾配の増加等の作用によっのための調節が急速に起こるが，両者の対応は必ずて，運動開始初期から活動筋での血流増加が素早く

しも同時ではなく，運動実施上留意すべき循環応答

起こるものの，全身性の血管収縮作用は高まらずに，も見られる．

この時期には血流再分配は適切になされていないこ

また，動静脈血流には重力の影響が強く，心臓ととが示唆される．非活動肢での血流量増加や，総末

活動体肢の位置関係が循環調節に影響を与えている梢血管抵抗の減少による血圧の低下はそれを支持すことが示唆された．運動条件との関係についてはさる結果であると考えられる．

らに検討を進める必要があろう．

律動的な運動が持続すると，活動筋での血管拡張

Fig. III.1.10-1 Regional and central circulatory adjustment to exercise.

49

同研究における成果 p. 139）
．また，強度が高くなると，運動持続に伴う筋の電気活動漸増の割合が高くなり，筋疲労耐性の低い筋が動員されるようになる
ことが示唆されたが，その強度は血圧変移点と類似であった（IV．プロジェクトの共同研究における成果 p. 139）．筋の酸素代謝をみると，運動中の活動肢
筋酸素化動態が負荷強度に対して低負荷とは異なる対応をするようになるのは，血圧変移点負荷よりやや低い負荷からであった．そして，これらの負荷は主観的筋疲労感覚の急上昇より高い負荷であり，筋疲労感覚では 10 段階中の 4 に相当することがわかった．
血流量が最高値に達する運動負荷強度について，最終的な結論を得るには至っていないが，現段階でFig. III.1.10-2 Deflection loads of circulatory and metabolic responses to exercise in relation to exercise intensity, exercise duration and blood pressure. Muscle fatigue

は，負荷強度が 50 ％ MVC で比較的テンポの速い運

sensation is also indicated.

くの負荷強度・運動頻度・持続時間を組み合わせた動においてであった．この点については，さらに多実験によりデータを蓄積する必要がある．

1.10.2

1.10.3

運動強度と血流再分配

活動筋血流量に効果的なトレーニン

グ条件

運動プログラムを考える上で，運動強度は極めて重要な運動条件である．本プロジェクトでは運動強本研究では，先行研究と同様に，長年トレーニン度を筋収縮強度と収縮頻度から検討した．筋収縮強グを行っているテニス選手の利き腕の血流量が非利度がある強度を超えると筋交感神経の亢進が起こる

き腕に比べて高い値に増加することを確認した．そ（Saito et al. 1986）ことが知られているが，その結果，して，それが，心臓の拡張期に当たる時期の血管径強度変化に対する血圧上昇が顕著になる（Kagaya etの拡大によるという新しい知見を報告した．しかし，al. 2001）．そこで，血圧上昇が高くなる負荷（血圧

これまでの研究でも，また，本研究でも，最も効果

変移点負荷）を基準として強度をとらえ，本研究の的なトレーニング条件を明らかにするには至らなか

骨格筋への血流再分配の知見をまとめた（Fig.

った．本研究者らは，上記 1.10.2 で示した生理的なIII.1.10-2）．

運動強度を用いて，血圧変転負荷以下とそれ以上の活動筋への血流量が運動負荷強度の増加に伴って負荷によるトレーニングが末梢循環系と骨格筋に対増加し，頭打ちになるかどうかは議論のあるところする効果が異なるかどうかを明らかにする研究を本である．本プロジェクトでは動的膝伸展運動・足底

プロジェクトで開始した．このトレーニングによっ

屈運動や間欠的な静的掌握運動において検討し，前て，これまで別々に行われてきた筋肥大を起こすト

者では頭打ちが観察され，後者では筋弛緩期血流がレーニング条件と循環系に効果を及ぼすトレーニン

負荷の増加と共に増加するという結果を得た．動

グ条件を総合的に検討して，両者の関係を明らかに

的・静的運動共に，運動後血流量に対する運動中血したいと考えている．本学術フロンティア事業を契

流量の比は，血圧変移点負荷とほぼ類似の負荷強度機に多くの研究者が参画する共同研究に発展して，で急激に低下し，運動中の血流需要を満たす割合がトレーニングに関する指針の得られることが望まれ低くなることが確認された（IV．プロジェクトの共

る．

50

2

運動時の内臓器官および脳の血流動態とその調節機構
定本

朋子 1）

Control of renal and splanchnic circulations during exercise
Tomoko Sadamoto■本課題の共同研究者
佐藤1）耕平 1），平澤

愛 1），島田奈央子 1），森山真由美 1），大森芙美子 1），岩館雅子 1, 3），石田良恵 2）

日本女子体育大学基礎体力研究所，2）女子美術大学，3）日本大学

2.1

運動時の内臓器官血流動態とその調節
定本 朋子，佐藤 耕平，平澤愛，島田奈央子

2.1.1 静的運動時における腎動脈および上腸間膜動脈の血流応答
2.1.2 多段階の動的運動時における腎動脈および上腸間膜の血流応答
2.2

運動時の脳血流動態とその調節
定本 朋子，佐藤 耕平，森山真由美，平澤愛

2.2.1 静的運動および運動後筋虚血に対する脳血流動態2.2.2 Comparison of the blood flow responses between internal carotid and vertebral arteryduring dynamic graded exercise
2.3

発育期の子どもにおける循環機能の発達
定本 朋子，佐藤 耕平，大森芙美子，森山真由美，岩館 雅子，石田 良恵

2.1

運動時の内臓器官血流動態とその調節

定本

朋子，佐藤

耕平，平澤

愛，島田奈央子

Control of renal and splanchnic circulations during exercise

2.1.1

静的運動時における腎動脈および上腸間膜動脈の血流応答

Renal and splanchnic vascular responses during static exercise andpostexercise muscle ischemia
Abstract
Since visceral regions are consisted of functionally different organs such as kidneys and gastrointestinal tracts, it was hypothesized that blood flow regulation induced by the autonomic activation during exercise is different among arteries supplying to specific organs. To verify the hypothesis. We studied blood flow responses in renal artery (RA) and the superior mesenteric artery (SMA) during static
handgrip exercise and the postexercise muscle ischemia (PEMI). Ten healthy female volunteers performed a sustained static handgrip exercise at 30 ％ of maximum voluntary contraction for 2 min followed by a 6-min recovery period (control condition). Subjects also underwent the occlusion condition, in which arterial blood flow in the upper arm was arrested immediately after the handgrip exercise. Mean arterial blood pressure (Finapres), heart rate (ECG), and blood flow in RA (RABF) and SMA(SMABF) were measured by Doppler ultrasound technique. Vascular resistance in RA and SMA (RAVR
and SMAVR) were calculated. During handgrip exercise, RAVR significantly increased and sustained at
the higher level during PEMI in occlusion condition, whereas RAVR in control condition returned to
the resting level. On the contrary, SMAVR in both conditions slightly increased during exercise andreturned to the resting level during PEMI. These results supported the hypothesis that blood flow regulation among different visceral organs is differential during exercise and PEMI. RA appeared to be
more sensitive to exercise stimulus and the reflex signals arising from muscle metaboreceptors than
SMA. The artery supplying to the digesting gastrointestinal tract such as SMA might be to some degree
exempt from flow-reducing participation during exercise.

る SMA と RA における血流動態を比較検討すること● 研究目的にした．

安静時には心拍出量の 20 ％もの血流配分がある内臓器官であるが，運動時には骨格筋血流への配分を● 研究方法増大させるために，血流減少の対象となるといわれる（Osada et al. 1999）．しかし，運動に対して個々

腎動脈（RA）および上腸間膜動脈（SMA）の 2 つの内臓器官の血流が画一的に血流減少を示すのかどの実験に 10 名の健康な成人女性〔年齢： 22 ± 1 歳，

うかについては明らかではない．本研究では，内臓

体重： 54 ± 5kg，身長： 158 ± 7cm，随意最大筋力器官の中でも消化器官（主に小腸）への血液を送る（MVC）： 32 ± 5kp〕が参加した．各実験では随意最上腸間膜動脈（superior mesenteric artery : SMA）

大筋力（MVC）の 30 ％の負荷で 2 分間握力発揮運動と腎臓へ血液を送る腎動脈（renal artery : RA）の 2を維持する対照条件（Control）と，同一の運動の後つを取り上げ，静的運動および運動後筋虚血に対すに，上腕部血流を 3 分間阻止し運動後筋虚血（PEMI）

53

Fig. III.2.1.1-1 Renal artery (RA) vascular resistance and superior mesenteric artery (SMA) vascular resistance during rest, static handgrip (HG) exercise and postexercise muscle ischemia (PEMI) in control and occlusion conditions.

を実施する虚血条件（Occlusion）の 2 条件が実施さる MAP と HR の反応は RA 実験と同様の結果を示しれた．RA 実験は食後 4 時間以上，SMA 実験は 8 時間た．しかし上腸間膜動脈血流（SMBF）は RABF とは以上を経過した後に行った．RA および SMA の動脈異なり，静的運動時には両条件の値が安静時値に等血流（BF）は平均血流速度および血管径（MCA は平

しく，有意な変化を示さなかった．また PEMI 時には，

均血流速度のみ）を超音波ドップラー法（Logic 3,

Control 条件が安静時値に戻るのに対し，Occlusion

Logiq5 GE Medical systems）により計測し，各動条件は著しく上昇した．そのため PEMI 時の SMA 血脈の血流量（BF）を算出した．平均動脈血圧（MAP，管抵抗は条件間の相違はなく，両条件ともに安静時

Finapress の指動脈圧波形計測）および心拍数（HR，に近い値を示した．本研究の SMA 実験における結果

ECG 法）により測定した．また RA および SMA 血管

は，大筋群による動的運動を用いた研究（Perko et

抵抗を MAP ／ RABF または MAP ／ SMABF の式から

al. 1998; Puvi Rajasingham et al. 1997; Qamar MI算出した．

and Read AE 1988）の成果とは異なっていた．これらの先行研究では，運動時の SMBF の低下あるいは● 結果と考察SMA 血管抵抗の上昇が報告されていた．しかし，本（1）RA 実験：静的運動時には MAP および HR が実験と同様の掌握運動による静的運動を用いた有意に上昇し，それらの上昇量は Control とWaaler et al.（1999）の研究では，本研究と同様に

Occlusion の条件間で等しかった．PEMI 時には，

SMA 血管抵抗の有意な上昇は見られないことを報告

Occlusion 条件の MAP だけが高値を示し HR は安静していた．

時値に戻った．腎動脈血流（RABF）は両条件ともに

これらの結果から，腹部内臓器官の血流は運動に運動時に有意に低下し，PEMI 時に安静時値に戻った．

対して画一的な反応を示すのではなく，腎動脈のよこのため RA 血管抵抗（Fig. III.2.1.1-1）が運動時にうに運動刺激および筋代謝受容器からの反射性入力

顕著に増大し，PEMI 時には Occlusion 条件がに顕著に反応する組織（器官）と上腸間膜動脈のよControl 条件よりも有意に高い値を示した．このよううに反応の低い組織（器官）があり，そのために運な静的運動時および PEMI に対する RA 血管抵抗の応動時の血流調節に関わる機構も異なることが示唆さ

答は先行研究に一致していた（Momen et al. 2003）．

れた．

また PET を用いて腎皮質の組織血流量を測定した● 文

Middlekauff et al.（1997）における成果ともほぼ一

献Middlekauff HR, Nitzsche EU, Nguyen AH, Hoh CK,
Gibbs GG: Modulation of renal cortical blood flow
during static exercise in humans. Circ Res, 80: 62-

致していた．
（2）SMA 実験：静的運動時および PEMI 時におけ54

J Physiol, 513: 907-913, 1998.
Puvi Rajasingham S, Smith GD, Akinola A, Mathias
CJ: Abdominal regional blood flow responses during and after exercise in human sympathetic denervation. J Physiol, 505: 841-849, 1997.
Qamar MI, Read AE: Effects of ingestion of carbohydrate, fat, protein, and water on the mesentericblood flow in man. Scand J Gastroenterol, 23: 2630, 1988.
Waaler BA, Toska K, Eriksen M: Involvement of thehuman splanchnic circulation in pressor response
induced by handgrip contraction. Acta Physiol
Scand, 166: 131-136, 1999.

68, 1997.
Momen A, Leuenberger UA, Ray CA, Cha S, Sinoway
LI: Renal vascular responses to static handgrip:
role of the muscle mechanoreflex. Am J Physiol,
285: H1247-H1253, 2003.
Osada T, Katsumura T, Hamaoka T, Inoue S, Esaki K,
Sakamoto A, Murase N, Kajiyama J, Shimomitsu
T, Iwane H: Reduced blood flow in abdominal viscera measured by Doppler ultrasound during onelegged knee extension. J Appl Physiol, 86: 709719, 1999.
Perko MJ, Nielsen HB, Skak C, Clemmensen JO,
Schoreder TV, Secher NH: Mesenteric, celiac andsplanchnic blood flow in humans during exercise.

2.1.2 多段階の動的運動時における腎動脈および上腸間膜動脈の血流応答
Renal and splanchnic vascular responses during dynamic exercise withgraded worklord
Abstract
From our previous report observed during static exercise it was hypothesized that the blood flow inthe renal artery (RA) decreased more than the blood flow in the superior mesenteric artery (SMA) during dynamic exercise. To verify this hypothesis, we studied the blood flow responses in RA and SMA
during dynamic exercise with graded workloads. Nine healthy female volunteers participated in thepresent study. After 10-min resting, the subject performed a 15-min bicycling exercise including threeworkloads of 30%, 50%, and 70 % of peak oxygen uptake for 5 min for each workload. During dynamic exercise, the responses in oxygen uptake, minute ventilation, mean arterial blood pressure, cardiac
output, and heart rate, respectively, increased linearly with three workloads from rest to 30%, 50%, to
70% of the peak oxygen uptake. The conductance in RA, however, demonstrated a significant reduction during three workloads, by 19 ± 11 (SD) %, 29 ± 13 %, 45 ± 13 % of the value at rest for 30%,
50%, and 70% of the peak oxygen uptake, respectively. In contrast, the conductance in SMA showedno significant change from the resting level. The percent reduction of the conductance in SMA during
exercise was 5 ± 15 %, 11 ± 16 %, and 19 ± 16 % for the three workloads, respectively. Thus, thepresent data supported the hypothesis that the renal blood flow decreased more than that in SMA during dynamic exercise with graded loads.

行った．その結果，腹部内臓器官の血流は運動に対● 研究目的

安静時の腹部内臓器官には，心拍出量の約 20 ％のして画一的な反応を示すのではなく，腎動脈は運動

血流が配分されるが，運動時には血流量が減少する

による血流減少が顕著であるが，上腸間膜動脈ではといわれている．しかし，その減少量が，個々の腹運動刺激に対する有意な変化が見られないことが示部内臓器官により異なるのかどうかについては十分された．しかし動的運動時におけるこれらの腹部内な検討がなされていない．著者らは，一定負荷（随臓血流動態に関する研究は数少ないといえる．Endo

意最大筋力の 30 ％）の静的運動時における腎動脈血

et al.（2008）は，若年女性が一定負荷強度（40 W）

流と消化器官へ連絡する上腸間膜動脈血流の検討をの自転車運動をした際における上腸間膜動脈および55

Fig. III.2.1.2-1 Heart rate, cardiac output, mean arterial blood pressure, oxygen uptake, mean flow velocity andperipheral conductance in renal artery (RA) and superior mesenteric artery (SMA) at rest and during exercise withintensity of 30%, 50% and 70% of peak oxygen uptake.

腎動脈の血流応答が異なることを報告している．彼

1000，Arco System）は，3 段階の各負荷の最後の 1

らは種々の強度における動的運動時について比較検分間のデータを平均した．SMA および RA の血管コ

討してはいなかった．このようなことを踏まえ，本ンダクタンスを，平均血流速度／平均血圧の式から算研究では，多段階負荷による自転車運動時における出し，SMA と RA の血管コンダクタンス（CSMA，

上腸間膜動脈（SMA）および腎動脈（RA）の血流応CRA）とした．また安静時値を 100 ％とした時の変答を比較検討し，静的運動時で得られた同様の結果

化率（％）で表示した．

が示されるのかどうかについて検討することにした．
● 結果と考察● 研究方法

Fig. III.2.1.2-1 にみられるように，SMA 平均血流

健康な女子大学生 9 名（年齢： 23 ± 3 歳，身長：速度は運動により有意な変化が見られないが，RA で162 ± 5 cm，体重： 58 ± 5 kg，最高酸素摂取量・
VO2peak ： 36 ± 6 ml ／ kg・min-1）が実験に参加した．
・
5 分間の安静後，30 ％，50 ％および 70 ％ V O 2peak のは運動強度とともに大きく減少した．また血管コン

負荷で各 5 分間，計 15 分間の自転車運動を行った．

時でみられた RA および SMA の血流応答の相違と等

SMA および RA の平均血流速度を，超音波ドップラ

しい結果となった．また先行研究の報告とも一致し

ー法により（Vivid7pro，GE Medical systems）にていた（Endo et al. 2008; Flamm et al. 1990）．しより測定した．測定には 3.0 MHz のコンベックス型

かし，動的運動時の SMA 血流応答についてみると，プローブを用いた．SMA は腹部大動脈分岐部より遠中高齢者を被験者とした Puvi-Rajasingham et al.

位 1 〜 2 cm，RA は右腎への流入部から近位 1 〜 3（1997）の結果よりも本研究の低下率がやや少なかっ

cm の部位で測定した．心拍数（HR，心電図法），動た．これは被験者の年齢の相違によると考えられた．

脈平均血圧（MAP，Finometer，Finapres Medical

このような SMA と RA にみられる同一運動に対するsystems），心拍出量（CO，圧波形から Model flow・法により算出）および酸素摂取量（V O 2 ，ARCO-応答の相違をもたらす要因として，アンギオテンシ

ダクタンスでみると，RA の低下率が SMA に比較す
ると著しく大きかった．これらの結果は，静的運動

ン II（ Tidgren et al. 1991）， エ ン ド セ リ ン -1

56

and organ blood volume and effect on cardiac
function in relation to upright exercise intensity inhealthy human subjects. Circulation, 81: 15501559, 1991.
Maeda S, Miyauchi T, Iemitsu M, Tanabe T,
Irukayam-Tomobe Y, Goto K, Yamaguchi I,
Matsuda M : Involvement of endogenous endothelin-1 in exercise-induced redistribution of tissue
blood flow: an endothelin receptor antagonist
reduced the redistribution. Circulation, 106 :2188-2193, 2002.
Momen A, Leuenberger UA, Ray CA, Cha S, Sinoway
LI : Renal vascular responses to static handgrip:
role of the muscle mechanoreflex. Am J Physiol,
285 : H1247-H1253, 2003.
Puvi Rajasingham S, Smith GD, Akinola A, Mathias CJ: Abdominal regional blood flow responses during
and after exercise in human sympathetic denervation. J Physiol, 505 : 841-849, 1997.
Tidgren B, Hjemdahl P, Theodorsson E, Nussberger J:
Renal neurohormonal and vascular responses todynamic exercise in humans. J Appl Physiol, 70 :
2279-2286, 1991.

（Maeda et al. 2002），交感神経活動の地域差等が考えられる．また交感神経活動の地域差をもたらす要因として圧受容器（Collins et al. 2001），筋代謝受容器や筋機械受容器（Momen et al. 2003）からの反射性制御が腎と消化器官では異なるということも考えられる．今後の詳細な検討が必要である．
● 文

献Collins HL, Augustyniak RA, Ansorge EJ, O’Leary DS :Carotid baroreflex pressor responses at rest andduring exercise: cardiac output vs. regional vasoconstriction. Am J Physiol, 280: H642-H648,
2001.
Endo MY, Suzuki R, Nagahata N, Hayashi N, Miura A,
Koga S, Fukuba S : Differential arterial blood flow
response of splanchnic and renal organs during
low-intensity cycling exercise in women. Am J
Physiol, 294: H2322-H2326, 2008.
Flamm SD, Taki J, Moore R, Lewis SF, Keech F,
Maltais F, Ahmad M, Callahan R, Dragotakes S,
Alpert N, Strauss HW : Redistribution of regional

57

2.2
定本

運動時の脳血流動態とその調節

朋子，佐藤耕平，森山真由美，平澤愛

Cerebral blood flow regulation during exercise

2.2.1

静的運動および運動後筋虚血に対する脳血流動態

Cerebral blood flow responses to static exercise and postexercise muscle ischemia
Abstract
To elucidate the cerebral blood flow responses to static exercise, we measured arterial blood flow
responses in three sites of “the carotid artery root” and one site of “the vertebral artery root”. Ten
healthy female volunteers performed a 3-min sustained static handgrip exercise with ramp loadincreasing from 10% to 30% of maximum voluntary contraction followed by a 3-min postexercise muscle ischemia (PEMI). The blood flow (BF) in left common carotid artery (CCABF), the left internal
carotid artery (ICABF), and the left vertebral artery (VABF) was measured by ultrasonography. Meanflow velocity in the left middle cerebral artery (MCAV) was also recorded. Mean arterial blood pressure (MAP; Finapres) and heart rate (HR; ECG). The vascular resistance (VR) was calculated from theratio of MAP to the CCABF, ICABF, VABF, or MCAV. During static exercise (Fig. 1) the vascular resistance in all arteries increased from the resting level in parallel with the increase in MAP, but the magnitude of increase was greater in the “carotid artery root” than the “vertebral artery root”. During
PEMI, CCABF-VR, ICABF-VR, and MCA-VR were significantly higher than the resting level, whereas
VABF-VR returned to the resting level. These data suggested that the static exercise produced greater
vasoconstriction in the “carotid artery root” than the “vertebral artery root” and that the muscle metaboreflex played an important role in vasoconstriction in the “the carotid artery root” but not in the“vertebral artery root”.

かどうかについては不明である（Hellestrom et al.

● 研究目的

脳への血流は左右の内頸動脈経路（主に大脳皮質

1996; Pott et al. 1997）．このような点を踏まえ，本側頭葉，前頭葉，頭頂葉，島皮質へ潅流）と椎骨動

研究では静的運動時および運動後筋虚血時における脈経路（主に延髄，小脳，後頭葉へ潅流）の 2 経路に頸動脈経路と椎骨動脈経路の血流動態を検討するこより供給される．しかし頸動脈経路における中大脳ととした．

動脈の血流動態をみた研究は多いが（Jørgensen et● 研究方法

al. 1999），椎骨動脈経路の血流動態に関する報告は数少ない．内頸動脈経路は大脳への血液供給が主体

被験者は 10 名の健康な成人女性〔年齢： 21 ± 1 歳，

であるが，椎骨動脈経路の血流は，延髄，小脳，脳身長： 158 ± 7cm，体重： 57 ± 9kg，随意最大筋力幹といった運動遂行に重要な部位への血液供給を担（MVC）： 30 ± 5kp〕が，2 分間の安静後，最大筋力っている．この両経路が潅流する部位の違いを反映の 10 ％から 30 ％まで上昇するランプ負荷を維持する

するような血流動態の相違が運動時にもみられるの

静的握力発揮を 3 分間行った．その後，3 分間の運動58

&&$%)95,&$%)959$%)95

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SHULSKHUDOO UHVLVWDQFHH  3(0,(;(5&,6(

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Fig. III.2.2.1-1 Percent changes in vascular resistance in common carotid artery (CCABF-VR), internal carotid
artery (ICABF-VR), middle cerebral artery (MCA-VR) and vertebral artery (VABF-VR) during rest, static handgrip
exercise, and postexercise muscles ischemia (PEMI). For the calculation of MCA-VR, mean flow velocity was usedinstead of volume blood flow. Resting vascular resistance was defined as 100%, and shadow area indicates exercise
period in the figure.

後筋虚血（PEMI）を行った．平均動脈血圧（MAP，脈経路と椎骨動脈経路の血流動態が異なることを示

Finapress 指動脈圧波形計測）および心拍数（HR，していた．頸動脈経路では，血圧上昇に対して血管ECG 法）により測定した．総頸動脈（CCA），内頸動収縮作用により血流を制限するが，椎骨動脈では血脈（ICA）および椎骨動脈（VA）における血流量

管収縮作用が少なく血流の流入を許す経路という特（BF）を，また中大脳動脈（MCA）では平均血流速度徴がみられた．このような経路の相違をもたらす仕を超音波ドップラー法（Logic 3，Vivid 7）により計

組みは，運動時に活性化する脳細胞代謝に起因する測した．各動脈の血管抵抗を平均血圧と BF（MCA はのか，両経路の脳血管の自動調節能の相違なのか，

平均血流速度）の比として算出した．

あるいは圧反射などの神経調節活動の関与の相違なのかは明らかではない（Querido and Sheel 2007）．

● 結果および考察● 文

HR および MAP は，運動後半にかけて著しく上昇

献Helleström G, Fischer-Colbrie W, Wahlgren NG,
Jogestrand T : Carotid artery blood flow and middle cerebral artery blood flow velocity duringphysical exercise. J Appl Physiol, 81: 413-418,
1996.
Jørgensen LG, Nowak M, Ide K, Secher NH : Cerebral
blood flow and metabolism. In : Eercise andCirculation in Health and Disease. Edited by
Saltin B, Bouchel R, Secher NH, Mitchell JH, pp.
113-123, 1999.
Pott F, Ray CA, Olesen HL, Ide K, Secher NH : Middle
cerebral artery blood velocity,arterial diameterand muscle sympathetic nerve activity during
post-exercise muscle ischeamia. Acta Physiol
Scand, 160: 43-47, 1997.
Querido JS, Sheel AW : Regulation of cerebral bloodflow during exercise. Sports Med, 37: 765-782,
2007.

した．そして，PEMI 時には HR は安静値に戻るが，MAP は安静値より高い値を示した．頸動脈経路における BF は，運動開始早期に増加するが，その後は一定値で維持された．そして PEMI 時には安静値まで戻った．一方，椎骨動脈経路における BF は，静的運動
開始から終了まで漸増した．また PEMI 時においても安静値よりも高い値を維持した．このため血管抵抗が（Fig. III.2.2.1-1），頸動脈経路では静的運動時の値が安静値から約 50 ％も上昇したが，椎骨動脈経路
では約 10 ％程度の上昇にすぎなかった．PEMI 時では，頸動脈経路の値は安静値に比べ有意に高いが，
椎骨動脈経路ではほぼ安静値またはそれ以下の値を示した．このような結果は，運動負荷に対する頸動59

2.2.2 Comparison of the blood flow responses between internal carotid andvertebral artery during dynamic exercise

Abstract
The development of the Doppler ultrasonography technique enabled the measurement of the change
in the blood flow in the extra- and intracranial arteries at rest and during exercise. The purpose of thepresent study was to clarify the effect of exercise intensity on the cerebrovascular response in the ICA
and VA during semi-recumbent bicycle exercise by using the Doppler ultrasound technique. A total of
10 healthy young adults (1 man, 9 women) [age: 22.5 ± 2.5 years (mean ± SD)] participated in thisstudy. The exercise consisted of a 5-min baseline followed by levels of exercise load at 30%, 50%, and・
70% of the power of the VO2peak with 5-min duration of each stage. We continuously monitored
cardiovascular (Model flow method with finometer), ventilatory (breathe-by-breathe method), internal・・・
carotid artery blood flow (QICA), and vertebral artery blood flow (QVA) at rest and during exercise. QICA
・and QVA was measured by a Doppler ultrasound system and cerebrovascular resistance index (CVRICA
and CVRVA) were also calculated as MAP divided by CBF. In this study, mean arterial pressure (MAP)and end-tidal partial pressure of CO 2 (PET CO2) increased significantly with increase of exercise
・・
intensity. QICA increased by 12 ± 2% during 30% VO2peak and reached a maximum 8 ± 3% during 50%・・・VO2peak. However, during 70% VO2peak, increase in QICA had a level off, in contrast to a continued
・
increase in CVRICA throughout exercise. On the other hand, QVA increase in proportion to the increase・of exercise intensity (17 ± 3, 33 ± 4, and 40 ± 4% at 30, 50, and 70% VO2peak, respectively). In addition,
CVRVA did not change from the resting level throughout exercise. These data suggested that during
dynamic exercise the blood flow responses in VA and ICA are different. The difference might be mainly explained by CVR responses.

intensity on CBF during dynamic exercise is less

● Purpose

The development of the Doppler ultrasonogra-

clear. Therefore, the purpose of the present study

phy technique enabled the measurement of thewas to clarify the effect of exercise intensity onchange in the blood flow in the extra- andthe cerebrovascular response in the ICA and VA

intracranial arteries at rest and during exercise,during dynamic exercise by using the Doppler

i.e., the common carotid artery (CCA), internal

ultrasound technique.

carotid artery (ICA), vertebral artery (VA), and● Methods

middle cerebral artery (MCA). Hellstrom et al.
(1996) demonstrated using the Doppler ultrasoundA total of 10 healthy young adults (1 man, 9that the blood flow in the CCA, ICA, and MCA

women) [age: 22.5 ± 2.5 years (mean ± SD),

increases during graded dynamic exercise, indicating an increase in the blood flow in the carotid

height: 163.0 ± 5.9 cm, body mass: 57.6 ± 5.1 kg,
・
and peak oxygen uptake (V O 2peak ): 37.3 ± 5.4

artery and a large part of the brain. Interestingly,

ml/kg・in-1] participated in this study. The proce-they reported that compared with moderate exer・
cise (60% maximal oxygen uptake (VO2max), heavy
・
exercise (80% VO2max) tended to reduce blood flow

dure consisted of a 5-min baseline period (Rest),in the ICA and MCA. However, the blood flow

upright position, with each stage lasting for 5 min.
・The mean blood flow in the ICA (QICA) and the VA
・(Q VA ) were measured with a high-resolution

followed by exercise with loads of 30%, 50%, and・
70% of the power at with VO2peak occurred in the

response in the VA during dynamic exercise has
not been evaluated and the effect of exercise
60

ϱϬultrasound system (VIVID7 PRO and LOGIQ5, GE%ORRG )ORZ 

Medical Systems, Japan) equipped with a 10 MHz
linear transducer. The mean MAP was measured
non-invasively by photoelectric plethysmography
with a Finometer (Finapres Medical Systems BV,
Netherlands). Furthermore, the heart rate (HR),stroke volume (SV), and thus cardiac output (CO),



ϰϬ

/
s

ΎΎ

ϯϬ

ΎΎ

ϮϬ

ϭϬ

ηη

were determined from the blood pressure wave

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ΎΎ
Ώ
ΎΎ

ηη

ηη

Ώ

ϱϬй

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ZĞĐ

Ϭ

form with the aid of the Modelflow software pro-ZĞƐƚ ϯϬй

gram, which incorporates gender, age, height, andϰϬ

&HUHEURYDVFXODU
5HVLVWDQFH 

weight (Beat Scope 1.1, Finapres Medical Systems
BV, Netherlands). The CO was calculated as SV ×
HR. Ventilatory parameters were determined withan online system for the breath-by-breath method.

● Results and Discussion

Carotid blood flow studies using Doppler ultrasound measurements have been used to evaluate

ϮϬ

/
s

ϭϬ

ηη
η

Ώ

Ώ

Ϭ
ͲϭϬ
ͲϮϬ

changes in the gCBF. Such measurements might



ϯϬ

ZĞƐƚ

ϯϬй

ϱϬй

ϳϬй

ZĞĐ

Fig. III.2.2.2-1 (A) Change (%) in blood flow in the
ICA and VA during dynamic exercise and recovery.
(B) Change (%) in the cerebrovascular resistance in
ICA and VA during dynamic exercise and recovery.
・
Values are means ± SE. 30%, 30% VO2peak; 50%, 50%・・VO2peak; and 70%, 70% VO2peak; Rec, Recovery. *, ##:significantly different from the Rest (P < 0.05). †: significant (P < 0.01) difference between ICA and VA.

be of value when estimating changes in the blood・
flow in the ICA. We observed that QICA increased
・by 〜 12% during exercise with 30% VO2peak andwith a maximum increase of 〜 18% during exer・
cise with 50% VO2peak. However, exercise with 70%・・VO2peak did not further increase QICA compared with・・
the value at 50% V O 2peak . In contrast to Q ICA
・response that leveled off at 70% VO2peak, graded・
exercise significantly increased Q VA withtion, given that there is no evidence to suggest

increasing exercise intensity. Thus, we consideredregional differences in sympathetic and autoregu-

that the blood flow responses during dynamic

latory control in humans brain study. The otherexercise should differ in responses between ICA

mechanism could contribute the difference in theand VA.

CVR in the ICA and VA. First, the difference in

The differential responses of the ICA and VA

the areas of the brain supplied by the ICA and VA

blood flow during dynamic exercise should be

may be a contributory factor. In a previous ani-

mainly explained by the difference in the CVR

mal study, submaximal and maximal exercise

responses. It is possible that there is little sympa-

induced small increases in the vascular resistancethetic and autoregulatory control of the bloodin the regions of the brain that were related toflow and cerebrovascular in the peripheral

motor control and locomotion (spinal cord andbranches of the VA as compared with the periph・
eral branches of the ICA. In this case, Q VA

cerebellum), maintenance equilibrium (cerebellum

passively increased with the MAP and CO during(medulla and pons), which are mainly supplied bydynamic exercise. Nevertheless, this is specula-

the peripheral arteries of the vertebrobasilar sys-and vestibule), and cardiorespiratory control

61tem, as compared with the cortical regions associ-in the CVR in the ICA and VA. However, theated with motor and somatosensory functions

detailed mechanism underlying the differential(frontal cortex), which are mainly supplied by the

CVR responses of ICA and VA are unclear.

peripheral branches of the ICA (Delp et al. 2001).

Further investigation is required to clarify this.

A second, possibility is that two or more opposing

are present in peripheral branches of vertebral-

In conclusion, during dynamic exercise, the・・increase in the QICA had leveled off at 70% VO2peak,・in contrast to a continued increase in the Q VA

basilar system. There may be a sympathetic vaso-

increased with increasing exercise load. This dif-constriction in response to the increase in perfu-

ference might be induced by the difference in thesion pressure, and simultaneously an equivalent

CVR response to graded dynamic exercise.

and offsetting vasodilatory stimuli and substancevasodilatory stimulus resulting from increase neu● References

ronal metabolic release. In this case, the net

Delp MD, Armstrong RB, Godfrey DA, Laughlin MH,
Ross CD, Wilkerson MK : Exercise increases bloodflow to locomotor, vestibular, cardiorespiratory
and visual regions of the brain in miniature swine.
J Physiol, 533: 849-859, 2001.
Hellstrom G, Fischer-Colbrie W, Wahlgren NG,
Jogestrand T : Carotid artery blood flow and middle cerebral artery blood flow velocity duringphysical exercise. J Appl Physiol, 81: 413-418,
1996.

effect is that vascular resistance remains
unchanged as in our result of CVRVA. Third, morphological differences in the two arteries might bedirectly connected with this phenomenon. Within
the cranium, the two VA fuse into the basilar
artery. In contrast, the two ICA independently run
up to the brain. Accordingly, it is considered thatseveral factors may contribute on the difference

62

2.3

発育期の子どもにおける循環機能の発達

定本

朋子，佐藤 耕平，大森芙美子，森山真由美，
岩館 雅子，石田 良恵

Development of cardiovascular function in children
Abstract
To understand the development of cardiovascular functions, we studied age-related changes in cardiac
output, total peripheral resistance, cerebral blood flow and the index of cerebral flow distribution in 207
healthy female children between 10 and 18 years of age. Mean arterial blood pressure (MAP) was measured non-invasively by photoelectric plethysmography with a Finometer. Heart rate (HR) and stroke volume (SV) and cardiac output (CO) were determined from the blood pressure waveform by using Model
flow software program. The blood flow in left common carotid artery (BFCCA) was measured during sitting rest by ultrasonography. The index of cerebral blood flow distribution (%) was calculated as
BFCCA/CO × 100. The total peripheral resistance, an index for changes in vascular growth, was calculated
as MAP/CO. CO began to increase from 11 years and was nearly complete by 15 years. The increase in
CO was due to a significant increase in SV since HR tended to decrease from 10 to 15 years. TPR
decreased also from 10 to 15 years indicating a significant growth in the vascular beds of whole body.
BFCCA gradually decreased from 10 to 15 years and the index of cerebral flow distribution (18 %) was
highest at 10 years and followed by a gradual decline to 15 % at 15 years of age. Over the age of 15
years, the values in CO, TPR, BFCCA and the index of cerebral blood flow distribution were almost stable
and identical to those in adult females. The present data suggested that the development in cardiovascular functions and cerebral flow distribution are accomplished by the age of 15 years in females.

● 研究目的● 研究方法循環機能の発達について知ることは，発育期の子

健康な小学生 5 年生（10 〜 11 歳），6 年生 （11 〜どもの運動を考えるために不可欠である．しかし循

12 歳），中高生（12 〜 18 歳）の合計 207 名の被験者

環機能の発育に関する研究は数少ない（加賀谷,とした．本研究では，座位安静時の循環変数として動2006）．本研究では，心臓および血管機能の発達とい脈血圧（MAP），心拍数（HR），1 回拍出量（SV），心う観点から，心臓のポンプ能力の指標となる心拍出

拍出量（CO）を測定した．また脳血流量の指標とし量と血管床の成長指標として総末梢血管抵抗の変化て，左総頸動脈の血流量（BFCCA）を計測することにしを検討することにした．また中心循環と末梢循環のた．MAP はフィノメーター（Finapres Medical

発達という観点から，心拍出量に対する脳血流量のSystems BV）により測定し，またその指動脈波形か比（脳血流配分）について検討することにした．末ら SV を Model Flow 法を用いて推定し，同じく圧波梢組織のなかから脳を取り上げる理由は，脳血流量形の間隔から HR を算出した．そして SV と HR の積かの発育に関する研究が特に少ないからである

ら CO を算出した．BFCCA の測定には超音波画像診断装（Schöing and Hartig,1996; 1998）．

置（Logiq5，GE Medical Systems）を用いた．総末

本研究の目的は，10 歳から 18 歳における発育期に梢血管抵抗（TPR）は MAP ／ CO の式から，脳血流量

おける心拍出量，総末梢血管抵抗，脳血流量，脳血配分指標（%）は BFCCA ／ CO × 100 の式から算出した．

流配分の変化を検討し，子どもの循環機能の発育過● 結果および考察

程を明らかにすることである．なお本報告では女子の結果について報告する．

HR は小 5（10 歳）から高 1（16 歳）にかけて徐々に減少したが，SV が小 6（11 歳）から高 1（16 歳）
63

Fig. III.2.3-1 Developmental changes in cardiac output (CO), total peripheral resistance (TPR) and cerebral blood flow
(CCA) and index of cerebral flow distribution (CCA/CO*100) from 10 to 18 years of age in female. The horizontal axis
indicates the grade of elementary school (E), junior high school (J), and high school (H). *; p < 0.05, **; p < 0.01.

にかけて急激な上昇を示した．その結果，CO が小 6

末梢血管抵抗），脳血流配分が小学高学年から中学生

から高 1 間において著しく増大した．その後の CO ににかけて発達することが示された．このような結果は有意な変化はみられなかった（Fig. III.2.3-1）．同から，最も発育するこの時期に循環機能を高めるた様に，全身の血管床の発達を示す指標である TPR のめ適切な運動や働きかけが必要であると考えられる．

低下は，小 5（10 歳）から始まり中 3（15 歳）にか

本研究は女子に関する知見であり，今後男子のデー

けてみられた．このような SV および CO の変化に関タを含めた検討が必要である．

する結果は，心エコー法により 8 歳〜 18 歳までの男
女の左心室の拡張期内径と収縮期内径を計測した清● 文水ら（1999）の結果とほぼ一致していた．また HR

加賀谷淳子 : 循環器からみた思春期. 子どもと発育発達,
3: 209-214, 2006．
Malina RM, Roche AF : Manual of physical status andperformance in childhood. Vol. 2. Physical performance, New York, Plenum, 1983.
Schöing M, Hartig B : Age dependence of total cerebral blood flow volume from childhood to adulthood. J Cereb Blood Flow Metab, 16: 827-833,
1996.
Schöing M, Hartig B : The development of hemodynamic in the extracranial carotid and vertebral
arteries. Ultrasound Med Biol, 24: 655-662, 1998.
清水静代, 村岡慈歩, 西田ますみ, 東香寿美, 浅井利夫, 加
賀谷淳子 : 発育に伴う心形態と有酸素能力の変化. 日本体育学会第 50 回記念大会, 体育・スポーツ関連学会連合大会日本運動生理学会第 7 回大会, 1999．

の低下についても先行研究（Malina and Roche
1983）と一致した．BFCCA は小 5 から中 2，3 にかけて減少した．そして中 3 〜高 1 間において有意な増加がみられ，高 1 以降には変化がみられなかった．このような BFCCA の変化は，ドイツ人の脳血流を検討した
先行研究と類似していた（Schöing and Hartig,
1996; 1998）．上述したように，BFCCA は小 5 から中2，3 にかけて減少し，同時に CO が小 6 から高 1 間において著しく増大するため，脳血流配分指標は，小 5で最も高く，中 2 にかけて低下し、中 3（15 歳）ではほぼ成人に近い値を示すことになった．
このように心機能（推定心拍出量），血管機能（総
64

献

3

運動時の筋交感神経活動からみた中枢指令および反射性制御の調節機構
斉藤

満 1）

Analysis of central command and reflex regulation of cardiovascularsystem during exercise with respect to muscle sympathetic nerve activity
Mitsuru Saito■本課題の共同研究者
相澤1）清香 1），神谷厚範 2），蜂矢鉄心 1），岩瀬敏 3）

豊田工業大学，2）国立循環器病センター，3）愛知医科大学

3.1

利き腕，非利き腕運動時の交感神経反応
斉藤

3.2

満，相澤 清香，神谷 厚範

運動時の筋交感神経活動に及ぼすレジスタンストレーニングの効果
斉藤満，蜂矢 鉄心，岩瀬

敏

3.1

利き腕，非利き腕運動時の交感神経反応
斉藤

満，相澤

清香，神谷

厚範

Comparison of sympathetic nerve activity responses between dominant
and nondominant arm
Abstract
The aim of this study was to investigate whether muscle sympathetic nerve activity (MSNA) during
handgrip exercise performed with the dominant (D) and nondominant arm (ND) was different.
Intermittent static handgrip with maximal effort and rhythmic handgrip under the forearm circulationarrest with maximal effort followed by two 2-min post exercise arterial occlusion (PEAO) were used fortest exercises. MSNA was recorded from the tibial nerve by microneurography. MSNA increased during intermittent static exercise while the response was not different between D and ND. During rhythmic handgrip and PEAO, MSNA increased 197% and 369% of resting value for D and 140% and 197%
for ND respectively, and those differences between D and ND was significant. The different MSNA
responses in D and ND may be due to the difference in size of muscle metaboreflex than that exercise
effort.

● 目

た．MSNA はバースト総面積として定量化した．HG

的張力曲線より運動時の作業量を計測した．

左右の手の使い方には差があり，使用頻度は一般

主効果および左右の比較は繰り返しのある分散分に利き腕で高く，大きな力発揮や調節が必要なとき析で検定した．

に用いられることが多い．このような手の使い方の違いは大脳皮質レベルでの差や前腕筋機能，運動時● 結果および考察の交感神経活動反応の差としてみることができる．
本研究では，神経性循環調節の中心的な役割を果た

利き腕，非利き腕の最大 HG 張力はそれぞれ 48 ±す筋交感神経活動（MSNA）を左右のハンドグリッ

2kg，44 ± 2 kg（SD ± SEM）（P ＝ 0.056）であり，

プ運動において比較検討することにより，循環調節

利き腕が高い傾向にあったが差は認められなかった．

に対する中枢性および末梢性の効果を明らかにする
1）運動 1 ：間欠運動ことを目的とした．

間欠 HG 運動のピーク張力，作業量は運動回数とと● 方もに低下したが，MSNA は運動の 1 回から有意に増法

健康な右利き成人男子 16 名を対象とし，2 種類の加し 10 回まで高値を維持した．心拍数は運動開始と運動を行わせた．運動 1 として，中枢指令の左右差をともに増加したが MSNA 反応と同様に 1 回から 10 回確認するため，15 秒間最大努力静的ハンドグリップ

までほぼ一定値を示した（Fig. III.3.1-1）．HG 張力，（HG）運動を 15 秒の休止を挟んで左右交互に 20 回

MSNA，心拍反応ともに左右差は認めなかった．

繰り返す間欠運動．運動 2 として，代謝受容器反射の運動時の MSNA 増加には中枢指令と活動筋反射が比較として動脈阻血下において律動的 HG を 1 分間に関係するが（Mitchell 1990），運動開始直後の活動

40 回，最大努力で実施し，運動後阻血（PEAO）の筋反射の効果は小さい（Hashimoto et al. 1998）．従MSNA を比較した．

って，本研究で用いた 15 秒間の間欠的 HG 運動において，運動回数の増加とともに HG 張力が低下し，筋測定項目は MSNA，HG 張力，心拍数，血圧であっ67

Fig. III.3.1-1 Comparison of muscle sympathetic nerve activity between dominant and nondominant arm during
intermittent static handgrip exercise (left panel) and ischemic rhythmic handgrip exercise and post exercise arterial
occlusion (right panel). ▲: dominant arm, ●: nondominat arm, * p < 0.05 compare to the resting control, # p < 0.05
dominant vs nondominantarm.

応はともに左右差は認められなかった．

機械受容器の刺激が弱まったにもかかわらず MSNA
が最後まで高値を持続した原因として中枢指令の効HG 作業量は左右で差がなかったことから，運動時果が考えられる．他方，代謝受容器反射については，の代謝量に違いがあったとは考えられない．したが間欠運動休止期の MSNA 活動が安静値に戻ったことって，利き腕の代謝受容器反射が高くなった原因にから，代謝受容器刺激の効果は小さい．したがって，は，代謝以外の要因が考えられる．運動時の MSNA

MSNA 増加に対する中枢指令の効果は考えられるが，反応は速筋線維分布の高い筋の収縮時に高くなるこ

左右差はないといえる．また，心拍反応に関してもとから 3），利き腕と非利き腕の筋線維組成が異なるの

左右差はないと考えられる．これらの結果から，交かもしれない．あるいは，利き腕調査の結果，「重い感神経活動に対する中枢指令の効果は随意運動に共ものを持つには利き腕を使う」という回答が多いこ

通する効果を持ち，活動肢の違いによる影響はないとから（Saito 1995），速筋線維の動員が非利き腕運と考えられる．

動より促進された可能性が考えられる．
左右運動時の代謝受容器反射の差には利き腕と非2）運動 2 ：動脈阻血下運動

利き腕の日常的な手の使い方が反映され，この差は動脈阻血下運動のピーク張力は利き腕，非利き腕

中枢より末梢レベルで生じる可能性の高いことが示がそれぞれ 40 ± 2 kg，35 ± 1 kg，仕事量が 880 ± 8

唆される．

kg ／分，760 ± 45 kg ／分で，左右差は認められなか
● 文

った．

献

Hashimoto I, Miyamura M, Saito M : Initiation ofincrease in muscle sympathetic nerve activity
delay during maximal voluntary contraction. Acta
Physiol Scand, 164: 293-297, 1998.
Mitchell JH : Neural control of the circulation during
exercise. Med Sci Sports Exerc, 22: 141-154, 1990.
Saito M : Differences in muscle sympathetic nerve
response to isometric exercise in different muscle
groups. Eur J Appl Physiol, 70: 26-35, 1995.

運動の後半 30 秒間の TSNA は利き腕運動が安静値
より 344 ％，非利き腕運動が 192 ％増加した．PEAO
2 分間の MSNA は利き腕，非利き腕がそれぞれ安静
値より 369 ％，197 ％増加した．運動および PEAOの MSNA 増加率は非利き腕より利き腕運動が高かった（Fig. III.3.1-1）．運動時の心拍数は高まったが，
PEAO では安静値まで低下した．心拍および血圧反

68

3.2

運動時の筋交感神経活動に及ぼすレジスタンストレーニングの効果
斉藤

満，蜂矢

鉄心，岩瀬

敏

Effect of resistance training on the muscle sympathetic nerve activity
during handgrip exercise
Abstract
To reveal the effect of resistance training on central and muscle reflex control of muscle sympathetic
nerve activity (MSNA) during exercise, MSNA was investigated pre- (PRE), post-training (POST) and4 weeks detraining after resistance training using fatigue-inducing handgrip exercise and post-exercise forearm occlusion (PEFO). Eighteen volunteers underwent forearm training, which contained 30
maximal effort, 10-s-duration static handgrips 4 days per week for 4 weeks. MSNA was recorded
from the tibial nerve by microneurography. Maximal handgrip force increased at POST. The MSNA
response during fatigued handgrip also increased at POST, as compared to PRE (52 ± 5 vs. 40 ± 4
bursts/min (mean ± SEM) respectively. However, at detraining, MSNA activity returned to PRE level(44 ± 5 bursts/min; p < 0.0001). The MSNA response during PEFO was constant throughout the experiment. The results indicate that an increased MSNA response after resistance training is likely to be
the result of central command rather than the muscle metaboreflex.

● 目

確かめる目的で最大 HG 張力（MVC）の 33 ％張力が的

身体トレーニングは心拍出量の増大や筋血流量の維持できなくなるまで持続する静的 HG とこれに続く増加，運動時の心拍数や血圧の低下を伴う．これら

2 分間の運動後阻血を用いた．運動テストはトレーニの適応変化には交感神経活動の変化が関係すると考ング前，トレーニング後，およびトレーニング停止 4

えられる．これまで，持久トレーニングに対する運週後に実施した．

動時の筋交感神経活動の反応は低下することが報告

測定項目は MSNA，心拍数，血圧，HG 張力であっされているが，レジスタンストレーニング（RT）にた．MSNA は脛骨神経より記録，1 分間のバースト発

関しては一定の見解は得られていない（斉藤 2004）．

射数（BF）で表した．心電図は胸部双極誘導により，

本研究では，RT は末梢活動筋だけでなく上位中枢か

血圧はフィナプレスにより測定した．

らの中枢指令にも影響するとの仮説に基づいて，トトレーニング前後の最大握力，仕事量，運動およ

レーニング前後の運動時の筋交感神経活動（MSNA）

び運動後阻血下の MSNA，心拍数，血圧反応は繰り反応からレジスタンストレーニングの効果について返しのある分散分析で検定し，下位検定には検討した．

Wilcoxon test を適用した．

● 方● 結果および考察

法1）ハンドグリップ張力

健康な成人男子 18 名を対象とし，9 名は非利き腕を用いた RT を実施，残り 9 名は対照群とした．トレ

トレーニング群の最大 HG 張力はトレーニング後

ーニングは 10 秒間の最大努力静的ハンドグリップ

17.6 ％（P ＜ 0.05）増加し，トレーニング停止 4 週（HG）運動を 10 秒間の休憩を挟んで 10 回繰り返す後も有意に高い HG 張力が維持された．これに対し，手順を，1 日 3 セット，週 5 回，4 週間実施した．

対照群の最大 HG 張力はトレーニング前，後，トレーニング停止 4 週後の期間に有意な変化は認められなか

テスト運動：中枢指令と代謝受容器反射の効果を
69

Fig. III.3.2-1 Comparison of the changes in burst frequency (dBF) during fatiguing handgrip exercise (HG) and post
exercise forearm occlusion (PEFO) at pre-training (B), 1 week post-training (A) and 4 weeks post-training (D) in the
trained (left panel) and control group (right panel). * p < 0.05 compared to the pre-training or 4 weeks post-training
values.

変化は認められなかった．

った．
6 週以下の短期間の RT に伴う筋力向上は筋収縮に筋反射が反映される運動後阻血時の MSNA 反応が動員される運動単位数の増加が主要因とされる

トレーニング期間を通して一定であったことから，（Sale 1988）．今回は 4 週間の最大努力 HG 運動を用運動時の MSNA 反応の増大には中枢指令の効果が大いたことから，中枢指令を含めた運動神経機能の向きく関与した可能性が推察される．本結果は，上が筋力増加の主要因と考えられる．トレーニング

MSNA 反応は RT の影響を受けないか低下するとされ停止後も高い張力が持続した背景には，高い運動神

るこれまでの結果（斉藤 2004）とは異なった．おそ

経機能が維持されたためと考えられる．

らくこの背景にはトレーニングに用いた運動強度の違いが影響したと考えられる．これまでの RT 研究では 30 ％ MVC 程度の負荷を用いているが，本研究で

2）運動時の生理反応
Fig. III.3.2-1 に 33 ％ MVC 張力が維持できなくな

はより高強度の最大努力筋収縮を用いた．このことるまで持続する HG 運動とそれに続く動脈阻血時のが，中枢指令に対する効果を有意にしたと推察されMSNA 反応の結果を示す．運動時の MSNA 反応はトる．

レーニング後有意に増加し，トレーニング停止 4 週後

本結果から，高強度レジスタンス運動は運動時のにはトレーニング前値に戻った．しかし，代謝受容中枢指令に影響を及ぼすが，代謝受容器反射への効器反射が反映される運動後阻血時の MSNA 反応は研

果は小さいことが明らかとなった．

究期間を通して一定であり，トレーニング効果は認● 文

められなかった．対照群の MSNA 反応は運動時およ献斉藤 満 : 運動および安静時の交感神経活動に対する身体トレーニングの効果− Microneurography による研究−. 東海保健体育科学, 26: 1-8, 2004.
Sale DG : Neural adaptation to resistance training.
Med Sci Sports Exerc, 20: S135-S145, 1988.

び運動後阻血時ともに研究期間を通してほぼ一定であった．トレーニング群，対照群ともに運動時，運動後阻血時の心拍数，血圧反応は研究期間を通して70

4 Effects of Different Exercise Modalities on
Skeletal Muscle and Prefrontal Cortex
Oxygenation Monitored by Near Infrared
Spectroscopy
Valentina Quaresima1）■ Co-worker（本課題の共同研究者）
Marco Ferrari 1）

1）

Department of Health Sciences, University of L’Aquila

4.1

Metabolic pattern of the leg skeletal muscle groups during very short and intense isometric
exercise

4.2

Acute effects of whole body vibration exercise (an alternative exercise intervention) on gastrocnemius medialis and vastus lateralis oxygenation

4.3

Biceps brachii myoelectric and oxygenation changes during static and sinusoidal isometric exercises

4.4

Auxiliary muscles oxygenation during a rowing exercise

4.5

Effects of handgrip exercise on frontal cortex oxygenationEffects of Different Exercise Modalities on Skeletal Muscle
and Prefrontal Cortex Oxygenation Monitored by Near
Infrared Spectroscopy
Valentina Quaresima
Abstract
The research activity has mainly been focused on the study of the vascular and metabolic mechanism regulating the cerebral and muscular oxygenation and metabolism by using near infrared spectroscopy (NIRS) and functional NIRS with a multidisciplinary approach. In particular, the results want
to give a contribution for: 1) understanding the mechanism of the muscle fatigue during exercise andthe kinetics of the transition rest-exercise, and 2) supporting the hypothesis that prefrontal/frontal lobe
plays a role in maintaining strength of the forearm muscles and ensuring a correct execution of motor
tasks which require a fine motor control and coordination.

4.1 Metabolic pattern of the leg skeletal muscle groups during very short and intense isometric exercise
The purpose of the study was to assess ondrop immediately after the exercise end. Fig.

heavy-resistance strength trained and untrained

III.4.1-1 right panel shows the typical TOI patternsubjects the vastus lateralis (VL) muscle O2 satura-of a sedentary subject. TOI was stable only overtion (TOI) time course in response to a brief maxi-

the first 1.5-2.0 s of the exercise; thereafter, TOI

mal voluntary isometric contraction.

started to decline. The time to the onset of TOI
decrease was consistently shorter in the untrained● Methods

than in the trained subjects. In all the trained sub-Trained (n = 10) and untrained (n = 10) sub-jects, TOI started to decrease 0.5-1.0 s after thejects performed a trial consisting of: 1) a 1-min

end of the contraction. After the end of the exer-

rest period, 2) a leg press exercise of about 3 s,

cise, TOI transiently decreased reaching its mini-and 3) a 2-min recovery period. The leg press

mum value in about 15 and 10 s in the trained

exercise consisted of a static maximal voluntary

and untrained subjects, respectively.

contraction using only the dominant leg. The leg

In conclusion, the results of this in vivo studypress strength was recorded using a load cell. The

demonstrated that the aerobic oxidative metabolic

TOI was measured by NIRS (NIRO-300; 0.17 s

system occurs earlier in untrained than insampling time).

strength power trained subjects upon a very shortisometric high-intensity exercise. From this point● Resultsof view, NIRS could be employed to: 1) profile inFig. III.4.1-1 left panel shows the VL oxygena-each muscle group the aerobic and, indirectly,

tion pattern observed in a athlete. TOI wasanaerobic energy system contribution during evenunchanged over the 3-s exercise and started tosingle brief maximal exercise, and 2) follow the73

Fig. III.4.1-1 Left: Time course of leg force output (upper panel), and vastus lateralis TOI and tHb (lower panel)
before, during, and after static leg press exercise. Right: Time course of leg force output (upper panel), and vastus
lateralis TOI and tHb (lower panel) before, during, and after static leg press exercise.

alteration of the profile as function of specific aer-

The details of this study are reported in the pre-obic or anaerobic training or rehabilitation pro-vious study (Cettolo et al. 2007).

grams.

4.2 Acute effects of whole body vibration exercise (analternative exercise intervention) on gastrocnemius
medialis and vastus lateralis oxygenation
Whole body vibration (WBV) has been promoted

In most of the vibrating plates currently available

as an alternative exercise intervention able toon the market, vibration frequency is the only

affect neuromuscular performance in young andparameter that can be changed, and notwithstand-old individuals. This new neuromuscular training

ing manufacturers’ instructions, there is no real

method consists of squatting on specially designed

evidence to suggest the optimal training frequency

plates producing sinusoidal oscillations of different

to be adopted. Therefore, the determination of thefrequencies and amplitudes. It has been suggested

effects of different WBV frequencies on muscle

that the sinusoidal vibration generated by the plate

oxidative metabolism represents an important

oscillations elicits reflex muscle activity in the

aspect to be analysed in order to provide guide-lower limbs mainly via monosynaptic pathways.

lines for WBV training programs. Considering the

Muscle activation during squat exercise on vibrat-lack of information regarding muscle oxygenation

ing surfaces is still a controversial topic. Vibration

during WBV exercise, we aimed at investigating

exercise intensity can be determined by manipu-

the effects of different WBV frequencies on oxy-lating two parameters: amplitude and frequency.

genation of VL and gastrocnemius medialis (GM)74

muscles during static squatting in sedentary andment by time interactions in both TOI and Δ total

physically active healthy males. We hypothesized

hemoglobin volume (tHb) in VL and GM muscles.

that vibration would determine a decrease in mus-A significant main effect of time in TOI of both VL

cle oxygenation in GM and VL greater than control

and GM muscles was identified (P < 0.001). TOI

condition, due to an increase in muscle activation.

significantly decreased from baseline in VL in

Furthermore, we hypothesized that the oxygena-

control conditions after 90 s and 110 s (P < 0.05

tion of GM muscle, due to its proximity to theand P < 0.05, respectively), in 30 Hz condition

vibration source, would be more affected than theafter 110 s (P < 0.01), in 40 Hz condition after 30

oxygenation of VL during WBV.

s (P < 0.05), and significantly increased after 30 s
in 50 Hz condition. GM TOI was found to be sig-

● Methods

nificantly lower than baseline at 60 s (P < 0.05),

Ten subjects were sedentary individuals and ten

90 s (P < 0.01) and 110 s (P < 0.01) in control con-were athletes practicing different sports. All sub-dition, and at 110 s (P < 0.05) in 30 Hz condition.

jects completed 4 trials (Control, 30 Hz, 40 Hz

In conclusion, this study showed that WBV

and 50 Hz WBV) in a randomised-controlled

exercise with frequencies of 30, 40 and 50 Hz andcross-over design. The trials consisted of static

small amplitudes does not affect muscle oxygena-

squatting on a vibrating platform for a total dura-tion of VL and GM muscles to a higher degreetion of 110 s. Muscle oxygenation status wasthan a non-vibration condition.
The details of this study are reported in the pre-recorded with NIRS (NIRO-300).

vious study (Cardinale et al. 2007).
● Results

The data analysis revealed no significant treat-

4.3 Biceps brachii myoelectric and oxygenation changes
during static and sinusoidal isometric exercises
MVC and sinusoidal (SIN) at 40 ± 20 and 60 ±Surface myoelectric signal changes occurring

20% MVC.

during sustained isometric contractions have been
extensively studied with quantitative surface elec-● Results

tromyography (sEMG) and are described bymeans of some sEMG global variables in time andResults clearly indicate the presence of an ini-frequency domain (such as the median powertial fast phase of muscle O2 desaturation followed

spectral frequency).

by a slow phase, regardless of the contraction

The purpose of this work was to combine NIRS

modality. Moreover, the initial rate of muscle O2

and sEMG techniques to analyze the relationshipdesaturation was related to the level of force out-

between modifications of sEMG parameters andput (R = 0.92), but it was independent on the con-the underlying metabolic status of the exercising

traction modality (P < 0.05). Similarly, changes inbiceps brachii muscle. This relationship was test-sEMG parameters were related to force level

ed under different isometric contraction modali-(Conduction Velocity - CV vs. Force: R = 0.87;

ties, namely static (ST) at 20, 40, 60 and 80%

sEMG Median Frequency - MDF vs. Force: R =75

0.86). The high correlation found between CV-high force levels is influenced by the type of

MDF and Tissue Oxygenation Index (TOI) slope (Ractive motor units and not from the type of iso-

= 0.73 and 0.72, respectively) suggests a strong

metric exercise modality.

relationship between NIRS and sEMG data.

The details of this study are reported in the pre-Finally, this study indicates that muscle O 2

vious study (Felici et al. 2007).

demand during isometric contractions from low to

4.4 Auxiliary muscles oxygenation during a rowing exercise
The aim of this study was to investigate the● Results

contribution of the auxiliary muscles, utilized to

The slow component amplitude, in absolute val-sustain the subject’s position on the ergometer, toues resulted statistically lower for rowing (343.9 ±the oxygen uptake slow component phenomenon.

232.2 ml ・ min -1) than for arms (795.6 ± 405.6
ml ・ min-1) and legs (695.8 ± 292.8 ml ・ min-1) exer-● Methods

cise modes. The same result was found when theThree tests were performed at the same severe

slow component amplitude was calculated as per-relative intensity on a rowing ergometer: a stan-centage of VO2 peak (7.1 ± 5.0 % for Rowing; 17.2 ±dard rowing exercise test, a rowing exercise per-6.6 % for Arms; 17.3 ± 6.4 % for Legs). The lower

formed with the arms and one performed with theslow component amplitude measured for the rowing

legs only. During the three exercise modalities

exercise mode with respect to both arms and legs

oxygen uptake, local oxyhemoglobin saturation

modes, demonstrates that the auxiliary muscles

and surface electromyography signals of theinvolved in the exercise contribute to the increasing

trapezius and vastus lateralis muscles were meas-

energetic cost due to the slow component.

ured.

The details of this study are reported in the previous study (Demarie et al. 2008).

4.5 Effects of handgrip exercise on frontal cortex oxygenation
Neuroimaging studies have reported a propor-

The purpose of the study was to investigate thetional relationship between cortical signals andtime course of the oxygenation of the frontal cor-exerted joint force in humans, indicating thattex (FC) during a handgrip task performed sepa-

brain signals are positively correlated to voluntary

rately with right and left hand.

efforts, as a high level of effort is required for● Methods

exerting greater muscle force. The effect ofdiverse skeletal muscle exercises on brain cortex

Mean (± SD) age, height, and body mass of theoxygenation, and in particular on ipsi- and con-

12 right-handed subjects were 27 ± 4 y, 177 ± 5

tralateral prefrontal cortex (PFC) has not been

cm and 76 ± 12 kg, respectively. Participants

fully clarified yet.

completed two separate experimental sessions

76performed at the same time of day and separated

lecting ones were assembled into a specificallyby a minimum period of 24 hours. In the first ses-designed flexible probe holder (Elastomer

sion each subject performed 5 maximal voluntary

LCG20R, Chiorino S.p.A, Italy) ensuring that thecontractions (MVC) for each hand. The partici-

position of the 10 optodes, relative to each other,pant was instructed to squeeze a handgrip device

was fixed. The probe holder consisted of two mir-with each hand to his maximum ability while stay-ror-like units (10 × 8 cm each) held together by aing in a supine position. Each MVC lasted approx-

flexible junction. The 8 fNIRS measurement points

imately 2-s with a 120-s rest period between tri-(channels) were defined as the midpoint of theals. In the second session, two identical rhythmiccorresponding detector-illuminator pairs (distancehandgrip exercises at MVC were executed, one

set to 3 cm). The optodes were inserted into theexercise for each hand. The exercise consisted of:elastomer probe holder through fiber optical bun-a 5-min rest condition, a 5-min rhythmic exercise

dle socket connectors, and then placed over the(100 MVCs; 2-s contraction and 1-s relaxation)

forehead of both hemispheres. The probe holder

and a 5-min recovery. Fifteen min later, the same

was fixed to the head by a velcro brand fastener,

exercise was repeated with the other hand.

adapting them to the individual size and shape ofHandgrip force was measured by a system con-the different heads. This flexible probe holder andsisting of a handgrip device and a digital handgrip

its position on the head allowed the creation ofanalyzer (MIE, Medical Research, UK). Subjects

stable optical contact with the forehead’s scalp

exerted handgrip contractions looking at a traffic

for all optodes. The channels 8, 5, 4, and 1 corre-

light generated by the handgrip analyzer software.

sponded to Fp1, AF3, Fp2, and AF4 respectively,

The visual stimulus was projected towards theaccording to the extended international 10/20 sys-ceiling over the subject by a video-projector.

tem of electrode placement. The quantification of

When the traffic light was green the subject hadconcentration changes, expressed in ΔμM, wasto exert his maximum force upon the transducer

obtained by including an age-dependent constantand maintain the force at his peak until the traffic

differential pathlength factor (DPF) (5.13 ＋ 0.07 ×light changed to red. Upon a red traffic light sig-

age0.81). Data were acquired at 1 Hz and trans-

nal, the subject had to relax so that did not exert

ferred online from the NIRO-200 monitor to aany force upon the transducer. The subject

computer.

repeated this process for each cycle following theStatistical analyses were performed using thetraffic light prompts. The sampling rate for force

SigmaStat 3.5 package (Systat Software Inc.,

data was 33 Hz. Heart rate (HR) was measured by

Richmond, CA). The average values werea pulse oximeter equipped with a ear lobe probe

expressed as mean ± SD. The criterion for signifi-(Nellcor N600, USA).

cance was P < 0.05.

In order to determine theA 8-channel fNIRS system (NIRO-200 withsignificance of [O2Hb], [HHb] heart rate and force

multi-fiber adapter, Hamamatsu Photonics K.K.,

changes one way repeated measures analysis ofJapan) was used to measure frontal changes invariance (one way RMANOVA) and post-hoc[O2Hb] and [HHb]. Two optical fiber bundles (2.5

Tukey test were performed. For [O 2Hb], [HHb]m length; 3 mm diameter) carried the light to theand HR the control condition was the mean value

left and the right frontal cortex; whereas eightof the 30-s rest condition.

optical fiber bundles of the same size (4 for eachTo examine the effect of the handgrip exerciselobe) collected the light emerging from the frontal

on [O2Hb] and [HHb] changes, areas under theareas. The two illuminating bundles and the col-curve (AUCs) were computed using the curves

77Fig. III.4.5-1 Force tracings; heart rate tracing and FC oxygenation changes during right and left handgrip exercise(left and right panels, respectively). Although the force was decreasing and the HR was constantly high during theexercise period, FC was found activated (increase in O2Hb and a concomitant decrease in HHb) throughout theinvestigated frontal region. A higher activation was found ipsilateral to the exercising hand. The horizontal lines
indicate the significance interval. Means ± SD.

over the time associated with the exercise. This

The AUC of the rest period was subtracted toanalytic approach is well established in the quan-

the AUC of the exercise period and resulting datatification of concentration change over time and it

were analyzed by using a three-way analysis ofwould be maximally sensitive to task-related

variance model using post hoc Tukey test tochanges on [O2Hb] and [HHb] regardless of thedetermine the significance of individual changes

shape of the response profile.

between three experimental factors[hemisphere78Fig. III.4.5-2 Laterality index for the [O2Hb] and [HHb] changes of the 12 subjects for the right (filled circle) andleft (empty circle) hand exercises. The two dashed lines indicate the significant thresholds for the two exercises.

HR and O2Hb changes suggest that the observed(2)× channels (4)× task execution(2)].
In order to determine left/right asymmetry ofFC oxygenation changes were task related. The

FC activity during the handgrip task, a laterality

laterality index for [O2Hb] changes (the most sen-index (LI) for the [O2Hb] concentration changes

sitive parameter to cortical blood flow changes) is

was calculated using the formula (R-L)/(R+L),

reported in Fig. III.4.5-2. The amplitude of [O2Hb]

where R and L indicated the sum of the AUC val-changes was found greater in the FC ipsilateral toues of the right side (channels 1, 2, 3, 4) and thethe exercising hand with respect to the contralat-

left side (channels 5, 6, 7, 8). LI > 0 indicateseral one.

greater activity of the right FC, while LI < 0 indi-

These results confirm the previous ones

cates greater activity of the left FC. When the acti-

obtained by others using fMRI and provide fur-vation of one side was 1.4 times greater than thatther evidence that FC plays a role in maintaining

one found on the other side, the absolute value ofstrength of the forearm muscles and ensuring a

LI became greater than 0.15. One side predomi-

correct execution of motor tasks which require anance was arbitrarily defined as the absolute LI

fine motor control and coordination.

greater than 0.15.
● References

The summary of the study is reported in Fig.

Calvisi V, Angelozzi M, Franco A, Mottola L,
Crisostomi S, Corsica C, Ferrari M, Quaresima V :Influence of whole-body vibration static exercise
on quadriceps oxygenation. Adv Exp Med Biol,
578: 137-141, 2006.
Cardinale M, Ferrari M, Quaresima V : Gastro-cnemius medialis and vastus lateralis oxygenation
during whole body vibration exercise. Med Sci
Sports Exerc, 39: 694-700, 2007.

III.4.5-1. A significant progressive decline (up to
about 60%) of force was observed over the exercise duration. The so-called cortical activation ofboth frontal areas (ipsi and contralateral) was
observed in all subjects during rhythmic maximal
handgrip exercise. The mismatched patterns of79

e1-11, 2009.
Mottola L, Crisostomi S, Ferrari M, Quaresima V :Relationship between handgrip sustained submaximal exercise and prefrontal cortex oxygenation.
Adv Exp Med Biol, 578: 305-309, 2006.
Quaresima V, Crisostomi S, Mottola L, Angelozzi M,
Franco A, Corsica C, Calvisi V, Ferrari M : Vastus
lateralis metabolic response to explosive maximal
isometric leg press exercise oxygenation. Adv Exp
Med Biol, 578: 167-172, 2006.

Cettolo V, Ferrari M, Biasini V, Quaresima V : Vastus
lateralis O2 desaturation in response to fast andshort maximal contraction. Med Sci Sports Exerc,
39: 1949-1959, 2007.
Demarie S, Quaresima V, Ferrari M, Billat V, Sbriccoli
P, Faina M : Auxiliary muscles and slow component. Int J Sports Med, 29: 823-832, 2008.
Felici F, Quaresima V, Fattorini L, Sbriccoli P, Filligoi
GC, Ferrari M : Biceps brachii myoelectric andoxygenation changes during static and sinusoidal
isometric exercises. J Electromyogra Kinesiol, 19:80

5 Technical Developments of Multi-channel Nearinfrared Devices for Studying Oxygenation and
Hemodynamics in Brain Cortex and Skeletal
MuscleMarco Ferrari1）■ Co-worker（本課題の共同研究者）
Valentina Quaresima 1）

1）

Department of Health Sciences, University of L’Aquila

5.1

Test a 31-channel near infrared spectroscopy-continuous wave imager

5.2

Test a 8-channel near infrared spectroscopy-continuous wave imager

5.3

Test a 8-channel time-resolved imager

5.4

Prepare two review articles on NIRS technical developments and applications

5.5

Contribute to the refinement of NIRS muscle and brain measurements

Technical Developments of Multi-channel Near-infrared
Devices for Studying Oxygenation and Hemodynamics in
Brain Cortex and Skeletal Muscle
Marco Ferrari
Abstract
The research activity has mainly been focused on the development and application of near infrared
spectroscopy (NIRS) or imaging (NIRI) in different fields of medicine including sports medicine, cognitive neuroscience and psychiatry. In particular, 1) specific probe holders were designed and realized
for measuring oxygenation changes at cortical frontal lobe level of both hemispheres, 2) a software fordata handling and statistical analysis was developed/tested, and 3) research efforts were made on therefinement of NIRS muscle/brain measurements and data analysis.

5.1 Test of a near infrared spectroscopy-continuous wave
imager (NIRStation 16, Shimadzu)
Thanks to relatively low cost, simplicity and

the NIRS-CW imager (NIRStation 16, Shimadzu)

overall robustness, near infrared spectroscopy-(http://www.med.shimadzu.co.jp/products/om/01.

continuous wave (NIRS-CW) systems have beenhtml) was utilized for investigating the effect of an

widely used not only in basic research, but also in

exhaustive handgrip exercise on the oxygenation

clinical applications including tissue oximetry andof the frontal cortex. The subject (with eyes

functional brain/muscle imaging. Recently, sever-closed) was sitting and, when requested, exerted

al groups began to use multi-channel NIRS-CW

his maximum effort grasping a builder grip withimaging systems that allow, with high temporal

the right hand.

resolution (up to 10 Hz), the generation of images● Results

of a large area of the subject’s head and muscle
and, thereby, the production of maps of cortical

A cortical activation (decrease in deoxy-hemo-

and muscle oxygenation changes. Unfortunately

globin (HHb) accompanied by an increase in oxy-

few imagers are commercially available and they

hemoglobin (O 2Hb)) was observed over the 31

are quite expensive.

measurement points in the right and left frontal
cortex (source-detector distance: 3 cm). The high-● Methods

est increase in O2Hb was found in the measure-In the framework of the project, two imagers

ment point #3 of the left frontal cortex. The

produced by Japanese companies (Shimadzu and

NIRStation 16 is not commercially available out-

Hamamatsu), were tested. During a visit in Tokyo,

side Japan.

83

5.2 Test of a 8-channel near infrared spectroscopy-continuous wave imager (Hamamatsu)
A 8-channel-NIRS-CW imager (NIRO-200 with ato the 8 channels) are defined as the midpoint ofmulti-fiber adapter, Hamamatsu; http://jp.hama-

the corresponding detector-illuminator pairs (dis-matsu.com/resources/products/sys/pdf/eng/e̲niro

tance set to 3 cm) (Fig. III.5.2-2). The optodes are

200.pdf) was installed in our laboratory in 2006.

inserted into the elastomer probe holder throughThis is the only system operating in Europe.

fiber optical bundle socket connectors, and thenProbe holders, dedicated for carrying out corti-

placed over the forehead of both hemispheres.

cal oxygenation measurements over the frontal

The probe holder can be fixed to the head by alobe of both hemispheres, were custom made.

velcro brand fastener, adapting them to the indi-

Two optical fiber bundles (2.5 m length; 3 mm

vidual size and shape of the different heads.

diameter) carry the light to the left and the rightA software was developed and tested for thefrontal cortex; whereas eight optical fiber bundles

data handling and statistical analysis. The possi-of the same size (4 for each lobe) collect the lightbility to adapt the software “Functional Opticalemerging from the frontal areas. The two illumi-

Signal Analysis (fOSA)” developed by thenating bundles and the collecting ones were

“Department of Medical Physics and Bioengine

assembled into a specifically designed flexible

ering of the University College” of London wasprobe holder (Elastomer LCG20R, Chiorino S.p.A,

also investigated.

Italy) ensuring that the position of the 10 optodes,

This instrumental set up has been utilized inrelative to each other, was fixed (Fig. III.5.2-1).

two cognitive neuroscience studies (Curcio et al.

The probe holder consists of two mirror-like units

2005; Quaresima et al. 2009) and in other ones as(10 × 8 cm each) held together by a flexible junc-

stated in the report by Quaresima.

tion. The 8 fNIRS measurement points (associatedFig. III.5.2-1 Schematic drawing of the flexible probe holder.

84

Fig. III.5.2-2 Eight measurement points (channels, Ch) over the frontal lobe. S: source; D: detector.

5.3 Test of a 8-channel time-resolved imager (Politecnico,Milan, Italy)
The key limitation of NIRS-CW is the coupling

resolution (200 ms) and a fast image reconstruc-between the absorption and the scattering coeffi-tion/data analysis. The instrument was used forcient causing the lack of quantitative assessment.

monitoring spatial changes in calf oxygen satura-

The simultaneous estimation of both absorption

tion (SO2) during dynamic plantar flexion exercise

and scattering can be achieved by NIRS-time(Torricelli et al. 2004). The same system was uti-

resolved (NIRS-TR) systems, which deliver ultra-

lized to investigate the bilateral PFC oxygenation

short laser pulses into tissue and record the time

responses to a letter-fluency task (Quaresima et al.

distribution of diffusive photons. In the past, for2005). The cross-subject mean values of PFC SO2

both technological and financial constraints,

were 68.8 ± 3.2% (right) and 71.0 ± 3.6% (left),

NIRS-TR systems have grown on a complex labo-

and of tHb were 69.6 ± 9.6 μ M (right) and 69.5 ±ratory scale, yet, in recent times, they have

9.9 μ M (left). The typical cortical activation

evolved towards compact and portable instru-

response to the cognitive task was observed atments. Up to now, such systems have not beeneach measurement point. O2Hb is the most sensi-

commercially available either on the market or attive indicator of increases in cerebral blood flow

the research and laboratory stage.

(neurovascular coupling) and the direction of the

In collaboration with Politecnico of Milanchanges in HHb is determined by the oxygenation(Italy), a compact eight-channel NIRS-TR system

and volume of the venous blood.

was developed for the non-invasive measurement

The same system was used to monitor the opticalof tissue oxygen saturation and total hemoglobin

response following a motor task (finger opposition,

volume (tHb). The system has a high temporal

3 Hz) (Contini et al. 2006). The Fig. III.5.3-1 (left85

Fig. III.5.3-1 Panel A) Time course of changes in O2Hb (open symbols) and HHb (filled symbols) of the left motor
area during the exercise performed with the right hand (triangle) and with the left hand (square). The vertical lines
represent the task interval.
Panel B) Grey level maps representing changes in O2Hb (top row) and HHb (bottom row) over the left motor area
cortex during the baseline period (left column), the finger opposition task performed with the right hand (middle
column), and the recovery period (right column).

panel) shows the time course of the changes inand their application in functional imaging studies

O2Hb and HHb for a single detection channel. The

will serve not only to definitely set its potentiality,

grey level maps of O 2 Hb and HHb changes

but also as a feedback to the development of(obtained by interpolating the results from the eight

improved NIRS-CW set-ups for next-generationcollection points) is shown in the right panel. As it

optical imaging devices. In the future we want towould be expected, during the task, the activatedcontinue in giving a contribution to the develop-area is revealed by an increase in O2Hb (black area

ment of multi-channel NIRS systems for betterin the central image of the upper line) and by astudying oxygenation and hemodynamic changes

concomitant decrease in HHb (white area in thein brain cortex and skeletal muscle during differ-central image of the lower line).

ent challenges.

The development of improved NIRS-TR systems

5.4 Preparation of two review articles on NIRS technicaldevelopments and applications
Two review articles (Hamaokaet al. 2007; Wolfcle clinical applications. The article summarizes

et al. 2007) were written to give a contribution to

the main characteristics of the present commer-

the Special Section of the Journal of Biomedical

cially available NIRS and NIRI instrumentation.

Optics entitled: “Pioneers in Biomedical Optics forMoreover, it discusses strengths and limitations.
The second one (Wolf et al. 2007) highlights thehonoring Professor Frans F. Jobsis of Duke

progress that has been made in developing andUniversity” (Delpy et al. 2007).
The first one (Hamaoka et al. 2007) reports theadapting NIRS and NIRI technologies for evaluat-

progress of the in vivo NIRS and near infrareding skeletal muscle oxygen dynamics and oxida-

imaging (NIRI) instrumentation for brain and mus-tive energy metabolism. NIRS measurements have86

been extended to resting, ischemic, localized

health conditions, including patients with chronic

exercise, and whole body exercise conditions. In

heart failure, peripheral vascular disease, chronic

addition, the review article describes the applica-

obstructive pulmonary disease, varying muscle

tion of NIRS to the study of a number of chronic

diseases, spinal cord injury, and renal failure.

5.5 Contribution to the refinement of NIRS muscle measurements
Delpy DT, Ferrari M, Piantadosi CA, Tamura M :Pioneers in biomedical optics: special section
honoring professor Frans F. Jobsis of Duke
University. J Biomed Opt, 12: 062101, 2007.
Ferrari M, Cettolo V, Quaresima V : Light sourcedetector spacing of near-infrared-based tissue
oximeters and the influence of skin blood flow. J
Appl Physiol, 100: 1426-1427, 2006.
Hamaoka T, McCully KK, Quaresima V, Yamamoto K,
Chance B : Near-infrared spectroscopy/imaging
for monitoring muscle oxygenation and oxidative
metabolism in healthy and diseased humans. J
Biomed Opt, 12: 062105, 2007.
Quaresima V, Ferrari M : Evaluation of skin bloodflow contribution to the non-invasive measurement of muscle oxygenation by near infrared
spectroscopy. J Physiol Sci, 56: 267-268, 2006.
Quaresima V, Ferrari M : Quantification of calf oxygenation in paraplegic patients during passive leg
movement. Med Sci Sports Exerc, 38: 189, 2006.
Quaresima V, Ferrari M : Quantification of quadriceps
O 2 desaturation in response to short sprint
cycling. Med Sci Sports Exerc, 39: 1205, 2007.
Quaresima V, Ferrari M : Clinical significance of cerebral oxygenation during exercise in patients withcoronary artery disease. Circ J, 73: 388, 2009.
Quaresima V, Ferrari M, Torricelli A, Spinelli L, Pifferi
A, Cubeddu R : Bilateral prefrontal cortex oxygenation responses to a verbal fluency task: amultichannel time-resolved near-infrared topography study. J Biomed Opt, 10: 11012, 2005.
Quaresima V, Giosuè P, Roncone R, Casacchia M,
Ferrari M : Improved presentation of prefrontal
cortex dysfunction evidenced by functional nearinfrared spectroscopy: individual responses ofcortical oxygenation to cognitive tests. Psychi-atr
Res : Neuroimaging, 2009 (in press).
Torricelli A, Quaresima V, Pifferi A, Biscotti G,
Spinelli L, Taroni P, Ferrari M, Cubeddu R :Mapping of calf muscle oxygenation and haemoglobin content during dynamic plantar flexion
exercise by multi-channel time-resolved nearinfrared spectroscopy. Phys Med Biol, 49: 685699, 2004.
Wolf M, Quaresima V, Ferrari M : Progress of nearinfrared spectroscopy and topography for brain
and muscle clinical applications. J Biomed Opt,
12: 062104, 2007.

Unfortunately in several recent publications thepresentation of the CW NIRS muscle or brain datais still confusing and inadequate. In order to givea contribution to the correct use of the NIRS
instrumentation in skeletal muscle and brain studies, five letters were submitted to the Editor-inChief of different International Journals. All theletters, related to one of the following topics:
・ the light source-detector spacing of nearinfrared-based tissue oximeters and the influence of skin blood flow (Ferrari et al. 2006)
・ the evaluation of skin blood flow contribution
to the muscle oxygenation measurement(Quaresima and Ferrari 2006a)・ the quantification of quadriceps oxygen
desaturation at the onset of exercise(Quaresima and Ferrari 2007)
・ the quantification of calf oxygenation in paraplegic patients (Quaresima and Ferrari 2006b)
・ the clinical significance of cerebral oxygenation during exercise in patients with coronary
artery disease (Quaresima and Ferrari, 2009)
have been accepted for publication.

● References

Contini D, Torricelli A, Pifferi A, Spinelli L, Taroni P,
Quaresima V, Ferrari M, Cubeddu R : Multi-channel time-resolved tissue oximeter for functional
imaging of the brain. IEEE Trans Instrum Meas,
55: 85-90, 2006.
Curcio G, Ferrara M, Limongi T, Tempesta D, Di
Sante G, De Gennaro L, Quaresima V, Ferrari M :Acute mobile phones exposure affects frontal cortex hemodynamics as evidenced by functional
near-infrared spectroscopy. J Cereb Blood Flow
Metab, 2009 (in press).
87

6

運動様式，運動強度，運動時間および筋代謝からみたモーターユニットの動員特性
加茂

美冬 1）

Discharge properties of motor unit with respect to the mode, intensity,
duration of the exercise and muscle metabolism
Mifuyu Kamo

■本課題の共同研究者
森本1）茂 2），板倉尚子 3）

日本女子体育大学，2）横浜国立大学，3）日本女子体育大学健康管理センターリハビリテーション室

6.1

反復電気刺激に対するヒト筋線維群の張力応答
加茂 美冬，森本

6.2

茂

最大下一定筋力発揮におけるモーターユニット活動を規定する要因
加茂 美冬

6.3

等尺性筋力発揮におけるモーターユニット活動と循環系機能の関係
加茂 美冬

6.4

膝関節前十字靱帯損傷再建術後の筋力回復に関する研究
板倉 尚子，加茂 美冬

6.1

反復電気刺激に対するヒト筋線維群の張力応答
加茂

美冬，森本

茂

Force output of human muscle fibers during repetitive electrical stimulation using physiological rates
Abstract
This study examined changes in an evoked force of human muscle fibers by electrical stimulation
using inter-stimulus interval within physiological range occur during submaximal contraction. Muscle
fibers in vastus medialis muscle were percutaneously stimulated for 3min using constant inter-stimulusinterval at 100 and 50ms. The evoked tetanic forces of muscle fibers initially appeared significant
increment during the electrical stimulation. The initial increment force had two peaks; initial transientand following gradual slow increase during 100 ms and had one peak during 50 ms simulation. The
results confirmed that increase in tetanic force of muscle fibers like potentiation is evident during
repetitive activation within physiological rate in human. Therefore, spike interval elongation would benecessary to achieve a constant force during isometric contraction at low level.

● 目

ms とした．収縮時間（contraction time : CT）が一的筋力を決定するモーターユニット（MU）活動は，定となる最低の強度を刺激強度として用いた．この

神経筋機能はもとより循環系機能との間にも相互に強度は被験者の痛み閾値以下であった．刺激間隔に密接な関係をもつと考えられる．したがって，運動は 5 s，100 ms および 50 ms を用いた．各間隔での時の循環調節を統合的に理解するためには，MU 活動

刺激期間は 3 分であった．電気刺激中，誘発張力と誘およびその発現メカニズムを知ることが重要となる．

発電位を記録した．

等尺性一定筋力発揮において筋力発揮初期より活動● 結果および考察する MU 放電間隔は漸次延長する．この現象は，出現期が数秒から数分と強度に依存しているものの全

100 ms および 50 ms 間隔刺激により誘発された張ての筋力レベルで共通して観察されている（DeLura

力は不完全強縮であり，3 分間一定あるいは単調な変et al. 1996; Kamo 2002; Kamo and Morimoto化を示さなかった．100 ms 刺激においては非常に複2001）．しかし，放電間隔延長の合目的性およびメカ

雑な変化を示した（Fig. III.6.1-1）．まず，最初に一

ニズムについては未だ十分に明らかにされていない．

過性に増大，低下を示した．その後，約 15 秒目まで

本実験では，その合目的性を知るために，一定筋力

緩徐に増大し，低下に転じた．一方，50 ms 刺激で発揮中に単一 MU が発揮している張力の推定を行おは 100 ms で観られた一過性のピークは出現せず，うとした．すなわち，随意一定筋力発揮時の MU 放

200

電間隔の範囲内にある刺激間隔を用いて筋線維群に緩徐に増大した後低下に転じた．誘発張力が，増減

電気刺激を加え，その誘発張力変化を観察した．

する複雑なパターンを示したことは，MU が一定間隔

ms まで急峻に張力が融合し，その後約 10 秒間で放電する条件では，一定筋力を保持することは困● 方難であることを示唆している．変化パターンのなか法

被験筋は内側広筋とし，被験者は股関節および膝でも，特に，初期に増大するフェーズをもつことが関節角度 90 度で椅座位姿勢をとった．電気刺激は，特徴的であった．一般的に，MU の放電間隔延長は，

motor point へ経皮的に加えた．刺激持続時間は 1

張力融合の程度を低下させ発揮張力を低下させる．

91

誘発張力の増大率（最高張力／初期張力）は，100
ms 刺激に比較して 50 ms 刺激で必ずしも大きい値を示さなかった．このことから，MU 活動レベルが高い
場合のみならず，放電間隔 100 ms という低活動レベ
ルにおいても放電間隔延長が一定筋力保持に貢献していることが示唆された．

● 文

献

DeLuca CJ, Foley RJ, Erim Z : Motor unit control
properties in constant-force isometric contractions. J Neurophysiol, 76: 1503-1516, 1996.
Kamo M, Morimoto S : Discharge properties of humanmotor units during low level contraction. J
Electromyogr Kinesiol, 11: 255-261, 2001.
Kamo M : Discharge behavior of motor units in knee
extensors during the initial stage of constant-force
isometric contraction at low force level. Eur J
Appl Physiol, 86: 375-381, 2002.

Fig. III.6.1-1 Representative changes pattern of
evoked force during constant inter-stimulus interval
stimulation at 100ms. Vertical line shows magnitude ofpeak force of twitch.

したがって，随意一定筋力発揮時の放電間隔延長は
MU 発揮張力の初期の増大を防ぎ，一定筋力保持に貢献している可能性が考えられた．また，刺激初期の6.2

最大下一定筋力発揮におけるモーターユニット活動を規定する要因
加茂美冬

Mechanisms responsible for spike interval elongation of motor unit
during submaximal contractions
Abstract
Discharge of motor units (MU) is well known to show elongating trends in the spike interval during
voluntary constant-force isometric contraction, but neural mechanisms underlying those trends remain
unclear. This study examined effects of peripheral afferent stimulation on MU activity during voluntary
contraction. Some MUs were discharged at the longer interval without an elongating trend during
involuntary constant-force contraction via tonic vibration reflex. Furthermore, irrespective of peripheral afferent manipulation, the spike interval’s elongating trend did not disappear during the contraction
after prolonged vibration and during the contraction with intermittent vibration. Results suggest thatchanges in neural input information to single MUs with peripheral afferent stimulation do not eliminate the spike interval's trend of elongation in the presence of voluntary drive.

● 目る（DeLura et al. 1996; Kamo 2002; Kamo and的

運動時の循環調節を統合的に理解するためには，

Morimoto 2001）．先に，筋の収縮特性の変化と放電

酸素需要の源となるモーターユニット（MU）活動お間隔延長の関係を調べ，放電間隔延長は反復収縮によびその発現メカニズムを理解することも必要であ伴い生じる筋張力増大（potentiation）を補償する効る．最大下一定筋力発揮初期に観られる特徴的な MU

果をもつことを確かめた．続いて，本実験では MU

活動に数秒から数分にわたる

放電間隔延長発現のメカニズムを探るために，一定放電間隔延長があ92

筋力保持に必要とされる感覚情報のフィードバックに注目し，それらの情報と放電間隔延長の関係を調
べようとした．

● 方法

膝関節角度 90 度条件における内側広筋単一 MU を観察対象とした．単一 MU 活動電位は直径 5 mm の銀・塩化銀表面電極にて双極導出した．また，内側広筋，外側広筋，大腿直筋および大腿二頭筋から表面筋電位を導出した．感覚情報の操作は，腱へ振動刺激を与えることにより行った．振動刺激は膝蓋腱

Fig. III.6.2-1 A typical change in the mean spike interval of a single motor unit during contractions. Filledに経皮的に加え，条件は頻度 75 および 100 Hz，振and open points respectively represent the means (±SD) of results in vibration-induced response (Vib) andvoluntary reproduction (Vo). Asterisks and daggers indicate statistically significant differences from value at
0min, and between Vo and Vib, respectively.

幅 0.5 〜 0.8 mm とした．弛緩筋に振動刺激を加える
条件（緊張性振動反射），観察する MU の活動参加閾
値張力直上の随意筋力をコントロール収縮とし，その前に持続的に振動刺激（10 分以上）を加える条件
およびコントロール収縮に間欠的に振動刺激を加える条件（10 秒間隔で 5 秒間）において，単一 MU の力の低下とあわせて，central drive による興奮入力

放電間隔変化を観察した．

の低下あるいは抑制の制御が重要な役割を果たしていると考えられた．

● 結果および考察● 文

随意収縮においては全ての単一 MU が放電間隔延献

DeLuca CJ, Foley RJ, Erim Z : Motor unit control
properties in constant-force isometric contractions. J Neurophysiol, 76: 1503-1516, 1996.
Kamo M, Morimoto S : Discharge properties of humanmotor units during low level contraction. J
Electromyogr Kinesiol, 11: 255-261, 2001.
Kamo M : Discharge behavior of motor units in knee
extensors during the initial stage of constant-force
isometric contraction at low force level. Eur J
Appl Physiol, 86: 375-381, 2002.

長を示すにも関わらず，弛緩筋に振動刺激を加え一定筋力を発揮した条件では放電間隔が延長する MUと延長を示さない MU が観察された（Fig. III.6.2-1）．
随意筋力発揮前に持続的に振動刺激を加えた条件では，放電間隔の延長量は低下したが延長は消失しな
かった．また，収縮中に振動刺激を加えた条件においても延長は観察された．これらの結果から，一定筋力発揮時の MU 放電間隔延長発現には末梢興奮入

93

6.3

等尺性筋力発揮におけるモーターユニット活動と循環系機能の関係
加茂美冬

Effects of motor unit activity on circulatory responses and muscle oxygenation
Abstract
Motor unit activities and cardiovascular responses during voluntary ascending ramp contraction(30s, - 10% maximal voluntary contraction) were compared with those during involuntary via tonic
vibration reflex. Heart rate and blood pressure changed immediately before and after the onset of theascending ramp contraction, but no change occurred during vibratory contraction. Integrated value ofelectromyography and decreased oxygenated hemoglobin in the muscle during the voluntary contraction were larger than those during the reflex contraction. More efficient muscle oxygen consumption
during voluntary contraction will result not only from cardiovascular regulation by central cardiovascular command, but also from motor unit activities by central motor command.

数の増大と参加した MU の放電頻度の上昇により実● 目 的運動は，時間的，空間的に様々な組み合わせで起現される．先に，緊張性振動反射による誘発収縮とこるモーターユニット（MU）活動を基礎として成り

随意収縮では同一筋力発揮時の MU 活動が異なるこ立っている．すなわち，筋力は，筋を構成する MUとを報告した．そこで，反射性収縮と随意収縮の比の発揮張力の総和であり，筋力増大は，活動する MU

較を行うことにより，随意筋力発揮時の循環調節に

Fig. III.6.3-1 Motor unit activities and oxygenated hemoglobin during a representative experiment.
A: force, B: force impulse/integrated value of electromyogram, C: decrease in oxygenated hemoglobin. Black andgray lines represent value during voluntary contraction and during reflex contraction, respectively in A.

94

ついて検討を加えた．

は大きい傾向にあった．VC において心拍数と血圧は
これまでに報告されている随意筋力発揮における● 方

法

central cardiovascular command の制御による変筋力発揮様式および振動刺激の頻度・振幅は先の化（Matsukawa et al. 2007）と同様な傾向を示した

報告（2．最大下一定筋力発揮におけるモーターユニ

が，RC では観られなかった．筋酸素化へモグロビン

ット活動を規定する要因）と同様であった．先ず，の筋力発揮開始時からの低下量は VC に比較し RC で弛緩筋に 30 s 間刺激を加え誘発された張力（RC）を大きかった（Fig. III.6.3-1）．これらのことは，随意

記録し，その後，十分な休息をとり，誘発張力と同収縮では，central cardiovascular command による様な張力を随意的に発揮させた（VC）．両条件にお循環系機能制御とともに central motor command にける MU 活動と循環系機能および代謝変化を比較しよる筋力発揮効率のよい MU 活動が効率のよい酸素

た．MU 活動は筋電位積分値（IEMG）により評価し利用に貢献していることを示唆している．

た．循環系機能および代謝変化の指標には心拍数，血圧および筋酸素化ヘモグロビンを用いた．

● 文● 結果および考察

Matsukawa K, Nakamoto T, Inomoto A : Gadolini- um
does blunt the cardiovascular responses at theonset of voluntary static exercise in cat: a predominant role of central command. Am J Physiol
Heart Circ Physiol, 292: H212-H219, 2007.

IEMG は VC より RC において有意に大きいあるい

6.4

献

膝関節前十字靱帯損傷再建術後の筋力回復に関する研究
板倉

尚子，加茂

美冬

Effect of exercise proguram on the recovery of mucsle strength after anterior
cruciate ligament reconstruction
Abstract
To investigate how muscle strength is recovered after the reconstructing operation of anterior cruciate ligament (ACL), we examined the effects of two exercise programs, distal and proximal resistance
exercise (DPRE) and proximal resistance with traction exercise (PRTE), in 7 female subjects. The peakforce exerted during dynamic knee extension in low (60 deg/s) and high (180 deg/s) speeds was measured in the operated leg and the contralateral control leg before and 3 months after the operation.
Both programs of DPRE and PRTE recovered the muscle force in the operated leg by 76-79 % from thepre operation level and by 98-100 % from the control leg in both speeds. These data suggested thatboth exercise programs of PRTE and DPRE are effective for recovering muscle force after ACL reconstructing operation.

● 目

リテーションを施行する．しかし，これにより膝関

的

膝前十字靱帯（以下，ACL）再建術後 3 ヵ月間は再節 30 °屈曲位から伸展域での大腿四頭筋の収縮が制建靱帯の力学的強度が脆弱であるため，大腿四頭筋

限されるため，この可動域で作用しやすい内側広筋

収縮による生じる前方剪断力を制限し，また膝関節が萎縮し改善しにくい症例が多い．当センターでは可動域を制動して ACL へのストレスを回避しリハビ

大腿四頭筋の筋力回復運動を実施する際に，抵抗を95

1）近位抵抗（DPRE）
椅子座位にて近位の脛骨粗面上にゴムチューブを強く二重に巻き，下腿遠位に軽く 1 本つけ膝関節を屈曲 90 〜 45 °の範囲で伸展する．

2）PRTE
椅子座位にて下腿近位部に徒手抵抗をかけ膝関節
屈曲 90 〜 45 °の範囲で伸展する．その際，下腿内旋位をとらせ，遠位方向へ牽引力をかけることで内側広筋の収縮を促しやすい．
Fig. III.6.4-1 Experimental setup● 方

加える位置を脛骨粗面部とし大腿四頭筋収縮による法

膝関節前十字靱帯再建術施行前および術後 3 ヵ月に

脛骨前方変位を制動する方法（以下，DPRE）と，膝筋力測定を下記の通り実施した．

関節 90 °から 60 °でも内側広筋の筋収縮を誘発させ

1）測定機器られるとされる proximal resistance with traction

品名：バイオデックスシステム３（納品／平成 16

exercise（以下，PRTE）を導入し，リハビリテーシ

年 10 月 20 日）ョンプログラムを実施している．今回，手術前と手

型式： BDX-3C（製品番号： S61FX010）

術後 3 ヵ月に筋力測定を行い当センターでのリハビリ

2）対象者

テーションプログラムを評価した．なお本研究は本・膝前十字靱帯再建術を施行（半腱様筋を採取）

人の同意を得て，本学「人を対象とする実験・調査した本学女子体育大生 7 名

に関する倫理指針」に基づき配慮し，また個人情報

・平均年齢 19.7 歳

管理については責任者の管理のもと適正に実施した．

・右膝 3 件，左膝 4 件（受傷から手術施行までの平均期間 3 ヵ月 10 日）●

膝関節前十字靱帯損傷術後の膝関節伸展運

3）プロトコール動に対するプログラム（術後 3 ヵ月まで）

・膝関節伸展運動を 60 deg/sec を 5 回，180 deg/

Fig. III.6.4-2 Peak force during dynamic knee extension at the speed of 60 deg/sec before operation and 3 month
to 6 month after operation.
Pre-ope; before operation, 3M; 3 month after operation, 4M; 4 month after operation, 5M; 5 month after operation,
6M; 6 month after operation.

96

Fig. III.6.4-3 Peak force during dynamic knee extension at the speed of 180 deg/sec before operation and 3 month
to 6 month after operation.
Pre-ope; before operation, 3M; 3 month after operation, 4M; 4 month after operation, 5M; 5 month after operation,
6M; 6 month after operation.

sec を 10 回施行し測定（Fig. III.6.4-1）．

じて術後のリハビリテーションも徐々に加速化が図られている．再建術後 3 ヵ月までのリハビリテーショ● 結果ン期間は，再建靱帯が治癒，再構築するまでの期間

1） 手術後 3 ヵ月の膝関節伸展筋力ピークトルク健患比であり，再建靱帯への伸張ストレスを回避したリハ

角 速 度 60 deg/sec ： 76.2 ％ ± 10.4 ％ （ Fig.

ビリテーションプログラムが行われている．本センIII.6.4-2），角速度 180 deg/sec ： 78.6 ％± 11.3 ％ターにおいても，膝前十字靱帯損傷術後のリハビリ（Fig. III.6.4-3）．

テーションプログラムとして DPRE と PRTE を導入

2） 患側の手術前および手術後 3 ヵ月の膝関節伸展筋

し，内側広筋の筋力回復を図っている．DPRE とPRTE の効果を検討した本研究において，手術後 3 ヵ

力ピークトルク比
角 速 度 60 deg/sec ： 98.3 ％ ± 11.6 ％ （ Fig.

月における膝伸展筋力のピークトルク値の健患比がIII.6.4-2），角速度 180 deg/sec ： 99.8 ％± 16.6 ％60 deg/sec で 76.2 ％± 10.4 ％であり，180 deg/sec（Fig. III.6.4-3）．

では 78.6 ％± 11.3 ％であり，患側の手術前と手術後3 ヵ月の術前後比は 60 deg/sec で 98.3 ％± 11.6 ％，● 考

察

180 deg/sec では 99.8 ％± 16.6 ％となり，健側比率

近年，前十字靱帯再建術は複数の骨孔を移植腱の80 ％にまで回復することが示された．この結果は，断面形状に応じて作製することにより，移植腱と骨ジョギングなどの運動を許可する条件を満たすもの

孔の接触断面が拡大され，再建靱帯の治癒，再構築であり，リハビリテーションプログラムとして DPREが期待されるものに進化されてきている．これに応と PRTE が有効であることを示すものと考えられた．

97

7

運動時の心拍出量の変化と各種血管への血流配分
奥山（清水）靜代 1）

Cardiac output during exercise and distribution of blood flow into thevarious vessels
Shizuyo Shimizu-Okuyama■本課題の共同研究者
大森芙美子 2, 3），佐藤1）

耕平 3），村岡

慈歩 4），岩館雅子 3, 5），加賀谷淳子 3）慶應義塾大学，2）鹿屋体育大学大学院，3）日本女子体育大学，4）明星大学，5）日本大学

7.1

多段階静的足底屈運動時における心拍出量と膝窩動脈血流量の関係
奥山（清水）靜代，大森芙美子，佐藤 耕平，加賀谷淳子

7.2

筋活動期および活動休止期における大動脈血流速度と活動体肢血流速度の対応
奥山（清水）靜代，大森芙美子，岩館 雅子，佐藤 耕平，加賀谷淳子

7.3

高齢者における左室重量と骨格筋量との関係
奥山（清水）靜代，村岡 慈歩，大森芙美子，加賀谷淳子

7.1

多段階静的足底屈運動時における心拍出量と膝窩動脈血流量の関係
奥山（清水）靜代，大森芙美子，佐藤耕平，加賀谷淳子

Cardiac output and leg blood flow during incremental plantar flexion
exercise prolonged to exhaustion
Abstract
The purpose of this study was to determine central and peripheral hemodynamic responses to incremental exercise. Seven physically active women performed static plantar flexions until exhaustion.
Exercise comprised of incremental 30-s static plantar exercise separated by 30-s recovery. The initialload was 5% MVC, and then the load was increased by 5%MVC until exhaustion. During exercise wemeasured stroke volume using a Doppler ultrasound method and the heart rate using an electrocardiogram (ECG). Cardiac output was calculated as products of SV and HR. The mean blood velocity andthe vessel diameter of the popliteal artery were measured by using a Doppler and B-mode ultrasoundmethod. Cardiac output began to increase from 50%MVC (3.8 ± 0.1 l/min). In contrast to popliteal
arterial blood flow began to increase slightly from 25%MVC. These results suggest that popliteal arterial blood flow began to increase earlier than cardiac output at low intensity exercise during incremental
exercise to exhaustion on the planter flexion. In addition, the percentage of cardiac output the
popliteal arterial blood flow was increased with exercise intensity. In conclusion, peripheral blood flow
was differentially regulated from central circulation, and the increase in peripheral blood flow demand
did not always require the increase in cardiac output. Relationships between central and peripheral
circulatory changes were intensity-depending.

● 目椅座位姿勢で足関節伸展力を発揮させた．測定項目

的は心拍出量および膝窩動脈血流量で，超音波ドップ

循環の中枢である心臓の拍出量と末梢の血流量はラー法により測定した．

互いに影響しあい，末梢循環のみで調節できる場合と，中心循環を促進させて調節する場合がある（清● 結果および考察

水ら 2001）が，活動する筋量が変わった場合，負荷増加に伴う活動筋の血流需要増加に心拍出量がどの

心拍出量は負荷増加が増加しても，50 ％ MVC

ように対応するかは明らかではない．そこで，本研（3.8 ± 0.1 l ／ min）まで変化しなかったが，55 ％究の目的は多段階静的足底屈運動時の心拍出量と膝MVC（4.5 ± 0.3 l ／ min）では安静時に対して有意窩動脈血流量関係を明らかにすることにより，負荷（p ＜ 0.05）に増加した．一方，膝窩動脈血流量は負増加に伴う活動筋の血流需要増加に心拍出量がどの荷増加に伴い徐々に増加する傾向を示し，40 ％ MVC

ように対応するかを明らかにすることである．

（0.6 〜 0.8 l ／ min）以上では，安静時（0.1 ± 0.01
l ／ min）に対して有意差（p ＜ 0.05）が認められた．

● 方

心拍出量を規定する要因である心拍数は，負荷増加法

健康な成人女性 7 名を対象とした（年齢 22 ± 1 歳）．

にともなう有意な変化はみられなかったので，一回被験者には椅座位姿勢にて 30 秒間の静的足底屈運動

拍出量の負荷増加にともなう変化が，心拍出量を増を 30 秒の休息を挟んで繰り返す運動を行わせた．負大させたと考えられる．また，心拍出量に対する膝荷強度は初期負荷を 5 ％ MVC とし，以後 5 ％ MVC

窩動脈血流量の割合をみると（Fig. III.7.1-1），そのずつ増加して，疲労困憊まで運動を続けた．運動は

割合は安静時に対して 40 ％ MVC 以上で有意（p ＜101

Fig. III.7.1-1 Popliteal arterial blood flow of cardiac output during incremental plantar flexion exercise to exhaustion.
At 40, 45, 50 and 55 %MVC increased significantly from baseline value.
*, **: p < 0.05, p < 0.01 compared to baseline value.

0.05）に高値（16.6 〜 17.7 ％）を示した．これらの上の強度においては心拍出量が上昇することにより，

結果をまとめると，多段階静的足底屈運動時の活動

活動体肢の血流需要に対応していることが明らかに筋への血流量と心拍出量は，負荷増加に対して必ずなった．

しも一致した変化を示さなかった．すなわち，低強● 文

度では心拍出量の増加なしに活動肢への血流増加が

献Calbet JA, Gonzalez-Alonso J, Helge JW, Sondergaard
H, Munch-Andersen T, Boushel R, Saltin B :Cardiac output and leg and arm blood flow during
incremental exercise to exhaustion on the cycle
ergometer. J Appl Physiol, 103: 969-978, 2007.
Seals DR : Influence of muscle mass on sympathetic
nural activation during isometric exercise. J Appl
Physiol, 67: 1801-1806, 1989.
清水靜代, 本間幸子, 加賀谷淳子 : 片側および両側掌握運動に対する心拍出量と活動体肢血流量の応答. 体力科学, 50: 633-641, 2001．

起こり，強度が高くなると両パラメータが増加を示した．そして，心拍出量が増加するにもかかわらず，
高い負荷では心拍出量に占める活動体肢への血流の割合が高くなり，活動体肢への血流分配が高くなっていることが示された．すなわち，負荷増加に伴う活動筋における血流需要増加に対して，50 ％ MVC
までは心拍出量の増加なしに運動が行われ，それ以102

7.2 筋活動期および活動休止期における大動脈血流速度と活動体肢血流速度の対応
奥山（清水）靜代，大森芙美子，岩館雅子，佐藤耕平，加賀谷淳子

The influence of aorta and femoral arterial blood flow valocity duringcontraction and relaxation phases
Abstract
The purpose of this study was to observe the changes in the blood velocity in aorta and femoral
artery during muscle contraction and relaxation phases of knee extension exercise. Seven female subjects (aged 22.4 ± 1.9 years) participated in this study. They performed one-legged knee extension
exercise (KE) in upright position at 10% and 50% of maximal voluntary contraction (MVC) until
exhaustion. Blood velocity was measured using the Doppler ultrasound method for aorta artery andfemoral artery. Blood pressure was monitored from the finger of the left hand at the heart level.
During the muscle contraction phase of KE, the blood velocity in femoral artery was significantly (p <0.01) lower than in aorta artery. In contrast, the blood velocity in femoral artery higher than the aorta
during the relaxation phase. The femoral/aorta rations were -67.4 ± 9.2% (10%MVC), and -80.6 ± 4.9%
(50%MVC) during the contraction phase. However, during the relaxation phase, they were 30.0 ±11.6% (10%MVC), 50.7 ± 22.3% (50%MVC). Mean blood pressure was not different significantly
between the contraction and relaxation phase. These results suggest that the effect of muscle contraction and relaxation on blood velocity differs between aorta artery and femoral artery. The femoral
artery blood flow velocity was more accelerated compared to aorta during the relaxation phases.

● 目

的● 結果および考察

本研究は，筋の活動期および活動休止期の大腿動

大腿動脈血流速度において筋活動期では，10，脈血流速度が，心臓から拍出される血流速度とどの

50 ％ MVC ともに時間経過にともなう変化がみられような関係にあるかを明らかにすること，さらに異なかったのに対して，活動休止期では安静値と比較なる強度で両者の関係に相違があるか否かを明らか

し有意に増加し，10 ％ MVC では 8.8 倍，50 ％ MVCにすることを目的とした．

では 13.7 倍増加した．大動脈血流速度は 50 ％ MVC
のみ有意に増加したが，その増加は 1.3 倍であった．

● 方法

大動脈および大腿動脈血流速度を筋の活動期と休止

健康な成人女性 7 名（年齢 22.4 ± 1.9 歳）を被験期で比較した場合，低強度および高強度どちらにお者とし，股関節角度 110 °とした椅座位姿勢で右脚にいても，筋活動期では大腿動脈血流速度は大動脈血よる動的膝伸展運動（30 °伸展，1 秒収縮 1 秒弛緩）

流速度より低く，筋活動休止期では大動脈血流速度を行わせた．負荷は最大筋力の 10 および 50 ％に相より高値を示した．また，大動脈速度に対する大腿当する負荷とし，10 ％ MVC は 3 分間，50 ％ MVC は動脈速度の相対的な割合は，筋活動時には抑制され，疲労困憊に至るまで行わせた．安静時および運動中

筋活動休止期には亢進された．さらに，低強度よりの大動脈血流速度，活動肢大腿動脈血流速度（超音も高強度の方が両血管における血流速度の差が大き

波ドップラー法）を測定した．

かった（Fig. III.7.2-1）．筋活動期および活動休止期の平均血圧には差はみられず，どちらの時相においても 50 ％ MVC の方が 10 ％ MVC よりも高い値を示
103

Fig. III.7.2-1 The femoral/aorta rations during the contraction and relaxation phases at 10, 50%MVC.
The femoral/aorta rations were -67.4 ± 9.2% (10% MVC), and -80.6 ± 4.9% (50% MVC) during the contraction
phase. However, during the relaxation phase, they were 30.0 ± 11.6% (10% MVC), 50.7 ± 22.3% (50% MVC).

したが，有意には至らなかった．以上のことをまとその結果，中心動脈および末梢動脈の血流速度の関

めると，活動筋近位の末梢動脈における血流速度は

係は筋の活動期と休止期で異なり，活動期では中心筋の活動期に低く休止期には高いというように，筋動脈血流速度が活動筋へ血液を供給する末梢動脈血

活動による大きな変動が起きるが，中心動脈の血流流速度を上回り，休止期では逆に末梢動脈血流速度

速度は筋の活動期と休止期により大きな影響を受けが中心動脈速度より早くなるという関係にあることないことが示された．すなわち，筋活動は，中心循が示された．

環ではなく末梢循環の変動を起こすことが示された．

104

7.3

高齢者における左室重量と骨格筋量との関係

奥山（清水）靜代，村岡

慈歩，大森芙美子，加賀谷淳子

The relationship between cardiac muscle and skeletal muscle mass inelderly women
Abstract
The purpose of this study was to clarify the relationship between left ventricular muscle mass
[LVmass] and skeletal muscle volume in elderly women. We measured the thigh muscle thickness(Vastus intermedius and Rectus femoris) using B-mode ultrasound method. Posterior wall thickness,interventricular septal thickness and left ventricular end-diastolic internal diameter were measured by
B-mode echocardiography. A significant correlation coefficients were obtained between vastus intermedius and interventricular septal thickness (r = 0.221, p < 0.05), rectus femoris and posterior wall
thickness (r = 0.240, p < 0.05). In addition, significant correlation coefficients were also obtained
between the estimated skeletal muscle volume and left ventricular mass in elderly women (r = 0.561, p< 0.05). These results indicate that the left ventricular muscle is closely related to the skeletal muscle
volume in ordinary elderly women.

● 目

左縁 3 − 5 肋間に 2.5 MHz の探触子をあて，仰臥位安的

心臓は活動筋の酸素需要に応えるために，心拍出静時の左室長軸画像を記録した．後日，得られた記量を増加あるいは血流配分を増減させ，運動に必要録から大動脈径（AO），左室後壁厚（LVPWT），心な酸素の需要を満たそうとする．一方，骨格筋では

室中隔厚（IVST），左室拡張（LVIDd）および収縮末筋収縮時に筋ポンプ作用が静脈還流量を高め，心臓期内径（LVIDs）の計測を行った．また Devereux らの前負荷を増加させる（Froelicher et al. 2000）．す（1977）の式を用いて左室重量を算出した．

なわち，加齢による骨格筋量の低下（Kanehisa et al.
2004）は心筋や血管動態に対する刺激を低下させると考えられる．そこで，本研究は高齢者における心形態と骨格筋量の関連を明らかにし，その関連から
高齢者における運動の重要性を明らかにすることを目的とした．

● 方法

測定の対象者は女性 61 名（年齢： 75.6 ± 5.2 歳）であった．被験者には事前に目的と内容，測定にともなう危険性と実験参加の任意性を説明した上で，実験参加への同意を書面によって得た．

Fig. III.7.3-1 Relationship between estimated skeletal
muscle volume and left ventricular muscle mass
[LVmass] in elderly women.
Significant correlation coefficients were obtained
between the estimated skeletal muscle volume andLVmass in elderly (r = 0.543, p < 0.01).

1．心形態の測定
心形態の測定には循環器用超音波診断装置（SYSTEM V, GE）を用い，B モード法で測定した．胸骨105

筋体積が高値を示すほうが，左室重量も高い値を示

2．筋形態の測定
大腿部筋厚の測定は超音波 B モード法（ALOKA

し，両者の間には有意（r ＝ 0.561, p ＜ 0.05）な正SSD1000, 7.5 MHz）を用いて行った．測定部位は大の相関関係がみられ，左室重量は大腿部筋体積と密腿長の 50 ％部位とし，後日，得られた記録より大腿接に相関することが示された．以上のことから，心直筋（VI）の浅部腱膜から，中間広筋（RF）を含み

形態から求めた高齢者の心臓の重量は大腿部筋体積

大腿骨までを大腿前部の筋厚として計測した．また，と密接に相関し，心臓の形態を大きく保つためには，

大腿前面筋厚を二乗しその値に大腿長を乗じること

高齢者も身体運動による筋量の維持が必要と示唆さにより，大腿部筋体積を算出した．

れた．

● 結果および考察● 文

献Devereux RB, Reichek N : Echocardiographic determination of left ventricular mass in man - Anatomic
validation of the method. Circuration, 55: 613618, 1977.
Froelicher VF, Myers JN : Exercise and Heart.
Philadelphia, PA, WB Saunders, 2000.
Shimizu S, Muraoka Y, Ohmori F, Kagaya A : The
relationship between cardiac muscle, skeletal
muscle mass and vessel structure in elderly
women. Jpn J Phys Fitness Sports Med, 55 Suppl :S213-S216, 2006.

大腿直筋と心室中隔厚（r ＝ 0.221, p ＜ 0.05）および中間広筋と左室後壁厚（r ＝ 0.240, p ＜ 0.05）との間に有意な関係がみられた．また，心筋および大腿部筋厚を体表面積で正規化した値においても，
大腿直筋と心室中隔厚との間には有意（r ＝ 0.610,
p ＜ 0.05）な関係がみられた．Fig. III.7.3-1 に大腿部筋厚から推定した大腿部筋体積と心形態より算出した左室重量との関係を示した．その結果，大腿部

106

8

有疾患者における運動および筋虚血に対する血流調節プロファイル−下肢閉塞性動脈硬化保有者における運動下肢血行動態の検討−
長田

卓也 1）

Blood flow profile in relation to exercise-induced muscle ischemia in
the patients with peripheral arterial disease
Takuya Osada■本課題の共同研究者
勝村1）俊仁 1），村瀬

訓生 1），木目良太郎 1），下村浩祐 1）および東京医科大学病院血管外科学スタッフ

東京医科大学健康増進スポーツ医学

8.1

有疾患者における運動および筋虚血に対する血流調節プロファイル−下肢閉塞性動脈硬化保有者における運動下肢血行動態の検討−
長田 卓也，勝村 俊仁，村瀬 訓生，木目良太郎，下村 浩祐

8.1

有疾患者における運動および筋虚血に対する血流調節プロファイル−下肢閉塞性動脈硬化保有者における運動下肢血行動態の検討−
長田

卓也，勝村

俊仁，村瀬

訓生，木目良太郎，下村浩祐

Blood flow profile in relation to exercise-induced muscle ischemia in
the patients with peripheral arterial disease
Abstract
The present study examined the femoral arterial blood flow response in each leg during intermittent
isometric knee extension at incremental exercise intensities in patients with peripheral arterial disease.
Changes in blood flow during exercise tend to be higher in the more-affected leg (PAD side) than thecontrol healthy leg. Hyperemic response in the working skeletal muscle may be different in both legs.
It is speculated that peripheral vascular disease may influence the blood flow response in muscle contractions during a state of exercise. The peripheral blood flow regulation may be altered due to theseverity in the vascular disease during limb exercise as well as resting state.

● 目

的

● 方

法

末梢循環障害（Fontaine 分類第 II 度）をきたす下末梢循環障害（血管造影にて確認されている）を

肢閉塞性動脈硬化症保有者を対象に，運動時におけきたす 5 名の男性閉塞性動脈硬化症保有者（平均年齢

る血行動態について検討を行うこととした．

71 ± 2 歳）を対象に，座位姿勢での多段階負荷等尺性片側膝伸展運動を行った．運動開始前の安静時にFig. III.8.1-1 Limb blood flow response during incremental intermittent isometric knee extensor exercise. Changes
in blood flow during exercise tend to be higher in the more-affected leg (PVD side) than the control healthy leg.

109

足関節上腕血圧比（ankle-brachial index : ABI）を● 考

察

測定し，運動は一足ごとに両側について行った．両動脈硬化が強い下肢動脈血管（ABI 値が低い下肢側）

下肢で ABI が低い下肢を患側とし，反対側の下肢をにおける，運動時の血流増加反応が高い事が明かと健側（対照肢）とした．運動強度は，最大随意収縮なった．この事は，より運動強度の上昇に伴う骨格力の 5 ％，10 ％，30 ％そして 50 ％とそれぞれの強筋酸素消費量を代償するための血流増加調節，虚血度で 3 分間とし，多段階的漸増負荷とした．下肢運動に伴う血管拡張代謝産物なの影響が強い事が示唆さの頻度は，5 秒間の等尺性膝伸展運動にひき続き，5れる（Green 2002; Stewart et al. 2002）．本研究で秒間の休止期を 1 サイクルとした．下肢血流の評価は，は，運動に伴う患側下肢血流反応は，健側と比べて超音波ドプラー法にて大腿動脈部位において行い，異なることが明らかとなり，今後は末梢循環障害が血管径と血流速度により算出した．血流速度は，5 秒

安静時のみならず運動中の骨格筋循環に与える影響

間の等尺性膝伸展運動及び 5 秒間の休止期のそれぞれを検討する必要があると思われる．特に，基本的身に得られた 3 〜 4 拍動の波形を計測し，血流量評価に体活動である下肢運動・歩行と骨格筋循環動態の検使用した．運動中の血流反応は，筋弛緩期である休討は，疾病保有者の運動耐容能向上やトレーニング

止期血流量から筋収縮期のそれを差し引いた血流増効果等，将来的に運動処方や QOL 向上への糸口とし加量を指標とした．

ての参考データになりうる事が考えられる．

● 結

● 文

果

献

Green S : Haemodynamic limitations and exercise performance in peripheral arterial disease. Clin
Physiol Funct Imaging, 22: 81-91, 2002.
Stewart KJ, Hiatt WR, Regensteiner JG, Hirsch AT :Exercising trianing for claudication. N Engl J
Med, 347: 1941-1951, 2002.

安静時において患側下肢の ABI 値は，健側に比べ低い値を示した．安静時下肢血流量は，患側が健側より低い傾向を示したが，運動中の下肢血流増加量は，患側において大きい傾向を示した．

110

9

運動時の呼吸循環系変化に対する中枢性・末梢性の
神経調節
佐藤

耕平 1）

Central and peripheral neural control of respiration and circulation
during exercise
Kohei Sato

■本課題の共同研究者
森山真由美 2），平澤

1）

愛 2），定本朋子 1）

日本女子体育大学，2）日本女子体育大学基礎体力研究所

9.1

Cerebral blood flow response at the beginning of voluntary exercise and passive movement
Kohei Sato, Mayumi Moriyama, Tomoko Sadamoto

9.2

Effect of mode of ventilation on cerebral blood flow response during static arm exercise
Kohei Sato, Ai Hirasawa, Tomoko Sadamoto9.1 Cerebral blood flow response at the beginning ofvoluntary exercise and passive movement
Kohei Sato，Mayumi Moriyama，Tomoko Sadamoto
Abstract
In this study, we try to reinvestigate the role of central command in regulating the cerebral bloodflow at the onset of exercise under a non-invasive condition. Eleven young women performed voluntary elbow flexion-extension exercise with no-load (VOL), activating both the central command andthe muscle mechanoreflex, and passive elbow flexion-extension (PAS), selectively activating the muscle mechanoreflex. We continuously monitored the cardiorespiratory and cerebrovascular responses at・rest and during VOL and PAS over a 2-min duration. The VMCA and QCCA began to increase before theonset of VOL and peaked immediately after the onset of exercise. VOL simultaneously produced a significant increase in the heart rate (HR) and cardiac output (CO) and a decrease in the mean arterial
blood pressure (MAP), thereby inducing a significant decrease in the cerebrovascular resistance at theonset of VOL. There were no significant changes in these parameters at the onset of PAS. These
results suggested that the increases in cerebral blood flow at the beginning of no-load voluntary exercise were most likely mediated by feedforward control of central command. To the contrary, the muscle mechanoreflex appeared to have little effect on the adjustments in cerebral blood flow responses atthe onset of no-load voluntary exercise.

instructed to move their forearm between elbow● Purpose

We aimed to investigate the role of central com-angles of 50 °and 90 °(0 °equaling full extension)

mand in regulating the cerebral blood flow at theat an angular velocity of 90 deg・sec-1 in time to a

onset of exercise. The comparison of the cere-rhythmic sound from a cassette being played in a

brovascular adjustments between voluntary exer-

tape-recorder. Voluntary exercise was continued

cise and passive movement would provide thefor 2-min. Passive movement was achieved by acontribution of central command (Nóbrega et al.

motor-driven lever arm that rotated around an

1994; Williamson et al. 1997). In the present

axis at a constant velocity. All the subjects werestudy, we studied the time course of the responses

requested to relax and not to resist the arm move-in cerebral blood flow at the onset of voluntaryment. Passive movement was performed with theexercise with no-load and passive movement

same range of movement, angular velocity, andaccomplished by dynamic elbow flexion andfrequency as the voluntary exercise. Common
・carotid artery blood flow (QCCA) and mean middle

extension of a single arm.

cerebral blood flow velocity (VMCA) examination
was performed using a high-resolution ultrasound● Methods

Eleven young women (age, 23.5 ± 0.7 years)

system (LOGIQ5; GE Medical Systems, Japan).

participated in this study. In this study, the single

The cardiovascular responses were measured

arm elbow flexor-extensor exercise and passive

noninvasively by photoelectric plethysmography

movement were performed using a computer-using a Finometer (Finapres Medical Systems BV,

based multifunctional dynamometer device. For

Arnhem, Netherlands) and the respiratory param-

the voluntary dynamic exercise, the subjects were

eters were determined using an online system for113

Fig. III.9.1-1 Changes in the cardiorespiratory and cerebral blood flow responses at the onset of voluntary exercise
and passive movement. Relative changes were obtained by normalizing to the resting values. The time courses ofthe variables are shown from 30 s before to 60 s after the onset of exercise and movement. (A) VMCA, middle cere・
bral artery mean blood velocity; (B) QCCA, common carotid artery mean blood flow; (C) HR, heart rate; (D) CO,
cardiac output; (E) MAP, mean arterial blood pressure; (F) PETCO2, end-tidal CO2; (G) MAP/VMCA, index of the cere・
brovascular resistance; (H) MAP/QCCA, common carotid artery resistance. Values are expressed as the mean (SE).
* Different from the resting value (P < 0.05). †Difference between the voluntary exercise and passive movement at
each time point (P < 0.05).

were no significant changes in these parameters

the breath-by-breath method.

during passive movement, and thus, significant● Results and Discussion

differences were observed in these parameters

The major findings of this study were as fol・
lows. VMCA, QCCA, HR, and CO began to increase

between voluntary exercise and passive move-significantly immediately before and at the onset

indicate that the rapid adjustment in the cere-of voluntary exercise in parallel with a transient

brovascular responses at the beginning of volun-

decrease in the cerebrovascular resistance. There

tary exercise with no-load was probably attributa-

ment immediately after their onset. These results114

ble to the feedforward control of central com-mand-mediated brain activity in several regions

mand descending from the higher brain centers.

and/or the increase in circulatory variables, par-The mechanism concerning the central com-

ticularly the CO response, may significantly con-mand-related increase in the cerebral blood flow

tribute to the rapid adjustment of the cerebral

may be mainly explained by based on the follow-

blood flow responses at the beginning of exercise.

ing two possibilities. Studies investigating the● References

functional anatomy of the central command-

Ide K, Pott F, Van Lieshout JJ, Secher NH : Middle
cerebral artery blood velocity depends on cardiac
output during exercise with a large muscle mass.
Acta Physiol Scand, 162: 13-20, 1998.
Nóbrega AC, Williamson JW, Friedman DB, Araujo
CG, Mitchell JH : Cardiovascular responses toactive and passive cycling movements. Med Sci
Sports Exerc, 26: 709-714, 1994.
Ogoh S, Brothers RM, Barnes Q, Eubank WL, Hawkins
MN, Purkayastha S, O-Yurvati A, Raven PB : The
effect of changes in cardiac output on middle
cerebral artery mean blood velocity at rest andduring exercise. J Physiol (Lond), 569: 697-704,
2005.
Williamson JW, Nóbrega AC, McColl R, Mathews D,
Winchester P, Friberg L, Mitchell JH : Activationof the insular cortex during dynamic exercise in
humans. J Physiol (Lond), 503: 277-283, 1997.
Williamson JW, McColl R, Mathews D, Mitchell JH,
Raven PB, Morgan WP : Brain activation by central command during actual and imagined handgrip under hypnosis. J Appl Physiol, 92: 13171324, 2002.
Williamson JW, Fadel PJ, Mitchell JH : New insights
into central cardiovascular control during exercise
in humans: a central command update. Exp
Physiol, 91: 51-58, 2006.

induced changes in the regional cerebral bloodflow have shown a network of cortical structures
involved (Williamson et al. 2006). Therefore, thefirst possibility is neural activation in theseregions, which may serve as a central command
network, is responsible for observed increases inbrain blood flow (Williamson et al. 2002;
Williamson et al. 2006). Second, the central command is generally thought to have a greater effecton HR and, thus on CO, than blood pressure.
Thus, it is possible that an abrupt increase in HR
and CO at the onset of exercise may contribute to・
the rapid change in VMCA and QCCA because in this・
study, VMCA and QCCA changed during voluntary
exercise in parallel with the HR and CO responses. Recent studies have suggested that CO is an
important factor involved in the change in VMCA
during exercise (Ide et al. 1998; Ogoh et al. 2005).
Accordingly, it is suggested that the central com-

115

9.2

Effect of mode of ventilation on cerebral blood flow
response during static arm exercise
Kohei Sato，Ai Hirasawa，Tomoko Sadamoto
Abstract

Heavy resistance exercise may be associated with a small risk of cerebral aneurysm rupture, subarachnoid hemorrhage, and symptoms of dizziness or outright weight-lifters' blackout, which may be
induced by a rapid change in the cerebral blood flow. We hypothesized that these changes during
heavy exercise could be associated with the mode of ventilation. The purpose of the present study was
to elucidate the effect of the mode of ventilation on cerebral blood flow response during heavy upper
body exercise. Subjects performed 15-s static exercises at 80% maximum voluntary contraction (MVC)
under different modes of ventilation. In this study, we observed that heavy exercise with breath holding induced marked and rapid changes in the cerebral blood flow velocity in the middle cerebral
artery during and after exercise as compared with that with continued normal ventilation. We also
observed that hyperventilation before exercise could largely contribute to a lower cerebral blood flow
velocity during exercise and extending to the recovery phase. Our data suggested that even during
heavy upper body exercise, the mode of ventilation is very important for maintaining cerebral circulation.

tion on the cerebral blood flow response during● Purpose

Change in the cerebral blood flow during heavy

upper body heavy exercise involving a small mus-exercise could be associated with the mode ofcle mass. Therefore, the purpose of the present

ventilation, including the forced expiration against

study was to elucidate the effect of the mode ofa closed glottis (breath holding induced aventilation on cerebral blood flow response dur-

Valsalva-like maneuver) and hypocapnia induced

ing heavy upper body exercise.

by hyperventilation before and during exercise. A● Methods

previous study reported marked change in themean cerebral blood flow velocity in the middle

A total of 10 male field athletes (7 shot putters

cerebral artery (MCA V mean) during heavy two

and 3 hammer throwers; mean age ± SD: 21.2 ±legged extension with concomitant Valsalva-like

1.2 years) volunteered to participate in this study

maneuver (Pott et al. 2002). Romero and Cookeafter providing informed consent to the protocol,(2006) demonstrated that hyperventilation before

as approved by the ethics committee of Japan

exercise exacerbates the reduction in MCA Vmean

Women’s College of Physical Education. In thisduring leg-press resistance exercise. These studies

study, single arm elbow flexion exercise was per-suggested that during heavy exercise the associat-

formed with the use of a multifunctional

ed mode of ventilation may be of deterministic

dynamometer device. The exercise load selected

importance for cerebral circulation. However,was 80% of the maximal voluntary contraction

these investigations focus on cerebral blood flow(MVC) force. After a 3-min resting period, theregulation during lower-body exercise involving a

subjects performed 15-s static exercises at 80%

large muscle mass. To date, there is no informa-

MVC with the following 3 different modes of ven-tion regarding the effect of the mode of ventila-

tilation (in random order): 1) continued normal

116

Fig. III.9.2-1 Cerebrovascular responses at rest, during, and after heavy exercise. (A) MCA Vmean, Mean middle
cerebral artery mean blood velocity and (B) CVR, Cerebrovascular resistance index.

ventilation (EX), 2) exercise with concomitant(SV), and cardiac output (CO), from the blood

breath holding (EX+BH), and 3) pre-exercisepressure wave form by using the Modelflow

hyperventilation till an end tidal partial pressure

method. Respiratory parameters were determinedof CO2 (PET CO2) of 3.5% was achieved (HV). In

with an online system for the breath-by-breath

HV, after a 2-min rest, the subjects were instruct-

method. The ratio of MAP/ MCA Vmean was calcu-

ed to perform voluntary hyperventilation for 1-

lated as an index of cerebrovascular resistance

min in order to achieve a PET CO2 of 〜 3.5%. After(CVR).

the 1-min hyperventilation, the subjects per● Results and Discussion

formed 15-s static exercises with continued normal ventilation. MCA Vmean measurement was per-

The expiratory strain during a Valsalva-likeformed with an ultrasound system (Vivid 7pro; GE

maneuver might reduce blood flow to the brain.

Yokogawa Medical Systems) equipped with a 2.0

Forced expiration against a closed glottis increas-

MHz sector transducer. The MCA V mean was

es intrathoracic pressure and central venous pres-defined as the time-averaged mean velocity

sures and marked reduces in SV and thus CO.

obtained in automatic calculation mode. Mean

Previous studies indicated that CO is an important

arterial pressure (MAP) was measured non-inva-

determinant of cerebral blood flow during exer-

sively by photoelectric plethysmography withcise (Ogoh et al. 2005). However, our data suggest-

Finometer (Finapres Medical Systems BV).

ed relationship between CO and MCA Vmean was

Furthermore, we determined the stroke volume

not simply under this situation. Furthermore, the117rapid increase in the CVR at the onset of exercise

tion of hyperventilation before heavy exercise andmay also contribute to the change in MCA Vmean

breath holding during exercise is the worst sce-and the increase in the CVR may be induced bynario from the perspective of cerebral circulation.

sympathoexcitation due to heavy exercise and/or

It may be that continued normal ventilation dur-

the reduction in CO and Pa CO2. The increase ining heavy upper body exercise may be safer, in

the CVR during EX+BH suggested vasoconstric-

that it helps to avoid rapid changes in the cere-tion of the peripheral branches of the MCA. On

bral blood flow and CVR that may in turn cause

the other hand, over shooting of the MCA Vmean

symptoms of dizziness or outright weight lifter’s

immediately after the end of exercise may be”black out” and intracranial hemorrhage.

induced by rapid decrease in CVR, with rapid● References

recovery of CO and Pa CO2.

Ogoh S, Brothers RM, Barnes Q, Eubank WL, Hawkins
MN, Purkayastha S, O-Yurvati A, Raven PB : The
effect of changes in cardiac output on middle
cerebral artery mean blood velocity at rest andduring exercise. J Physiol (Lond), 569: 697-704,
2005.
Pott F, Van Lieshout JJ, Ide K, Madsen P, Secher NH :Middle cerebral artery blood velocity during
intense static exercise is dominated by a Valsalva
maneuver. J Appl Physiol, 94: 1335-1344, 2003.
Romero SA, Cooke WH : Hyperventilation before
resistance exercise: cerebral hemodynamics andorthostasis. Med Sci Sports Exerc, 39: 1302-1307,
2007.

In the HV trials, reduced MCA Vmean occurred inconjunction with increased CVR. This reductionin MCA Vmean before, during, and after exercise
was attributable to the reduction in Pa CO2. These
results indicate that the increase in CVR was
probably associated with vasoconstriction of thecerebral blood vessels. In summary, our data suggested that even during upper body heavy exercise involving small muscle mass, the mode ofventilation was very important for maintaining
cerebral circulation. We think that the combina-

118

10

運動準備期のセントラルコマンドの働き
岩館

雅子 1, 2）Central command during the preparatory period before voluntary exercise
Masako Iwadate■本課題の共同研究者
定本1）

朋子 2），澁谷

顕一 2）

日本大学，2）日本女子体育大学基礎体力研究所

10.1 運動準備期の大脳皮質運動野酸素動態と循環応答の対応
岩館 雅子，定本 朋子
10.2 運動準備期と運動時の大脳皮質運動野酸素動態
岩館 雅子，澁谷 顕一，定本 朋子

10.1

運動準備期の大脳皮質運動野酸素動態と循環応答の対応
岩館

雅子，定本

朋子

Relationship between cortical oxygenation in the motor area and cardiovascular responses during the resting preparatory period before voluntary exercise
Abstract
We studied the cortical oxygenation in motor area (MA) and the concomitant cardiovascularresponses during resting preparatory period either with sustaining handgrip exercise (Ex) or without
handgrip exercise (Con) in 13 healthy subjects. The oxygenated hemoglobin (oxyHb), deoxygenatedhemoglobin (deoxyHb) and total hemoglobin (totalHb) in the left motor cortex were measured by nearinfrared spectroscopy. Heart rate (HR), cardiac output (CO), mean arterial blood pressure, and the oxygenation in the right forearm flexors muscles were simultaneously recorded in both Ex and Con experiments. During the resting preparatory period in Ex, the oxyHb and totalHb in motor cortex were significantly higher than those in Con while deoxyHb was similar to that in Con. These changes in Ex
indicated the increase in regional cerebral blood flow resulting from the increases in the regional cerebral oxygen metabolic rate in MA. In accord with these changes, HR, CO, and the muscle oxyHb were
elevated significantly in Ex but not in Con. However, the muscle totalHb was not higher significantly
in Ex than that in Con. These results suggested that the increases in HR and muscle flow rate in Ex
were coupled with the increase in cortical activation resulting from a preparation for exercise.

的
ԥ0&[ R[\O+E P0 FP● 目

本研究の目的は，運動準備・想起により発現する
セントラルコマンドが，大脳皮質運動野周辺領野の活動へ及ぼす影響を明らかにすることである．

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被験者は 13 名の健康な女子大学生とした．被験者
ԥ+5 ESPは，掌握運動を行う運動条件と行わない対照条件の 2
条件に参加した．運動条件では，1 Hz の音の回数を

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検者の合図に合わせて数え，50 回まで数えた後には

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+*

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右腕による掌握運動（運動負荷： 30 ％ MVC）を 10秒間実施した．対照条件では，音の計数の後の掌握
ԥ0XVFOH R[\O+E P0 FP



運動は行わず，音の計数のみを続けて行った．
脳活動の指標として，左右運動野手領域脳酸素動
態を近赤外分光法により記録した．循環応答の指標

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としては，心拍数，平均動脈血圧，心拍出量，前腕Ფ+*

WLPH VHF

屈筋の筋酸素動態を記録した．本研究では被験者がFig. III.10.1-1 Changes in oxygenated hemoglobin
obtained left motor cortex (MCx oxyHb), Heart Rate(HR), oxygenated hemoglobin obtained right forearm
flexors muscles (muscle oxyHb) during preparatory
period before handgrip exercise (HG). Values aremeans ± SD in 13 subjects. ○, control condition; ●,exercise condition; *, p < 0.05; **, p < 0.01.

音の回数を数え始めてから運動開始直前までの 50 秒
間を運動準備期とし，解析対象とした．

121

心拍出量増加および活動肢の筋血流速度上昇が生じ● 結果および考察

るとき，大脳運動野周辺の脳活動も同時に亢進する

運動準備や想起に伴い，循環応答としては，心拍ことが示された．

上昇および心拍出量増加および筋血流速度上昇という応答がみられた．これに対し，大脳皮質運動野酸● 文

素動態においても，oxyHb および totalHb の上昇，

献

Williamson JW, McColl R, Mathews D, Mitchell JH,
Raven PB, Morgan WP : Brain activation by central command during actual and imagined handgrip under hypnosis. J Appl Physiol, 92: 13171324, 2002.

deoxyHb の低下傾向という，神経活動賦活に伴う血流増加を反映する脳酸素動態変化がみられた．
このことから，運動開始前において運動準備や想起により（Williamson et al. 2002），心拍数の上昇，

10.2

運動準備期と運動時の大脳皮質運動野酸素動態の関係
岩館

雅子，澁谷

顕一，定本

朋子

Cortical oxygenation in the motor area during the resting preparatory
period and the following voluntary exercise
Abstract
We have compared the oxygenation changes in the motor cortex (MCx) during the maximal heart
rate (HR) change session and minimum HR change session during the resting preparatory period withthe sustaining handgrip exercise in 6 healthy subjects. During the resting preparatory period with theexercise, the oxygenation changes were larger during maximal HR change session than that of minimum HR change sessions. On the other hand, no significant differences in the oxygenation change
during the sustaining handgrip exercise were observed between the maximal and minimum HR change
sessions. These results indicate that the oxygenation changes in the MCx during the exercise are independent from that of the resting preparatory period with the exercise.

● 目

態 を 近 赤 外 分 光 法 に よ り 記 録 し た （ Hoshi and的

前課題において，運動準備・想起により心拍上昇

Tamura 1993）．循環応答の指標としては，心拍数をと運動野酸素化動態上昇が同時にみられるという対記録した．本研究では，心拍数と脳酸素動態の対応応が示された（岩館と定本 2008）．本研究では，運を確認するため，準備期の心拍変化が最大の試行と動準備期と運動時の運動野酸素化動態の関係を明ら

最小の試行を選び，両試行における運動野酸素化動

かにすることとした．

態を比較した．

● 方● 結果および考察法

被験者は 6 名の健康な女子大学生とした．被験者は運動準備期の運動野酸素化動態は，酸素化 Hb およ

15 秒間の運動準備期（検者の合図 5 秒＋カウントダ

び総 Hb において試行間に差がみられ，心拍最大変化

ウン 10 秒）の後，掌握運動（60 ％ MVC）を 10 秒間

試行においては，ベースラインからの酸素化 Hb の上行う課題を 10 セット行った．

昇および脱酸素化 Hb の減少が有意であった．このことから，心拍最大変化試行では，運動野血流速度の脳活動の指標として，左右運動野手領域脳酸素動122

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Fig. III.10.2-1 The oxygenation in the contralateral motor cortex during the resting preparatory period and the sustaining right hand grip exercise. Filled circles show that of maximal HR change session during the resting preparatory period and open circles show that of minimum HR change session during resting preparatory period.

上昇が生じていたことが確認された．一方，運動時● 文

献

岩館雅子, 定本朋子 : 運動準備期の大脳皮質運動野周辺における酸素動態と循環応答の対応. 脈管学, 48: 389396, 2008.
Hoshi Y, Tamura M : Dynamic multichannel nearinfrared optical imaging of human brain activity. J
Appl Physiol, 75: 1842-1846, 1993.

については，準備期でみられたような，両試行間の差がみられなかった．このことから，運動準備期における運動野の活性化は，運動時に生じる活性化には関連しないことが示唆された．

123

11

筋の酸素代謝特性と運動時循環応答との連関
笹原（上田）千穂子 1, 2）

Associated changes in muscle oxygenation with circulatory responses
during exercise
Chihoko Ueda-Sasahara■本課題の共同研究者
加賀谷淳子 2）1）

東海学園大学，2）日本女子体育大学基礎体力研究所

11.1

異なる強度での静的膝伸展運動後における筋の浅部と深部の再酸素化
笹原（上田）千穂子，加賀谷淳子

11.1 異なる強度での静的膝伸展運動後における筋の浅部と深部の再酸素化
笹原（上田）千穂子，加賀谷淳子
Reoxygenation of muscles at the superficial and in the deep regions
during static knee extension exercise at varying intensities
Abstract
The purpose of this study was to investigate a hypothesis that circulatory responses to various exercise intensities closely relate to muscle fiber type dominantly recruited during the exercise. We examined that muscle oxygenation in the vastus lateralis (VL) and circulatory responses to static knee extension exercise at various intensities. Method: Ten healthy female subjects performed static knee extension exercise at 10%, 20%, 30%, 40%, 50%, 60% and 70% maximal voluntary contraction (MVC) for 1min at each level in sitting position. Muscle oxygenation in the VL was monitored using multi channel
near-infrared spectroscopy and arterial mean blood pressure (MBP) was measured by photoelectric
plethysmography. Result: Half time reoxygenation, the time taken to reach a value of half-maximal
recovery after exercise, for all channels was significantly delayed in exercise at 70% MVC comparedwith the other intensities. However there were no significant differences between the channels. MBP
also increased with respect to exercise intensity. Conclusion: This study shows that reoxygenation timein the VL after static knee extension was prolonged in accordance with increasing circulatory responses
to ascending exercise intensities. However, reoxygenation was more delayed at higher exercise intensity
than those expected from lower intensities, whereas circulatory parameters increased linearly.

● 目

Medical Systems BV）で測定した．筋酸素動態は近的

本研究は，運動強度の増加に伴う循環指標の変化

赤外分光法装置（OMM-3000，Shimadzu）により，は動員される運動単位の代謝特性に密接に関与して骨格筋の酸素化ヘモグロビン，脱酸素化ヘモグロビ

いるのではないかという仮説を検証することを目的

ン，総ヘモグロビンを測定し，T1 ／ 2 reoxy time は先とした．具体的には，①運動後の筋再酸素化時間行研究（Hamaoka et al. 1992; Ichimura et al. 2006）（T1 ／ 2 reoxy time，筋の有酸素性代謝貢献度が低いとと同じ方法で酸素化ヘモグロビンより算出した．測延長する）が運動強度の上昇に伴い顕著に延長し始定プローブの送受光間距離を 2 cm，3 cm，4 cm，5

める負荷強度が存在するか否か，②筋の浅い部位とcm として，同一筋内の深さの異なる部位での T1 ／ 2

深い部位で筋線維組成が異なることが知られている

reoxy time を求めた．

が，これが T1 ／ 2 reoxy time と運動強度の関係に影響● 結果および考察を与えるが否かについて検討した．

MBP は負荷強度の増加に伴い上昇し，10 ％ MVC● 方に対して 30 ％ MVC 以上の強度で有意に高かった．

法

被験者は健康な成人女性 10 名であり，座位姿勢で一方，T1 ／ 2 reoxy time は負荷強度に対して指数関数

静的膝伸展運動を行った．運動強度は最大随意筋力的な上昇を示し，10 ％ MVC に対して 70 ％ MVC に（MVC）の 10，20，30，40，50，60，70 ％とし，おいて有意に高い値を示した．T1 ／ 2 reoxy time の筋

各強度の運動負荷後十分な休憩時間をとった後，次の浅い部位と深い部位とにおける比較では，どの強の強度の測定を行った．運動時の平均血圧（MBP）

度においても有意差はなかった．以上の結果から，を連続指血圧測定装置（Finometer，Finapres

筋再酸素化時間が顕著に延長する運動強度が存在す

127

Fig. III.11.1-1 Half time reoxygenation (T1/2 reoxy time) after knee extension exercise. (A) The effects of exercise
intensities. Light source and detector distance of NIRS prove was 4 cm. (B) The effects of light source and detector
distance at the intensities of 30% and 60% MVC. Values are expressed as mean ± SE, n=10. *** Different from
10%MVC (P < 0.001).

method for the evaluation of muscle aerobic
capacity in relation to physical activity measured
by near-infrared spectroscopy. Med Sport Sci, 37:
421-429, 1992.
Ichimura S, Murase N, Osada T, Kime R, Homma T,
Ueda C, Nagasawa T, Motobe M, Hamaoka T,
Katsumura T: Age and activity status affect muscle reoxygenation time after maximal cycling
exercise. Med Sci Sports Exerc, 38: 1277-1281,
2006.

ることが明らかになったが，筋の深さによる相異はみられなかった．筋再酸素化時間も血圧も，運動強度により変化しているが，筋再酸素化時間はより高強度の運動負荷で有意に延長することが明らかにな
った．

● 文

献

Hamaoka T, Albani C, Chance B, Iwane H: A new

128

12

運動時における一次運動野の酸素化動態
澁谷

顕一 1）

Oxygenation kinetics in the primary motor cortex area during exercise
Kenichi Shibuya■本課題の共同研究者
定本1）

朋子 1），佐藤耕平 1），森山真由美 1），岩館雅子 1, 2）

日本女子体育大学基礎体力研究所，2）日本大学

12.1 Quantification of delayed oxygenation in ipsilateral primary motor cortex compared with contralateral side during a unimanual dominant-hand motor task using near-infrared spectroscopy
Kenichi Shibuya, Tomoko Sadamoto, Kohei Sato, Mayumi Moriyama, Masako Iwadate
12.2 Reduced activity of the ipsilateral primary motor cortex during repetitive handgrip exercise
Kenichi Shibuya, Masako Iwadate, Tomoko Sadamoto
12.3 A comparison between sedentary subjects and athletes of oxygenation kinetics in the contralateral primary motor cortex area during exercise leading to voluntary exhaustion
Kenichi Shibuya

12.1．Quantification of delayed oxygenation in ipsilateral primary motor cortex compared with contralateral side
during a unimanual dominant-hand motor task usingnear-infrared spectroscopy
Kenichi Shibuya, Tomoko Sadamoto, Kohei Sato,
Mayumi Moriyama, Masako Iwadate
Abstract
Using near infrared spectroscopy (NIRS) techniques, it is possible to examine bilateral motor cortex
oxygenation during a static motor task. Cortical activation was assumed to be reflected by increased
oxygenation. The purpose of the present study was to examine the time course of oxygenation in thebilateral motor cortex during a low-intensity handgrip task. Six healthy, right-handed subjects participated in the study. The near-infrared spectroscopy probes positioned over the bilateral motor cortex wereused to measure the cortical activation throughout a handgrip task carried out. The subjects performed
a 3-min handgrip task with increasing intensity in a ramp-like manner [10-30% of the maximal voluntary contraction (MVC) at 6.67% MVC.min-1]. Contralateral motor cortex oxygenation increased significantly from 100 to 180 s after the start of the motor task compared with the baseline value (p < 0.05).
Ipsilateral motor cortex oxygenation also increased significantly from 130 to 180 s after the start of the
motor task (p < 0.05). The onset of increase in oxyhemoglobin ([HbO2]) and decrease in deoxyhemoglobin ([Hb]) in contralateral motor cortex area (M1) were significantly earlier than in ipsilateral M1(respectively, p < 0.05). These results show that there is a delayed oxygenation in ipsilateral primary
motor cortex area compared with contralateral side during a unimanual dominant-hand motor task.

tus (780, 805, and 830 nm; NIRStation,● Purpose

Muscle fatigue is characterized by an exercise-

OMM3000, Shimadzu Co., Kyoto, Japan) for

induced loss of power- and force-generating abili-

measuring motor cortex oxygenation. The opticalty of the muscle during the course of or afterprobe consisted of one emitter and one detector

exercise (Bigland-Ritchie and Woods, 1984; Booth(comprising three separate sensors). These probes

and Thomason, 1991; Nybo and Nielsen, 2001;

were guided on the subjects' heads using glass

Gandevia, 2001). The purpose of the present

fiber bundles and positioned over the bilateral

study was to examine bilateral M1 oxygenation

motor cortex areas. The distance between theduring a low-intensity unimanual handgrip task.

transmitting and the receiving probes was 3.0 cm.
The probes were positioned over bilateral motor
cortex areas for hand enclosing C3 and C4,● Methods

Six right-handed, healthy volunteers (age:according to the modified international EEG 10-20

21.4 ± 0.2 y, height: 159.1 ± 1.3 cm, weight:

system (American Electroencephalo graphic

56.3 ± 1.9 kg, MVC: 315.6 ± 11.8 N) participatedSociety, 1994).
Before the start of the study, the subjects werein the present study.
Near-infrared spectroscopy (NIRS) techniquesfamiliarized with the protocol. They performed ahave been described elsewhere (Elwell et al.

static 3-min right-handgrip task with a ramp-like1994). We used a three-wavelength NIRS appara-

increase in intensity from 10% MVC to 30% MVC

131

Table III.12.1-1

The time for oxygenation after theM1 oxygenation during the course of a low-inten-

start of motor task. Astarisks shows significant differences between the response on hemispheres (p < 0.05).

sity static motor task. The increase in ipsilateral

HbO2
Hb
tHb

Contralateral

Ipsilateral50.8 ± 35.4
32.5 ± 15.7
45.0 ± 17.3

60.0 ± 31.3 *94.2 ± 38.1 *64.2 ± 9.2 *M1 oxygenation was delayed compared with theincrease in contralateral M1 oxygenation. To thebest of our knowledge, this is the first reportshowing that ipsilateral M1 oxygenation isdelayed compared with contralateral M1 oxygena-(6.67%・min ). The subjects were seated and were-1tion during the course of a motor task.

given a handgrip meter.

In conclusion, the results of the present study
show a delayed oxygenation in the ipsilateral pri-

● Results and Discussion

mary motor cortex during the course of a uniman-

Changes in cerebral oxygenation reflect cere-

ual low-intensity motor task. The increasing oxy-bral functional activation (Colier et al. 1997, 1999;

genation in the ipsilateral motor cortex suggests a

Kleinschmidt et al. 1996; Obrig et al. 1996). In thereal-time interaction between bilateral hemi-

present study, we observed a bilateral increase inspheres during a motor task.

12.2 Reduced activity of the ipsilateral primary motor cortex during repetitive handgrip exercise
Kenichi Shibuya, Masako Iwadate, Tomoko Sadamoto
Abstract
The brain function controlling muscle force modulation during exercise has remained unclear. The
purpose of the present study was to examine the bilateral primary motor cortex (M1) oxygenation during static and repetitive handgrip exercise performed with the right hand (60% maximal voluntary contraction; 10 s exercise/75 s rest; 5 sets). Seven healthy, right-handed subjects participated in the present study. Near-infrared spectroscopy (NIRS) probes were positioned over the bilateral M1 area tomeasure cortical oxygenation during handgrip exercises. The oxygenation levels of the bilateral M1
significantly changed compared with their resting values in all trials (p < 0.0001). The oxygenation levels of the contralateral M1 did not change significantly across the trials (oxyhemoglobin (HbO2): p =0.8050; deoxyhemoglobin (Hb): p = 0.8036), while those of the ipsilateral M1 significantly decreased
across the trials (HbO2: p = 0.0371; Hb: p = 0.0317). The present results suggest an intracortical inhibition from the contralateral M1 to the ipsilateral M1 during the repetitive exercise.
M1 with the increase in repetition.

● Purpose

The purpose of the present study was to investi● Methods

gate the effect of exercise task repetition on theipsilateral M1 activity. The most noteworthy

Seven healthy, right-handed volunteers partici-

results of the present study were the constancy ofpated in the present study. Informed consent was

oxygenation in the contralateral M1 and the sig-

obtained from each subject after the subject

nificant decrease of oxygenation in the ipsilateral

received a complete explanation of the nature of132

Fig. III.12.2-1 The peak value changes in oxygenation from resting levels. Upper panels represent the results ofoxyhemoglobin (HbO2) changes. Lower panels represent the results of deoxyhemoglobin (Hb) changes. Right panels
represent the results of ipsilateral primary motor cortex oxygenation changes, and left panels represent the resultsof contralateral primary motor cortex oxygenation changes. The asterisks show significant differences from the firsttrial (p < 0.05). Error bars indicate s.e.m.

min after the detection of an optimal position forthe study procedure and its noninvasiveness.
The Near-infrared spectroscopy (NIRS) tech-

the probe. The subjects performed a static right-

nique has been described elsewhere (Elwell et al.

handgrip task [exercise: 10 s, rest: 75 s; the tasks

1994). We used a three-wavelength NIRS appara-

were performed five times at 60% of MVC, taking

tus (780, 805, and 830 nm; NIRStation,a rest between sessions].

OMM3000, Shimadzu Co., Kyoto, Japan) to meas● Results and Discussion

ure motor cortex oxygenation. The distance
between the transmitting and the receiving probes

In the present study, we found the early signifi-

was 3.0 cm. The probes were positioned over thecant changes in HbO2 and Hb after the start ofbilateral C3 and C4 hand motor areas according

exercises. The previous studies found the gradualto the modified international EEG 10-20 systemchanges in HbO2 and Hb after the start of tasks(American Electroencephalographic Society,with the exception of exercise (ef: Taga et al.

1994).

2003). We excluded the data just before the start

Subjects performed five to 10-s duration hand-of exercise to calculate the baseline values ingrip exercises. The subjects took a rest over 30

HbO2 and Hb for avoiding the inclusion of the133effects of the preparation and/or attention for thethe first trail might be affected by the inhibition

exercise on the oxygenation changes in the analy-

from the contralateral M1 to the ipsilateral M1

ses. The early changes in HbO2 and Hb after thedue to the voluntary fatigue as reported by thestart of exercises might be influenced by the way

previous studies (Shibuya et al. 2006; Shibuya eetof analysis we used. Another possible explanation

al. 2007). On the other hand, the results of thefor the early changes in HbO2 and Hb in the pres-present study might reflect that the ipsilateral M1

ent study was the effect of blood flow changes

partially contributes to the force modulation.

after the start of exercise. It is generally believed

Muscle power output during exercise is funda-that the cerebral blood flow does not change dur-mentally controlled by the contralateral M1.

ing static exercise (Rogers et al. 1990). The possi-

The present results suggest an intracortical inhi-

bility of the influence of cerebral blood flow

bition from the contralateral M1 to the ipsilateralchanges on the oxygenation in the bilateral M1

M1 during the repetitive exercise and the possibil-

must be low. The early changes during exercise in

ity a collateral contribution of the ipsilateral M1

the present study might be the effects of attention

to force production, and that this contribution

and/or preparation for the start of exercise.

declines with the habituation for exercise. Further
studies should focus on elucidating the contribu-

The lack of oxygenation in the ipsilateral M1tion of the ipsilateral M1 to force production.

during exercise at the fifth trial compared with

12.3 A comparison between sedentary subjects and athletesof oxygenation kinetics in the contralateral primary
motor cortex area during exercise leading to voluntaryexhaustion
Kenichi Shibuya
Abstract
Motor signals are commanded fundamentally from the primary motor cortex contralateral to theexercising limb (M1contralateral). The signals from the M1contralateral reach the contracting muscle through thecorticospinal and spinal motoneurons. When muscle fibers are repeatedly contracted, energy supplies
are depleted, and the muscles become fatigued. Physiological fatigue is characterized by exerciseinduced loss of the power- and force-generating ability of the muscle during the course of or after
exercise. It remains unclear whether the activation kinetics in the motor cortex area could be different
between athletes and sedentary subjects during exercise leading to voluntary exhaustion. We examined this in 7 athletes and 7 sedentary subjects. We performed near-infrared spectroscopy over the
positioned motor cortex area to measure oxygenation throughout a handgrip exercise leading to voluntary exhaustion. The subjects performed a sustained 50%-60% maximal voluntary contraction handgrip
exercise until voluntary exhaustion. In athletes, oxygenation in the M1contralateral decreased significantly atvoluntary exhaustion compared with the resting values (p < 0.05). On the other hand, in sedentary
subjects, oxygenation in the M1contralateral increased throughout the exercise (p < 0.05). These results suggest that the motor signals from the motor cortex area may be different between athletes and sedentary subjects, especially in a fatiguing exercise.

134

Fig. III.12.3-1 The values of changes in the sedentary subjects in the contralateral motor cortex from resting values in (a) oxyhemoglobin concentration (HbO2), (b) deoxyhemoglobin concentration (Hb), and (c) total-hemoglobin
concentration (tHb) during the handgrip exercise in left panels, and in the athletes in the right panels. Values are
represented as means ± SD. Asterisks show significant differences, p < 0.05.

with little experience who did not exercise habitu-● Purpose

ally.

Using near-infrared spectroscopy to determine
whether adaptation for exercise changes cortical

Four wavelengths (775, 810, 850, and 905 nm)

activation dynamics during exhaustive exercise, inof near infrared spectroscopy (NIRS) were used

the present study, we compared the M1 contralateral(NIRO-300L, Hamamatsu Photonics, Japan) for

oxygenation kinetics between athletes and seden-

motor cortex oxygenation. The optical probe con-tary subjects during exercise reaching to volun-

sisted of an emitter and a detector (comprising 3tary exhaustion.

separate sensors). The system was guided on thesubjects' heads through glass fiber bundles. The
probes were positioned over the M1contralateral areas● Methods

Male, right-handed sedentary subjects and ath-

enclosing C3 according to the modified interna-

letes (n = 7 each) participated in the present

tional EEG 10-20 system (American Electroen-

study. The sedentary subjects were individuals

cephalographic Society, 1994).

135

They performed a static right-hand handgrip● Results and Discussion

task at 50%-60% MVC until they could sustain

The notable findings in the present study were

50% MVC. While resting in an inclining position,

the different oxygenation kinetics between thethey were asked to pinch the hydraulic handgrip

sedentary subjects and athletes during exercise

meter, a nylon tube connecting the handgrip

reaching to exhaustion. In the sedentary subjects,

device and transducer that was held at heart

the oxygenation in the M1 contralateral continued tolevel. The exercise trials were repeated 3 times

increase even at voluntary exhaustion. By con-for each subject. A static right-hand handgrip task

trast, in the athletes, the oxygenation in the M1con-

at 50%-60% MVC until they could sustain 50%

tralateral

MVC. While resting in an inclining position, they

the resting values. In conclusion, the noteworthy

were asked to pinch the hydraulic handgrip

findings in the present study were that the oxy-meter, a nylon tube connecting the handgrip

genation kinetics in the M1contralateral were dif-

device and transducer that was held at heart

ferent between elite athletes and sedentary sub-level. The exercise trials were repeated 3 times

jects during the handgrip exercise leading to vol-for each subject.

untary exhaustion.

136

decreased at exhaustion as compared with

IV．プロジェクトの共同研究における成果共同研究 1
Redistribution of blood flow during exercise;
Critical exercise intensity for circulatory andmetabolic changes in response to knee extension
exercise and its relationship to blood flow to
exercising limb
Atsuko Kagaya1）, Mitsuru Saito2）, Tomoko Sadamoto1）, Marco Ferrari3）,
Valentina Quaresima3）, Mifuyu Kamo1）, Takuya Osada4）,
Shizuyo Shimizu-Okuyama5）, Kohei Sato1）, Masako Iwadate1, 6）,
Fumiko Ohmori1, 7）, and Valentina Cettolo3）

1.1

General introduction and methods for the present study
A. Kagaya, M. Saito, M. T. Sadamoto, Kamo1), M. Ferrari, V. Quaresima, M. Kamo, T. Osada,S. Shimizu-Okuyama, K. Sato, M. Iwadate, F. Ohmori, and V. Cettolo

1.2

Exercise intensity-dependent changes in femoral blood flow, electrical muscle activity

andmuscle oxygenation during dynamic knee extension exercise
A. Kagaya, M. Kamo, F. Ohmori, M. Iwadate, K. Sato, S. Shimizu-Okuyama, T. Osada, T. Sadamoto,
M. Saito, M. Ferrari, V. Quaresima, and V. Cettolo
1.3

The effect of the exercise intensity on the blood pressure response at the onset of dynamic exercise
K. Sato, F. Ohmori, M. Iwadate, T. Sadamoto, and A. Kagaya

1.4

Peak blood flow in the femoral artery during the contraction and relaxation phase of knee
extension exercises
F. Ohmori, M. Kamo, M. Iwadate, S. Shimizu-Okuyama, and A. Kagaya

1.5

Aorta and femoral arterial blood flow velocity during the contraction and relaxation phases ofdynamic knee extension exercise
S. Shimizu-Okuyama, F. Ohmori, M. Iwadate, K. Sato, and A. Kagaya

1.6

The quadriceps oxygenation heterogeneity during dynamic knee extension exercise
V. Cettolo, V. Quaresima, and M. Ferrari

1.7

The relationship between the oxygenation in active muscle and local fatigue sensation during
dynamic knee extension exercise
M. Iwadate, M. Saito, M. Kamo, K. Sato, F. Omori, and A. Kagaya

Japan Women’s College of Physical Education，2）Toyota Technological Institute，3）University of L’Aquila，4）Tokyo

1）

Medical University，5）Keio University，6）Nihon University，7）National Institute of Fitness and Sports in Kanoya

1.1 General introduction and methods for the present study
A. Kagaya, M. Saito, T. Sadamoto, M. Ferrari, V. Quaresima, M. Kamo,
T. Osada, S. Shimizu-Okuyama, K. Sato, M. Iwadate, F. Ohmori,and V. Cettolo
General introduction

General Methods● Subjects

Muscle contraction force is one of the mostimportant factors in controlling blood flow to exer-

Eight female physical education major students

cising muscles. Mechanically, it determines arterial

with no medical problems participated in thisinflow and venous outflow in exercising muscles bystudy after giving their written informed consent.

changing intramuscular pressure. As to muscle

Their mean (± SD) age, height, body mass, themetabolism, a muscle action at different force

femoral fat layer thickness, the thickness in thechanges muscle fiber type recruitment, thereby

lateral vastus muscle (VL) and VL +the rectuschanging muscle metabolism, which will directly

femoris muscle (RF) were 22.1 ± 1.9（SD）years

influence the blood vessels of exercising muscles. In

old，159.7 ± 4.7 cm，55.1 ± 9.9 kg，7.5 ± 2.1

addition, it affects various tissues of different organs

mm，22.4 ± 2.6 mm (VL），and 36.6 ± 3.2 mm

such as the spleen, inactive muscles, skin, etc.

(VL ＋ RF), respectively．

In response to the increasing demand of blood● Experimental design(oxygen) supply to the active muscles, the cardiovascular system adjusts itself either by increasing

The subjects performed dynamic knee extension

cardiac output or by attenuating blood flow to theexercise with right leg using specially devised

other tissues. In previous literature, the regulation

ergometer (Vine Co). They sat on a high chairof cardiovascular system was discussed from sever-with their back fixed to a support, and theiral aspects of the system but was not discussed in anankles were connected to the pedal of cycle by aintegrative manner.

strap. Starting position of the knee was 90 °from

In this study, we hypothesized that increasing

the horizontal, where the participants moved themuscle force requires recruiting type II fibers andweight through a range of 20 °．We used six work

switching metabolism from aerobic to anaerobic

loads (5-60 ％ MVC）for dynamic knee extension.

dependency, which will evoke metabo-receptor

Exercise frequency and exercise time were 60

mediated sympathetic activation. Therefore, a criti-

times/min and three minutes or until exhaustion

cal intensity at which the physiological response tofor all work loads, respectively.

exercise should exist for limiting further increases in● Measurements and analysis

blood flow, despite an increase in exercise intensity.
The purpose of this study, therefore, was to test

Local Fatigue Sensation (LFS) and RPE

this hypothesis by studying blood flow redistribu-

During dynamic knee extension, the rate of sub-tion to exercising muscles, in relation to cardiac

jective fatigue sensation from the working right

output, muscle oxygenation, subjective muscle

femoral muscles was reported by having the sub-fatigue sensation, etc.

jects point to a number with their blinking every
30s using a category scale by Saito (1989) for LFS
141

5201, Westron, Chiba, Japan). Breath-by-breathand Borg(1982) for RPE.

data were analyzed using customized software on acomputer (PC-9821, NEC, Tokyo, Japan).

Femoral artery blood flow velocity and vessel

Systolic and diastolic arterial blood pressure (SBP

diameter
Blood velocity and vessel diameter of common

and DBP) were measured no-invasively by photo-

femoral artery were measured using a Doppler andelectric plethysmography with a Finometer

B-mode ultrasound apparatus (Vivid7pro). A 7.5(FinapresMHz liner array transducer was placed over femoral

Netherlands). Furthermore, the heart rate (HR),artery, approximately 1 cm above the bifurcation

stroke volume (SV), and thus cardiac output (CO)into the superficial and profunda femoral branch.

were determined from the blood pressure wave

The probe position was stable and the sample vol-form using the Model flow software program, incor-

ume was precisely placed in the center of the vessel,

porating gender, age, height, and weight (Beatand then adjusted to cover the width of the diame-

Scope1.1, Finapres Medical Systems BV, Arnhem,ter. A Doppler spectrum signal was recorded contin-

Netherlands). CO was calculated as SV × HR.

MedicalSystems

BV,

Arnhem,uously.
EMG recording
EMGs were recorded using Ag-AgCL electrodes

Cardiac output and stroke volume
During exercise, stroke volume (SV) was meas-

placed on 4 sites, the right medial vastus muscle

ured using a Doppler ultrasound method with a 2.5(VM) , right lateral vastus muscle (VL), right rectus

MHz transducer (SYSTEM V，ALOKA). Two-femoris muscle (RF), left lateral vastus muscle (VL)

dimensional echo-cardiographic images wereusing bipolar lead，the details of which have beenrecorded in the parasternal long-axis view, thedescribed elsewhere (Ebenbichler et al. 1998; Kamo,

place where the aortic annulus diameter was meas-

2002) except for the sites of RVL. The electrodes for

ured, and in the apical 3 chamber view, immedi-

RVL were placed at the proximal area and distal

ately proximal to the aortic valve. The blood flow

area close to the sites of optical probe of NIRS.

velocity was recorded on aorta continuously by the
NIRS measurements

Doppler method throughout the experiment. Before
each Doppler ultrasound recording, the transducer

The near infrared spectroscopy (NIRS) data

direction was adjusted in the 2D mode according

were acquired with a sampling time of 0.19 s overto the Doppler signal sound and the aorta image.

the exercising vastus lateralis muscle by using a

All the signals were stored on video tape recorder54-channel imager (NIRStation OMM3000,(VTR) for later analysis.

Shimadzu, Japan). The optical probe covered anarea of 4 × 6 cm2 and it consisted of 12 transmit-

Cardiorespiratory responses

ters and 12 receivers positioned in a rectangular

Respiratory parameters were determined with anmatrix of 4 rows, 6 columns with a 1 cm separa-

on-line system for the breath-by-breath method.

tion. The center of the matrix corresponded to the

Respiratory gas was sampled continuously from acenter of the selected thigh muscle body verified

face mask. The gas fractions were analyzed by a

by ultrasonography. Each channel resulted by amass spectrometer (ARCO-1000, Arco system,

given association of a transmitter and a receiver

Chiba, Japan) that was calibrated and confirmed

placed at different distances parallel to the axis ofbefore each test. The expired gas volume was

the thigh muscle (from 1 cm to 5 cm) or obliquemeasured by a Fleisch pneumotachometer (WLSU-(from 1.41 cm to 5.1 cm).

142

1.2

Exercise intensity-dependent changes in femoral
blood flow, electrical muscle activity and muscle oxygenation during dynamic knee extension exercise

A. Kagaya, M. Kamo, F. Ohmori, M. Iwadate, K. Sato,S. Shimizu-Okuyama, T. Osada, T. Sadamoto, M. Saito, M. Ferrari,
V. Quaresima, and V. Cettolo● Purpose● Results and Discussion

Blood flow to exercising muscles increased withThe Qfa during the relaxation phases of 25-30s in

exercise intensity, and reached its peak during

exercise increased with exercise intensity and lev-

regional exercise using small muscle masseled off around 40% MVC, whereas it decreased(Kagaya 1994), under the conditions when theduring contraction phases at higher intensities.

cardiac pumping capacity was not a limiting fac-

The ratio of Qfa during the contraction phase totor. Additional findings were that the peak bloodthat during the relaxation phase, used as an indica-

flow during exercise did not reach maximal value

tor of blood flow impairment, significantly

obtained during maximal metabolic vasodilatation

decreased when exercise intensity exceeded 30%(Sinoway et al. 1999). These findings lead us to

MVC (Fig. IV.1.2-1). Increasing rate of iEMG withhypothesize that an inhibiting mechanism will

exercise duration was examined in relation to exer-

work during exercise to overwhelm further

cise intensity. Steeper elevation of iEMG was

vasodilatation. The purpose of this study was toobserved at the exercise intensities above 30%

clarify the physiological mechanism for regulating

MVC. The de-oxygenation in the muscle was signifi-

regional blood flow, in order to prevent increase

cantly accelerated at the higher intensities above

to its maximal vasodilatation capacity. For this

30% MVC. These results suggested that the exer-

purpose, the exercise intensity to induce criticalcise intensity approximately at 30% MVC will be achanges in the femoral arterial blood flow, electri-

critical point to augment vasoconstriction effect via

cal muscle activities, and muscle oxygenation ofmuscle metabo-reflex and mechanical compression

different depths of muscle layer were studied.

of the vessel. Greater recruitment of type II fibers,
elevated intramuscular pressure, and accumulation● Methods

Seven healthy females (22 ± 2 yrs) participatedin the study as subjects. They performed dynamic
knee extension exercise in upright position at 6
different intensities (5-60% MVC). Femoral arterial
blood flow (Qfa) and muscle oxygenation (NIRS),
were measured and EMG was recorded from thighmuscles (VL). The optical probes of NIRS werelaced over VL at the distances of 1, 3, and 5 cm.

* p < 0.05 vs 17%, # p < 0.05 vs 25%
Fig. IV.1.2-1 Qfa during muscle contraction (C) relative to that during the relaxation (R) phase.

143cle oxygenation during incremental exercise. J
Appl Physiol, 87: 348-355, 1999.
Kagaya A : Maximal exercise-induced vasodilation andpeak pulmonary oxygen uptake during dynamic
forearm and calf exercise. J Exerc Sci, 4: 55-62,
1994.
Sinoway L, Prophet S : Skeletal muscle metaboreceptor
stimulation opposes peak metabolic vasodilatationin humans. Circ Res, 66: 1576-1584, 1990.

of muscle metabolites (Grassi et al. 1999) accelerates
vasoconstriction and prevents the vessels in exercising muscle from maximally dilating.

● References

Grassi B, Quaresima V, Marconi C, Ferrari M,
Cerretelli P : Blood lactate accumulation and mus-1.3 The effect of the exercise intensity on the blood pressure response at the onset of dynamic exercise
K. Sato, F. Ohmori, M. Iwadate, T. Sadamoto, and A. Kagaya
exercise in humans, and to elucidate whether the● Purpose

The purpose of the present study was to deter-

decrease in TPR at the onset of dynamic exercise

mine the effect of the exercise intensity on the rel-was simply reflected change in peripheral vascu-

ative change of the total systemic peripheral

lar response in exercising muscle.

resistance (TPR) and cardiac output (CO) in estab● Methods

lishing mean arterial blood pressure (MAP)

Cardiavasular [MAP, CO, TPR, heart rate (HR),response to immediately after the start of dynamic

Fig. IV.1.3-1 The time course of averaged relative changes in the cardiovascular responses from 30-s before theonset of exercise to 40-s after the onset of exercise for 10% and 40% MVC. * # Different from Rest (P < 0.05). †Difference between 10% and 40% MVC at each time point (P < 0.05).

144

Fig. IV.1.3-2 Averaged relative change in CO (A) and TPR (B), and absolute change in MFBF (C) and FVR (D), calculated as difference between Rest and the average value for 5-s at 5-10-s, 15-20-s, and 25-30-s each time points
after the start of exercise. † Difference between 10% and 40% MVC at each time point (P < 0.05)

and stroke volume (SV)], mean femoral vascularincrease in exercise intensity; 2) The magnitude ofblood flow (MFBF), and then femoral vasculardecrease in FVR at the onset of 40% MVC wasresistance (FVR) were measured in 7 healthy

significantly larger than that of 10% MVC.

females at the onset of knee extension dynamic● Discussion

exercise at 10% and 40% maximal voluntary contraction (MVC).

These results indicated that MBP responses at theonset of dynamic exercise is the variable being reg-

● Results

ulated with increasing exercise intensity. Therefore,

In the present study, the following results werecombination mechanisms of TPR and CO responses

obtained (Fig. IV.1.3-1 and 2): 1) An initial fall indue to baroreflex and central command mediated

MAP at 〜 10-s after the start of exercise wasautonomic activity would produce an appropriate

reduced by an increase in the exercise intensity at

MBP response at the onset of dynamic exercise.

10% MVC to 40% MVC, combined with same

Furthermore, change in TPR at the onset of dynam-

level of decrease in TPR for 10% and 40% MVC,

ic exercise would not simply and necessarily reflect

and enhanced CO response that accompanies ana change in peripheral vascular response.

1.4

Peak blood flow in the femoral artery during the contraction and relaxation phase of knee extension exercises

F. Ohmori, M. Kamo, M. Iwadate, S. Shimizu-Okuyama, and A. Kagaya
exercise, and the increase was linearly related to● Purpose

exercise intensity at lower intensity (Lind andBlood flow to exercising limbs increases during145

eter of systolic and diastolic phase of cardiac
cycle and blood pressure were measured during
muscle contraction and relaxation phase.

● Results and Discussion

The diameter of vessels became larger with theincrease of exercise intensity, and was significantly(p < 0.05) larger at 25-55% MVC than that at 8%
MVC during the muscle relaxation phase.
Adjustment for systolic blood pressure during the

Fig. IV.1.4-1 Femoral arterial blood flow in relation
to exercise loads during contraction (lower) and relaxation phases of dynamic knee extension exercise.

muscle relaxation phase was significantly (p <0.05) higher in exercise at 55% MVC than those at
8-34% MVC. Femoral arterial blood flow during

McNicol, 1967; Lind and Williams, 1979; Kagaya,

the contraction phase was unchanged with1996). However, it is still a matter of issue whether

increasing contraction force. In contrast, it

it continues to increase linearly up to maximal

increased during the relaxation phase with anintensity (Radegran and Saltin, 1998), or it levels off

increase in exercise intensity up to 25% MVC, andat higher intensity (Lind and Williams, 1979;

leveled off when exceeding 25% MVC (Fig. IV.1.4-

Kagaya et al. 1996). One possible reason for the1). The highest blood flow during exercise was

opposing results may include whether the studies

obtained within a significantly (p < 0.05) shorter

included intensive exercise with high contraction

time at 55% MVC compared with at 25% MVC. In

force that induced exhaustion within one minute.

conclusion, the femoral arterial blood flow during

The purpose of this study, therefore, was to test theknee extension exercise reaches its peak at 25-

hypothesis that the regional blood flow to exercising

55% MVC, and the time reaching peak blood flow

limb levels off at higher intensity and reaches peak

was shorter during exercise at higher intensity.

blood flow during dynamic exercise at high contrac-

The increase in blood flow velocity and enlarge-

tion force. For this purpose the femoral artery blood

ment of vessel diameter during the systolic phaseflow for the respective contraction and relaxation

contributed to the increase of the blood flow.

phase was studied during knee extension exercise at● References

various intensities including exhausting high-intensi-

Kagaya A, Homma S : Distribution of blood flow with
the increase of exercise intensity during handgrip
exercise. Jp J Phys Fitness Sports Med, 45: 672,
1996 (in Japanese).
Lind AR, McNicol GW : Local and central circulatory
responses to sustained contractions and the effectof free or restricted arterial inflow on post-exercise hyperemia. J Physiol, 192: 575-593, 1967.
Lind AR, Williams CA : The control of blood flow
through human forearm muscle following brief
isometric contractions. J Physiol, 288: 529-5547,
1979.
Rådegran G, Saltin B : Muscle blood flow at onset ofdynamic exercise in man. Am J Appl Physiol,
274: H314-H322, 1998.

ty exercise with short duration.

● Methods

Seven physically active women participated in
the study after giving their informed consents.
Blood velocity and vessel diameter of femoral
artery were measured using a Doppler and Bmode ultrasound apparatus (Vivid7) with a 7.5
MHz transducer.

Blood pressure was measured

using Finapres. Blood velocity signal, vessel diam-

146

1.5

Aorta and femoral arterial blood flow velocity during
the contraction and relaxation phases of dynamic
knee extension exercise

S. Shimizu-Okuyama, F. Ohmori, M. Iwadate, K. Sato, and A. Kagaya
the femoral artery was higher than the aorta dur-

● Purpose

The purpose of this study was to observe theing the relaxation phase (fa: 10% 61.6 ± 5.8, 50%changes in the blood flow velocity in the aorta

79.2 ± 11.9, Ao: 47.6 ± 2.6-53.8 ± 3.7 cm/s). The

and femoral artery during the muscle contraction

femoral/aorta ratios were − 67.4 ± 9.2% (10%),and the relaxation phases of dynamic knee exten-

and − 80.6 ± 4.9% (50%) during the contraction

sion exercise (KE).

phase (Fig.IV.1.5-1). However, during the relaxation phase, they were 30.0 ± 11.6% (10%), and50.7 ± 22.3% (50%), respectively. Mean blood● Methods

pressure was not significantly different between

Seven female subjects (aged 22.4 ± 1.9 years)

the contraction and relaxation phase.

participated in this study. All subjects gave
informed consent prior to their participation after

These results suggest that the effect of muscle

receiving a full written explanation of the experi-

contraction and relaxation on blood flow velocity

ment. They performed one-legged knee extension

differs between the aorta artery and femoral

exercise in the upright position at 10% and 50% ofartery. The femoral artery blood flow was moremaximal voluntary contraction (MVC) until

accelerated compared to aorta during the relax-

exhaustion. Blood velocity was measured using

ation phases.

the Doppler ultrasound method for aorta artery[ao] and femoral artery [fa] (SYSTEM V, GE).
Blood Pressure was monitored from the finger ofthe left hand (Finapres, Ohmeda, USA) at theheart level.

● Results and Discussion

During the muscle contraction phase of KE, theblood velocity in femoral artery was significantly(p < 0.01) lower than that in the aortic artery (fa:
10% 15.8 ± 4.9, 50% 10.7 ± 3.1, ao: 47.6 ± 2.6Fig. IV.1.5-1 The femoral/aorta blood velocity ratios

53.8 ± 3.7 cm/s). In contrast, the blood velocity in

147

1.6

The quadriceps oxygenation heterogeneity during
dynamic knee extension exercise
V. Cettolo, V. Quaresima and M. Ferrari
dynamic response within each exercise intensity,● Purpose

The heterogeneity muscle oxygenation during

and the effect of the exercise intensity on muscle

exercise has been reported for distal and proximal

response, the mean changes in Hbdiff and tHb

or lateral or medial, but not for vertical into mus-were calculated over the last 5 s of exercise forcle layer. The purpose of this study was to clarify

each data-set.

the vertical heterogeneity of quadriceps oxygena● Results and Discussion

tion during dynamic knee extension exercise.

As expected, the duration of the exercise was1) Quadriceps oxygenation heterogeneity

variable and it depended on the exercise intensi-

during dynamic knee extension exer-ty. The changes in Hbdiff in response to eachcise measured by multi-channel near

exercise intensity were clearly evident. In theinfrared spectroscopy

most medial muscle portion, the rate of Hbdiff
decrease raised with the increase of the exercise● Methods

The near infrared spectroscopy (NIRS) dataintensity. At the end of the exercise, Hbdiff

were acquired with a sampling time of 0.19 s overreached the plateau in all the intensities (20-60%

the exercising vastus lateralis muscle by using a

MVC) except for the 80% MVC. A similar kinetics

54-channel imager (NirStation, Shimadzu, Japan).

was found also in the most lateral portion of the

The optical probe covered an area of 4 × 6 cm2thigh muscle. A not statistically significant differ-and it consisted of 12 transmitters and 12

ence for the Hbdiff changes was found when thereceivers. NIRS measurements were performed

exercise was performed at the lowest intensity

while the 8 subjects were performing maximal(i.e. 10% MVC, channel effect, F=2.80, P=n.s).

voluntary contraction (MVC) or dynamic knee

For the other exercise intensities, the most lateralextension exercises at 10, 20, 30, 40, 50 and 60%

portion (i.e. channel #36) showed Hbdiff decrease

MVC. For each channel, maximal oxyhemoglobin

significantly lower than that observed in the medi-(O2Hb), deoxyhemoglobin (HHb) and total hemo-

al portion (channel effect, F = 4.40, P < 0.02, 20%

globin (tHb=O2Hb+HHb) changes observed during

MVC; F=4.24, P < 0.02, 30% MVC; F = 9.69, P <the post MVC phase were calculated as the aver-

0.0005, 40% MVC; F = 3.87, P < 0.05, 50% MVC;

age, over the time interval 3-6 s after the end of

F = 4.34, P < 0.02, 60% MVC). The tHb changes

the MVC exercise. Only the 4 channels (9/18, andwere not statistically different between the medial

27/36) corresponding to the medial and lateraland lateral portions for all exercise intensities

portions, respectively, of the investigated muscle(channel effect, F < 2.45, P = n.s.). However, thearea with the longest receiver-transmitter distance

amplitude of Hbdiff decrease was lower in thewere considered. Changes in Hbdiff (O2Hb-HHb)

most lateral than in the most medial portion ofand in tHb were calculated. To explore the possi-

thigh muscle. This suggests that the most medial

ble heterogeneity of muscle metabolic and hemo-

portion, having a higher oxidative metabolic148

Fig. IV.1.6-1 Concentration changes in Hbdiff (panel A) and tHb (panel B) as function of the exercise intensity(expressed in % MVC). Each data point represents the average over the 8 subjects. For each subject the mean value
was calculated over the last 5 s of the exercise for each considered channel.

activity, is more involved than the most lateral

medial portion of the thigh muscle was more

portion in the dynamic knee extension performed

involved than the lateral one, especially for mod-at any intensity. As expected, after a transient

erate-high intensity exercises. Furthermore, thedecrease at the onset of the exercise, the tHb

decrease in Hbdiff and the increase in tHb wereincreased during the exercise but only in thedependent on the exercise intensity until the

medial muscle portion and for lower intensity

intensity did not induce exhaustion in most of theload (i.e. 20 and 30% MVC) the tHb reached thesubjects.

plateau. Therefore, only in these cases it is possi-

2) Quadriceps

ble to consider the changes in Hbdiff as an index

oxygenation

duringof muscle oxygenation. Unlike the Hbdiff changes,

dynamic knee extension exercise on

the amplitude of tHb changes were almost similar

non-exercising leg measured by two-

in both portions of the investigated thigh muscle.

channel near infrared spectroscopy.
● Methods

The concentration changes in Hbdiff and in tHb
during the last 5 s exercise as function of the

The NIRS measurements over the nonworking

exercise intensity are depicted in the figure. It isleft leg were performed by the NIRO-200 oximeter

evident that at low-moderate intensity exercise(Hamamatsu Photonics K.K., Japan). The two opti-(10-30% MVC) the Hbdiff and the tHb changes

cal probes (consisting of one emitter and one

decreased and increased, respectively; whilst

detector 4.0 cm apart) were attached to the skin ofwhen the exercise was stopped for exhaustion of

the vastus Lateralis (VL) and rectus Femoralis (RF)the subjects (i.e. prevalently at 40, 50 and 60%

main body muscles. The NIRS data were collectedMVC) the Hbdiff intensity reached a minimum

with a sampling rate of 6 Hz. The measured NIRS

stable value, whilst the tHb changes did notdata were: 1) tissue oxygenation index (TOI,

increase.

expressed in %), 2) concentration changes in O2Hb

In conclusion, these results suggest that theand HHb (expressed in (M (cm), and 3) the derived

hemodynamic response (expressed as tHb) waschanges in tHb. TOI reflects the local balancealmost uniform over the investigated muscle thighbetween O2 supply and O2 consumption. The tHbarea for all exercise intensities, whilst the muscle

volume changes, being strictly related to blood vol-oxidative metabolic response (expressed as

ume changes, can be considered an indirect meas-

Hbdiff) was heterogeneous. In particular, theure of local blood flow changes. NIRS measure-149

ments were performed while the 8 subjects weresimilarly in both muscles; instead tHb decreased

performing dynamic knee extension exercises atmore in the RF muscle. The tHb and TOI of left

10, 20, 30, 40, 50 and 60% of MVC with the rightleg changed significantly during exercise withleg. The maximal duration of each exercise was ofrespect to the rest condition (Exercise effect: F =3 min or until the exhaustion of the subject.

12.47, P < 0.0001 and F = 14.13, P < 0.0001 for

To explore the muscle metabolic and hemody-tHb and TOI, respectively). The amplitude of

namic response within each exercise intensity, andthese changes was similar in both muscles for TOI

the effect of the exercise intensity on muscle(Muscle effect: F = 1.38, P = 0.42; Muscle x

response, the mean changes in TOI and tHb were

Exercise effect: F = 1.17, P = 0.32), instead thecalculated over the last 5 s of rest and of exercise.

tHb changes were larger in RF respect to VL mus-For each trial we calculated the mean tHb and TOIcle (Muscle effect: F = 6.39, P < 0.001; Muscle xchanges during exercise ((tHb and (TOI, respective-

Exercise effect: F = 6.67, P < 0.005). Analyzingly) as the exercise minus the relative rest values.

the tHb and TOI as function of the exercise intensity, only the tHb of RF muscle decreased as the● Results and Discussion

exercise levels increased (F = 7.40, P< 0.01).

During contralateral exercise the TOI increased

1.7

The relationship between the oxygenation in active
muscle and local fatigue sensation during dynamic
knee extension exercise
M. Iwadate, M. Saito, M. Kamo, K. Sato, F. Omori and A. Kagaya
Thus, the depth of penetration was suposed to be● Purpose

We have examined whether local fatigue sensa-〜 2.5 cm，1.5 cm and 0.5 cm, respectively . Intion (LFS) was related to the oxygenation of exer-

this manner, we examined the difference in thecising muscles during dynamic knee exercise.

metabolic changes in the superficial and deeper
layers of the VL, and investigated the most relative area to LFS changes. These data were ana-

● Methods

Six female subjects participated in three exer-

lyzed at 2 time points of 30 s after the onset ofcise experiments (low intensity 10% MVC, middle

exercise and the end of exercise in three kinds ofintensity 30% MVC, high intensity 50% MVC). The

exercise.

changes of fatigue sensation in working muscles● Results and Discussion[levels of fatigue sensation (LFS); scale 0-10] andthe oxygenation in the lateral vastus muscle (VL)

LFS increased significantly from 30 s after theand the mean arterial blood pressure (MAP) wereonset of exercise to the end of exercise during

analyzed. In this study, we used three distances

three intensity exercises.

between the light source and an optical detector

The oxygenation changes were shown in thein the NIRS probe; 5.0 cm, 3.0 cm and 1.0 cm.

low-intensity exercise, and ΔO2Hb increased at150

Fig. IV.1.7-1 Relationship between local fatigue sensation and Δ Hb in active muscle in low-intensity exercise. SL :superficial layer of VL, DL : deeper layer of VL.

the medial and lateral superficial layers from 30 s

onset of exercise and the end of exercise; howev-

after the onset of exercise and the end of exer-

er the significant changes were not observed incise. ΔHHb also increased significantly at the lat-the low-intensity exercise.

eral deeper layer and medial superficial layers of

The correlation between LFS and muscle oxy-

the lateral vastus muscle. However, ΔHbT did not

genation was statistically significant in ΔHHb ofchange significantly from 30 s after the onset ofthe low-intensity exercise but not in that of exer-

exercise and at the end of exercise. In the middle-

cise of other intensities. The correlation between

intensity exercise, ΔHHb increased in the medial

LFS and ΔMAP was also significant in the middle-

superficial layer of the muscle. However, ΔO2Hb

and high-intensity exercise.

did not change significantly from 30 s after the

These results indicate that LFS changes wereonset of exercise and at the end of exercise. In

related to the muscle oxygenation of active mus-the high-intensity exercise, ΔHHb increased incle in the low-intensity exercise. In the middle-

the medial deeper layer of the muscle.

and high-intensity exercises which MAP changed

The MAP increased significantly in the middle-

prominently, LFS changes were independent fromand high intensity exercise from 30 s after thethe muscle oxygenation changes during exercise.

151

共同研究 2
Role of central command in the cerebral and renal
blood flow responses during static exercise

Tomoko Sadamoto1）, Kohei Sato1）, Ai Hirasawa1）,
Chihoko Ueda-Sasahara1, 2）, Kenichi Shibuya1）, Mitsuru Saito3）,
Mifuyu Kamo1）, Sizuyo Shimizu-Okuyama5）, Takuya Osada4）,
and Atsuko Kagaya1）

2.1

Effect of tendon vibration during submaximal static elbow flexion exercise on muscle oxygenation
C. Ueda-Sasahara, M. Kamo, M. Saito, A. Kagaya, T. Osada, K. Sato, K. Shibuya,
S. Shimizu-Okuyama, A. Hirasawa, and T. Sadamoto

2.2

Perceived exertion is not necessarily associated with altered brain activity during exercise
K. Shibuya, C. Ueda-Sasahara, K. Sato, S. Shimizu-Okuyama, M. Saito, A. Kagaya, M. Kamo,
T. Osada, and T. Sadamoto

2.3

Role of central command for the increase in middle cerebral artery mean blood flow velocity
during static exercise in humans
K. Sato, K. Shibuya, C. Ueda-Sasahara, S. Shimizu-Okuyama, M. Saito, A. Kagaya, M. Kamo,
T. Osada, and T. Sadamoto

2.4

Role of central command in the renal arterial blood flow responses during static elbow flexion
in humans
T. Sadamoto, K. Sato, A. Hirasawa, C. Ueda-Sasahara, K. Shibuya, M. Saito, M. Kamo,
S. Shimizu-Okuyama, T. Osada, and A. Kagaya

Japan Women’s College of Physical Education，2）Tokai Gakuen University，3）Toyota Technological Institute，

1）Tokyo Medical University，5）Keio University

4）

2.1

Effect of tendon vibration during submaximal static
elbow flexion exercise on muscle oxygenation

C. Ueda-Sasahara, M. Kamo, M. Saito, A. Kagaya, T. Osada, K. Sato,K. Shibuya, S. Shimizu-Okuyama, A. Hirasawa, and T. Sadamoto
purpose of this study was to investigate the influ-● Purposeence of tendon vibration during submaximal static

Previous studies reported that muscle vibration

exercise on muscle oxygenation.

stimulus effect on motor units recruitment(Bongiovanni & Hangbarth 1990; Shinohara2005). Whole limb vibration stimulus induces a● Methods

lower tissue oxygenation during submaximal

Nine healthy females (mean ± SD: 23.8 ± 4.1

dynamic exercise because of a greater recruitment

years, 162.6 ± 4.4 cm, 56.6 ± 4.2 kg) completedof fast twich motor units (Mileva et al. 2006).

two trials, non-vibrated exercise (Ex) and vibrated

However it remains unclear whether static exer-

exercise trials (Vib+Ex). In both trials, an elbow

cise with direct vibration on the contracting mus-flexion exercise at 30% of their maximum volun-

cles also produces the lower oxygenation. The

tary contraction (MVC) was statically sustained forFig. IV.2.1-1 The changes in oxygenated hemoglobin (oxyHb), deoxygenated hemoglobin (deoxyHb), total hemoglobin (totalHb) and the Tissue Oxygenation Index (TOI). Values are Mean ± SE, n = 9．Significant differences
between Ex and Vib+Ex; ＊: P < 0.05．

1552-minutes by a visual feedback system. In Vib+Ex,

sumption and supply, there are two possible rea-an oscillating stimulation by a vibrator (frequency

sons for the greater deoxygenation in Vib+Ex in

100 Hz, amplitude 0.8 mm) was applied to thethe present study. One is a greater recruitment of

distal tendon of the biceps brachii during exer-

fast twitch motor unit caused to increase muscle

cise. The changes in oxygenated hemoglobin

oxygen consumption. The other is decrease in(oxyHb), deoxygenated hemoglobin (deoxyHb)

oxygen supply due to limitation of blood flow into

and total hemoglobin (totalHb) in the biceps

the working muscle.
In conclusion, this study suggested that the sub-brachii were recorded by near-infrared specHamamatsu

maximal static exercise with tendon vibration

Photonics, Japan). The tissue oxygenation index

reduces muscle oxygenation as similarly observed(TOI) was measured by the technique utilizing

during dynamic exercise.

troscopy(NIRS,

NIRO-200,

near-infrared spatially resolved spectroscopy● References(Matcher et al. 1994).

Bongiovanni LG, Hagbarth KE, Stjernberg L :Prolonged muscle vibration reducing motor output in maximal voluntary contractions in man. J
Physiol, 423: 15-26, 1990.
Matcher SJ, Cooper CE : Absolute quantification of
deoxyhaemoglobin concentration in tissue nearinfrared spectroscopy. Phys Med Biol, 39: 12951312, 1994.
Mileva KN, Naleem AA, Biswas SK, Marwood S,
Bowtell JL : Acute effects of a vibration-like stimulus during knee extension exercise. Med Sci
Sports Exerc, 38: 1317-1328, 2006.
Shinohara M : Effects of prolonged vibration on motor
unit activity and motor performance. Med Sci
Sports Exerc, 37: 2120-2125, 2005.

● Result and Discussion

The torque output of elbow flexion was identical between Ex and Vib+Ex. The decrease in
oxyHb during exercise was greater in Vib+Ex thanthat in Ex whereas there were similar increases indeoxyHb and totalHb in both trials. The decreasein TOI during exercise was greater in Vib+Ex thanthat in Ex.
Since muscle oxygenation measured by NIRS
reflects the balance between muscle oxygen con-

2.2

Perceived exertion is not necessarily associated withaltered brain activity during exercise

K. Shibuya, C. Ueda-Sasahara, K. Sato, S. Shimizu-Okuyama, M. Saito,
A. Kagaya, M. Kamo, T. Osada, and T. Sadamoto
The purpose of the present study was to determine● Purpose

The vibration technique gives the changes in thewhether perceived exertion was associated with pre-perceived exertion at the same internal- and exter-

frontal cortex activity by using the muscle-spindle

nal-workloads (Goodwin et al. 1972), and it helps instimulation technique during static exercise.

understanding the effects of the changes in perceived exertion on prefrontal cortex activity. This

● Methods

technique has been commonly used in previous

Subjects and paradigm
Ten normal, right-handed females (age, 21.0 ±studies (e.g., Ogoh et al. 2002; Goodwin et al. 1972).
156

Fig. IV.2.2-1 Oxyhemoglobin ([HbO2]) levels in the prefrontal cortex. Changes in the baseline values of [HbO2] concentration in the prefrontal cortex during exercise without (Ex) or with muscle spindle stimulation (Ex-Vib). Values
are represented as means ± SD. The asterisks show significant differences from the baseline values, p < 0.05.

0.7 years; height, 159.9 ± 4.8 cm; and weight,

and no significant changes between the Ex and55.6 ± 5.9 kg) participated in the present study. A

Ex-Vib conditions. The post-hoc test for changes

vibrator was used to induce muscle contractionin the [HbO2], [Hb], and [tHb] levels under the Ex

by the reflex stimulation of the distal tendon ofand Ex-Vib conditions revealed that the values

the biceps brachii. In the present study, the oscil-from the start of exercise to the end of exercise

lating vibration was applied to the distal tendon ofwere significantly higher than those at the base-the biceps brachii, while the subjects performed

line (p < 0.05).

sustained isometric contractions of the biceps

The present study revealed no significant differ-brachii. Each subject performed 2 sessions ofence in the prefrontal cortex activity during exer-

elbow-flexion exercise with or without muscle-cise under the Ex and Ex-Vib conditions. Borg’s

spindle stimulation (Ex-Vib and Ex respectively).

RPEs have enabled the measurement of impend-

The order of these sessions was randomized. The

ing fatigue during exercise testing (Borg, 1982;

RPE [the subject rated her perceived effort on the

Ekblom and Goldbarg, 1971). The RPE increases

Borg scale (Borg, 1975)] was recorded immediate-with increase in exercise intensity (Ceci andly after the exercise. Prefrontal tissue oxygenation

Hassman 1991; Ueda et al. 2006). Additionally,levels were recorded from the muscle and brain

Nybo and Nielsen (2001) found a significant cor-by using an NIRS unit (Hamamatsu NIRO-200;

relation between the RPEs and prefrontal cortex

Hamamatsu Photonics KK, Tokyo, Japan).

activity. The prefrontal cortex is most likely
involved in the initiation of volitional movements● Results and Discussion(Nowak et al. 1999; Pedersen et al. 1998). The

With regard to [HbO2], [Hb], and [tHb] levels,

activity (oxygenation) of the prefrontal cortex

ANOVA revealed significant changes with timeincreases with increase in exercise intensity (Ide et157

Goodwin GM, McCloskey DI, Mitchell JH : Cardiovascular and respiratory responses to changes in central command during isometric exercise at constant muscle tension. J Physiol, 226: 173-190,
1972.
Ide K, Secher NH : Cerebral blood flow and metabolism during exercise. Prog Neurobiol, 61: 397414, 2000.
Nowak M, Olsen KS, Law I, Holm S, Paulson OB,
Secher NH : Command-related distribution ofregional cerebral blood flow during attempted
handgrip. J Appl Physiol, 86: 819-824, 1999.
Nybo L, Nielsen B : Perceived exertion is associatedwith an altered brain activity during exercise with
progressive hyperthermia. J Appl Physiol, 91:
2017-2023, 2001.
Ogoh S, Wasmund WL, Keller DM, O-Yurvati A,
Gallagher KM, Mitchell JH, Raven PB : Role ofcentral command in carotid baroreflex resetting inhumans during static exercise. J Physiol, 543:
349-364, 2002.
Pedersen JR, Johannsen P, Bak CK, Kofoed B,
Saermark K, Gjedde A : Origin of human motor
readiness field linked to left middle frontal gyrus
by MEG and PET. Neuroimage, 8: 214-220, 1998.
Ueda T, Nabetani T, Teramoto K : Differential perceived exertion measured using a new visual analogue scale during pedaling and running. J Phyiol
Anthropol, 25: 171-177, 2006.

al. 1999). As such, the prefrontal cortex activity
described by Nybo and Nielsen (2001) is a reflection of 2 dimensions, i.e., exercise intensity andthe RPE. Thus, in order to determine the relationship between the RPE and prefrontal cortex activity, the effect of the RPE should be separated fromthat of exercise intensity. In conclusion, the present study revealed that oxygenation of the prefrontal cortex did not significantly differ in the Ex
and Ex-Vib conditions. The results of the present
study suggest that perceived exertion is not necessarily associated with prefrontal cortex activity.

● References

Borg GA : Psychophysical bases of perceived exertion.
Med Sci Sports Exerc, 14: 377-381, 1982.
Ceci R, Hassman P : Self-mentioned exercise at threedifferent RPE-intensities in treadmill vs field running. Med Sci Sports Exerc, 23: 732-738, 1991.
Ekblom B, Goldbarg AN : The influence of physicaltraining and other factors on the subjective ratingof perceived exertion. Acta Physiol Scand, 83:
399-406, 1971.

2.3

Role of central command for the increase in middle
cerebral artery mean blood flow velocity during static
exercise in humans

K. Sato, K. Shibuya, C. Ueda-Sasahara, S. Shimizu-Okuyama, M. Saito,
A. Kagaya, M. Kamo, T. Osada, and T. Sadamotoon the muscle mechanoreflex (Jørgensen et al.

● Purpose

Cerebral blood flow (CBF) increases along with

1992; Jørgensen et al. 1993). In contrast,

cardiovascular responses upon the transition from

Williamson et al. (2002) reported an increase in

rest to exercise. The exercise-mediated increase inregional blood flow of the insular cortex during

mean blood flow velocity in middle cerebral

imagined exercise. Nowak et al. (2005) showed aartery (VMCA) is eliminated after the arm is blocked

significant increase in regional CBF during

by regional anesthesia (Jørgensen et al. 1993), sug-

attempted movement in spinal cord-injured sub-gesting that CBF during exercise determined byjects. These observations argue in favor of a cen-neural integration of afferent input from the exer-

tral command effect with regard to changes incising muscle. Also evidence is provide by from

CBF during exercise. Tendon vibration reflexlythat the increase in CBF is likely to be dependentassist an exercising muscle while developing a158

given force and thereby decrease the cardiovascu-

elbow flexion with and without vibrations. In thislar responses during static exercise (Goodwin et al.

study, the elbow flexion exercise was performed

1972; Ogoh et al. 2002). Using tendon vibration tousing

the biceps brachii, we evaluate whether central

dynamometer (VINE, Japan). The subjects werecommand influence on V MCA during static arm

seated in an exercise chair in which a constant

exercise. The purpose of the present study was tobody position could be maintained throughout theclarify the role of central command for the

exercise. The right elbow was kept (90 °) on aincrease in CBF during static exercise.

padded armrest and the wrist was attached to theacomputer-based

multifunctionalarm lever by a Velcro strap.
● Methods

After a 2-min resting period in the seated posi-

Eleven young women (mean ± SE: age, 21.2 ±tion, each subject performed the two-exercise pro-

1.0 years) participated in this study. Written,

tocol as follows: (1) elbow flexion (CONT) and (2)informed consent was obtained according to theelbow flexion with biceps brachii tendon vibration

Ethics Committee of the Japan Women’s College(EX+VIB). The protocol consisted of a 3-min rest-of Physical Education, and the study was conduct-

ing control period followed by 2 min of static con-ed in accordance with the Declaration of Helsinki.

traction at 30% of the predetermined MVC ending
with a 2-min recovery period. The subjects wereshown the tension that was being achieved after

Maximal voluntary contraction trials
On the first day, subjects performed three maxi-

which the subjects were asked to reach the line ofmal static 90 °elbow angle flexions of the rightrequired tension. In the resting condition, 7.9 ±arm to determine the maximal voluntary contrac-

2.9% of the MVC was achieved by the application

tion strength (MVC). After the MVC trials, theof vibration. Therefore, static elbow flexion was

subjects were familiarized with the exercise proto-

performed at 〜 22% MVC in this study. Beforecol.

exercise, subjects were read standardized instructions on the use of the 6-20 Rating of Perceived
Exertion (overall RPE) category scale developed

Muscle spindle vibration
The custom-made vibrator was used to induce

by Borg (1973). These ratings were obtained

muscle contraction by the reflex stimulation of theimmediately after the end of exercise. In addition,

distal tendon of the biceps brachii. In the present

arm rating of muscle fatigue sensation (arm RPE)

study, the oscillating vibration was applied to thewas taken after the end of the exercise by using a

distal tendon of the biceps brachii while the sub-1-10 category scale (Saito et al. 1989).

jects performed sustained isometric contractionsof the biceps brachii muscle (elbow flexion). The

Measurement

oscillating frequency of the vibrator was 100 Hz,

Middle cerebral artery mean velocity

and its amplitude was 0.8 mm. Vibration of the

VMCA measurement was performed with an ultra-

tendon of the biceps brachii during elbow flexion

sound system (VIVID 7; GE Medical Systems,

aided tension development in the biceps brachii

Japan) equipped with a 2.0-MHz sector transduc-muscle and thereby lessened the degree of theer. We first used B-mode imaging to visualize thecentral command required.

ipsilateral MCA, and then the real-time Doppler
velocity spectrum was identified in PW-mode.

Exercise protocol

Blood flow velocity measurements were taken

On the second day, subjects performed staticwith the sample volume set at 7-8 mm and with159

the vector of the cursor positioned in the centerage changes in cerebrovascular and cardiorespira-of the blood stream, parallel to the vessel axis.

tory parameters were obtained by calculating theMean blood flow velocity of middle cerebral

ratio of the changes in the resting values (Rest).

artery (V MCA) was defined as the time-averaged

The cardiorespiratory (MAP, HR, CO, and PET CO2)

mean velocity (cm・s ) obtained in the automaticand cerebrovascular (VMCA and CVCi) parameter

calculation mode.

values at rest were defined as the 0% control lev--1

els for each subject.
Cardiorespiratory responses

Differences in the cardiorespiratory and cere-

The mean arterial blood pressure (MAP) was

brovascular responses between the two exercise

measured non-invasively by photoelectric plethys-

conditions (CONT or EX+VIB) were tested bymography with a Finometer (Finapres Medical

using two-way ANOVA with repeated measure-

Systems BV, Arnhem, Netherlands). Furthermore,

ment. If a significant F-value was present between

the heart rate (HR), stroke volume (SV), and thus

the two conditions, the mean values at a given

cardiac output (CO), were determined from thetime were compared by a non-parametricblood pressure wave form using the Modelflow

Wilcoxon’s signed rank test. These statisticalsoftware program, incorporating gender, age,

analyses were computed by the SPSS 12.0 soft-height, and weight (Beat Scope 1.1; Finapres

ware (SPSS, Japan), and P < 0.05 was considered

Medical Systems BV, Netherlands). The CO was

to indicate a significant difference. All data are

given by SV × HR. Respiratory parameters wereexpressed as mean ± SE.

determined with an online system for the breath● Results and Discussion

by-breath method. Respiratory gas was sampled
continuously from a face mask. The gas fractions

We observed that the increase in the VMCA dur-

were analyzed by a mass spectrometer (ARCO-

ing exercise with tendon vibration (i.e., decreased

1000; Arco System, Japan) that was calibrated

central command) was significantly lower thanand confirmed before each test. Breath-by-breaththat during control exercise without vibration

data were analyzed using customized software on(Fig. IV.2.3-1). The effect of vibrations on VMCA

a computer (Dynabook; Toshiba, Japan), and the

response was similar to their effect on cardiovas-

end-tidal partial pressures of CO2 (PET CO2) werecular responses. Our results suggested that central

calculated.

command actively contributed to the CBF
responses as well as the cardiovascular responses
during static exercise.

Data processing and statistics
In the present study, the ratio VMCA / MAP wasPrevious studies have suggested that the VMCA

calculated as an index of averaged cerebrovascu-

responses during voluntary exercise are predomi-

lar conductance (CVCi). The beat-to-beat values

nantly controlled by a peripheral neural reflex

for MAP, HR, SV, and CO and the breath-by-arising from exercising muscles and that the cen-breath values for PET CO2 were averaged over 30-

tral command has a minor role in CBF regulation

sec intervals. Moreover, VMCA and CVCi values for(Jørgensen et al. 1992; Jørgensen et al. 1993).

each subject were averaged over 30-sec intervals.

However, our data supports the theory that a

To calculate the percentage change (relativechange in the VMCA during static exercise may bechange) from resting values, all resting parameters

mediated by central command, which is reflected

were obtained during the 2-min resting period 30

by the individuals’ RPE or “effort sense” during

sec before the beginning of exercise. The percent-physical activity. With the decrease in VMCA during160

EX+VIB, the mechanism(s) that may drive theattenuated flow are of interest. Studies concerning
the functional anatomy of central command-related changes in regional CBF have identified a network of structures activated in the human brain(Williamson et al. 2006). Their studies have suggested that the insular cortex, anterior cingulate
cortex, the medial prefrontal region, and thalamic
regions may be activated in response to anincreased perception of effort during exercise
when circulatory responses are elevated(Williamson et al. 2006). Therefore, it is possible
to speculate that the attenuated activation ofthese regions in the brain, namely the central
command network, may be related to theobserved decrease in VMCA during EX+VIB.
The other mechanisms that may contribute to
the CBF regulation in exercise are MAP and CO.
The VMCA recorded at the end of the EX+VIB was
lower (by 〜 11%) than that in CONT, and theeffect of vibrations on the VMCA response during
exercise was similar to their effects on MAP and

Fig. IV.2.3-1 The relative changes in middle cerebral
artery mean blood flow velocity (VMCA) and index of
cerebrovascular conductance (CVCi) during and after

CO. Furthermore, despite the effect of vibration
on VMCA, the CVCi values did not differ significant-static exercise. Baseline cardiorespiratory values
before exercise were defined as the 0% control levels
in each subject. Their relative percent changes for thecontrol levels were sequentially calculated during

ly during exercises with and without vibration,
indicating that the central command-mediateddecrease in MAP and/or CO responses during

static exercise. Values are expressed as mean ±S.E.M. † Significant difference between CONT and
EX+VIB, P < 0.05.

EX+VIB may contribute to the reduction in the
CBF responses. In this case, central command
may have an indirect and secondary effect on the
CBF during static exercise via the cerebral perfu-

VMCA at rest and during exercise (Ogoh et al. 2005).

sion pressure and/or perfusion rate.

These results demonstrated that any regulation of

Recent studies have suggested that CO is an

CO via the cardiac baroreflex would directly influ-

important factor involved in the change in VMCA

ence dynamic CBF regulation during exercise

during dynamic exercise (Ide et al. 1998; 2000;(Ogoh et al. 2005). Considering these observations

Ogoh et al. 2005). When CO was reduced by using

and our results together, the CO response-induceda β 1-blockade or atrial fibrillation, the increase in

decrease via the reduction in central command

V MCA during bicycling was reduced (Ide et al.

may have affected VMCA during exercise.

2000). These findings were confirmed in healthy

In conclusion, the present investigation sup-subjects by changing the central blood volume

ports the hypothesis that central command active-

and CO at rest and during dynamic exercise; thisly contributes to CBF regulation during static

indicated a linear relationship between CO andexercise. The decrease in VMCA when central com-161

dynamic exercise in humans. J Appl Physiol, 73:
1825-1830, 1992.
Ogoh S, Brothers RM, Barnes Q, Eubank WL, Hawkins
MN, Purkayastha S, O-Yurvati A, Raven PB : The
effect of changes in cardiac output on middle
cerebral artery mean blood velocity at rest andduring exercise. J Physiol (Lond), 569: 697-704,
2005.
Ogoh S, Wasimd WL, Keller DM, O-Yurvati A,
Gallagher KM, Mitchell JH, Raven PB : Role ofcentral command in carotid baroreflex resetting inhumans during static exercise. J Physiol (Lond),
543: 349-364, 2002.
Williamson JW, Fadel PJ, Mitchell JH : New insights
into central cardiovascular control during exercise
in humans: a central command update. Exp
Physiol, 91: 51-58, 2006.
Williamson JW, McColl R, Mathews D, Mitchell JH,
Raven PB, Morgan WP : Brain activation by central command during actual and imagined handgrip under hypnosis. J Appl Physiol, 92: 13171324, 2002.

mand was reduced is caused by attenuated brain
activation, probably representing neural activity
in the central command network and/or by the
reduction in CO.

● References

Goodwin GM, McCloskey DI, Mitchell JH : Cardiovascular and respiratory responses to changes in central command during isometric exercise at constant muscle tension. J Physiol (Lond), 226: 173190, 1972.
Ide K, Boushel R, Sorensen HM, Fernandes A, Cai Y,
Pott F, Secher NH : Middle cerebral artery blood
velocity during exercise with β-1 adrenergic andunilateral stellate ganglion blockade in humans.
Acta Physiol Scand, 170: 33-38, 2000.
Jørgensen LG, Perko G, Payne G, Secher NH : Effectof limb anesthesia on middle cerebral response tohandgrip. Am J Physiol, 264: H553-H559, 1993.
Jørgensen LG, Perko G, Secher NH : Regional cerebral
artery mean flow velocity and blood flow during

2.4

Role of central command in the renal arterial bloodflow responses during static elbow flexion in humans

T. Sadamoto, K. Sato, A. Hirasawa, C. Ueda-Sasahara, K. Shibuya,
M. Saito, M. Kamo, S. Shimizu-Okuyama, T. Osada, and A. Kagaya
invasively” decreased or increased in the previous● Purpose

The role of central command in the renal flow

studies. By using tendon vibration to assist or to

regulation has remained elusive. A prior study

oppose an exercising muscle group while develop-

reported that central command was not essential

ing a given force one can decrease (agonist activa-

for producing the renal vasoconstriction duringtion) or increase (antagonist inhibition) the influ-

exercise because the renal vascular resistance wasence of central command without inducing noci-

almost identical during voluntary and electrically

ceptor afferent input or augmenting normal exer-

induced (involuntary) contractions (Momen et al.

cise pressor reflex activation (Goodwin et al. 1972;

2003). However, the studies in conscious animals

Ogoh et al. 2002). Using this manipulation of ago-demonstrated a significant role of central com-nist activation, we examined whether a decreased

mand during voluntary static and dynamic exercis-

influence of central command would produce aes (Matsukawa K et al. 1991; O’Hagan et al. 1993).

concomitant decrease in renal flow responses dur-

One reason for the discrepant data was due to theing voluntary static exercise.

lack of non-invasively studies during exercise in● Methods

humans. The magnitude of involvement of theTen healthy female volunteers whose mean age

central command during exercise can be “non162

Table IV.2.4-1 Resting values in vibration (VIB), vibration plus static elbow flexion exercise (VIB+Ex), and static elbow flexion exercise (Ex) conditions.
Condition
VIB

VIB ＋ EX

EX

HR
MAP

（bpm）
（mmHg）

70.91 ± 4.31
75.49 ± 9.90

71.65 ± 5.31
80.54 ± 9.59

71.31 ± 5.83
83.86 ± 9.53

CO
SV
MBV
RVR

（L/min）（mL）（cm/sec）（a.u.）

4.57 ± 0.54
64.60 ± 7.34
21.27 ± 3.75
3.58 ± 0.78

4.56 ± 0.65
63.68 ± 8.58
22.41 ± 3.63
3.68 ± 0.87

4.83 ± 0.61
67.65 ± 5.67
23.06 ± 3.32
3.76 ± 0.65

HR, heart rate; MAP, mean arerial blood pressure; CO, cardiac output; SV, stroke volume, MBV, mean blood velocity; RVR, renal vascular resistance . Values are mean ±SD in 10 subjects.

Fig. IV.2.4-1 Percent changes in heart rate (HR), mean arterial blood pressure (MAP), mean blood velocity inrenal artery (MBV) and renal vascular resistance (RVR) at rest and during 2 min exercise and recovery. Vibrationin the resting arm during rest indicates VIB. Values are mean (SD in 10 subjects. Time from 0 to 120 sec indicatesthe static voluntary exercise. Changes in HR and muscle fatigue sensation were significantly lower in Vibration +Exercise (VIB+EXER) than those in Exercise (EXER).

was 22 ± 3.3 (SD) yr participated in the present

applied in the resting arm (VIB) as control experi-

study. After 10-min resting, the subject performed a

ment to test what to degree the vibration itself

2-min static elbow flexion at a constant load of 30%

induce muscle force and cardiovascular responses.

of maximum voluntary contraction (MVC) with

Time-averaged mean blood flow velocity (MBV) in

vibration (EX+VIB) and without vibration (EX). In

the renal artery (RA) was measured by using

the experiments of EX+VIB and EX, the vibration

Doppler method (Logic 5, GE Medical systems).

(frequency, 100 Hz; amplitude, 0.8 mm) was

Muscle fatigue sensation of the subject, as an index

applied to the distal tendon of the biceps brachii inof the magnitude of central command (Saito et al.),the exercising arm. The same vibration was only

was monitored. Heart rate (HR: ECG) and arterial163

mean blood pressure (MAP: Fino- meter, Finapres

mand was not essential for regulating blood flow

Medical Systems BV) were continuously measured.

responses in RA but the actual work load of force

Cardiac output (CO) was estimated from a arterial

production was an important determinant forpressure curve by Model Flow method (Finapres

renal flow adjustment during voluntary static

Medical Systems BV). The index of resistance in RA

exercise.

(RVR) was calculated as MAP/MBF.
● References

Gandevia SC : Neurophysiological mechanisms underlying proprioceptive sensations. In: Struppler A,
WeindleA (Eds), Clinical Aspects of Sensory Motor
Integration, Springer-Verlag Berlin, pp. 14-24,
1987.
Goodwin GM, McCloskey DI, Mitchell JH : Cardiovascular and respiratory responses to the changes incentral command during isometric exercise atconstant muscle tension. J Physiol (Lond), 226:
173-190, 1972.
Matsukawa K, Mitchell JH, Wall PT, Wilson LB : The
effect of static exercise on renal sympathetic
nerve activity in conscious cats. J Physiol (Lond),
434: 453-467, 1991.
Momen A, Leuenberger UA, Ray CA, Cha S, Sinoway
LI : Renal vascular responses to static handgrip:
role of the muscle mechanoreflex. Am J Physiol,
285: H1247-H1253, 2003.
Ogoh S, Wasimd WL, Keller DM, O-Yurvati A,
Gallagher KM, Mitchell JH, Raven PB : Role ofcentral command in carotid baroreflex resetting inhumans during static exercise. J Physiol (Lond),
543: 349-364, 2002.
O’Hagan KP, Bell LB, Mittelstadt SW, Clifford PS :Effect of dynamic exercise on renal sympathetic
nerve activity in conscious rabbits. J Appl Physiol,
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● Results and Discussion

Table IV.2.4-1 shows the resting levels in HR,
MAP, CO, SV, MBV and RVR in three conditionsof VIB, VIB+EX, and EX. The muscle force, muscle fatigue sensation, HR, MAP, MBV and RVR
are shown in Fig. IV.2.4-1. The vibration itself
reflexly induced the tension corresponding to 78% of MVC but had no significant effects on the
cardiovascular responses. The increase in HR during exercise and the muscle fatigue sensation in
the exercising arm were significantly lower during
EX+VIB than those during EX. These results indicated that the vibration technique of agonist activation substantially decreased the influence ofcentral command during EX+VIB because themuscle fatigue sensation (Gandevia 1987; Saito etal. 1989; Williamson et al. 2001) and HR (Victor etal. 1989) responses have been considered to dictate the magnitude of central command. The MAP
responses during EX+VIB also tended to be lower
than those during EX. In contrast, the MBF andRVR were identical during both EX+VIB and EX
suggesting that the decreased influence of central
command was not effective in the renal flow regulation.

The present data verified the previous

report in humans (Momen et al. 2003) examined
under “non-invasive” condition that central com-164

V．研究業績一覧

● 平成 16 年度

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Quaresima V, Ferrari M, Torricelli A, Spinelli L,
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task: a multichannel time-resolved near-

加茂美冬: 筋電図. スポーツ医学検査測定ハンドブッ

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Spinelli L, Taroni P, Ferrari M, Cubeddu R:

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Mapping of calf muscle oxygenation and

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Zaramella P, Freato F, Quaresima V, Ferrari M,
Vianello A, Conte L, Saracen E, Chiandetti L:〈学会発表〉

Foot pulse oximeter perfusion index corre-

加賀谷淳子, 清水靜代, 大森芙美子, 熊谷真奈, 村岡慈

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M, Franco A, Corsica C, Calvisi V, Ferrari M:からの静脈血流出量のバランス. 第 55 回日本体

Vastus lateralis metabolic response to explo-

育学会大会. 長野. 2004.

sive maximal isometric leg press exercise.

大森芙美子, 清水靜代, 村岡慈歩, 久野譜也, 松田光生,

32thAnnual Conference of the International

加賀谷淳子: 掌握運動時の血流増加における高齢Society on Oxygen Transport to Tissue. Bari,

者と若齢者の相違. 第 55 回日本体育学会大会. 長Italy. 2004.
Quaresima V, Giosuè P, Roncone R, Casacchia

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吉澤睦子, 清水靜代, 加賀谷淳子: 上肢による局所的

M, Ferrari M: Exploring prefrontal cortex

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oxygenation in schizophrenia by functional

影響. 第 55 回日本体育学会大会. 長野. 2004.

near-infrared spectroscopy. 32th Annual

大森芙美子, 清水靜代, 加賀谷淳子: 筋活動後の血流Conference of the International Society on

量最高値発現時間に対する運動持続時間の影響.

Oxygen Transport to Tissue. Bari, Italy. 2004.
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第 59 回日本体力医学会大会. 埼玉. 2004.
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Quaresima V, Ferrari M: Functional cortical

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割合. 第 59 回日本体力医学会大会. 埼玉. 2004.

spectroscopy. OSA Biomedical Optics Topical

Shimizu S, Kagaya A: Age-associated changes in

Meetings. Washington DC, USA. 2004.

vessel diameter and blood velocity of the

Mottola L, Ferrari M, Quaresima V: Evaluation of

carotid and brachial artery in women aged 18-

forearm muscle groups recruitment during con-

88 years. The American Physiological Society

tinuous or rhythmic isometric exercise by aIntersociety Meeting. Austin, USA. 2004.

continuous wave near infrared spatially清水靜代, 村岡慈歩, 大森芙美子, 加賀谷淳子: 高齢者

resolved oximeter. OSA Biomedical Optics

における心形態, 骨格筋量および血管形状の関Topical Meetings. Washington DC, USA. 2004.
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連. 第 12 回日本運動生理学会. 千葉. 2004.
定本朋子, 増田晶子, 松浦まり子: 静的運動および運

V: Relationship between handgrip sustained

動後虚血時にみられる腎動脈血流の変化. 第 59

submaximal exercise and prefrontal cortex

回日本体力医学会大会. 埼玉. 2004.

oxygenation. 32th Annual Conference of the

Saito M: Effects of resistance training on muscle

International Society on Oxygen Transport to
Tissue. Bari, Italy. 2004.

sympathetic nerve response to static contrac-

Calvisi V, Angelozzi M, Franco A, Mottola L,tion. The American Physiological SocietyIntersociety Meeting. Austin, USA. 2004.

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一之瀬真志, 斉藤 満, 近藤徳彦, 西保 岳: ハンドグ

Quaresima V: Influence of whole-body vibra-

リップ運動時における動脈圧受容器反射調節のtion

経時的変化-筋交感神経活動からみて. 第 59 回日

tion. 32th Annual Conference of the Inter

本体力医学会大会. 埼玉. 2004.

national Society on Oxygen Transport toFerrari M: Frontal lobe cortical functions meas-

static exercise on quadriceps oxygena-

Tissue. Bari, Italy. 2004.

ured as task-related oxygenation by multi-

Kamo M, Morimoto S: Contractile property ofchannel near infrared spectroscopy. 32th

muscle fibers during repetitive electrical stim-

Annual Conference of the Internationalulation in humans. 15th Congress of theSociety on Oxygen Transport to Tissue. Bari,International Society of Electrophysiology and

Italy. 2004.

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加茂美冬, 弓削田会, 森本

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満: 利き腕, 非利き腕運動時の筋交感神経活動

活動電位波形の変化. 第 59 回日本体力医学会大に対するレジスタンストレーニングの影響. 日本会. 埼玉. 2004.

運動生理学雑誌, 13: 63-70, 2006.

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Ichinose M, Saito M, Kondo N, Nishiyasu T: Time-

化−運動単位レベルでの推定−. 第 133 回日本体

dependent modulation of arterial baroreflex

力医学会関東地方会. 神奈川. 2005.

control of muscle sympathetic nerve activity

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detector spacing of near-infrared-based tissue
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続的筋力発揮による持続時間延長と振動・筋電位

oxygenation in paraplegic patients during pas-

信号. 第 59 回日本体力医学会大会. 埼玉. 2004.

sive leg movement. Med Sci Sports Exerc, 38:

森本茂, 遠藤千草, 加茂美冬: 筋疲労時の筋力振戦

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M, Franco A, Corsica C, Calvisi V, Ferrari M:
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maximal isometric leg press exercise oxygena-〈学術論文（査読あり）〉

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maintain physical activity of daily life in eld-tion. Adv Exp Med Biol, 578: 137-142, 2006.

erly people. Int J Sports Health Sci, 4 (Special

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Heubert R, Quaresima V, Laffite L, Koralsztein J,

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Mastuda M, Kagaya A: Blood flow during

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Contini D, Torricelli A, Pifferi A, Spinelli L, Taroni

women. Int J Sports Health Sci, 4 (Special

P, Quaresima V, Ferrari M, Cubeddu R: Multi

Issue 2): 480-488, 2006.

channel time-resolved tissue oximeter for func-

斉藤 満, 相澤清香, 神谷厚範: 利き腕, 非利き腕運動

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Medicine Congress. Tokyo, Japan. 2005.

Osada T, Rådegran G: Alterations in the rheologi-

清水靜代, 大森芙美子, 熊谷真奈, 加賀谷淳子: 上腕静

cal flow profile in conduit femoral artery dur-

脈血流速度パラメータに及ぼす掌握運動の強度

ing rhythmic thigh muscle contractions inの影響. 第 13 回日本運動生理学会. 東京. 2005.

humans. Jpn J Physiol, 55: 19-28, 2005.

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動 態 と の 関 係 . 第 56 回 日 本 体 育 学 会 . 茨 城 .

Muraoka Y, Kagaya A: Heterogeneity of change

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in muscle circulation among synergists during

大森芙美子, 清水靜代, 浜岡隆文, 加賀谷淳子: 動的足

dynamic muscle action. 10th Congress of the

底屈運動トレーニングにおける 2 種の動作間隔がInternational Society of Biomechanics.

運動時血流量に与える効果の相違. 第 60 回日本

Cleveland, USA. 2005.

体力医学会. 岡山. 2005.

Shimizu S, Muraoka Y, Ohmori F, Kagaya A:

吉澤睦子, 清水靜代, 菅原 順, 加賀谷淳子: 片脚膝伸

Relationship between cardiac muscle, skeletal

展運動中の非活動肢血流動態と呼吸交換比の関muscle mass and vessel structure in elderly

係. 第 60 回日本体力医学会. 岡山. 2005.

women. 8th Asian Federation of Sports

大森芙美子, 清水靜代, 村岡慈歩, 久野譜也, 松田光生,

Medicine Congress. Tokyo, Japan. 2005.

加賀谷淳子: トレーニングは高齢者の加齢に伴うMuraoka Y, Ohmori F, Shimizu S, Itakura H,

血圧急上昇負荷の低下を抑制する− SAT プロジ

Akama T, Nakamura I, Kagaya A: Effect ofェクト 189 −. 第 56 回日本体育学会. 茨城. 2005.

thigh muscle thickness on daily physical

定本朋子, 岡島真由美: 月経周期が運動時における経activity and active range of dorsiflexion in

口摂取グルコースの酸化利用動態に及ぼす影響.

elderly men. 8th Asian Federation of Sports

第 60 回日本体力医学会. 岡山. 2005.

Medicine Congress. Tokyo, Japan. 2005.

岡島真由美, 定本朋子: 握力発揮時の血圧上昇に対す

Kumagai M, Shimizu S, Kagaya A: Insufficient

る脳血流の変化. 第 60 回日本体力医学会. 岡山.
2005.

blood supply to exercising muscles at high斉藤

intensity accelerates muscle deoxygenation.
8th Asian Federation of Sports Medicine

満: ハンドグリップ運動時の筋交感神経反応の左右差. 第 13 回日本運動生理学会. 東京. 2005.

Congress. Tokyo, Japan. 2005.

斉藤

Ohmori F, Shimizu S, Hamaoka T, Kagaya A:

満: 運動時の心拍反応からみた高い運動努力の自律神経機能に及ぼす影響. 第 56 回日本体育学会. 茨城. 2005.

Blood flow after contraction of short duration
reaches its peak by 3rd cardiac cycle. 8th

Ferrari M, Quaresima V: Hemodynamic differ-

Asian Federation of Sports Medicine

ences in the activation of the prefrontal cor-

Congress. Tokyo, Japan. 2005.

tex for maintaining muscle strength by func-

Yoshizawa M, Shimizu S, Kagaya A: Changes intional NIRS. Optical Imaging of Brainbrachial and femoral artery vascular conduc-

Function. Bad Honnef, Germany. 2005.

tance non-exercising limbs during handgrip

Kamo M, Morimoto S: Force output in muscle

exercise. 8th Asian Federation of Sports

fibers during repetitive stimulation in

Medicine Congress. Tokyo, Japan. 2005.

Humans. 8th Asian Federation of Sports

Sadamoto T, Okajima M, Masuda A, Matsuura M:

Medicine Congress. Tokyo, Japan. 2005.

170

Int J Sports Health Sci, 4: 480-488, 2006.

Morimoto S, Endoh C, Kamo M: Myoelectric,
myomechanical signals and tension fluctua-

Ohmori F, Shimizu S, Hamaoka T, Kagaya A:

tion during prolonged isometric constant con-

Blood flow after contraction of short duration

traction at low target tension. 8th Asianreaches its peak by 3rd cardiac cycle. Jpn J

Federation of Sports Medicine Congress.

Phys Fitness Sports Med, 55: S153-S158,

Tokyo, Japan. 2005.

2006.

加茂美冬, 森本茂: 随意筋力発揮における表面導出

Yoshizawa M, Shimizu S and Kagaya A: Changes

した運動単位活動電位波形の変化. 第 60 回日本in brachial and femoral artery vascular con-

体力医学会. 岡山. 2005.

ductance in non-exercising limbs during

加茂美冬: 運動に対する神経系の適応. 第 133 回日本

handgrip exercise. Jpn J Phys Fitness Sports
Med, 55: S159-S162, 2006.

体力医学会関東地方会. 神奈川. 2005.

Muraoka Y, Shimizu S, Fukunaga T, Nishijima T,

森本 茂, 遠藤千草, 池田聡史, 加茂美冬: 疲労（筋力）振戦と同期した

筋音波形の発現. 第 60 回日

Kuno S, Mastuda M, Kagaya A: Relationship

本体力医学会. 岡山. 2005.

between forearm muscle volume and pressure

佐藤耕平, 片山敬章, 堀田典生, 石田浩司, 小池晃彦,
宮地元彦, 増田和実, 秋間

response during static handgrip in elderly
women. Int J Sports Health Sci, 4: 440-450,

広: 片脚サスペンジ

2006.

ョンによる運動時の呼吸循環応答の変化. 第 60

Ichinose M, Saito M, Fujii N, Kondo N, Nishiyasu

回日本体力医学会. 岡山. 2005.
佐藤耕平, 堀田典生, 片山敬章, 宮村実晴, 石田浩司:

N: Modulation of the control of muscle sym-

短期間の持久的トレーニングが運動開始直後のpathetic nerve activity during severe orthosta-

呼吸循環応答に及ぼす影響. 第 13 回日本運動生

tic stress. J Physiol, 576: 947-958, 2006.
Quaresima V, Ferrari M: Evaluation of skin

理学会. 東京. 2005.
岩館雅子, 森 昭雄, 久保木優: 運動競技者における体blood flow contribution to the non-invasive

性感覚事象関連電位および事象関連スペクトル

measurement of muscle oxygenation by nearの 出 現 様 式 . 第 60 回 日 本 体 力 医 学 会 . 岡 山 .

infrared spectroscopy. J Physiol Sci, 56: 267-

2005.

268, 2006.
Shimizu S, Muraoka Y, Ohmori F, Kagaya A:● 平成 18 年度

Relationship between cardiac muscle, skeletal〈学術論文（査読あり）〉

muscle mass and vessel structure in elderly

Kagaya A, Shimizu S: Circulatory functions to

women. Jpn J Phys Fitness Sport Med, 55:
S213-S216, 2006.

maintain physical activity of daily life in eld-

Osada T, Rådegran G: Differences in exercising

erly people. Int J Sports Health Sci, 4: 304315, 2006.

limb blood flow variability between cardiac

Tanaka H, Shimizu S, Ohmori F, Muraoka Y,

and muscle contraction cycle related analysis

Kumagai M, Yoshizawa M, Kagaya A:

during dynamic knee. J Sports Med Phys

Increases in blood flow and shear stress toFitness, 46: 590-597, 2006.
Osada T, Rådegran G: Alterations in the blood

nonworking limbs during incremental exercise. Med Sci Sports Exerc, 38: 81-85, 2006.

velocity profile influence the blood flow

Ohmori F, Shimizu S, Muraoka Y, Matsuda M,

response during muscle contractions andKuno S, Kagaya A: Blood flow during graded,relaxations. J Physiol Sci, 56: 195-203, 2006

submaximal static handgrip exercise at differ-

Hotta N, Sato K, Sun Z, Katayama K, Akima H,

ent intensities in elderly and young women.

Kondo T, Ishida K: Ventilatory and circulato-171ry responses at the onset of exercise after

evidenced by functional near infrared spec-

eccentric exercise. Eur J Appl Physiol, 97:

troscopy. 2006 Human Brain Mapping meet-

598-606, 2006.

ing, Florence, Italy. 2006.

Hotta N, Sato K, Katayama K, Koga S, Masuda K,

Kamo M, Morimoto S: Wave form of motor unit

Miyachi M, Akima H, Ishida K: Oxygen

action potentials during constant force contrac-

uptake kinetics following 20 days of unilateraltion in human muscle. 11th Annual Congress

lower limb suspension. J Physiol Sci, 56: 347-

of European College of Sport Science. Invited353, 2006.

symposia, Lausanne, Swiss. 2006.

斉藤満, 相澤清香, 神谷厚範：利き腕, 非利き腕運

Sato K, Katayama K, Hotta N, Ishida K, Miyachi

動時の筋交感神経活動に対するレジスタンスト

M, Masuda K, Koike T, Akima H: The influ-

レーニングの影響. 日本運動生理学雑誌, 13: 63-

ence of unilateral lower limb suspension on

70, 2006.

cardiorespiratory response during exercise.

後藤玲子, 工藤博章, 佐藤耕平, 堀田典生, 石田浩司,

The 53rd Annual Meeting of American Col-昇: 自己運動感覚を誘発する視覚刺激に対

lege of Sports Medicine, Denver, USA. 2006.

する生体反応. 映像情報メディア学会誌, 60 ：Katayama K, Sato K, Hotta N, Ishida K, Iwasaki

大西

589-596, 2006.

K, Miyamura M: Effect of intermittent hypoxia

Sadamoto T: Effect of preparative instruction

on exercise ventilation at a simulated moder-about load change on the cardiorespiratory

ate altitude. The 53rd Annual Meeting ofadjustments during cycling exercise. J Exerc

American College of Sports Medicine.

Sci, 15: 8-17, 2005.

Denver, USA. 2006.

定本朋子, 辻かよこ, 藤井瑠美, 森山真由美: 長時間運加賀谷淳子, 加茂美冬, 大森芙美子, 岩館雅子, 佐藤耕動時における外因性糖質の酸化利用動態に及ぼ平, 清水靜代, 長田卓也, 定本朋子, 斉藤 満: 動す月経周期の影響. 日本女子体育大学附属基礎体

的膝伸展運動時の負荷増加に対する活動肢血流力研究所紀要, 16: 1-12, 2006.

量, 筋放電増加率及び筋酸素動態との関係, 第 61

村松 憲, 牛山潤一, 清水靜代, 村山光義, 佐々木玲子:

回日本体力医学会. 兵庫. 2006.
加賀谷淳子, 清水靜代, 大森芙美子：律動的運動によ超音波法を用いた塾生の形態評価について. 慶應
義塾大学体育研究所紀要, 46: 17-24, 2007.

る静脈血流出量の増加は動脈血流入量の増加を

村山光義, 村松 憲, 佐々木玲子, 清水靜代, 野口和行:

促進するか. 第 14 回日本運動生理学会. 広島,
2006.

動作映像の即時フィードバックを用いた技術指導効果−フライングディスク・サイドアームス

加賀谷淳子, 加茂美冬, 大森芙美子, 岩館雅子, 佐藤耕

ロー導入時の事例−. 慶應義塾大学体育研究所紀平, 清水靜代, 長田卓也, 定本朋子, 斉藤 満: 動要, 46: 1-16, 2007.

的膝伸展運動時の負荷増加に対する活動肢血流量, 筋放電増加率および筋酸素動態との関係. 第〈学会発表〉

61 回日本体力医学会. 兵庫. 2006.

Sadamoto T, Sato K, Ohmori F, Okajima M,

大森芙美子, 加茂美冬, 岩館雅子, 清水靜代, 加賀谷淳

Iwadate M, Kagaya A: Age-related changes

子: 膝伸展運動時の大腿動脈血流量が最高値に達

in the cerebral blood flow from 12 to 18 years

する負荷の検討. 第 61 回日本体力医学会. 兵庫.

of age in females. 11th European College of2006.

Sport Science, Lausanne, Swiss. 2006.

大森芙美子, 清水靜代, 村岡慈歩, 佐藤耕平, 加賀谷淳

Quaresima V, Crisostomi S, Fallavollita L,

子: 静的掌握運動時の主観的筋疲労感覚と血圧急

Mottola L, Ferrari M: Maintaining the hand-

上昇負荷との関係. 第 57 回日本体育学会. 青森.

grip strength by using the prefrontal cortex as

2006.

172

定本朋子, 江森千春, 安藤理沙, 森山真由美, 佐藤耕平:

勝村俊仁: 下肢閉塞性動脈硬化保有者における運

メンタルストレスが血流依存性血管拡長機能に

動下肢血行動態の検討, 第 61 回日本体力医学会.

及ぼす影響. 第 14 回日本運動生理学会. 広島.

兵庫. 2006.
佐藤耕平, 定本朋子: 随意および受動的肘伸展屈曲運2006.
定本朋子, 佐藤耕平, 大森芙美子, 森山真由美, 岩館雅動時における脳循環応答. 第 136 回日本体力医学会関東大会. 東京. 2006.

子, 石田良恵: 発育期の女子中高生にみられる心佐藤耕平, 堀田典生, 片山敬章, 小池晃彦, 石田浩司,

機能, 脳循環および筋力の変化. 第 61 回日本体力医学会. 兵庫. 2006.

秋間

定本朋子, 江森千春, 安藤理沙, 森山真由美, 佐藤耕平:

広: 片脚サスペンジョン中のインターバル

トレーニングが運動時の呼吸循環応答に及ぼすメンタルストレスが血流依存性血管拡張作用に影響. 第 61 回日本体力医学会. 兵庫. 2006.

及ぼす影響. 第 14 回日本運動生理学会. 広島.

佐藤耕平, 大森芙美子, 定本朋子, 加賀谷淳子: 運動強2006.

度の違いが動的運動開始直後における活動筋血森山真由美, 佐藤耕平, 定本朋子: 静的運動時におけ流応答と血圧応答に与える影響. 第 57 回日本体育学会. 青森. 2006.

る頸動脈経路および椎骨動脈経路の血流応答. 第秋間

14 回日本運動生理学会. 広島. 2006.

広, 堀田典生, 佐藤耕平, 石田浩司, 片山敬章,

森山真由美, 佐藤耕平, 定本朋子: 静的運動時の脳血小池晃彦: 片脚サスペンジョン中のインターバル

流調節に対する筋代謝受容器反射の関与. 第 61

トレーニングが筋機能・形態に及ぼす影響. 第回日本大学体力医学会. 兵庫. 2006.

61 回日本大学体力医学会. 兵庫. 2006.
河野

島田奈央子, 佐藤耕平, 森山真由美, 定本朋子: グルコ

寛, 宮地元彦, 堀田典生, 佐藤耕平, 片山敬章,

ース摂取が動的肘屈曲運動時の上腸間膜動脈血

増田和実, 樋口 満, 石田浩司, 秋間 広: 局所的流に及ぼす影響. 第 61 回日本大学体力医学会. 兵不活動による血管機能低下に対するインターバ

庫. 2006.

ルトレーニングの抑制効果. 第 61 回日本体力医

石田良恵, 定本朋子, 鈴木志保子, 金久博昭: 女子中高学会. 兵庫. 2006.
岩館雅子, 定本朋子: 運動準備に伴う大脳皮質運動野

生の皮下脂肪厚・筋厚の変化. 第 61 回日本体力医学会. 兵庫. 2006.
斉藤

周辺の酸素動態の変化, 第 14 回日本運動生理学

満: 運動時の筋交感神経活動反応に及ぼす脱ト会. 広島. 2006.
岩館雅子, 斉藤 満, 加茂美冬, 佐藤耕平, 大森芙美子,

レーニングの効果. 第 61 回日本体力医学会. 兵庫. 2006.
斉藤

加賀谷淳子: 動的な間欠運動における筋疲労感覚

満: 照度の違いが運動時の生理反応, 主観的運と筋酸素動態および血圧の関係. 第 61 回日本体力医学会. 兵庫. 2006.

動感覚に及ぼす影響. 平成 18 年度（第 39 回）照岩館雅子, 定本朋子: 運動準備期の大脳皮質運動野周明学会全国大会. 大阪. 2006
高石鉄雄, 金若美幸, 小原史朗, 斉藤 満: 自転車運動

辺における酸素動態と循環応答の対応, 医用近赤外分光法研究会. 兵庫. 2006.

による筋力づくりの可能性. 第 61 回日本体力医学会. 兵庫. 2006.

● 平成 19 年度

清水靜代, 大森芙美子, 岩館雅子, 佐藤耕平, 加賀谷淳子: 筋活動期および活動休止期における大動脈血〈学術論文（査読あり）〉

流速度と活動体肢血流速度の対応. 第 14 回日本

Ohmori F, Shimizu S, Kagaya A: Exercise-induced

運動生理学会. 広島. 2006.

blood flow in relation to muscle relaxation

村山光義, 村松 憲, 佐々木玲子, 清水靜代, 野口和行:

period. Dynamic Medicine, 6: 5, 2007.
Osada T, Murase N, Kime R, Shiroishi K,

動作映像の即時フィードバックを用いた技術指導の効果. 第 57 回日本体育学会. 青森. 2006.

Shimomura K, Nagata H, Katsumura T:

長田卓也, 村瀬訓生, 木目良太郎, 白石 聖, 下村浩祐,

Arterial blood flow of all abdominal-pelvic

173

Metab, 17: 556-573, 2007.

organs using Doppler ultrasound: range, vari-Matsumura M, Ueda C, Shiroishi K, Esaki K,

ability, and physiological impact. Physiol
Meas, 28: 1303-1316, 2007.

Ohmori F, Yamaguchi K, Ichimura S,

Cardinale M, Ferrari M, Quaresima V: Gastrocne-

Kurosawa Y, Kime R, Osada T, Murase N,

mius medialis and vastus lateralis oxygena-

Katsumura T, Hoshika A, Hamaoka T: Low-

tion during whole body vibration exercise.

volume muscular endurance and strength

Med Sci Sports Exerc, 39: 694-700, 2007.

training during 3-week forearm immobilization

Quaresima V, Ferrari M: Quantification of

was effective in preventing functional deterioration. Dyn Med, 15: 1, 2008.

quadriceps O 2 desaturation in response to

Shibuya K, Sadamoto T, Sato K, Moriyama M,

short sprint cycling. Med Sci Sports Exerc, 39:
1205-1206, 2007.

Iwadate M: Quantification of delayed oxy-

Cettolo V, Ferrari M, Biasini V, Quaresima V:

genation in ipsilateral primary motor cortex

Vastus lateralis O2 desaturation in response tocompared with contralateral side during afast and short maximal contraction. Med Sci

unimanual dominant-hand motor task using

Sports Exerc, 39: 1949-1959, 2007.

near-infrared spectroscopy. Brain Res, 1210:
142-147, 2008.

Wolf M, Quaresima V, Ferrari M: Progress ofnear infrared spectroscopy and topography

Felici F, Quaresima V, Fattorini L, Sbriccoli P,

for brain and muscle clinical applications. J

Filligoi GC, Ferrari M: Biceps brachii myo-

Biomed Opt, 12: 062104, 2007.

electric and oxygenation changes during stat-

Hamaoka T, McCully KK, Quaresima V,

ic and sinusoidal isometric exercises. J

Yamamoto K, Chance B: Near-infrared spec-

Electromyogr Kinesiol, 19: e1-11, 2007.

troscopy/imaging for monitoring muscle oxy-

Hachiya T, Blaber AP, Saito M: Near-infrared

genation and oxidative metabolism in healthy

spectroscopy provides an index of blood flow

and diseased humans. J Biomed Opt, 12:

and vasoconstriction in calf skeletal muscle

062105, 2007.

during LBNP. Acta Physiol, 193: 117-127,

Hachiya T, Blaber AP, Aizawa S, Saito M: Heart

2008.
斉藤

rate responses at onset of contraction. Int J
Sport Med, 28: 1-6, 2007.

満, 相澤精香, 神谷厚範: 静的ハンドグリップ

運動時の筋交感神経反応に及ぼすレジスタンス

Hotta N, Yamamoto K, Sato K, Katayama K,

トレーニングの効果. 日本運動生理学雑誌, 14 ：41-48, 2007.

Fukuoka Y, Ishida K: Ventilatory and circulatory responses at the onset of dominant and

高石鉄雄, 島典広, 西井匠, 小原史朗, 植屋節子,

non-dominant limb exercise. Eur J Appl

斉藤

Physiol, 101: 347-358, 2007.

性. 体力科学, 56: 797, 2007.

満: 血糖調節における自転車運動の有効

Katayama K, Sato K, Hotta N, Ishida K, Iwasaki

Saito M: Reconsideration of the effect of resist-

K, Miyamura M: Intermittent hypoxia does

ance training on sympathetic nerve response

not increase exercise ventilation at simulated

to muscle contraction. Adv Exerc Sports

moderate altitude. Int J Sports Med, 28: 480-

Physiol, 13: 60, 2007.

487, 2007.

村松憲, 牛山潤一, 清水靜代, 村山光義, 佐々木玲子:

Burns SF, Miyashita M, Ueda C, Stensel DJ:

超音波法を用いた塾生の形態評価について. 慶應

Multiple bouts of resistance exercise and post-

義塾大学体育研究所紀要, 46: 17-24, 2007.

prandial triacylglycerol and serum C-reactive-

村山光義, 村松 憲, 佐々木玲子, 清水靜代, 野口和行:

protein concentrations. Int J Sport Nutr Exerc

動作映像の即時フィードバックを用いた技術指174

導効果−フライングディスク・サイドアームス

時および運動後筋虚血時の大脳皮質酸素化動態

ロー導入時の事例−. 慶應義塾大学体育研究所紀の変化. 第 62 回日本体力医学会. 秋田. 2007.
岩館雅子, 定本朋子: 種々の強度の掌握運動に伴う大要, 46: 1-16, 2007.

脳皮質運動野周辺の酸素動態と循環応答の関係.
〈書 籍〉

第 62 回日本体力医学会. 秋田. 2007.

加賀谷淳子：はじめに.「スポーツの科学」, 財団法人

定本朋子, 佐藤耕平, 大森芙美子, 森山真由美, 石田良日本学術協力財団, pp. 6-8, 2007.

恵: 発育に伴う脳血流配分の変化−小学 5 年から

加賀谷淳子：体力の性差とスポーツ. 学術会議書 14,

高校 3 年までの女子について−. 第 15 回日本運動生理学会. 青森. 2007.

性差とは何か−ジェンダー研究と生物学の対Kashima E, Matsukawa K, Tsuchmochi H,

話−. 財団法人日本学術協力財団, pp. 211-221,

Nakamoto T, Endo K, Sadamoto T: Modula-

2007.
定本朋子：循環系の概要. 斉藤

満編, 循環 II −運動

tion of muscle mechanosensitive reflex in

時の調節と適応−. ナップ, pp. 19-31, pp. 5-63,

humans: comparison of the cardiovascular2007.

responses to passive cycling between the

斉藤満

awake and sleep conditions. 第 85 回日本生理編著：循環 II ：運動時の循環調節と適応.

学会. 東京. 2008.

ナップ, 2007.

加賀谷淳子, 奥山靜代, 大森芙美子, 佐藤耕平, 村岡慈

斉藤 満：自律神経機能検査 第 4 版. 日本自律神経学会編, 文光堂, pp. 189-195, pp. 196-199, 2007.

歩, 森曜生: 活動体肢の位置と酸素ダイナミク

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as measured

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森 曜生, 村岡慈歩, 奥山靜代, 大森芙美子, 鈴木早紀

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子, 水村真由美, 加賀谷淳子: 受動的ストレッチ

175

ング時における下腿協働筋間への血流分配の相

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高石鉄雄, 島斉藤

典広, 西井性. 第 62 回日本体力医学会大会. 秋田. 2007.

flow to the contralateral non-exercising limb

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筋厚および皮下脂肪からみた男女大学生の形態
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牛山潤一, 村松

Comments on point: counterpoint: exercise

憲, 奥山靜代, 村山光義, 佐々木玲

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子：男女大学生にみられる性的立位時身体動揺

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Sato K: Blood flow and arterial vessel diame-

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● 平成 20 年度

Sato K, Sadamoto T: Internal carotid artery〈学術論文（査読あり）〉

blood flow and cerebrobascular resistanceIchinose M, Saito M, Fujii N, Ogawa T, Hayashi

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トラルコマンドが静的運動時の脳血流調節に及

T: Hemodynamic relationships among upper

ぼす影響. 第 63 回日本体力医学会. 大分. 2008.

abdominal aorta and femoral arteries: basis

佐藤耕平, 定本朋子: 最大下自転車運動時における内for measurement of arterial blood flow to

頸動脈と椎骨動脈の血流応答の特性. 第 16 回日

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佐藤耕平, 平澤Osada T, Rådegran G: Femoral artery blood flow

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呼吸法が高強度運動時の中大脳動脈血流速度に

and its relationship to spontaneous fluctua-

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tions in rhythmic thigh muscle workload. Clin

定本朋子, 佐藤耕平, 上田千穂子, 澁谷顕一, 加茂美冬,

Physiol Funct Imaging (in press).

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Saito M, Kagaya A, Kamo M, Osada T,に及ぼす影響. 第 63 回日本体力医学会. 大分.

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sarily associated with altered brain activity

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加茂美冬: 振動刺激が随意筋力発揮時の運動単位活動〈書 籍〉におよぼす影響. 第 63 回日本体力医学会. 大分.

定本朋子, 佐藤耕平: Section 10 トレーニングと循環.

2008.

トレーニングと血流量. 宮村実晴編, 身体トレー

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ニングの科学, 真興交易医書出版部, pp. 295-に伴う回復時筋再酸素化と循環応答の変化. 第300, 2009.

63 回日本体力医学会. 大分. 2008.
澁谷顕一, 上田千穂子, 佐藤耕平, 奥山靜代, 斉藤 満,〈学会発表〉

加賀谷淳子, 加茂美冬, 長田卓也, 定本朋子: セン

斉藤

トラルコマンドが脳酸素化動態に及ぼす影響. 第満: 運動強度の違いに対する心拍, 血圧, 筋交

63 回日本体力医学会. 大分, 2008.

感神経活動反応の比較. 第 59 回日本体育学会.東小田俊明, 姫野龍太郎, 大森芙美子, 森 曜生, 水村真

京. 2008.
満, 定本朋子: 運動時の主観的運動強度と交感

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末梢静脈体積変化の計測. 第 63 回日本体力医学

体力医学会. 大分. 2008.

会. 大分. 2008.

斉藤

高石鉄雄, 對馬斉藤明, 植屋節子, 島典広, 小原史朗,

平澤 愛, 佐藤耕平, 山本幸弘, 定本朋子: 多段階の動

満: 自転車走行による高齢者の脚筋力づく的運動時における上腸間膜動脈および腎動脈の血流応答. 第 63 回日本体力医学会. 大分. 2008.

り の 可 能 性 . 第 63 回 日 本 体 力 医 学 会 . 大 分 .

大森芙美子, 奥山靜代, 村岡慈歩, 森 曜生, 鈴木早紀

2008.
片山敬章, 石田浩司, 斉藤

満: 低酸素暴露後におけ子, 水村真由美, 加賀谷淳子: 最大位までの多段る運動時の呼吸応答について. 第 63 回日本体力階ストレッチングが筋の循環に与える影響. 第医学会. 大分. 2008.

15 回医用近赤外線分光法研究会. 東京. 2008.

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了直後の動脈血流加速と静脈血流減速の時間的時の循環調節研究から−. 運動と循環研究会. 東関係. 第 63 回日本体力医学会. 大分. 2008.

京. 2008.

佐藤耕平, 上田千穂子, 澁谷顕一, 奥山靜代, 加茂美冬,

加賀谷淳子: 学術連合の設立にあたって. 健康・スポ

長田卓也, 斉藤 満, 加賀谷淳子, 定本朋子: センーツ科学関連学術連合設立記念シンポジウム

177

「本学術連合の社会的役割とスポーツ・体育・健Different flow responses of renal and splanch-

康科学の未来展望」日本学術会議健康・生活科

nic arteries during Dynamic exercise. 13th

学委員会 健康・スポーツ科学分科会, 健康・ス

European College of Sport Science, Estoril,

ポ ー ツ 科 学 関 連 学 術 連 合 (仮 称 ) 共 催 . 東 京 .

Portugal. 2008.
Kamo M, Morimoto S: Changes in force output of2008.
加賀谷淳子: 中高年者のヘルスプロモーションにおけhuman muscle fibers during repetitive activa-

る運動生理学の役割. 第７回ヘルスケアソルーシ

tion at physiological rates 13th European

ョン研究会. 東京. 2008.

College of Sport Science, Estoril, Portugal.
2008.

加賀谷淳子: 子どもの遊びと身体活動. 第 19 回日本臨Ueda C, Kamo M, Saito M, Kagaya A, Osada T,

床スポーツ医学会学術集会. 千葉. 2008.
Saito M, Hachiya T: The effects of resistance

Sato K, Shibuya K, Okuyama S, Sadamoto

training on sympathetic neural activity

T: Effect of tendon vibration during submaxi-

response during fatiguing static handgrip

mal static elbow flexion exercise on muscle

exercise. 13th European College of Sport

oxygenation. 13th European College of Sport

Science, Estoril, Portugal. 2008.

Science, Estoril, Portugal. 2008.

Sato K,

Sadamoto T: Cerebral blood flow

Ueda C, Kagaya A: Muscle reoxygenation differ-

responses in internal carotid and vertebral

ence between superficial and deep regions ofartery during dynamic exercise. 13th

the muscles during static knee extension.

European College of Sport Science, Estoril,

36th Annual Meeting of International Society

Portugal. 2008.

on Oxygen Transport to Tissue, Sapporo.

Sato K, Hirasawa A, Sadamoto T: Cerebrovascu-

Japan. 2008.

lar response during heavy upper body exer-

Shibuya K, Iwadate M, Sadamoto T: Reduced

cise: effect of mode of ventilation on blood

contribution of the ipsilateral primary motor

flow velocity in the middle cerebral artery.

cortex to force modulation with habituation

The 36th Annual conference international

for exercise in humans: An NIRS study.

society on oxygen transport to tissue.

Society for Neuroscience, Washington D.C.,

Sapporo, Japan. 2008.

USA. 2008.

Kagaya A, Ohmori F, Okuyama S, Muraoka Y,

Kagaya A, Ohmori F, Okuyama S, Muraoka Y,

Sato K: Blood flow and arterial vessel diame-

Sato K: Blood flow and arterial vessel diame-ter change during graded handgrip exercise in

ter change during graded handgrip exercise indominant and non-dominant forearms of ten-dominant and non-dominant forearms of ten-

nis players. 36th Annual Meeting of

nis players. 36th Annual Meeting ofInternational Society on Oxygen Transport toInternational Society on Oxygen Transport to

Tissue, Sapporo. Japan. 2008.

Tissue, Sapporo. Japan. 2008.

Sadamoto T, Sato K, Hirasawa A, Yamamoto Y:

178

INSTITUTE OF PHYSICS PUBLISHINGPHYSICS IN MEDICINE AND BIOLOGY

Phys. Med. Biol. 49 (2004) 685–699

PII: S0031-9155(04)66557-2

Mapping of calf muscle oxygenation and haemoglobin
content during dynamic plantar flexion exercise bymulti-channel time-resolved near-infrared
spectroscopy
Alessandro Torricelli1, Valentina Quaresima2, Antonio Pifferi1,
Giovanni Biscotti1, Lorenzo Spinelli1, Paola Taroni1, Marco Ferrari2,3
and Rinaldo Cubeddu1
1 INFM-Dipartimento di Fisica and IFN-CNR, Politecnico di Milano,

Piazza Leonardo da Vinci 32, I-20133 Milan, Italy
2 Department of Biomedical Sciences and Technologies, University of L’Aquila,
I-67100 L’Aquila, Italy
3 Interdepartment Center of Sports Science, University of L’Aquila, I-67100 L’Aquila, Italy
E-mail: rinaldo.cubeddu@fisi.polimi.it

Received 24 July 2003, in final form 16 December 2003
Published 6 February 2004
Online at stacks.iop.org/PMB/49/685 (DOI: 10.1088/0031-9155/49/5/003)
Abstract
A compact and fast multi-channel time-resolved near-infrared spectroscopy
system for tissue oximetry was developed. It employs semiconductor laser
and fibre optics for delivery of optical signals. Photons are collected by eight1 mm fibres and detected by a multianode photomultiplier. A time-correlated
single photon counting board is used for the parallel acquisition of time-resolved
reflectance curves. Estimate of the reduced scattering coefficient is achieved byfitting with a standard model of diffusion theory, while the modified Lambert–
Beer law is used to assess the absorption coefficient. In vivo measurements were
performed on five healthy volunteers to monitor spatial changes in calf muscle(medial and lateral gastrocnemius; MG, LG) oxygen saturation (SmO2) andtotal haemoglobin concentration (tHb) during dynamic plantar flexion exercise
performed at 50% of the maximal voluntary contraction. At rest SmO2 was
73.0 ± 0.9 and 70.5 ± 1.7% in MG and LG, respectively (P = 0.045). At theend of the exercise, SmO2 decreased (69.1 ± 1.8 and 63.8 ± 2.1% in MG andLG, respectively; P < 0.01). The LG desaturation was greater than the MG
desaturation (P < 0.02). These results strengthen the role of time-resolved
near-infrared spectroscopy as a powerful tool for investigating the spatial andtemporal features of muscle SmO2 and tHb.

0031-9155/04/050685+15$30.00© 2004 IOP Publishing Ltd
179

Printed in the UK685

A Torricelli et al686

1. Introduction
The possibility of monitoring non-invasively the haemodynamics and the oxygenation
status/kinetics (indirect measurement of oxidative metabolism) in the muscle or in the brain isa challenging task. In the muscle, this can not only help in studying the mechanisms related toexercise physiology, but also to pathology caused by myopathies and/or peripheral circulatory
diseases. In the brain, it can lead to the monitoring of cerebral oxygenation and the reactivity inresponse to some stimuli (motor, visual, cognitive), and thus it can help in the study of cognitive
processes, evaluation of mental diseases, assessment of brain injuries, etc. These studies were
fostered by the capabilities offered by magnetic resonance imaging and positron emission
tomography (Posner and Raichle 1998). In this framework light is a powerful diagnostic tool
especially in the region between 650 and 1100 nm where penetration depth in biological tissues
is relatively high, and also oxygenated haemoglobin (O2Hb) and deoxygenated haemoglobin(HHb) exhibit distinct spectral features (see Delpy and Cope 1997 for a review). The
widespread use of near-infrared spectroscopy (NIRS) for non-invasive investigation has beenhampered by the high scattering coefficient typical of biological tissues that hinders spatial andspectral information contained in endogenous chromophores. Recently, deeper knowledge ofthe physics of photon migration and technical developments in optoelectronics components
have made it possible to extract valuable optical information from the probed medium. Also,
several instruments for optical tissue oximetry—either commercial systems or laboratory
prototypes—have been constructed. A first approach to monitoring tissue oxygenation is tomeasure light attenuation at two wavelengths between a couple of optical fibres set normal to thetissue surface at a known relative distance. Assuming a fixed value of the scattering coefficient,and applying the Lambert–Beer law, relative changes in the HHb and O2Hb concentrations
can be tracked. This rather straightforward technique has grown in time and led to instruments
working at more wavelengths, or with multiple source, multiple detector geometries4 . In
particular this latter feature offers the possibility of probing different regions in the tissue
under study and thus of producing functional maps. Actually, using such advanced continuous
wave (CW) systems the response of brain oxygenation and perfusion to finger tapping, mental
calculations, light flashing and other stimuli was demonstrated (see Obrig and Villringer 2003
for a review). Yet, the key limitations of this technique are the coupling between the absorption
and the scattering coefficients (µa, µ�s ) causing the lack of quantitative assessment, sensitivity
to artefacts and experimental conditions. A possible way to uncouple µa from µ�s still using
a CW source is to use a multi-distance approach, and to analyse the spatial decay of reemitted light (Kienle et al 1996). Some commercial instruments are available exploiting thisprinciple, yet the method relies on a strong correlation between different interfibre distances,and thus is based on the assumption of a homogeneous medium. Effects caused by theinherent multi-layer structure of the human body are still to be clarified (Farrell et al 1998).
A possible extension of the CW approach towards the spectral domain can overcome someof these limitations since the use of a full spectral range (e.g., 700–1000 nm) provides more
information and redundancy to get rid of scattering assumptions, interference from otherabsorbing chromophores or the heterogeneous tissue structure. Matcher et al (1994) describeda simple method for measuring the differential pathlength of photons in a scattering medium
utilizing the spectral absorption features of water. A completely different approach is basedon the use of sinusoidally modulated laser sources, and on the measurement of signal phaseand amplitude changes caused by propagation. The frequency-domain technique extracts both
4

Instruments: NIRO-300 (Hamamatsu Photonics Co., Japan), OXYMON (Artinis Medical Systems, The
Netherlands), INVOS 4100 (Somanetics Co., USA), OM-200 (Shimadzu Co., Japan), ETG-100 (Hitachi Co., Japan).

180

Calf muscle oximetry by multi-channel time-resolved NIRS

687

the mean µ�s and µa of the probed medium provided that a non-trivial calibration of collection
efficiencies is performed. This approach was successfully applied to the measurement oftissue oxygenation, and led to the first identification of a rapid change of µ�s following a
cerebral stimulus (Gratton et al 1997). The dual approach is the study of photon migrationin the time domain first introduced in vivo by Chance et al (1988) and Delpy et al (1988).
The temporal dispersion of a short laser pulse travelling through a diffusive medium canprovide both the mean µ�s and µa using a proper model of photon migration. By applying theFourier transform, the time-domain measurement can be converted into a set of frequencydomain measurements distributed over a wide range of frequencies ultimately limited by the
temporal resolution of the system in use, and by the strong attenuation of photon density waves
at a high frequency. Thus, the temporal approach could provide even broader information
than phase-resolved measurements. Yet, the real advantage of having a full time-resolved
curve instead of a single frequency measurement is still to be investigated. In the past, thecost, size and complexity of the time-resolved instrumentation have prevented this techniquefrom being effectively used in tissue oxygenation studies. Large laboratory systems havebeen developed for spectral (Andersson-Engels et al 1993, Cubeddu et al 1999a) or spatial(Cai et al 1999, Eda et al 1999, Schmidt et al 2000) characterization of turbid media, but are
unsuitable for fast tissue oximetry. Recently, semiconductor lasers have made it possible toconstruct more compact time-resolved instruments (Benaron and Stevenson 1993, Miwa et al
1995, Cubeddu et al 1999b, Grosenick et al 1999, Ntziachristos et al 1999), yet none of themoffers the required complexity of source/detector configuration needed to produce opticalmaps for functional monitoring and/or the short acquisition time essential to follow biologicaldynamics.
In this paper, we report on the development and characterization of a novel compact
multi-channel optical system, based on the time-resolved reflectance spectroscopy techniquewith two sources, eight detectors and 6 Hz acquisition frequency. Moreover, we report the
spatial changes in calf muscle (medial gastrocnemius (MG) and lateral gastrocnemius (LG))
oxygen (O2) saturation (SmO2) and total haemoglobin concentration (tHb) monitored onhealthy volunteers during dynamic plantar flexion exercise executed at 50% of the maximum
voluntary contraction (MVC).

2. Materials and methods
2.1. System set-up: eight-channel time-resolved tissue oximeter
The scheme of the system set-up is shown in figure 1. A couple of semiconductor pulsed
lasers (PDL, Picoquant, Germany), working at 685 nm and 780 nm, with 80 MHz repetition
rate and 1 mW average power, are used as light sources. Multimode graded index fibres(50/125 µm) of different lengths and a fibre optics integrated device (VIS/NIR 2 × 2 fused
splitter, OZ Optics, Canada) are used to multiplex in time the output pulses of the two laser
heads so as to create two independent injection points. A compact 16-anode photomultiplier(R5900-01-L16, Hamamatsu, Japan) and a PC board (SPC-630, Becker & Hickl, Germany) for
time-correlated single photon counting (TCSPC) are used to detect and acquire time-resolved
reflectance curves. Due to 20% optical cross talk among adjacent channels, only 8 out of 16
channels are used by placing the optical fibre only on odd channels (1, 3, 5, . . . , 15). In thisconfiguration the cross talk is lower than 3% (see section 3.1.1). The typical measurement
time for the parallel acquisition of time-resolved curves from the eight channels is 166 ms(6 Hz).
181

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laser heads
d
r
i
v
e
r

delay

Injection #1

fused
splitter

690 nm50%
780 nm

sync

50%

TCSPC

amp

8 channrouterPC

Injection #2

PMT

8 collection fibres

Figure 1. Scheme of the two-source eight-detector time-resolved tissue oximeter. (TCPSC:
time-correlated single photon counting; PMT: photomultiplier tube.)

2.2. System characterization
The performances of the system were tested on tissue phantoms in terms of reproducibility
among channels, stability and linearity in the determination of the optical properties (absorption
and scattering coefficients).
A cylindrical glass box (10 cm diameter and 10 cm height) was filled with an aqueous
solution of Intralipid (Kabi Vitrum, Italy), to mimic a scattering tissue and ink (Mod. R591-009
Blue, Rotring, Germany), to mimic tissue absorption. Throughout the paper, the concentrationof Intralipid refers to the fraction of solids in the examined solution, while the concentration of
ink pertains to the fraction of the original product, as obtained from the supplier, present in thesolution under study. The scattering properties of Intralipid and the absorbing properties of theink were characterized using time-resolved reflectance spectroscopy under optimal conditions
for both the technique and the theoretical method (Cubeddu et al 1996). This allowed us to fix
the absorbing and scattering properties of the phantom solutions to values typical for humantissues in the visible and near-infrared regions of the spectrum. The injection and collection
fibres, were placed at a relative distance ρ = 3.0 cm, in contact with and at a right angle to thesample surface. A black, rigid plastic strip firmly held the fibres, and avoided possible direct(not re-emitted) stray light to be collected by the fibre.
2.3. Data analysis
During data analysis an integration time of 1 s is used to increase the signal-to-noise ratio.
Summing six time-resolved reflectance curves, each of them acquired with a measurement
time of 166 ms, performs this operation.
Simultaneous estimate of µ�s and µa may be achieved by best fitting of time-resolved
reflectance curves with a standard model of diffusion theory (Haskell et al 1994). Therefore,
to reduce dispersion of the fitted absorption coefficient values, we use the methods described by
Nomura et al (1997) and known as the modified Lambert–Beer law. First, for each wavelengtha reference time-resolved reflectance curve R0 (ρ, t, λi ) is derived by averaging the curves
corresponding to an initial resting period (typically 0.5 min). Fitting of R0 (ρ, t, λi ) yields
the reference absorption value µa0 (λ). Then �µa, the variation from the reference value, isderived according to the following equations:µa (λ) = µa0 (λ) + �µa (λ)
��1R(ρ, t; λi )
�µa (λ) = − ln.
vt
R0 (ρ, t; λi )
182

(1)
(2)

Calf muscle oximetry by multi-channel time-resolved NIRS

689

10° extension

collection fibres

ergometer

injection fibre
50% MVC load

Figure 2. Scheme of the dynamic plantar flexion exercise (left) and a photograph of the footergometer (right). (MVC: maximal voluntary contraction.)

Improvement over the standard methods is more effective when the absorption is high. In
this condition in fact standard fitting with the non-linear least-squares methods yields highdispersion in the fitted data (Cubeddu et al 1996). Taking the assumption that O2Hb and HHb
are the main chromophores contributing to absorption, their concentrations are easily derived
by using the knowledge of the extinction coefficient (Prahl 2001). Water absorption in thisspectral region is in fact much lower than haemoglobin absorption (Prahl 2001). A fixedamount (30%) of absorption was attributed to water and subtracted from µa before calculationof HHb and O2Hb. Then, tHb (tHb = HHb + O2Hb) and muscle O2 saturation (SmO2 =O2Hb/tHb) are derived.
2.4. Protocols for in vivo measurements
In vivo measurements were performed on five healthy volunteers (male, age: 34–50 years) tomonitor SmO2 and tHb changes in the calf muscle during dynamic plantar flexion exercise.
All subjects gave their written informed consent. Figure 2 (left) shows the ergometer designed
and built at the Politecnico di Milano, Dipartimento di Fisica to perform the exercise (Kagaya
1992). The day before measurements all subjects received adequate training on the exercise,and their own MVC was measured (48, 50, 36, 34 and 42 kg). The protocol consisted of 1 min
rest condition, followed by 1 min plantar flexion (1 Hz, 50% of MVC, 10◦ extension) and3 min recovery. Time-resolved reflectance measurements were performed with 6 Hz
acquisition frequency (166 ms acquisition time). A pair of custom-made fibre holders were
designed so as to collect re-emitted photons from four points, equidistant (3 cm) from theinjection (see figure 3). The holder is made of soft black rubber, and is kept in place byadhesive strips wrapped around the leg of the subject (not too tight to avoid blockage of bloodflow). No downward sliding of the fibre holder was observed at the end of the measurements inany subject. Fibres are kept normal to the sample by black plastic hollow tubes. Measurement
points were located in the MG and LG, in the distal (D1 and D2) and proximal (P1 and P2)
regions. The typical distance between the light source located in the LG (MG) and detectors
placed over the MG (LG) was 10 cm. This avoided cross talk between the optical signals
detected simultaneously in the two areas.
Adipose tissue thickness underlying the monitored areas of the muscle groups wasmeasured with a skinfold calliper. The mean value of the adipose tissue thickness was 3.3 ±1.3 mm and 3.9 ± 1.0 mm over MG and LG, respectively. Considering that the thickness of
the adipose tissue over all the investigated area of the right calf was less than 5 mm, it can be
183

A Torricelli et al

690

MG P2

MG P1

LG P2

LG P1

MG D2

MG D1

LG D2

LG D1

sourcedetector

Figure 3. Scheme of the rubber pad probe designed to hold the fibres (left), and scheme of thepositioning of the probes on the calf muscles (right). The source–detector distance is 3 cm. (LG:lateral gastrocnemius; MG: medial gastrocnemius; P: proximal; D: distal.)assumed that SmO2 variations reflect the metabolic changes occurring mainly in the muscle
tissue (Matsushita et al 1998). In addition, the lack of difference in adipose tissue thickness
between MG and LG allowed their comparison.
Maximal desaturation observed in the exercising muscle was calculated by calculating
the difference of the absolute values of SmO2 between the rest condition (mean value overthe 1 min baseline) and the end of the exercise (mean value over the last 10 s). SmO2 was
calculated after 3 min recovery (mean value over the last 10 s). The same averaging procedure
was utilized for tHb.
The mean and standard deviation of SmO2 and tHb values within MG and LG were
determined separately and compared using analysis of variance. Significant differences wereidentified using Tukey’s honestly significant difference multiple comparison test. The paired t
test was used to compare the SmO2 and tHb values corresponding to MG and LG. The criterion
for significance was P < 0.05.
3. Results
3.1. System characterization
3.1.1. Detector uniformity and cross talk. To test detector uniformity and cross talk amongchannels, channel 1 of the photomultiplier was illuminated and photons were simultaneously
detected from channels 1 to 16. This test was then repeated also with illumination in channels 3,
5, 7, 9, 11, 13 and 15. All results are shown in figure 4. Detector uniformity (i.e. the dispersionof the peak intensity in the illuminated channel) is 13%. Cross talk between adjacent channels
is 20% while it reduces to 2% if the first non-adjacent channels are considered.
These results are in agreement with the typical values for anode uniformity and cross talkreported in the detector datasheet (see Hamamatsu, multianode photomultiplier tube R5900UL16 series, TPMH1146EO5, Sept. 1999, Japan). Anode uniformity is in fact 1:0.6 (relative
output is in the range 100–80%) and electronic cross talk is 3%.
In a further experiment, a configuration with a double source and a single detector wasused to study differences due to the use of multiple sources. Time-resolved reflectance curves
from a tissue phantom were measured (interfibre distance 3 cm, acquisition time 1 s) andestimates of µa and µ�s were derived. The coefficient of variation is 1.8% and 1.7% for µa andµ�s , respectively. Then, a configuration with eight detectors and a single source was employedwith the same measurement protocol. The coefficient of variation is 1.9% and 2.2% for µa
and µ�s , respectively.
184

Calf muscle oximetry by multi-channel time-resolved NIRS
1.E+06

691

S1

S3

S5

S7

S9

S11

S13

S15

intensity (counts)

1.E+05
1.E+04
1.E+03
1.E+02
1.E+011 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
detector #Figure 4. Photon counts in the 16 detectors as a function of the position of the illumination point.
S1 indicates that the light source is located in front of channel 1.
1.05
1.04

µ a /< µ a >

1.03
1.02
1.01
1.00
0.99
0.98

0

30

60
90
120
time (min)

150

180

Figure 5. Stability test: the variation as a function of time of µa is reported after normalization to
the average values estimated in the last 60 min of the test.

3.1.2. Stability. System stability was tested by performing a 3 h long measurement, startingfrom the turning on of the instrumentation. Figure 5 shows the variation of µa over the whole
period. Values are plotted after normalization to the average value calculated in the last 60 minof the test. Similar results were found for µ�s (data not shown). It is clear that the system needs
about 30 min warm-up time. Drift of power and sync timing of semiconductor diode lasers
mostly limit stability. After warm-up, the coefficient of variation (standard deviation/average)in the estimated absorption and reduced scattering coefficients is as low as 0.5% and 0.6%,
respectively.
3.1.3. Absorption linearity. In the absorption linearity experiment the blue ink concentration
was varied ranging from 0.3 × 10−5 to 2.1 × 10−5, while the Intralipid concentration was
7.0 × 10−3. Figures 6(a) and (b) show the absorption coefficient and the reduced scattering
coefficient respectively, as a function of ink concentration. Points represent the average values
while error bars are the dispersion among the eight channels. At both wavelengths, µa is found
185

14

14

12

12

10

10

8

8
6

-1

µ s' (cm )

0

1

2

3

4

5

16

MG D1 16

14

14

12

12

10

10

8

8

6

1

2

3

4

1

2

3

4

5

14

14

12

12

10

10

8

8

5

MG D1

1

2

3

4

5

Time (min)

1

2

3

4

0

16

LG D1 16

14

14

12

12

10

10

8

8

6
0

5

LG P2

6
0

6
0

16

LG P1

6
0

-1

6

693
16

MG P1
-1

MG P2 16

µ s' (cm )16µ s' (cm )-1µ s' (cm )Calf muscle oximetry by multi-channel time-resolved NIRS

1

2

3

4

5

LG D2

6
0

Time (min)

1

2

3

4

5

0

Time (min)

1

2

3

4

5

Time (min)

0

1

2

3

4

5

MG P1
0

1

2

3

MG D2 20

1

2

3

4

Time (min)

5

20
15
10
5
0
-5
-10
-15
20
15
10
5
0
-5
-10
-15

5

0

1

2

3

4

LG P1 20

5Time (min)

LG P2

15
10
5
0
-5
-10
-15

0

MG D1

15
10
5
0
-5
-10
-15

0

4

∆ HHb ( µ M)

20
15
10
5
0
-5
-10
-15

MG P2 20

15
10
5
0
-5
-10
-15

∆ O2Hb ( µ M)

∆ HHb ( µM)

20
15
10
5
0
-5
-10
-15

∆ O2Hb ( µ M)

Figure 8. Typical time course of µ�s at 690 nm (grey curve) and at 780 nm (black curve). Refer tofigure 7 for abbreviations and details.

1

2

3

4

5

0

1

2

3

LG D1 20
15
10
5
0
-5
-10
-15

0

1

2

3

4

Time (min)

5

4

5

LG D2

0

1

2

3

4

5

Time (min)Figure 9. Typical time course of changes in HHb (grey curve) and O2Hb (black curve). Refer tofigure 7 for abbreviations and details.

typical plots of µa at 690 nm and at 780 nm over the protocol. During the initial resting
period (0–1 min), µa is rather constant in all locations. The absorption coefficient is higher
at 690 nm than at 780 nm for all locations except MG P1, which also presents a higher noiselevel, suggesting a non-optimal optical coupling, or an inadequate positioning, between thecorresponding fibre and the muscle. Data from MG P1 were therefore not considered forthe analysis. Then, during the dynamic plantar flexion exercise (1–2 min) there is at both
wavelengths an abrupt increase of µa, with a saturation in the final part of the rise. After theend of the exercise, µa at 690 nm returns to the initial value with a slow recovery, while µa
at 780 nm presents a further increase followed by a very slow recovery. As expected, µ�s islower at 780 nm than at 690 nm (figure 8). µ�s is rather constant during the baseline, while itshows a 10% decrease during the plantar flexion exercise. At the end of the exercise µ�s rapidly
returns to values closer to the initial ones. SmO2 rapidly decreases within the first 20 s after
186

14

14

12

12

10

10

8

8
6

-1

µ s' (cm )

0

1

2

3

4

5

16

MG D1 16

14

14

12

12

10

10

8

8

6

1

2

3

4

1

2

3

4

5

14

14

12

12

10

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8

8

5

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1

2

3

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5

Time (min)

1

2

3

4

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16

LG D1 16

14

14

12

12

10

10

8

8

6
0

5

LG P2

6
0

6
0

16

LG P1

6
0

-1

6

693
16

MG P1
-1

MG P2 16

µ s' (cm )16µ s' (cm )-1µ s' (cm )Calf muscle oximetry by multi-channel time-resolved NIRS

1

2

3

4

5

LG D2

6
0

Time (min)

1

2

3

4

5

0

Time (min)

1

2

3

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0

1

2

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MG P1
0

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2

3

MG D2 20

1

2

3

4

Time (min)

5

20
15
10
5
0
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-15
20
15
10
5
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-5
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-15

5

0

1

2

3

4

LG P1 20

5Time (min)

LG P2

15
10
5
0
-5
-10
-15

0

MG D1

15
10
5
0
-5
-10
-15

0

4

∆ HHb ( µ M)

20
15
10
5
0
-5
-10
-15

MG P2 20

15
10
5
0
-5
-10
-15

∆ O2Hb ( µ M)

∆ HHb ( µM)

20
15
10
5
0
-5
-10
-15

∆ O2Hb ( µ M)

Figure 8. Typical time course of µ�s at 690 nm (grey curve) and at 780 nm (black curve). Refer tofigure 7 for abbreviations and details.

1

2

3

4

5

0

1

2

3

LG D1 20
15
10
5
0
-5
-10
-15

0

1

2

3

4

Time (min)

5

4

5

LG D2

0

1

2

3

4

5

Time (min)Figure 9. Typical time course of changes in HHb (grey curve) and O2Hb (black curve). Refer tofigure 7 for abbreviations and details.

typical plots of µa at 690 nm and at 780 nm over the protocol. During the initial resting
period (0–1 min), µa is rather constant in all locations. The absorption coefficient is higher
at 690 nm than at 780 nm for all locations except MG P1, which also presents a higher noiselevel, suggesting a non-optimal optical coupling, or an inadequate positioning, between thecorresponding fibre and the muscle. Data from MG P1 were therefore not considered forthe analysis. Then, during the dynamic plantar flexion exercise (1–2 min) there is at both
wavelengths an abrupt increase of µa, with a saturation in the final part of the rise. After theend of the exercise, µa at 690 nm returns to the initial value with a slow recovery, while µa
at 780 nm presents a further increase followed by a very slow recovery. As expected, µ�s islower at 780 nm than at 690 nm (figure 8). µ�s is rather constant during the baseline, while itshows a 10% decrease during the plantar flexion exercise. At the end of the exercise µ�s rapidly
returns to values closer to the initial ones. SmO2 rapidly decreases within the first 20 s after187

A Torricelli et al
MG P2 10

6

6

2

2

-2

-2

-6

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∆ SmO2 (%)

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MG D2 10

6

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2

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∆ SmO2 (%)

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∆ SmO2 (%)∆ SmO2 (%)

694

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∆ tHb ( µ M)

∆ tHb ( µ M)

25
20
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∆ tHb ( µ M)

Figure 10. Typical time course of changes in SmO2 (%). Refer to figure 7 for abbreviations anddetails.

1

2

3

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20
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0

1

2

3

4

5

Time (min)Figure 11. Typical time course of changes in tHb (µM). Refer to figure 7 for abbreviations anddetails.

the beginning of the exercise in all locations (figure 10), then it decreases more slowly up to
the end of the exercise with different patterns in the MG and LG. In particular, SmO2 of MG
P2 and MG D1 progressively decreases, while in the remaining locations it reaches a constantvalue. At the end of the exercise, in all locations SmO2 recovers with different patterns andreaches in 3 min values above the pre-exercise ones. Concomitantly tHb, after an abrupt
rise occurring within the first 20 s of exercise, is constant until the end of the exercise(figure 11). Immediately after, tHb increases very rapidly in LG and MGD1; then it
progressively decreases and maintains values above the pre-exercise ones 3 min after theend of the exercise (passive reactive hyperaemia).
Considering that no significant difference in SmO2 and tHb was found amongst thefour locations within each muscle group, SmO2 and tHb were averaged within LG and MG.
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Calf muscle oximetry by multi-channel time-resolved NIRS

695

Table 1. SmO2 (%) and tHb (µM) in the medial (MG) and lateral (LG) gastrocnemius muscle
groups of the right leg at rest (REST), at the end of the dynamic plantar flexion exercise (EXER),
and 3 min after the end of exercise (REC). CHANN is the number of measurement points averaged
in LG/MG, respectively. var: variable.
MG
Subject CHANN Var
A

3/4

B

4/3

C

4/2

D

4/3

E

4/3

Mean ±
sd

REST

EXER

LG
REC

REST

EXER

REC

SmO2 70.1 ± 1.1
63.4 ± 1.8
72.2 ± 0.9
69.2 ± 1.9
60.8 ± 1.4
71.6 ± 1.4
tHb
147.8 ± 22.7 155.2 ± 24.1 154.7 ± 22.2 130.0 ± 3.9 128.8 ± 5.6 136.6 ± 4.3
SmO2 69.5 ± 0.9
66.4 ± 1.7
71.0 ± 0.3
61.9 ± 1.5
56.0 ± 1.3
66.2 ± 0.8
tHb127.3 ± 3.5 138.3 ± 2.7
130.9 ± 3.7
133.4 ± 1.8 141.3 ± 3.0 137.8 ± 2.7
SmO2 75.9 ± 0.9
71.0 ± 2.6
78.4 ± 0.4
74.9 ± 1.9
68.7 ± 3.5
75.8 ± 2.0
tHb
162.7 ± 16.3 169.5 ± 21.5 171.8 ± 16.0 152.4 ± 8.6 159.8 ± 7.7 156.8 ± 9.6
SmO2 73.6 ± 0.9
69.7 ± 1.4
76.0 ± 1.2
68.9 ± 1.6
60.9 ± 2.5
71.7 ± 2.0
tHb
157.3 ± 7.4 161.2 ± 8.2
163.9 ± 7.7
151.9 ± 19.2 155.5 ± 20.1 155.0 ± 19.2
SmO2 78.7 ± 0.5
75.4 ± 1.5
80.3 ± 0.7
77.8 ± 1.5
72.8 ± 1.8
79.8 ± 1.6
tHb112.0 ± 5.7 128.8 ± 5.7
119.3 ± 6.4
111.8 ± 7.4 116.3 ± 9.4 117.2 ± 7.2
SmO2 73.6c ± 0.9 69.1a,c ± 1.8
75.6a,b,c ± 0.7 70.5 ± 1.7
63.8a ± 2.1 73.0a,b ± 1.6
a,c
a
tHb
141.4 ± 11.1 150.6 ± 12.4 148.1 ± 11.2 135.9 ± 8.2 140.3a ± 9.1 140.7a ± 8.6

aSignificantly different from the corresponding value at REST.
Significantly different from the corresponding value at the end of the exercise (EXER).
c
Significantly different from the corresponding value in LG. Significance was set at P < 0.05.
b

Table 1 summarizes for each subject the absolute values of SmO2 and tHb measured at rest,at the end of the dynamic plantar flexion exercise and 3 min after the end of the exercise. The
baseline value of SmO2 in LG is lower than in MG (P = 0.0447). Both in LG and MG, SmO2
decreases at the end of the exercise (P < 0.01) with lower values found in LG than in MG(P = 0.0199). Both in LG and MG, SmO2 at the end of the protocol reaches higher values
than the pre-exercise ones (P < 0.05). Either in LG or MG, tHb increases at the end of theexercise (P < 0.05) with lower values found in LG than in MG (P = 0.0499). tHb at the endof the protocol reaches higher values than the pre-exercise ones (P < 0.05).
4. Discussion
In this study we report the development of a fast eight-channel portable instrument aiming at
increasing the informative content of tissue oximetry data, as compared to existing devices. In
the last five years, several groups have begun to use multi-channel CW imaging systems thatallow the generation of images of a relatively large area of the subject’s head/muscle with hightemporal resolution (up to 100 ms) and, thereby, the production of maps of cortical/muscle
oxygenation changes (see Miura et al 2001, 2003, Niwayama et al 2000, Obrig and Villringer
2003 for a review of brain studies; Quaresima et al 2001a, 2002). In particular, Miuraet al (2003) using a multi-channel CW NIRS system found regional differences in theoxygenation of the gastrocnemius muscle during exercise and recovery performing the standing
plantar flexion exercises for 2 min (one contraction/s) with the distal portion having greater
deoxygenation and tHb changes. This is consistent with the distal portion having a greater
impairment of muscle blood flow possibly because of the higher intramuscular pressure during
the exercise. Quaresima et al (2001a) investigated vastus lateralis and rectus femoris O2
consumption at rest and during MVC using a 12-channel CW NIRS system (100 ms acquisitiontime). O2 consumption either at rest or during MVC was found to be non-uniform in the 12
measurement sites over a surface of 8 × 8 cm2.
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The results of the previous studies have strengthened the role of NIRS as a powerful toolfor investigating the spatial and temporal features of muscle oxygenation changes as well as
muscle O2 consumption. Unfortunately few CW imagers are commercially available; they arequite expensive, and lack the US Food and Drug Administration approval. Although many
interesting studies have been performed with multi-channel CW systems, the lack of pathlength
determination limits the accuracy of the results (Ferrari et al 1992, Zhao et al 2002).
Imagent (ISS Inc., Urbana, IL, USA) is a new device allowing the measurement of O2Hb
and HHb concentration maps in muscle and brain by the phase modulation method. The
instrument has been recently and successfully utilized in brain and muscle studies (Wolf et al
2002, 2003).
Absolute concentrations can also be measured by time-resolved spectroscopy. Few
instruments working in the time domain are nowadays present at the research level. A twowavelength and a three-wavelength instrument have been used in muscle studies, but they offer
poor acquisition time and are limited by the use of a single detection channel (Hamaoka et al
2000, Oda et al 2000). Companies and academic institutions have been developing multichannel time-resolved systems (Eda et al 1999, Schmidt et al 2000). The first multi-channel(64) time-resolved optical imaging system was developed by Japanese companies (Eda et al1999) and it has been successfully tested in human brain functional studies (Hoshi et al 2000).
However, the 64-channel system is characterized by an extremely poor time resolution (someminutes). A 16-source and 32-channel time-resolved optical imaging instrument has beendeveloped principally to study functional parameters of the newborn brain by the University
College of London. Images representing the internal scattering and absorbing properties of thearm, as well as images revealing physiological changes during a simple finger flexion exercise
were presented (Hillman et al 2001). Three-dimensional images (tomographic approach)of the newborn infant brain with a cerebral haemorrhage predominantly located within
the left ventricle have been recently generated (Hebden et al 2002). Unfortunately, thisimager is inherently limited to the acquisition of quasi-static images by the time needed tomultiplex the different sources. A recently developed compact system is characterized bya similar apparatus but it is limited by the reduced number of channels (Steinbrink et al2001).
The developed instrument was designed as a trade-off between imaging capabilities(i.e. need for a high number of measurement points) and fast monitoring requirements (i.e.
maintaining a high acquisition frequency).
A limitation of the developed instrument is related to the spectral sensitivity. It is worth
noting that the higher noise level in the absorption coefficient at 780 nm as compared to
690 nm is due to the reduced sensitivity of the photomultiplier at longer wavelengths. This
could also influence the estimate of O2Hb and subsequently tHb.
Moreover, the multi-channel acquisition could be specifically a key element to facepresently unsolved problems related to the presence of multi-layer structures in biologicaltissues (e.g., the undesired effects caused by the subcutaneous fat layer in muscle measurements
and by the extra-cranial contribution in brain measurements). To this purpose there is the needto collect data at multiple source–detector distances and apply recently developed methods(Martelli et al 2003). In this paper we preferred to focus on the monitoring of spatial variation
over a wide area, therefore positioning the eight collection fibres at a fixed equal distance fromthe source.
Work is in progress to replace the fused splitter with a fibre optics switch, so as to further
increase the number of injection points from 2 to 9, still keeping acquisition times as low as
200 ms (data not shown). Also, by means of a newly developed photomultiplier tube it isforeseen to double the number of independent collection channels.
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697

An intrinsic limitation of the NIRS applied to monitoring of biological tissues is the poor
spatial resolution due to the effect of light diffusion. On the other hand, the problem ofpenetration depth is still a research topic. However, it is foreseen that the TRS system may
have advantages over CW systems (Del Bianco et al 2002).
The NIRS technique is unable to differentiate between the amount of O2 released byhaemoglobin (Hb) and myoglobin (Mb). However, within a given volume of muscle there
are differences in the concentration of both Hb and Mb (i.e. Hb is about 1.5 fold higher
than Mb), and in their binding capacities (i.e. Hb has four times the oxygen binding sites)(Richardson et al 2002). Therefore, one can estimate the Mb mass as a confounding factor atabout 20% of the whole NIRS signal.
For the first time a fast multi-channel time-resolved instrument was effectively used tomonitor SmO2 and tHb regional differences in human calf muscle during dynamic plantar
flexion exercise. The possibility of mapping tHb, which is strictly related to the tissue
blood volume/flow, appears extremely interesting to evaluate regional vasodilatation and/or
capillary recruitment.
It has been previously demonstrated by the one-channel NIRS that MG is the muscle
mostly involved in dynamic plantar flexion exercise (Quaresima et al 2001b). The SmO2
values of MG measured at rest are comparable with those obtained by Boushel et al (2000)
and Quaresima et al (2001b, 2002). The heterogeneous SmO2 response to the dynamic plantar
flexion exercise found between the MG and LG (table 1) might be explained by either one or a
combination of the following points: (a) different local blood supply produced by differencesin the intramuscular pressure (Sejersted et al 1984); (b) divergence of the mechanical activity
within the triceps surae; (c) differences in oxidative metabolic activity; (d) variations in thevascularization, i.e. distribution of arterial, venous and capillary vessels; (e) the recruitment
of different fibre types within the investigated muscle volume. Indeed, muscle blood flow
heterogeneity was also found in the quadriceps during dynamic and isometric exercise byusing positron emission tomography imaging (Laaksonen et al 2003). Moreover, also 31Pmagnetic resonance spectroscopy revealed pH heterogeneity in the tibial anterior muscle
during isometric activity (Houtman et al 2001). This diverse pH distribution was attributed to
intramuscular differences in blood supply.
5. Conclusion
An instrument for multi-channel time-resolved tissue oximetry was developed. The system
operates with two wavelengths, two injection points and eight independent collection points,
and the typical acquisition time is 166 ms. In vivo measurements were performed on five
healthy volunteers to monitor spatial and temporal changes in calf muscle (medial and lateral
gastrocnemius; MG, LG) oxygen saturation (SmO2) and total haemoglobin concentration(tHb) during dynamic plantar flexion exercise performed at 50% of the maximal voluntary
contraction. The results strengthen the role of time-resolved near-infrared spectroscopy as
a powerful tool for investigating the spatial and temporal features of muscle SmO2 and tHb.
Considering that human cortical mapping is the most interesting challenge for multi-channel
TRS, work is in progress to test the TRS system with multi-layer models of the human head,
and to map the human cortical activation under different stimuli.
Acknowledgments
This work is partially supported by MEDPHOT Thematic Network (EC QLG1-CT-200001464) and by COFIN2000, contract no MM02163721.
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698

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SPECIAL COMMUNICATIONS
Letters to the Editor-in-Chief

QUANTIFICATION OF CALFOXYGENATION IN PARAPLEGICPATIENTS DURING PASSIVE LEG
MOVEMENT

Although Kawashima et al. (4) did not quantify properly
muscle oxygenation, the data shown in their Figure 4 clearlysuggest that the well-known postexercise hyperemic phase(evidenced as total Hb increase with respect to the pretestlevel) was evidenced only in the spinal cord injury patients,
and it was maintained over 5 min after the end of the
protocol. In addition, as previously found in walking mitochondrial disorders and muscular dystrophy patients (1,6),
muscle oxygenation is not a limiting factor during passivealternate leg movement in spinal cord–injured subjects.

Dear Editor-in-Chief:
A recent article (4) demonstrated that passive leg movement
can induce both EMG activity and alteration of calf oxygenation in a paralyzed lower limb of spinal cord–injured
subjects. Although these results are interesting, the presentation of the muscle oxygenation data is inadequate. For
measuring calf oxygenation, Kawashima et al. (4) used amultidistance spatially resolved tissue oximeter (NIRO-300,
Hamamatsu Photonics, Japan) without exploiting the offered advantage to quantify muscle oxygenation directly as
tissue oxy-hemoglobin (Hb) saturation (%). Tissue oxy-Hb
saturation reflects the dynamic balance between O2 supply
and O2 consumption and is independent on the path lengthof the near-infrared photons in the muscle tissue (3). Kawashima et al. (4) report the results only as changes in oxyand deoxy-Hb values calculated relative to the resting level,
and represented in micrometers. These changes should havebeen eventually presented at least as � �M*cm, because nopath-length data are available for the calf of spinal cord
injury patients. On the other hand, taking into account thatthese patients present consistent musculoskeletal degeneration (5), it would not be accurate the use of calf path-length
data from healthy subjects (2).
Subcutaneous adipose tissue thickness has a substantial
confounding influence on in vivo muscle near-infrared spectroscopy measurements, therefore it would be essential toincorporate this factor into muscle oximetry studies in orderto justify comparisons between different muscle groups (7).
Kawashima et al. (4) did not report the thickness of the
subcutaneous adipose tissue at the measurement position ineach spinal cord–injured subject. Consistent differences inthe thickness of subcutaneous adipose tissue are expectedamong patients, and between patients and controls. The lackof this information could compromise the results of thecomparison between spinal cord injury and control subjects.

Valentina Quaresima
Marco Ferrari
Department of Sciences and Biomedical Technologies
University of L’Aquila
L’Aquila, Italy
DOI: 10.1249/01.mss.0000183846.62185.87

REFERENCES
1. BANK, W., and B. CHANCE. Diagnosis of defects in oxidative muscle
metabolism by non-invasive tissue oximetry. Mol. Cell Biochem.
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measurements on adult head, calf and forearm and the head of thenewborn infant using phase resolved optical spectroscopy. Phys.
Med. Biol. 490:295–304, 1995.
3. FERRARI, M., L. MOTTOLA, and V. QUARESIMA. Principles, techniques, and limitations of near-infrared spectroscopy. Can. J.
Appl. Physiol. 29:463–487, 2004.
4. KAWASHIMA, N., K. NAKAZAWA, and M. AKAI. Muscle oxygenation of the paralyzed lower limb in spinal cord–injured persons.
Med. Sci. Sports Exerc. 37:915–921, 2005.
5. MODLESKY, C. M., C. S. BICKEL, J. M. SLADE, R. A. MEYER, K. J.
CURETON, and G. A. DUDLEY. Assessment of skeletal muscle mass inmen with spinal cord injury using dual-energy X-ray absorptiometry and magnetic resonance imaging. J. Appl. Physiol. 96:561–565,
2004.
6. QUARESIMA, V., and M. FERRARI. Assessment of quadriceps oxygenation in patients with myopathies by near-infrared spectroscopy. Neurology 51:1238–1239, 1998.
7. VAN BEEKVELT, M. C., M. S., BORGHUIS, B. G. VAN ENGELEN, R.
A. WEVERS, and W. N. COLIER. Adipose tissue thickness affects
in vivo quantitative near-IR spectroscopy in human skeletal
muscle. Clin. Sci. 101:21–28, 2001.

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85

Multichannel Time-Resolved Tissue Oximeter for
Functional Imaging of the Brain
Davide Contini, Alessandro Torricelli, Antonio Pifferi, Lorenzo Spinelli, Paola Taroni,
Valentina Quaresima, Marco Ferrari, and Rinaldo Cubeddu

Abstract—This paper reports the development and characterization of a novel multichannel time-resolved (TR) instrument forfunctional brain imaging studies. The instrument is based on picosecond diode lasers, fiber optics for light injection and delivery,
a compact multianode photomultiplier, and a personal computer(PC) board for time-correlated single photon counting (TCSPC).
The instrument has been characterized in terms of reproducibility
among the nine sources and the 12 collection channels, linearity inthe determination of optical properties (absorption and reduced
scattering), and stability. Preliminary in vivo measurements were
performed on volunteers to monitor the optical response to stimuli
following a motor task (finger opposition, 5 Hz).
Index Terms—Brain, laser biomedical applications, optical
spectroscopy, optical tomography, pulsed lasers, random media,
scattering, time-domain measurements.

I. I NTRODUCTIONNONINVASIVE functional human brain mapping by diffuse optical methods is a novel technique that employs
near-infrared light to probe the brain for changes in parameters
relating to brain function [1], [2]. Since the very first applications of near-infrared spectroscopy (NIRS) with diffusing
light for functional studies, three basic approaches have beendeveloped, namely 1) continuous wave (CW); 2) frequency
domain (FD); and 3) time resolved (TR). NIRS-CW systems
inject constant amplitude light power [provided by a lamp, alight-emitting diode (LED), or a laser] into tissue and monitor
the amplitude decay of incident light. Thanks to relatively low
cost, simplicity and overall robustness, NIRS-CW systems havebeen widely used not only in basic research but also in preclinical applications including tissue oximetry and functional
brain imaging [3]–[5]. The key limitation of NIRS-CW is thecoupling between the absorption and the scattering coefficient,causing the lack of quantitative assessment. To discriminate
between absorption and scattering contribution, NIRS-FD systems use amplitude modulated light sources and record amplitude decay and phase shift of remitted light. Recently, NIRS-FD
instruments have been effectively used for cerebral and musManuscript received June 15, 2004; revised October 10, 2005. This work waspartially supported by MEDPHOT Thematic Network (EC QLG1-CT-200001464) and by COFIN2000 (MM02163721).
D. Contini, A. Torricelli, A. Pifferi, L. Spinelli, P. Taroni, and R. Cubeddu arewith the ULTRAS-CNR-INFM and IFN-CNR, Politecnico di Milano-Dipartimento di Fisica, Milan I-20133, Italy (e-mail: alessandro.torricelli@polimi.it).
V. Quaresima is with the Department of Biomedical Sciences and Technologies, University of L’Aquila, L’Aquila I-67100, Italy.
M. Ferrari is with the Department of Biomedical Sciences and Technologies
and the Interdepartment Center of Sports Science, University of L’Aquila,
L’Aquila I-67100, Italy.
Digital Object Identifier 10.1109/TIM.2005.861502

cle oximetry and breast imaging [6]–[8]. On the other hand,simultaneous estimates of both absorption and scattering canbe achieved by NIRS-TR systems, which deliver ultrashortlaser pulses into tissue and record the time distribution ofdiffusive photons. In the past, for both technological and financial constraints, NIRS-TR systems have grown on a complex
laboratory scale, yet, in recent times, they have evolved towards
compact and portable instruments [9]–[13]. The state of the artof NIRS-TR systems embraces several setups that differ for thecharacteristics of light source (repetition frequency, number ofwavelengths, and geometry of injection points) and detectors(performance of electronics for signal acquisition and number
and geometry of detection points). A single source and detector
configuration is the very basic system, while more complex
setups comprise up to 64 sources and 64 detectors [14]. To track
functional changes in human tissues, by exploiting the information obtained with NIRS-TR, requires systems characterized byportability (aptness to different clinical environments and easeof use by nonqualified personnel), high acquisition frequency(acquisition time less than 1 s to follow rapid changes in humanhemodynamics and oxidative metabolism), and multichannel
configuration (number and geometry of sources and detectors,
to get rid of local heterogeneity, which may hamper the resultsof measurements). Up to now, such systems have not been available either on the market or at the research and laboratory stage.
In fact, on the one hand, more complex systems unavoidably
have long acquisition times (from 30 s up to 30 min) [14], [15]to multiplex the optical signals to the different injection points;
therefore, they are more suitable for the quasi-static monitoringof the physiological state. On the other hand, simpler systems
can have very short acquisition times (less than 100 ms) but,having a single channel or a limited number of channels, they
suffer from the ar tifacts that derive from the natural point-topoint variation in the physiological parameters and have poor
imaging capability. With the goal to overcome these limitations,
Cubeddu et al. have developed an eight-channel TR system forthe noninvasive measurement of tissue oxygenation [16].
In this work, we focus on the development and characterization of a novel compact multichannel NIRS-TR prototype fornoninvasive functional human brain mapping with a high temporal resolution and a fast image reconstruction/data analysis.
II. M ATERIALS AND M ETHODS
A. System Setup
Fig. 1 reports the scheme of the multichannel NIRS-TR
system developed at the Department of Physics, Politecnico0018-9456/$20.00 © 2006 IEEE

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IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT, VOL. 55, NO. 1, FEBRUARY 2006

Fig. 1. Scheme of the nine-source and 12-detector TR tissue oximeter. TCSPC: time-correlated single photon counting; PMT: photomultiplier tube.

di Milano. The system is based on the following: pulsed
diode lasers with 80 MHz repetition rate and 1 mW average
power (Picoquant GmbH, Germany); a couple of 1 × 9 fiber
optic switches (PiezoJena GmbH, Germany); a custom-mademultimode graded index fiber optics combiner; a compact
16-channel photomultiplier (R5900-01, Hamamatsu Photonics,
Japan); and a PC board (SPC630, Becker&Hickl, Germany) for
time-correlated single photon counting (TCSPC). It is operated
with two wavelengths (690 and 760 nm), up to nine injection
points, and 12 independent detectors. The laser sources can beeasily changed and an 818-nm laser head is also available. Using all the nine injection fibers and all the 12 collection fibers,
the system can measure tissue optical properties in 30 different
points over the sample surface. Using, for example, an interfiber
distance of 2 cm is possible to obtain an image covering
an area of 7 × 5.5 cm.
The whole system is driven by a custom-made software
written in ANSI C using the LabWindows/CVI environment(National Instruments, TX). It is optimized to obtain a whole
image of 30 points/s, and thus, each injection fiber emits
light for 100 ms. The system flexibility enables all combinations between the nine injection fibers and the 12 collection
fibers, so it is possible to obtain images with different dimension and at different sampling rates.
A robust and efficient probe was developed to hold injection
and collection fibers so as to achieve good stable optical contact
and sufficient light levels detected from the head. Several
factors affect good optical coupling, in particular, absorption
and instability due to hair and general fiber stability against
the head. In a previous system [16], we used two different
approaches based on fibers embedded in a neoprene rubber
pad and on adhesive black Teflon fiber holders. Both systems
were effectively used in preliminary in vivo tests and showedsufficient efficacy. The main disadvantage is the long timeneeded to fix the probe to the head and to precisely determine
fiber positioning on the head. Many solutions have been implemented by other research groups for holding the optical fibers
with a goal of rigidity, plus flexibility with respect to head
shape. A few examples include fibers inserted through modified
motorcycle helmets, thermoplastic molded to the contours ofeach subject’s head, spring-loaded fibers attached to semirigid

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Fig. 2. Fiber holder. The white pad is a thermoplastic material used to adapt
the fiber holder to the sample’s surface.

plastic forms, and fibers embedded in neoprene rubber forms[2]. The current system employs a thermoplastic pad with acustom grid of fiber positions, as shown in Fig. 2. This fiber
holder can receive up to 25 fibers, more than those effectively
used during the in vivo measurements presented in this work. In
this way, it would be possible in future experiments to change
the fibers’ position for a better covering of the activated area
without removing the holder from the patient head.
B. Measurement Protocols
A protocol for standardization of diffuse optical instrument
performances, developed within the framework of the European
Thematic Network “Medphot” [17], was applied to determine
linearity, uncertainty, and stability of the NIRS-TR setup. Solidtissue phantoms made of titanium dioxide particle (scattering
agent) and toner powder (absorbing agent) embedded in a
epoxy resin matrix [18] were used for system characterization.
A set of 28 phantoms with optical properties typical for biological tissue in the red and near-infrared spectral range wasmeasured: Phantoms labeled from 1 to 7 represent absorption
coefficient (µa ) changes from 0.07 to 0.49 cm−1 in 0.07 cm−1
steps, while phantoms labeled from A to D represent reduced

CONTINI et al.: MULTICHANNEL TIME-RESOLVED TISSUE OXIMETER FOR BRAIN IMAGING

87

scattering coefficient (µ�s ) changes from 5 to 20 cm−1 in
5-cm−1 steps.
Preliminary in vivo measurements were performed on volunteers to monitor the optical response to stimuli, particularly
to motor stimuli. The measurement protocol is composed of
20 s of baseline, 20 s of motor task, and 20 s of recovery.
The protocol was repeated five times with the right (R) handand five times with the left (L) hand. The effective motor task
consists of an exercise of finger opposition at the frequency
rate of 5 Hz. The optical probe was placed over the headin order to cover the underlying motor cortex, and it wascentered [according to the international 10–20 system for theelectroencephalogram (EEG) electrode placement] at the C3
point. The source–detector distance was 2 cm.
Fig. 3. Linearity of the measured absorption coefficient, at 690 nm, versus thetrue values of absorption coefficient. The four labels A, B, C, and D indicate
four different sample series with reduced scattering coefficient between 5 and20 cm−1 in 5-cm−1 steps.

C. Data Analysis
The temporal profile of the TR reflectance curve was analyzed using a solution of the radiative transport equation under
the diffusion approximation for a semiinfinite homogeneous
medium [19]. The extrapolated boundary condition was used
to take into account the refractive index mismatch at the surface. The reflectance R(r, t), i.e., the photon probability to beremitted from the tissue at a time t and a distance r from theinjection point, can be expressed as�r2
R(r, t) = AD t exp(−µa vt) exp −
4Dvt
��
�
�
�
�
zp2
zo2
− zp exp −× zo exp −
4Dvt
4Dvt
− 32 − 52

Improvement over the standard methods is more effective
when the absorption is high. In fact, in this condition, standard
fitting to (1) yields high dispersion in the fitted data [21].
Taking the assumption that oxy- and deoxy-hemoglobin are
the main chromophores contributing to absorption, their concentrations (O2 Hb and HHb, respectively) are easily derived
by using the knowledge of the extinction coefficient [22],following the well-know Lambert–Beer’s law

�

�
(1)

where A is a normalization constant, v = c/n is the speed oflight in the medium, zo = 1/µ�s is the scattering mean free path,and zp derives from the extrapolated boundary conditions anddepends on the refractive index of the tissue. The diffusion
coefficient D = 1/(3µ�s ) was taken to be independent of theabsorption properties of the medium. Simultaneous estimateof µ�s and µa may be achieved by best fitting to (1), with anonlinear least square method, the measured TR reflectancecurves.
To reduce the dispersion of the fitted absorption coefficientvalues, we use the methods described by Nomura et al. [20]and known as the modified Lambert–Beer’s law. First, for eachwavelength λ, a reference TR reflectance curve R0 (ρ, t, λ),at an interfiber distance ρ, is derived by averaging the curves
corresponding to an initial resting period (typically 20 s). Fitting of R0 (ρ, t, λ) yields the reference absorption value µa0 (λ).
Then, ∆µa (λ), the variation from the reference value, is derived
according to (2) and (3), taking the assumption that during theactivation, the scattering coefficient do not changeµa (λ) = µa0 (λ) + ∆µa (λ)
��R(ρ, t; λ)1ln.
∆µa (λ) = −vt
R0 (ρ, t; λ)

(2)
(3)

1
µλa 1 = O2 HbελO12 Hb + HHbελHHb2µλa 2 = O2 HbελO22 Hb + HHbελHHb.

(4)Since water absorption in this spectral region is much lower
than haemoglobins absorption [22], a fixed amount (30%) ofabsorption was attributed to water and subtracted to µa before
calculation of HHb and O2 Hb from (4). Then, total hemoglobin
content (tHb = HHb + O2 Hb) and tissue oxygen saturation(SO2 = O2 Hb/tHb) are derived.
During data analysis of in vivo measurements, a folding average over the five intervals associated with the left or the righthand and a 4-s moving average were applied to improve thesignal to noise ratio. Furthermore, changes in O2 Hb (∆O2 Hb)and HHb (∆HHb) were calculated by making the difference
between the concentration’s value at each time and their averagevalues during the baseline period (0–20 s).
By multiplexing the injection sources and using different
collection fibers, we were able to estimate optical properties andcalculate haemodynamic parameters in distinct spatial locations
to create a spatial map.
III. R ESULTS AND D ISCUSSION
Fig. 3 shows the results for the absorption linearity experiment at 690 nm. Similar results hold for the other wavelength.
The system proved to be linear in the range of 0–0.3 cm−1 .
An underestimation (about 20%) of absorption is found forvalues higher than 0.3 cm−1 , possibly as a result of the intrinsic limitations in the theoretical model used to analyze TR
reflectance data. The estimates of the absorption coefficient is

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Fig. 4. Time course of the measured absorption coefficient, at 690 nm, during
the warm-up stage of the system.

rather independent on the scattering properties of the probe
sample.
System stability was studied over a 3-h period to analyze
warm-up time and long-term drift. As it is clear in Fig. 4,
a 60-min warm-up time is needed before the coefficient ofvariation (CV; i.e., standard deviation over average) of theabsorption coefficient becomes lower than 1.6%.
A further test was performed to evaluate the noise level ofthe system, studying the effect of the number of counts in the
TR reflectance curve on the fitted absorption coefficient. The
CV for the absorption coefficient is found to be lower than 3%
for 60 000 counts, while it raises up to 10% if only 8000 counts
are detected (see Fig. 5). Depending on the applications (i.e.,on the expected signal-to-noise ratio), these results tailor the
optimization of the setup. For example, when the optical contrast is sufficient (e.g., during cuff occlusion on arm muscle),a 100-ms acquisition time can be effectively used. For brain
functional imaging experiments where the changes are dramatically smaller, there is the need to improve data robustness either
by increasing the acquisition time or by an off-line averaging
during data analysis. To show the typical features of brain
activation detected by optical noninvasive methods, we reportin Fig. 6 the time course of changes in ∆O2 Hb and ∆HHb for asingle detection channel. During baseline, both HHb and O2 Hbshow no features, while there is a marked decrease in HHb anda corresponding increase in O2 Hb when the test is performed
with the controlateral hand (R). As expected, minor changes are
noticed during the task if the ipsilateral hand (L) is used. In therecovery, both HHb and O2 Hb slowly return to baseline values.
Brain activation during motor task is limited to a small area inthe motor cortex [2]. Therefore, we present in Fig. 7 the grey
level maps of ∆O2 Hb and ∆HHb (obtained by interpolating
the results from the eight collection points). Images represent the start of the measure, the middle of the motor task, when
the test is performed with the controlateral hand (R), and theend of the recovery period. As expected, during the task, theactivated area is revealed by an increase in O2 Hb (black areain the central image of the upper line) and by a corresponding decrease in HHb (white area in the central image of thelower line).

312

Fig. 5. Uncertainity in absorption coefficient. Plot of the measurement’s CV,
at 690 nm, as a function of the number of photons collected.

Fig. 6. Time course of ∆O2 Hb (open symbols) and ∆HHb (filled symbols)
during the exercise performed with the right hand (triangle) and with the left
hand (square). The vertical lines represent the task interval. Each curve is anaverage of the five measures performed with the same hand. A mobile averageof 4 s was applied.

The spatial resolution of NIRS images is mainly determinedby the scattering, which imposes severe limitation to photon
propagation in diffusive media. A typical value for spatial
resolution is 1 cm. Improvements can be partially obtainedby a proper arrangement of source and detector fibers or by atomographic approach [2].
IV. C ONCLUSION
The potential advantage of NIRS-TR systems is the possibility to get a deeper insight into functional human brain mapping.
Key advantages of NIRS-TR are the discrimination between
absorption and scattering coefficient (not possible with NIRSCW and difficult with NIRS-FD), the increased penetration
depth and spatial resolution with respect to the other opticaltechniques, and the possibility to quantitatively evaluate thecontribution of cerebral tissue by naturally exploiting the information encoded in time. The development of improved NIRSTR systems and their application in functional imaging studies
will serve not only to definitely set its potentiality but also as afeedback to the development of improved NIRS-CW and NIRSFD setups for next-generation optical imaging devices.

CONTINI et al.: MULTICHANNEL TIME-RESOLVED TISSUE OXIMETER FOR BRAIN IMAGING

89

Fig. 7. Grey level maps representing changes in O2 Hb (top row) and HHb (bottom row) over the cortex region during the baseline period (left column), themotor task performed with the right hand (middle column), and the recovery period (right column).

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[12] R. Cubeddu, A. Pifferi, P. Taroni, A. Torricelli, and G. Valentini,“A compact tissue oximeter based on dual-wavelength multichannel
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[13] D. Grosenick, H. Wabnitz, H. H. Rinneberg, K. T. Moesta, andP. S. Schlag, “Development of a time-domain optical mammograph andfirst in vivo applications,” Appl. Opt., vol. 38, no. 13, pp. 2927–2943,
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[15] J. C. Hebden, A. Gibson, R. M. Yusof, N. Everdell, E. M. Hillman, D. T.
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Phys., vol. 23, no. 9, pp. 1625–1634, Sep. 1996.
[22] S. Prahl. (2001). Oregon Medical Laser Center website. [Online].
Available: http://omlc.ogi.edu/spectraDavide Contini was born in Angera, Italy, in 1978.
He received the Master’s degree in electronics engineering from the Politecnico di Milano, Milan, Italy,
in 2003.
In 2004, he joined the Biomedical Optics Groupat the Department of Physics, Politecnico di Milano,
as a Ph.D. student in physics. His research interests
include mainly the development of laser systems fortime-resolved optical imaging for functional studiesof the brain.

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Alessandro Torricelli was born in Modena, Italy, in1968. He received the Master’s degree in electronics
engineering in 1994 from the Politecnico di Milano,
Milan, Italy, and the Ph.D. degree in physics from the
Politecnico di Torino, Turin, Italy, in 1999.
In 1995, he joined for one year the “Mario Negri”
Institute for Pharmacological Research in Milan,
where he worked on flow cytometry and cell kinetics.
Since 1993, he has been working at the Departmentof Physics, Politecnico di Milano, focusing his research interests on time-resolved diffuse spectroscopy and optical imaging. Since 2005, he has been an Associate Professor
in physics.
Antonio Pifferi was born in Milan, Italy, in 1965. Hereceived the Master’s degree in nuclear engineeringin 1991 and the Ph.D. degree in physics in 1995 fromthe Politecnico di Milano.
Since 1996, he has been working at the Department of Physics, Politecnico di Milano, first as
Researcher, and then as an Associate Professor in
2003. His main research activities are devoted tothe development and application of new laser-based
techniques and instrumentation for biomedical diagnosis. In particular, he has focused on the study ofphoton migration through highly scattering media with applications to opticaltissue characterization, optical mammography, and tissue oximetry.
Lorenzo Spinelli received the M.S. and Ph.D degrees in physics from the University of Milan, Milan,
Italy, in 1994 and 1999, respectively.
Since 1999, he has been a Postdoc with the
Department of Physics at the University of Milan.
He devoted his research activity to the study ofstructures developing in the section of broad area
radiation beams. In particular, he focussed his attention to cavity solitons, which are stationary selforganized bright intensity peaks over a homogeneousbackground. In 2001, he became a Researcher for the
Italian Research National Council at the Politecnico di Milano. His researchinterests moved to the study of photon migration in turbid media for opticalbiopsy and imaging.

Paola Taroni received the Master’s degree in nuclear
engineering from the Politecnico di Milano, Milan,
Italy, in 1987.
From 1988 to 1999, she was with the National
Council for Research, Italy, as a Staff Researcher.
Since 1999, she has been an Associate Professor ofphysics at the Politecnico di Milano. Her research
activity concerns mainly the development of laser
systems for time-resolved spectroscopy and imaging, and their applications in biology and medicine (including the photophysical characterizationof pigments and photosensitizers, time-resolved fluorescence imaging forcancer detection, time-resolved reflectance/transmittance spectroscopy for thenoninvasive optical characterization of biological tissues, and time-resolved
optical mammography).

314

Valentina Quaresima received the Master’s degreein pharmacy from the University “La Sapienza” ofRome, Rome, Italy, in 1988, and the Ph.D. degreein the formation and treatment of biomedical images
from the University of L’Aquila Medical School,
L’Aquila, Italy, in 1994.
From 1994 to 1999, she was a Postdoc Fellow at
the University of L’Aquila. From November 1999
to December 2003, she was a Researcher of biochemistry at the Medical Faculty of the Universityof L’Aquila. Since January 2004, she has been an
Associate Professor of biochemistry at the Medical Faculty of the University of
L’Aquila. Her research interests include the study of localized measurementsof muscular and cerebral oxygenation in humans by different near-infrared
spectroscopy techniques.

Marco Ferrari received the Master’s degree inmedicine from the University “La Sapienza” ofRome, Rome, Italy, in 1977.
From 1982 to 1986, he was a Researcher at the“Istituto Superiore di Sanità” of Rome. From 1986
to 1987, he was a Visiting Assistant Professor at
the Johns Hopkins Medical School, Baltimore, MD.
From 1988 to 2000, he was an Associate Professor of Biochemistry at the Medical Faculty of the
University of L’Aquila, L’Aquila, Italy. Since 2001,
he has been a Full Professor of Biochemistry at the
Medical Faculty of the University of L’Aquila. His research interests include thedevelopment and the evaluation of near-infrared spectroscopy instrumentation
for medical applications.

Rinaldo Cubeddu was born in Alessandria, Italy,
on July 12, 1944. He received the Ph.D. degree inphysics from the University of Pavia, Pavia, Italy,
in 1967.
He joined the Politecnico di Milano, Milan, Italy,
also in 1967, where he became an Assistant Professor in Optics in 1983 and a Full Professor inphysics in 1986. He is the Head of the Laboratoryof Biomedical Optics at the Physics Department.
His research activity is in the field of lasers andtheir applications to biology and medicine. He hasdeveloped instrumentation for time-resolved fluorescence spectroscopy andimaging for application to photodynamic therapy and diagnosis. More recently,
he has been involved in the field of photon migration for applications in mammography, oxymetry, and functional imaging. Beside the field of biomedicine,the instrumentation developed has been applied for diagnostic purposes inagriculture for the evaluation of internal fruit quality and in cultural heritage
for the fluorescence analysis of fresco paintings and marble statues.

ARTICLE IN PRESS

Journal of Electromyography and Kinesiology xxx (2007) xxx–xxx
www.elsevier.com/locate/jelekin

Biceps brachii myoelectric and oxygenation changes during
static and sinusoidal isometric exercises
Francesco Felici a,b,*, Valentina Quaresima c, Luigi Fattorini d, Paola Sbriccoli a,b,
Gian Carlo Filligoi e,f, Marco Ferrari caDepartment of Human Movement and Sport Sciences, Istituto Universitario di Scienze Motorie, Piazza Lauro De Bosis 6, 00194 Roma, Italyb
Istituto Interuniversitario di Miologia (IIM), Chieti, Italyc
Department of Sciences and Biomedical Technologies, Università di L’Aquila, L’Aquila, Italyd
Department of Human Physiology and Pharmacology, Faculty of Medicine, Università di Roma ‘‘La Sapienza’’, Roma, Italye
Department of Information and Communication Sciences (INFOCOM), Faculty of Engineering, Università degli Studi ‘‘La Sapienza’’, Roma, Italyf
Biomedical Systems Research Center (CISB), Università degli Studi ‘‘La Sapienza’’, Roma, Italy
Received 19 March 2007; received in revised form 17 July 2007; accepted 17 July 2007

Abstract
Surface myoelectric signal changes occurring during sustained isometric contractions have been extensively studied with quantitative surface electromyography (sEMG) and are described by means of some sEMG global variables in time and frequency domain (such as the median power spectral frequency). Recently, the possibility of studying local muscle O2 saturation during exercise using non-invasive methods
has been enhanced thanks to the use of near-infrared spectroscopy (NIRS). The purpose of this work was to combine NIRS and sEMG
techniques to analyze the relationship between modiﬁcations of sEMG parameters and the underlying metabolic status of the exercising
biceps brachii muscle. This relationship was tested under diﬀerent isometric contraction modalities, namely static (ST) at 20, 40, 60 and
80%MVC and sinusoidal (SIN) at 40 ± 20 and 60 ± 20%MVC. Results clearly indicated the presence of an initial fast phase of muscle
O2 desaturation followed by a slow phase, regardless of the contraction modality. Moreover, the initial rate of muscle O2 desaturation
was related to the level of force output (R = 0.92), but it was independent on the contraction modality (p < 0.05). Similarly, changes in sEMG
parameters were related to force level (Conduction Velocity-CV vs. Force: R = 0.87; sEMG Median Frequency-MDF vs. Force: R = 0.86).
The high correlation found between CV-MDF and Tissue Oxygenation Index (TOI) slope (R = 0.73 and 0.72, respectively) suggests a strong
relationship between NIRS and sEMG data. This study indicates that muscle O2 demand during isometric contractions from low to highforce levels is inﬂuenced by the type of active motor units and not from the type of isometric exercise modality.
� 2007 Elsevier Ltd. All rights reserved.
Keywords: Surface electromyography; Near-infrared spectroscopy; Isometric exercise; Oxidative metabolism; Muscle O2 saturation; Myoelectric fatigue

1. Introduction
Abbreviations: sEMG, surface electromyography; RMS, root meansquare value; MDF, median frequency of sEMG power density spectrum;
MU, motor units; CV, muscle ﬁber action potential conduction velocity;
O2Hb, oxyhemoglobin; HHb, deoxyhemoglobin; tHb, total Hb volume;
NIRS, near-infrared spectroscopy; TOI, tissue oxygenation index; SmO2,
muscle oxygen saturation; BB, biceps brachii; MVC, maximal voluntary
contraction; ST, static isometric exercise; SIN, sinusoidal isometric exercise.
*
Corresponding author. Address: Department of Human Movement
and Sport Sciences, Istituto Universitario di Scienze Motorie, Piazza
Lauro De Bosis 6, 00194 Roma, Italy. Tel.: +39 06 36733540; fax: +39 06
36733214.
E-mail address: francesco.felici@iusm.it (F. Felici).

The analysis of surface electromyogram (sEMG) has
been extensively used to describe the early changes occurring during sustained isometric contractions (for a review
see De Luca, 1997). Such changes can be evaluated bymeans of sEMG global variables in time and frequency
domains. The root mean square value (RMS) of sEMG
and the average muscle ﬁber conduction velocity (CV)are the most frequently used in the time domain, and the
median frequency of the power density spectrum (MDF)

1050-6411/$ - see front matter � 2007 Elsevier Ltd. All rights reserved.
doi:10.1016/j.jelekin.2007.07.010

Please cite this article in press as: Felici F. et al., Biceps brachii myoelectric and oxygenation changes during ..., J Electromyogr Kinesiol (2007), doi:10.1016/j.jelekin.2007.07.010
315

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F. Felici et al. / Journal of Electromyography and Kinesiology xxx (2007) xxx–xxx

in the frequency domain. Amplitude changes of sEMG aremainly aﬀected by the number of active motor units (MU)
and their mean ﬁring rate, whereas MDF decay overtimeand concomitant reduction of the CV (Farina et al.,
2002b) observed during a sustained isometric contraction
have been interpreted as the result of local changes in muscle ﬁbers membrane properties (Farina et al., 2002a; Merletti et al., 1990). The sEMG power spectrum
compression over time is aﬀected by force level (Basmajan
and De Luca, 1985), showing a higher rate of decrease asforce increases, and this is thought to be due to the higher
blood occlusion at higher contraction levels.
Moreover, MDF and CV may be jointly used to provide
an indirect estimate of muscle ﬁber type composition(Sadoyama et al., 1988; Westbury and Shaughnessy,1987) and MU recruitment (Farina et al., 2002b; Sbriccoli
et al., 2003). To this respect, among the various possible
indicators of Henneman’s size principle, CV has been
recently validated also under dynamic cyclic exercise (Farina et al., 2007).
The ability to study local muscle oxidative metabolism
during exercise using non-invasive techniques has beenenhanced thanks to the use of near-infrared spectroscopy(NIRS) (Bhambhani, 2004; Boushel et al., 2001; Neary,
2004; Quaresima et al., 2003). Diﬀerent NIRS methods
have been proposed (Delpy and Cope, 1997) to assess muscle O2 saturation (SmO2), the most widely used being thenear-infrared spatially resolved spectroscopy (Delpy and
Cope, 1997). This technique provides both an average tissue O2 saturation (from small vessels, such as the capillary,arteriolar and venular bed), and the changes in oxyhemoglobin (O2Hb), deoxyhemoglobin (HHb) concentration,
as well as the changes in derived hemoglobin volume(tHb = O2Hb + HHb). SmO2 reﬂects the dynamic balance
between O2 supply and O2 consumption in the investigatedtissue volume.
A number of previous studies have combined sEMG
data with muscle oxygenation data (by NIRS) during exercise (Burnley et al., 2002; Kouzaki et al., 2003; Miura et al.,
2000; Praagman et al., 2003; Takaishi et al., 2002; Yoshitake et al., 2001). For example, Miura et al. (2000) andYoshitake et al. (2001) reported a correlation between
dynamic exercise intensity, increased neuromuscular activation and aerobic metabolism. Additionally, Praagman
et al. (2003) found a linear relationship between level of isometric eﬀort, sEMG amplitude and muscle O2 uptake.
While previous studies have indicated the feasibility andimportance of coupled sEMG-NIRS measurements, further investigations are needed using more advanced techniques and methodologies. In fact, the heterogeneity inthe tested muscles and exercise protocols, the somehow
limited sEMG analysis technique adopted, the methodological limitations of the utilized NIRS devices (ﬁrst generation) must be taken into account.
In addition, these previous study have not explored therelationship between muscle oxygen demand and quality of
the active MUs. According to the size principle for ordered

recruitment (Henneman et al., 1965), it can be hypothesized that during isometric static contractions any relationship between CV and O2 desaturation (DTOI) will bestrongly inﬂuenced by MU recruitment. At the same time,
this association could be modulated by adopting a non-stationary (i.e. oscillating) isometric contraction strategy.
Thus, the present study was designed to: (1) investigate the relationship between biceps brachii (BB) MU
recruitment and BB O2 desaturation time course duringsub-maximal isometric contractions; (2) additionally,
examine the inﬂuence of the modality (static vs. sinusoidal) of isometric contractions on MUs behavior (namely
MU recruitment). To these purposes, sEMG and NIRS
measurements were taken during 30-s isometric static
contractions performed at various percentages of the
maximal voluntary contraction (MVC) and during isometric sinusoidal contractions. We hypothesized that different isometric constant force levels, as well as diﬀerent
isometric contraction modalities, would have a diﬀerent
impact on local blood ﬂow, and MUs activity measured
from the NIRS and sEMG.
2. Methods
2.1. Subjects
Seven healthy subjects (3 Males, 4 Females, age: 34 ± 6 years,
body mass: 74 ± 6 kg, height: 173 ± 6 cm) participated in thisstudy. None had any previous history of neuromuscular disorderand each gave written informed consent prior to the experiment.
The study was approved by the University Ethics Committee andconformed to the regulations laid out in the Declaration of Helsinki on the use of human subjects in research.
All subjects attended the laboratory on two occasions. During
the ﬁrst visit subjects were familiarized with the experimental
procedures. In the second visit subjects were asked to perform two
diﬀerent tasks as described below.
Subjects seated comfortably in a custom-modiﬁed chair withthe dominant (right) forearm placed in a plastic shell. For eachsubject, the height of the shell was adjusted to obtain an elbow
angle equal to 90� (Sbriccoli et al., 2003). Subjects’ shoulder was
secured through a strap to the modiﬁed chair back. The hand
was maintained halfway between pronation and supination.
Forearm shell was connected to a piezoelectric force transducer(Kistler Instrument AG, type 9311A, Winterthur, Switzerland)connected to a charge ampliﬁer (Kistler Instrument AG, type5001).
Before probe placement, skinfold and subcutaneous thickness
was measured in correspondence of the central part of BB muscle
belly using a Harpenden caliper (Gima, Milano, Italy). An
experienced operator repeated the measure three times. Average
skinfold thickness was 4.2 ± 1.6 mm (means ± SD).
2.2. MVC assessment
The MVC task consisted of rapidly increasing the force exerted
and to follow the performance on the computer screen while being
encouraged to achieve a maximum, and to maintain it for at least
5 s before relaxing.

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Subjects performed three MVC attempts spaced by a 10-min
recovery time. During the second and the third attempt, a visualfeedback of the previous (or best) performance attained wasprovided to the subject who tried to improve his performance.
The MVC value was set as the maximum value obtained from thethree MVC trials.

2.3. Static isometric exercise (ST)ST exercises were performed at 20, 40, 60 and 80%MVC(indicated as ST20, ST40, ST60, ST80, respectively). A line representing the appropriate target level of force output was displayed on a computer screen along with the actual output of theforce transducer, providing the subject with continuous feedback.
Exercises lasted 30 s each with a 30-min interval between exercises, which was a convenient time to allow a complete recovery.
The diﬀerent force outputs were administered to subjects in random order to minimize the cumulative eﬀects of fatigue. One
attempt was performed at any force level.

2.4. Sinusoidal isometric exercise (SIN)
SIN exercise consisted of performing one 30-s contraction
matching a sinusoidal trace displayed on a computer screen. The
sinusoid frequency was set at 0.5 Hz. The sinusoidal target was set
at two ranges of force: from 20 to 60%MVC (mid value
40%MVC, indicated as SIN40), and from 40 to 80%MVC (midvalue 60%MVC, indicated as SIN60). SIN exercises were spaced
by a 30-min recovery. The entire experimental session lasted
approximately 150 min.
2.5. EMG measurements
The BB main motor point was identiﬁed by means of electricalstimulation (Farina et al., 2000). After abrasion and cleaning with
ethyl alcohol, NIRS optical probe (source-detector distance:
4.5 cm) supported by a rigid rubber shell, and a four linear arraysEMG electrode (silver bars, 5 mm long, 1 mm thick; 10 mmapart) were placed and ﬁxed with an adhesive tape symmetricallyon both sides of muscle belly midline. During this manoeuvre
particular care was taken to prevent excessive external pressure on
the muscle belly. The sEMG reference electrode was placed over
the olecranon.
The sEMG signals were ampliﬁed using a portable ampliﬁer(SATEM, Rome, Italy; mod. VD 10/4, pass band 10–1000 Hz).
Three single diﬀerential sEMG signals (SD1, SD2, SD3) wererecorded. From the three SD signals, two double diﬀerential signals (DD1, DD2) were then computed and used for CV calculation as described in the following paragraphs.

2.6. NIRS measurements
NIRS measurements were carried out using a tissue oximeter(NIRO-300, Hamamatsu Photonics, Japan) based on the nearinfrared spatially resolved spectroscopy (collection time 6 samples/s). The design and the features of this device have been
described previously (Suzuki et al., 1999). The theory behind thisapproach and the reliability to measure tissue O2 saturation has
been reported (Suzuki et al., 1999). The NIRO-300 provides atissue oxygenation index (TOI, expressed in %) which has beentested either in vitro or in vivo (Boushel et al., 2001; Suzuki et al.,1999). The TOI value reﬂects predominantly the mean of arteriolar, capillary, and venular O2 saturations with a minor (less than20%) contribution from myoglobin (Quaresima et al., 2001; Ferrari et al., 2004). In addition, the NIRO-300 provides concentration changes in O2Hb and HHb (expressed in DlM cm), andthe derived changes in tHb. The tHb changes (DtHb), being
strictly related to blood volume changes, can be considered anindirect measure of local blood ﬂow changes. Thus, consideringthat the measured adipose tissue thickness was relatively low andthe penetration depth of the NIRS signal is almost half of thesource-detection separation (Ferrari et al., 2004), the changes in
TOI (DTOI) and tHb reﬂected mainly BB metabolic and hemodynamic changes.
After the probe test on a phantom to analyse the total probesensitivity and the sensitivity diﬀerence between the three sensors of the detection probe, the optical probe supported by arigid rubber shell, was ﬁrmly attached to the skin overlying themuscle parallel to the major axis of the arm, by a double-side
adhesive sheet. Also the sEMG electrodes was ﬁxed over themuscle medially to the rigid rubber shell. The optical probe andthe sEMG electrode array were further secured by a soft elastic
band (Tensoplast, Smith + Nephew, England). Pen marks weremade on the skin to check for any sliding of the rubber shell
during the exercise. No downward sliding of the optical probe
was observed at the end of the measurements in any subject.
After ﬁxing the probe holders on the subject, an initialization
procedure was carried out. The latter sets each laser power
automatically establishing the optimum measurement condition.
The zero set procedure (carried out just before the beginning ofeach baseline condition) was adopted to return the O2Hb, HHb
and tHb parameters to the zero value. This procedure does not
aﬀect the TOI value because TOI is measured as absolute value
instead of a change with respect to the arbitrary initial zero
value.
After ampliﬁcation, all signals from force transducer, electromyograph and tissue oximeter were sent to a personal computer
via an A/D converter (DAQ Card 16X-E10, 12 bit resolution,
National Instruments, Austin, Tx, USA.). These signals were
sampled at 2048 samples/s and the acquisition lasted 60 s: 10 s ofrest, 30 s of exercise, 20 s of rest after exercise.
2.7. EMG data analysis
The analysis of sEMG during all isometric contractions was
performed in time and frequency domain. The RMS and MDF
were computed over the central single diﬀerential channel signal(Sbriccoli et al., 2003) on epochs of one second. Since NIRS data
were collected every 1/6 of second, sEMG data epochs were
properly overlapped (i.e., 341 samples @2048/6) in order to have
6 RMS and 6 MDF values per second.
Average muscle ﬁber action potential CV was assessed bymeans of cross-correlation function (Sbriccoli et al., 2003)
between the two double diﬀerential channels using the same
sEMG segmentation as for RMS/MDF data and NIRS data.
Estimates of CV were accepted only when the EMG cross-correlation function values were higher than 0.8 throughout thewhole duration of the test. All subjects were included in CV
computations. Only two CV computations (one for ST60 test and
one for SIN40 test) were not included due to a poor cross-correlation value. For each contraction performed, RMS, MDF andPlease cite this article in press as: Felici F. et al., Biceps brachii myoelectric and oxygenation changes during ..., J Electromyogr Kinesiol (2007), doi:10.1016/j.jelekin.2007.07.010
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CV data were normalized with respect to the corresponding
maximum value obtained during the respective MVC test.

performed using SPSS� software (v.11, 2001, SPSS Lead Technologies Inc., Chicago, IL, USA). Data are presented asmeans ± standard errors (SE).

2.8. NIRS data analysis

3. Results
Fig. 1 shows a typical time-course of BB DTOI at ST80 consisting of an initial rapid decrease (fast phase) followed by a phasewith a slower decay rate. The beginning and the end of the fastphase were automatically identiﬁed by a procedure that ﬁrstly
smoothed the DTOI time-course by a 7-degree polynomial interpolation, and then the procedure looked for a negative longplateau in the ﬁrst derivative of the relative smoothed time-course.
This plateau was preceded and followed by an easily detectabledecreasing and increasing phase, respectively. The fast DTOI
decreasing phase was quantiﬁed by the slope of least square
regression line.
In order to take into account the subsequent slow decreasingphase of DTOI, DTOI values corresponding to the end of exercise(indicated by STOP line in Fig. 1) were deﬁned as DTOImin.
The same time intervals deﬁned for the DTOI fast phases wereused also to compute the slopes of linear regression analysis on
CV and MDF data. On the contrary, considering the evident nonlinearity of tHb and RMS in the same time interval, these data
were not considered for regression analysis.

2.9. Statistical analyses
A two–way analysis of variance (factors: force level and contraction modality) was used to test the dependency of MDF, CV,
DTOI slopes during fast and slow phases from the force level(ST20, ST40, ST60, ST80, SIN40, SIN60) and the contraction
modality (ST and SIN). As a main eﬀect of either factor was
found, a two-tailed paired Student’s t-test with Bonferroni correction was implemented. Statistical signiﬁcance was set at
p < 0.05 for all tests performed. Statistical computations were

STOP

START

0

ΔTOI [%]

r2 = 0.99-20

4. NIRS data
Force, DTOI and DtHb data are depicted in the upper,
middle and lower panel of Fig. 2, respectively.
4.1. ST isometric exercise
All subjects were capable of tracking the force precisely
at any ST force level but ST80, where a progressive decline
in the target force was observed after the ﬁrst 10-s from the
beginning of the contraction (upper left panel).
At rest, absolute BB DTOI value (middle left panel) was
69.5 ± 6.3% (grand average over 7 subjects, 6 tests each;N = 42). DTOI started to decrease after a consistent delay
from the beginning of the contraction, ranging from 5.3 s(on average) at ST20 to 2–4 s for all the other force levels.
In any condition DTOImin was reached at the end of theexercise (see Table 1) because, at all ST force levels, DTOI
continued to slowly decline up to the end of exercise.
ST80 exercise turned out to be the most fatiguing, as
demonstrated by the early drop in force output, although
DTOImin values at ST60 and ST80 were not statistically different each other. DTOImin at ST20 was diﬀerent from all
the other DTOImin values (p < 0.025 after Bonferroni correction), and the greatest drop in DTOImin was obtained
between ST20 and ST40.
The relationship DTOI slopes vs. isometric force for ST
exercises had the form:
slope ½DTOI� ¼ 0:52 � 0:082x-40
r2 = 0.97-60

In Figs. 2 and 3, the time course of NIRS and sEMG
data at the diﬀerent force levels during the ST and SIN
exercises is shown (left and right panels, respectively).
Fig. 4 shows DTOI, MDF and CV slopes computed during
the fast phase in both ST and SIN exercises at any force
level, while in Fig. 5 the relationship between sEMG andDTOI data is shown for both ST and SIN exercises. For
the sake of clarity, in Figs. 2 and 3 a point every 10 isreported, and standard errors are omitted.

10

20

30

40

50

Time [s]Fig. 1. Least square method used to determine the linear portion of theﬁrst fast phase of DTOI decrease during biceps brachii exercise. The plot
refers to an isometric steady state exercise performed at 80% of the
maximal voluntary contraction. Dashed vertical lines denote the beginningand the end of steady state phase of the exercise. The ﬁrst and last sampleof the linear interpolation deﬁned the interval over which all the otherrelevant linear regressions were computed. See text for further details.

ð1Þwith x is force expressed in %MVC and R = 0.92.
At the beginning of the ST exercise, DtHb immediately
decreased with force output increase (lower left panel).
However, after the ﬁrst abrupt drop, DtHb started torecover toward corresponding pre-exercise values at
ST20. The same behavior was found, but less markedly,
during ST40. At ST60 and ST80, DtHb levelled oﬀ during
the ﬁrst 5–6 s of exercise steady state and then slowly recovered. An evident hyperaemic phase at the end of all thecontractions was present, its amplitude depending upon
the level of force.

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100

Force [%MVC]

80

60
40

60
40
20

0

0

10

10

0

0

-10

-10
Δ TOI [%]

20

-20
-30

-30
-40

-50

-50

400

400

200

200

0

-200

SIN 40
SIN 60-20-40

ΔtHb [μM cm]

ΔtHb [μM cm]

ΔTOI [%]

Force [%MVC]

80

SIN 40
SIN 60

100

ST 20
ST 40
ST 60
ST 80

0
-200
SIN 40
SIN 60

-400
-400
0

10

20

30 40
Time [s]

50

60

0

10

20

30 40
Time [s]5060Fig. 2. Force and NIRS data during ST and SIN exercises. Left Side: ST data (ST20, ST40, ST60, ST80); Right Side: SIN data (SIN40, SIN60). Upper
panel: force; Middle panel: DTOI; Lower panel: DtHb. The mean curves obtained in all trials by the 7 subjects are reported. Data are expressed as apercentage of the maximum value obtained during the MVC test. For the sake of clarity, standard errors are not reported.

4.2. SIN isometric exercise
As reported in the upper right panel of Fig. 2, on average subjects were capable of correctly tracking the force
task, although in this condition the subjects’ variability
associated with the force matching task was much moreevident.
Muscle O2 desaturation during SIN exercises increased
with force output although DTOImin values between
SIN40 and SIN60 contractions were not diﬀerent eachother (middle right panel).
DtHb oscillated in opposition of phase with force output. In particular, DtHb ﬂuctuations minima were associated with the maximum force of each cycle until the endof the exercise with a time lag of ±0.17 s. During SIN40
exercises, DtHb crossed the rest value in correspondenceof the 7th force oscillation cycle and then stabilized above

the rest value. The overall DtHb increase was reduced during SIN60 exercises suggesting a more consistent blood
ﬂow restriction in the BB muscle. At the end of the SIN
exercises, DtHb promptly increased.
The comparison between DTOI in ST and SIN exercises
showed a statistical diﬀerences for ST20 vs. SIN40 and
ST40 vs. SIN60 (p < 0.05).
DTOI slopes obtained during SIN contractions were different from each other (p < 0.05). However, there was nodiﬀerence in the DTOI between the ST and SIN contractions. The analysis of variance failed to show any statisticaldependence of DTOI slopes on contraction modality.
5. sEMG data
RMS, MDF and CV data are depicted in the upper,
middle and lower panel of Fig. 3, respectively.

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ST 20
ST 40
ST 60
ST 80

100

80

RMS [%max]

RMS [%max]

80
60
40

60
40

0

0

100

100

80

80

MDF [% max]

20

MDF [% max]

20

60

0

100

100

90

90

CV [% max]0

CV [% max]

40

80
70

SIN 40
SIN 6060

40

SIN 40
SIN 60

80
70
60

60
0

SIN 40
SIN 60

100

0

10

20

30

40

50

0

60

0

10

20

30

40

50

60

Time [s]Time [s]Fig. 3. sEMG data during ST and SIN exercises. Left side: ST data (ST20, ST40, ST60, ST80); Right side: SIN data (SIN40, SIN60). Upper panel: RMS;
middle panel: MDF; lower panel: CV. The mean curves obtained in all trials by the seven subjects are reported. Data are expressed as a percentage of the
maximum value obtained during the MVC test. For the sake of clarity, standard errors are not reported.

5.1. ST isometric exercises
The RMS for ST contraction showed dependence fromthe force level, being higher as a function of force increases(upper left panel of Fig. 3). In accordance with force data
(see Fig. 2, upper left panel), approximately at 2/3 of ST80
contraction RMS started decreasing.
The MDF values at the start of ST contraction were in
the range of 75–80% of maximum. MDF fast slopes showeddependence on the force level (p < 0.05) but not on the
motor task. The greatest diﬀerence in MDF fast phase slope
was obtained between ST60 and ST80 (p < 0.05; Fig. 4b).
The relationship MDF slopes vs. isometric force had theform:slope ½MDF� ¼ 0:22 � 0:027x
where x is force expressed in %MVC and R = 0.86.

ð2Þ

CV slopes during the fast phase were dependent on force
level (Fig. 4c, p < 0.05), being CV values computed at ST20
lower than those obtained at the other ST force levels.
The relationship CV slopes vs. isometric force for ST
experiment has the form:
slope ½CV� ¼ 0:064 � 0:0086x

ð3Þ

with x is force expressed in %MVC and R = 0.87.
5.2. SIN isometric exercises
During SIN contractions, RMS ﬂuctuated with force; at
SIN60 an increase over time in RMS was observed attributable to ongoing myoelectric fatigue.
As observed for the ST contractions, the MDF fastphase for SIN contractions were statistically dependent

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0

-3.0

a
-2.5

-2
-3
-4

MDF slope [% s-1]

ΔTOI slope [%s-1]

-1

-5
-6
-7
-8

-1.5

-1.0

-0.5

0

MDF slope [% s-1]

-2.0

b

0.0

-1
-1.0

-2
-0.8

c

-0.2

CV slope [% s-1]

CV slope [% s-1]

-3

-0.6

-0.4

-0.4
-0.2

-0.6
0.0

-0.8

-1.0
0

20

40

60

80

100

Force [%MVC]
Fig. 4. DTOI, MDF and CV slopes for ST and SIN contractions at
diﬀerent force levels. The abscissa of SIN contractions was chosen inaccordance to their respective force central value (i.e. 40 and 60% MVC).
Statistically signiﬁcant diﬀerences are omitted for the sake of clarity. See
text for further details. Closed circles: ST exercises; open squares: SIN
exercises. Means ± SE; N = 7.

on the force level but not on the motor task (p < 0.05;
Fig. 4b).
The statistical analysis showed a signiﬁcant diﬀerence
between SIN40 and SIN60 MDF slopes (p < 0.05).
No statistically signiﬁcant diﬀerences were present
between SIN40 and ST20 MDF slopes; the slope of
SIN40 was signiﬁcantly lower than that obtained at ST40
and ST60 (p < 0.05). The MDF slope at SIN60 was lower
than that at ST80 (p < 0.05).

0

-2

-4

ΔTOIslope [%s-1]-6-8Fig. 5. Relationship between MDF/CV slopes and DTOI slope during ST
and SIN contractions. From left to right: ST20 (d), ST40 (.), SIN40 (,),
ST60 (j), SIN60 (h), ST80 (r). Statistically signiﬁcant diﬀerences areomitted for the sake of clarity. See text for further details. Means ± SE;
N = 7.

6. NIRS and EMG data: comparisons
As mentioned above, DTOI, MDF and CV slopes
obtained during the fast phase in both experimental conditions are reported in Fig. 4. All these three parameters weresigniﬁcantly correlated with force level for ST and SIN
experiments (p < 0.05).
In Fig. 5, the relationship between MDF and CV slopes
versus DTOI slopes is shown for the fast phase for ST and
SIN experiments (ﬁlled and empty symbols). Each symbolrefers to a given force level for the ST and SIN experiments. The fast phase slopes of MDF and CV computed

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Table 1DTOImin (%) values reached by the diﬀerent subjects at the end of theisometric static (ST) and sinusoidal isometric (SIN) exercises
ST20

ST40

ST60

ST80

SIN40

SIN60

S1
S2
S3
S4
S5
S6
S7

�33.8
�22.7
�14.9
�29.9
�14.2
�10.7
�16.7

�49.3
�35.9
�27.1
�51.8
�39.5
�41.7
�41.6

�60.3
�39.6
�49.7
�62.5
�63.1
�41.0
�46.7

�67.1
�49.2
�62.2
�71.2
�73.2
�45.6
�53.0

�62.3
�31.4
�27.5
�56.6
�38.9
�41.5
�41.5

�62.1
�43.5
�51.8
�61.5
�62.5
�44.8
�57.2

Mean
SE

�20.4*
3.3

�40.9
3.1

�51.8
3.8

�60.2
4.2

�42.8
4.8

�54.8
3.1

See text for further details. *Denotes a statistically signiﬁcant diﬀerence(p < 0.05) of the DTOImin 20% from the other DTOImin values.

on ST contractions show a high degree of correlation withDTOI slopes, being:
CV ¼ �0:07 þ 0:081x

ð4Þ

MDF ¼ �0:22 þ 0:26x

ð5Þ

where x is DTOI slope and R = 0.73; and:

where x is DTOI slope and R = 0.72.
From this ﬁgure, it is evident that, in terms of DTOI fastphase slopes, SIN data ﬁt well with ST data. Namely,
SIN40 values fall between those at ST40 and ST60 whiledata from SIN60 are between ST60 and ST80. Considering
the MDF and CV slopes, SIN40 is between ST20 and
ST40, while SIN60 data fall between ST60 and ST80.
7. Discussion
The main ﬁnding of this study was the demonstration ofa relationship between sEMG changes and O2 desaturation(DTOI) of the BB muscle during static and cyclic isometric
exercises. The results of the present study can be summarized as follows:� two diﬀerent phases of DTOI decline, namely a fast anda slow phase, were found during isometric contractions
independently of the exercise intensity and modality;� the rate of the fast phase of BB desaturation as well as
DTOImin values reached at the end of slow phase wereinﬂuenced only by the level of force, and not by the exercise modality;� CV and DTOI data, from either ST and SIN exercises,
clearly indicates that MU recruitment strongly inﬂuences oxygen desaturation in the active muscle;
� tHb data during ST and SIN exercises, suggest that muscle blood ﬂow is not completely restricted even at thehighest force levels (80%MVC).
As reported in Table 1, the maximal O2 desaturation
was obtained at ST80; it is to note that the larger change
was observed between ST20 and ST40. In fact, the drop
in de-oxygenation between these two force levels is twice

as much the diﬀerences obtained between the other force
levels. This result is compatible with the Henneman’s size
principle (Henneman et al., 1965) that dictates the orderly
recruitment of individual MUs. Namely, MUs arerecruited in an orderly fashion, from type I, oxidative, totype IIb, mostly anaerobic, as the force output increases
as also summarized by Bottinelli and Reggiani (2000).
Accordingly, the rate of muscle CV and MDF decays isdependent on the type of recruited MUs that, in turn,depends on actual force output (Merletti et al., 1990). Following our results, this seems to be the case. A possible
explanation for the greater drop in DTOImin observed
between ST20 and ST40 can be that in the BB muscle therecruitment of large oxidative ﬁbers is prevalent between
20 and 40%MVC and almost completed at 60%MVC. Thisis also reﬂected by the trend shown by MDF-CV fast phaseslopes vs. DTOI reported in Fig. 5. In fact, between 40 and
60%MVC the increase in DTOI fast phase slope is notaccompanied by a correspondent change in MDF andCV slopes. Besides, from 60 to 80%MVC the rate of changeof sEMG parameters shows a new steep increase whereas
in the same force interval changes in DTOI are reduced(Figs. 4 and 5). As stated in the introduction, CV is now
accepted as a size principle parameter (Farina et al.,2007) also in dynamic conditions (cyclic exercises). Following the above description, these results can be explained on
the basis of an increasing and prevalent recruitment ofType IIB glycolitic ﬁbers in BB muscle after 60%MVC.
Considering the fact that either MDF and CV computed
over sEMG signals are average values a certain ‘‘inertia’’must be taken into account. However, although a scarcecapability of these parameters to promptly detect a significant recruitment of a given population of MUs, our results
seem to convincingly provide evidence of the Henneman’s
principle.
The maximal desaturation obtained at ST80 (see Table
1) is partly in agreement with Kahn et al. (1998), whoinvestigated brachioradialis oxygenation changes duringisometric contractions by single distance continuous wave
NIRS. However, those authors found a peak of muscle
de-oxygenation at 50%MVC, whilst at higher force levels
muscle de-oxygenation was lower. For the purposes ofthe present study, these diﬀerences have to be consideredmarginal, since they can simply come out from the diﬀerent
muscles explored (although having a similar functionalrole) and from the diverse NIR apparatus employed.
On the other hand, SIN contractions provide an indirectindication about the possible inﬂuence of MUs recruitment
on aerobic metabolism: it is to note, in this particular case,that the oxygen initial utilization is almost identical to thatof ST contractions, whilst the MDF and CV changes are
reduced, at least during the SIN40 exercise. This is possibly
due to the fact that this low contraction regimen is as suchto promote a marginal – intermittent – recruitment of fast
twitch, mostly anaerobic, MUs.
After the initial fast phase, BB desaturation rate slows
down. It has been well documented (Lippold et al., 1960;

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Sbriccoli et al., 2003; West et al., 1995), for several muscle
groups, that the amplitude of the sEMG during an isometric contraction increases with both the duration andintensity of an isometric steady state eﬀort. There is lessagreement on the relationship between changes of sEMG
spectral parameters and recruitment and or modulation of
MUs ﬁring rate (Farina et al., 2002b). However, it isaccepted that for a muscle to produce more force, it isnecessary to increase the excitatory drive to its MUs,
either in terms of newly recruited MUs or of increasing
the ﬁring rate of the already active. This is reﬂected, inthe present work by BB desaturation rate, MDF decay
and CV decay that all increase when the isometric force
output increases. To this respect, we should consider theunbalance between O2 supply and muscle O2 demand.
From data presented in Fig. 3, it is evident that the
RMS increases with force and a certain degree of change
in muscle blood volume, namely of DtHb, is always present. At low force levels (ST20 and ST40) the DtHb behavior seems to indicate that even during the contraction themuscle blood volume reaches values greater than thoseobtained at rest. This result cannot be explained only on
the basis of a blood displacement from the inner portionof the muscle toward muscle surface region, at least for
the ST20 exercise. In accordance with (Kahn et al.,1998) the DTOI stabilizes only during the ﬁnal part of
ST20 exercise, indicating that a new equilibrium point
between O2 supply and consumption is possible, whilst
at ST40 this seems not to be the case. Moreover, DtHb
is not stationary neither at ST60 and ST80 being more
likely, in this particular case, a redistribution of forces
between muscle units and namely of those attributableto viscoelastic tissues. On the other hand, an internal pressure unbalance between deep and superﬁcial part of themuscle and a rotation of the MUs could not be the solecauses of the instability of muscle blood volume as suggested in previous works (Sejersted et al., 1984; Sjögaard
et al., 1986; Søgaard, 1995). The RMS results presented
in this work are not compatible with the hypothesis of
MU rotation other than at ST80. In fact, the RMS iseither stable (ST20) or increases overtime at ST40 and
ST60. Only in the last third of ST80, a dip in RMS amplitude is present and this is timed in accordance with thedecrease in average force. However, it is noteworthy thatin this phase the slope of DtHb recovery remains
unchanged, thus the eﬀect of MUs rotation and/or internal pressure unbalance, if present, should be non-signiﬁcant. Furthermore, at ST60 and mostly at ST80, DtHb
starts to change few seconds after the mechanical steadystate is reached. With a fair approximation, this time corresponds to the beginning of the slow phase of muscle
desaturation. The scenario could be as follows: the reduction of internal muscle pressure allows for a minimal
blood supply that, however, is not enough to match muscle metabolic demand. A ‘‘contamination’’ of the muscle
oxygenation signal by an increased volume of oxygenatedblood in the skin, as suggested by Grassi et al. (2003), isstill possible but, under the present experimental conditions (isometric), a thermoregulatory mechanism cannot
be invoked.
7.1. Limitations
The two probes, metabolic and electromyographic(NIRS and sEMG), were as close as possible each otherbut not exactly on the same muscle portion. In substance,
they explored adjacent muscle portions on the two sidesof an ideal muscle mid line. This choice may raise somecriticism, however, this conﬁguration was chosen for thefollowing reason. The BB muscle oﬀers, in its middle portion, space enough to accommodate the two probes. Muscle deformations in the middle part are minimal withrespect to the distal portion as shown by cine phase contrast magnetic resonance imaging (Pappas et al., 2002).
On the other hand, an ‘‘in-series’’ arrangement of theprobes oﬀers the drawback of large muscle deformation
also during isometric contraction. Thus, since a relative
stability of muscle geometry is a main requisite for the optimal working of either probe, the middle portion of muscle
belly is the best choice for probes positioning. Besides, it
has been recently shown that BB metabolic demand during
exercise is much more homogeneous in correspondence ofthe central part of muscle belly (Pappas et al., 2002).
The major advantage of the NIRS measurements is thepossibility to be performed repeatedly. The main NIRS
results in sports science have been reported and discussed
in several recent reviews (Neary, 2004; Bhambhani,2004). Despite the advantages of NIRS, there are limitations of this study that warrant discussion. Some of thelimitations are related to the assumptions made in NIRS
in general. (1) Absorbing compounds. Haemoglobin is considered the main absorbing component in the tissue volumeinterrogated. (2) Sample volume. The use of NIRS allows
the investigation of only a few cubic centimetres of superﬁcial BB muscle. Therefore, it is assumed that the investigated portion of a given muscle is recruited in proportion
to the work performed. (3) The accuracy of TOI measurement relies on the assumption that muscle tissue is macroscopically homogeneous. This is not certainly true forin vivo measurement due to the skin-fat layer separating
the NIRS probe from the muscle. However, the multi-distance method (Suzuki et al., 1999) strongly reduces theeﬀect of superﬁcial layer on the determination of TOI
because the light intensity is measured at several diﬀerent
source–detector distances allowing the measurement of
the slope of light attenuation versus distance. This method
provides a high signal-to-noise ratio without being so sensitive to the optical coupling and to the presence of superﬁcial tissue layers such as the fat layer. The superﬁcial
layers of tissue aﬀect all the light bundles similarly andtherefore their inﬂuence cancels out. Only deeper tissue
layers have an eﬀect on the TOI values. (4) The lack ofmuscle biopsies or alternative non-invasive methods tosubstantiate metabolic claims. In the present study it was

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F. Felici et al. / Journal of Electromyography and Kinesiology xxx (2007) xxx–xxx

not possible to take muscle biopsy samples. Given theabove mentioned considerations, we have been careful
not to extend our ﬁnding beyond the limitations of the
NIRS technology that we utilized.
Another methodological issue, relevant to sEMG signal
analysis, is represented by motor point location withrespect to recording electrodes. The procedure we adopted
for localizing the motor point is well-tested (Farina et al.,2000). In addition, an electrodes array oﬀers the advantage,over the conventional two-electrode technique, that visualinspection of the raw sEMG signal allows an easy identiﬁcation of electrode misplacement and, thus, its prompt
repositioning in a more reliable portion of muscle.
Finally, it can be argued that MUs population below theprobes was not uniform or largely diﬀerent from subject tosubject. Muscle ﬁber distribution within individual humanskeletal muscles is far from being precisely deﬁned. However, high threshold MUs have been claimed to be superﬁcially located in the human BB muscle (Clamann, 1970;
Manta et al., 1996). In support of this view, more recent
studies that used ﬂuorodeoxyglucose positron emission
tomography indicated: (a) a decreased metabolic eﬃciency
in the most peripheral part of the BB muscle, and (b) aregionalization of slow twitch muscle ﬁber in the medialand superﬁcial portion of BB muscle (Pappas et al., 2001).
This combined study suggests that muscle aerobic
demand during isometric contractions from low to highforce levels is inﬂuenced by the kind of active MUs andnot by the isometric exercise modality thus conﬁrming
the relationship between ongoing changes of myoelectric
signal and changes in local muscle oxidative metabolism.
The combined NIRS-sEMG approach oﬀers the opportunity for a deeper non-invasive investigation of muscle function not only in sedentary healthy subjects but also in
special populations, from athletes to neuromuscularpatients.
Acknowledgement
This research was supported in part by Hamamatsu
Photonics K.K. (Japan).
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Farina D, Ferguson RA, Macaluso A, De Vito G. Correlation of averagemuscle ﬁber conduction velocity measured during cycling exercise withmyosin heavy chain composition, lactate threshold, and VO(2max). J
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Farina D, Fosci M, Merletti R. Motor unit recruitment strategies
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Ferrari M, Mottola L, Quaresima V. Principles, techniques, andlimitations of near infrared spectroscopy. Can J Appl Physiol
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Francesco Felici is an Associate Professor of
Human Physiology and Exercise Physiology at
the University Institute of Movement Sciences,Rome, Italy. He is the Director of the
Department of Human Movement and Sport
Sciences. He is a member of the Italian Physiological Society, of the International Society ofElectromyography and Kinesiology, of theEuropean College of Sport Sciences. He ismember of the Editorial Board of the Journalof Electromyography and Kinesiology and of
the Journal of Sports Medicine and PhysicalFitness. Research activity focused mostly in the human movement area –from energetic to control – in collaboration with national and international institutions. The main topics are: Neuromuscular control. Nonlinear analysis of surface electromyograms. Neuromuscular eﬀects ofexercise and sport. Exercise Physiology in healthy and pathologicalsubjects.
Valentina Quaresima received the Degree in
Pharmacy from the University ‘‘La Sapienza’’of Rome, Italy, in 1988, and the Ph.D. in‘‘Formation and Treatment of Biomedical
Images’’ from the University of L’Aquila
Medical School, L’Aquila, Italy, in 1994.
From 1994 to 1999 she was Post-doc Fellow
at the University of L’Aquila, Italy. From
November 1999 to December 2003 she was
Researcher of Biochemistry at the Medical
Faculty of the University of L’Aquila, Italy.
Since January 2004 she has been Associate
Professor of Biochemistry at the Medical Faculty of the University of
L’Aquila, Italy.
Her research interests include the study of localised measurements ofmuscular and cerebral oxygenation in humans by diﬀerent near-infrared
spectroscopy techniques.

11

Luigi Fattorini was born in 1962. He received
his Bio-Engineering degree in 1989 from University of Rome ‘‘La Sapienza’’. He worked as
student at the institute of physiology in thefaculty of medicine on the elaboration andinterpretation of EEG signal. Now is a
researcher in Sport physiology at the University of Rome ‘‘La Sapienza’’. Actually, hismain areas of scientiﬁc interest are the biomechanics and neuromuscular activation in healthy subjects. In particular, he has worked on
the EMG signal both during voluntary movement and as response from exogenous vibrating stimuli. He has studied
the biological signal using a non-linear approach providing a diﬀerent
approach in biological signals processing.
Paola Sbriccoli, Ph.D. in Physiopathology ofMovement, was born in 1964. In 1986 she graduated ‘‘cum laude’’ at the ISEF (Superior Institute of Physical Education) of Rome. In 1994 shereceived her Medical Doctor degree from the
University of Rome ‘‘La Sapienza’’ and in 1998
she specialized ‘‘cum laude’’ in Sport Medicine.
From May 2003 to April 2004 she has attended a
research fellowship at the Bioengineering Laboratory (Department of Orthopaedics) of theLouisiana State University Health Sciences
Center in New Orleans, Louisiana USA where
she worked on neuromuscular function and dysfunction in spine and knee inhumans and animal preparation. Her present appointment is at University
Institute of Motor Sciences of Rome, Faculty of Motor Sciences as Associate
Professor in Methods and Teaching in Movement Sciences. She is ordinary
member of the Physiological Society of Italy, the European College of Sport
Science, and the International Society for Electrophysiology and Kinesiology. From 2004 she is Member of the Editorial Board of the Journal of
Electromyography and Kinesiology. Her main interests in research are noninvasive assessment of muscle damage and repair, linear and non-linear
analysis of sEMG signals in healthy humans, and exercise physiology.
GianCarlo Filligoi is a researcher in Bioengineering at the Dpt. INFOCOM- Fac. Engineering, Rome, Italy. he is a member of the
A.I.I.M.B. (Italian Association of Medical
Engineering and Biology) I.F.M.B.E. (International Federation for Medical & BiologicalEngineering) since 1977. His research activity
focused mostly on evoked and event related
potentials acquisition and processing, neuroophthalmology, biomedical signal acquisitionand processing, arm movement control, sEMG
and PMG (Phonomyogram). He is also interested in linear and non linear analysis of sEMG.
Marco Ferrari received the Degree in Medicine
from the University ‘‘La Sapienza’’ of Rome,
Italy, in 1977.
From 1982 to 1986 he was Researcher at the‘‘Istituto Superiore di Sanità of Rome, Italy.
From 1986 to 1987 he was Visiting AssistantProfessor at the Johns Hopkins Medical School,
Baltimore MD, USA. From 1988 to 2000 he was
Associate Professor of Biochemistry at the
Medical Faculty of the University of L’Aquila,
Italy. Since 2001 he has been Full Professor of
Biochemistry at the Medical Faculty of the
University of L’Aquila, Italy.
His research interests include the development and the evaluation of nearinfrared spectroscopy instrumentation for medical applications.

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325

Letters to the Editor-in-Chief

2. the utilization of the aerobic oxidative metabolic
system (evaluated from the kinetics of muscle O2Hb
desaturation) is delayed (4,5).

QUANTIFICATION OF QUADRICEPS O2DESATURATION IN RESPONSE TOSHORT SPRINT CYCLING

Although Racinais et al. (8) did not accurately quantify
muscle oxygenation, the data shown in their Figure 1 would
suggest that the 30-s interval between bouts was not
sufficient for glycolytic and oxidative ATP synthesis
necessary for PCr resynthesis following intense short
exercise (6). The results of previous studies (3,7) support
that muscle oxygenation, measurable by near-infrared
spectroscopy, can be utilized also for following the effectsof specific aerobic or anaerobic training programs.

Dear Editor-in-Chief:
A recent article (8) investigated vastus lateralis O2
desaturation in response to 10 very short (6 s) sprint
cycling bouts. Although the results are interesting, thepresentation of the muscle oxygenation data is inadequate.
For measuring muscle oxygenation, Racinais et al. (8) useda multidistance spatially resolved tissue oximeter (NIRO300, Hamamatsu Photonics, Japan) without exploiting theoffered advantage to quantify muscle oxygenation directly
as tissue oxyhemoglobin (O2Hb) saturation (%). Tissue
O2Hb saturation reflects the dynamic balance between O2
supply and O2 consumption and is independent of thepathlength of the near-infrared photons in the muscle tissue(1,3). Near-infrared spatially resolved spectroscopy implies
that the light intensity is measured at several different
source–detector distances (1,3). Then, this noninvasive
technique allows the measurement of the slope of lightattenuation versus distance and provides a high signal-tonoise ratio, without being so sensitive to the optical
coupling and to the presence of superficial tissue layers.
Racinais et al. (8) drew their physiological conclusions
on the basis of the interpretation of the following data: 1)
percent changes of the deoxyhemoglobin (HHb) values
calculated relative to the rest level in their Figure 1, and 2)
HHb changes ($KM) in the Results section using thedifferential pathlength factor (2). Unfortunately, Racinais
et al. (8) did not report changes in total Hb ($tHb =$O2Hb + $HHb) and O2Hb saturation that are necessary
for a correct interpretation of muscle oxygenation changes.
HHb changes might represent tissue oxygenation changes
only when tHb is stable. Therefore, the speculations on themuscle oxygenation changes based only on the increase
and decrease of HHb during the sprint exercise are notfully reliable. On the other hand, at the onset of the sprint
cycling bout, it would be expected that:

Valentina Quaresima
Marco Ferrari
Department of Sciences and Biomedical Technologies
University of L_Aquila
L_Aquila, Italy
DOI: 10.1249/mss.0b013e3180686dff

REFERENCES

1. blood volume drops as a consequence of venous
compression (blood volume is measurable as relative
decrease in tHb), and1205

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326

SPECIAL COMMUNICATIONS

1. DELPY, D. T., and M. COPE. Quantification in tissue near-infrared
spectroscopy. Philos. Trans. R. Soc. Lond. B Biol. Sci. 352:
649–659, 1997.
2. DUNCAN, A., J. H. MEEK, M. CLEMENCE, et al. Optical pathlength
measurements on adult head, calf and forearm and the head of thenewborn infant using phase resolved optical spectroscopy. Phys.
Med. Biol. 490:295–304, 1995.
3. FERRARI, M., L. MOTTOLA, and V. QUARESIMA. Principles, techniques, and limitations of near-infrared spectroscopy. Can. J. Appl.
Physiol. 29:463–487, 2004.
4. GAITANOS, G. C., C. WILLIAMS, L. H. BOOBIS, and S. BROOKS.
Human muscle metabolism during intermittent maximal exercise.
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5. GRASSI, B., S. POGLIAGHI, S. RAMPICHINI, et al. Muscle oxygenationand pulmonary gas exchange kinetics during cycling exercise ontransitions in humans. J. Appl. Physiol. 95:149–158, 2003.
6. MCMAHON, S., and D. JENKINS. Factors affecting the rate ofphosphocreatine resynthesis following intense exercise. Sports
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7. NEARY, J. P. Application of near infrared spectroscopy to exercise
sports science. Can. J. Appl. Physiol. 29:488–503, 2004.
8. RACINAIS, S., D. BISHOP, R. DENIS, G. LATTIER, A. MENDEZVILLANEUVA, and S. PERREY. Muscle deoxygenation and neuraldrive to the muscle during repeated sprint cycling. Med. Sci. Sports
Exerc. 39:268–274, 2007.

Vastus Lateralis O2 Desaturation in Response
to Fast and Short Maximal Contraction
VALENTINA CETTOLO1, MARCO FERRARI1, VINCENZO BIASINI2, and VALENTINA QUARESIMA1
1

Department of Science and Biomedical Technologies, University of L_Aquila, L_Aquila, ITALY;
and 2Center of Sport Medicine, Federazione Medico Sportiva Italiana, Scoppito, ITALY

ABSTRACTT

he three main metabolic systems providing ATP
either at rest or in muscle exercise (phosphocreatine(PCr) hydrolysis, anaerobic glycolysis, and aerobic
oxidative metabolism) are recruited differently according to
the muscle characteristics, the exercise modality, and thetraining status (29). It is well established that humanskeletal muscle is a heterogeneous tissue and can adapt tothe variable functional requirements through mechanisms
based on changes in muscle mass, fiber size, fiber type
distribution, metabolic enzyme activities, and substrate
supply. Human muscles are mixed muscles expressing threemain fiber types: type I, IIA, and IIX, in variable
proportions (7). They exhibit increasing shortening velocities in this rank order. The relative importance of the twomain metabolic pathways of ATP production, that is,anaerobic glycolysis and aerobic oxidative metabolism,
varies between muscle types. The slow type I fibers cansustain prolonged low-power work in association with awell-developed oxidative metabolism. The fast type IIX
fibers are adapted to brief and intense contractions fueled by
the anaerobic glycolytic pathway and immediate availabilityof PCr; type IIX fibers are much better used for fast andpowerful movements (7). Type IIA fibers are fast oxidative–glycolytic and exhibit intermediate contractile function. Because short-duration, maximal-intensity exercise
involves the recruitment of all the fiber types (10), theresultant metabolic response needs to be investigated in
more detail, particularly in subjects whose responses may
be affected by training adaptations.
Currently, the available evidence indicates that metabolic
diversity involves many different aspects of muscle fiber
metabolism, from substrate availability to the rate of
enzymatic process of energy production and use (7).
Glycogen content at rest is higher in fast than in slow
fibers, and it was demonstrated that endurance training
increases glycogen content and the glycolytic enzyme
activities (37). Within the skeletal muscle cell at the onsetof muscular contraction, PCr represents the most immediate
reserve for the rephosphorylation of ATP. Nevertheless,muscle fibers differ in the availability of PCr. Several
studies consistently indicate that in human muscles, resting

Address for correspondence: Marco Ferrari, M.D., Department of Science and Biomedical Technologies, University of L_Aquila, Via Vetoio(Loc. Coppito), I-67100 L_Aquila, Italy; E-mail: ferrari@univaq.it.
Submitted for publication September 2006.
Accepted for publication June 2007.
0195-9131/07/3911-1949/0
MEDICINE & SCIENCE IN SPORTS & EXERCISE�
Copyright � 2007 by the American College of Sports Medicine
DOI: 10.1249/mss.0b013e3181453476

1949

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327

BASIC SCIENCES

CETTOLO, V., M. FERRARI, V. BIASINI, and V. QUARESIMA. Vastus Lateralis O2 Desaturation in Response to Fast and Short
Maximal Contraction. Med. Sci. Sports Exerc., Vol. 39, No. 11, pp. 1949–1959, 2007. Purpose: The purpose of this study was toinvestigate, in heavy-resistance strength-trained (N = 10) and untrained (N = 10) subjects, the vastus lateralis muscle oxyhemoglobin(O2Hb) desaturation time course in response to a brief, maximal, voluntary isometric contraction. Methods: The two groups were notstatistically different physically. Mean (T SD) age, height, and body mass of all the subjects were 28.0 T 6.3 yr, 1.8 T 0.1 m, and 77.8 T
9.9 kg, respectively. Each subject performed five trials. Every trial consisted of 1) a 1-min rest period, 2) a leg press exercise of 2–4 s,and 3) a 5-min recovery period. Leg press exercise consisted of a static maximal voluntary contraction performed using the dominantleg only. Leg press strength was recorded using a load cell. Muscle O2Hb saturation (SmO2) was measured noninvasively by nearinfrared spectroscopy (0.17-s sampling time). Results: Rate of force development was higher in the trained subjects than in theuntrained ones (6897 T 1654 vs 5515 T 1434 NIsj1; P G 0.05). Once the exercise began, the time to the onset of SmO2 decrease wasconsistently shorter in the untrained than in the trained subjects (2.81 T 0.40 vs 3.91 T 0.67 s, P G 0.01). In all the trained subjects and in
two of the untrained ones, SmO2 started to decrease once the exercise was stopped. After the end of the exercise, SmO2 transiently
decreased and reached its minimum value in 15.0 T 3.8 and 10.1 T 1.3 s in the trained and untrained subjects, respectively (P G 0.01).
Conclusion: These data suggest that the vastus lateralis muscle of heavy-resistance strength-trained subjects could have a late activationof the oxidative metabolic system, or greater stored oxygen available, during a very fast, short, isometric maximal contraction.
Key Words: NEAR-INFRARED SPECTROSCOPY, TISSUE OXYGENATION, SKELETAL MUSCLE, OXIDATIVE METABOLISM, MUSCLE EXERCISE, MAXIMAL VOLUNTARY CONTRACTION

BASIC SCIENCES

PCr content is greater in fast than in slow fibers (7,26) andthat sprint training increases the muscle PCr content (17).
On exercise, the PCr content decreases to reach similarvalues in both fast and slow fibers. In contrast, resting ATP
is similar in slow and fast fibers. Glycolytic and oxidative
ATP synthesis allows PCr recovery. The factors affecting
the rate of PCr resynthesis after intense exercise haverecently been reviewed (26). The recovery is faster in slow
than in fast fibers in the first minute after maximal exercise.
The information currently available for strength exercise
in vivo is limited to the postexercise phase.
So far, there is no reliable method for quantifying the
instantaneous contribution of different fiber types on muscle
recruitment and the resulting overall metabolic responses
in vivo. The most useful techniques capable of measuring
muscle metabolism noninvasively are 31P magnetic resonance spectroscopy (31P-MRS), 1H magnetic resonanceimaging (1H-MRI), proton magnetic resonance spectroscopy (1H-MRS), and near-infrared spectroscopy (NIRS).
However, these techniques do not allow direct discrimination of metabolic changes at the level of type I ortype II fibers in vivo. The 31P-MRS measures muscular
intracellular pH and the concentrations of the main
phosphorylated compounds with a poor time resolution(longer than 1–2 s) (13). In addition, the compounds canonly be quantified if the specific saturation factors remain
constant during the exercise. The 1H-MRI provides anatomic information (and also microvascular density) as wellas muscle perfusion/oxygenation. However, being sensitive
to motion artifacts, 1H-MRI can be used only to investigate
the postexercise recovery with a time resolution of about
0.03 s (13,38). The 1H-MRS measures muscle deoxymyoglobin signal, allowing the assessment of intracellular O2
availability at rest (33) and during exercise with a poor
time resolution (longer than 12 s) (9). NIRS measures
muscle oxyhemoglobin (O2Hb) saturation (SmO2), concentration changes of O2Hb, deoxyhemoglobin (HHb), andtotal hemoglobin volume (tHb = O2Hb + HHb), and,indirectly, blood flow and O2 consumption (12,28,31).
Therefore, NIRS has largely been used in muscle exercise
pathophysiology (5,8,12,30). NIRS is a relatively lowcost technique, and it is less sensitive to motion artifacts
than are 31P-MRS/1H-MRI/1H-MRS. Moreover, NIRS canreach a time resolution of about 0.1 s, allowing the measurement of SmO2 kinetics during the natural execution ofwhole-limb or whole-body exercise (not feasible inside themagnet by 31P-MRS, 1H-MRI, and 1H-MRS), including
very short exercises.
It is well established that skeletal muscle can adapt tovariable functional requirements, even through changes infiber-type characteristics and in contractile function. In
particular, high-intensity exercise training increases theability to develop force rapidly (7), the maximal integrated
electromyography activity, and the cross-sectional area ofthe muscle (by 12% after 12 wk) (34). For example, it has
recently been reported that the vastus lateralis (VL) muscle

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of bodybuilders was markedly adapted to hypertrophic
heavy resistance exercise through 1) an extreme hypertrophy, 2) a shift towards the stronger and more powerfulfiber types (IIX), and 3) an increase in specific force ofmuscle fibers (11). One-leg, heavy-resistance strength
training provoked hypertrophy of VL muscle fibers after
9 wk of training; the cross-section area of type I, IIA,
and IIX fibers increased by 18, 21, and 41%, respectively,
with no significant changes in fiber-type distribution (25).
Resistance training induced an increase in the VL muscle
capillarization (16) and leg myoglobin (Mb) concentration(9). So far, the effects of training on muscle metabolism
during intense exercise remain controversial (17,21). During cycling, the anaerobic ATP production was found to be
reduced in subjects after sprint training (17). In contrast,
during maximal isometric contractions, the anaerobic ATP
production was found to be two- to threefold higher insprint-trained subjects compared with endurance-trained or
untrained subjects (21).
The metabolic changes induced by heavy-resistance,systematic strength training have mainly been investigatedby 31P-MRS using tests of prolonged duration (from about
30 s up to several minutes) (21,36). Towse et al. (38) havefound, by 1H-MRI and NIRS in sedentary and active
subjects, a similar postexercise muscle O2Hb desaturation
after 1 s of ankle dorsiflexion of the anterior tibialis muscle.
The postexercise transient hyperemia measured by 1H-MRI
was more than threefold greater in active compared withsedentary subjects. To the best of our knowledge, there are
no studies on the recruitment of the diverse skeletal muscle
metabolic systems during very short, maximal, voluntary
contractions.
The main purpose of this study was to investigate theeffects of a brief and fast maximal isometric voluntary
contraction on VL SmO2 (measured by NIRS) in heavyresistance strength-trained and untrained subjects. On thebasis of the literature, we assumed that the heavy-resistancestrength-trained subjects would have, with respect to theuntrained subjects, 1) an increased ability to use nonoxidative resources and/or an increased supply of substrate
to be used nonoxidatively; 2) a higher PCr concentration on
average; 3) a hypertrophy of type I, IIA, and IIX fibers; 4) ahigher capillarization; and 5) a higher myoglobin content.
Therefore, we hypothesized that we would find a delayed
beginning of the use of the aerobic oxidative metabolic
system (evaluated as muscle O2Hb desaturation) in the VL
muscle of the heavy-resistance strength-trained subjects
during a very short maximal contraction that would provoke
a complete occlusion of the blood flow.

MATERIALS AND METHODS
Subjects. Two groups of healthy male volunteers(trained and untrained) took part in this study. The 10 trained
subjects were involved in heavy-resistance strength-training
programs for more than 1 yr (9 2 hIdj1; 3–7� wkj1). The

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seat to the foot board of the leg press machine. The force
signal was monitored and recorded (at a rate of 100 Hz) bymeans of a digital oscilloscope (TDS 210, Tektronix Inc,
Beaverton, OR); the data were stored on a personal
computer for offline analysis. Force transducer calibration
was performed according to the manufacturers_ specifications. In particular, the electrical signal, produced by
the transducer when 100-, 500-, 900-, 1500-, 2100-, and3300-N loads were placed on the load cell, was recorded todetermine the relationship between the force applied and thetransducer_s output. Before every testing session, thereproducibility of the measure was verified by applying a
1500-N load. The measured linearity and repeatability were
better than 0.3% and 0.2%, respectively. For each trial, theforce was continuously measured at least 5 s before, during,and 5 s after the exercise.
NIRS instrumentation. The NIRS measurements were
performed with a NIRO-300 oximeter (Hamamatsu
Photonics K.K., Japan) (35). After the probe testing on aphantom to analyze the total probe sensitivity and thesensitivity difference between the three sensors of thedetection probe, the optical probe (consisting of one emitterand one detector, 4.5 cm apart), supported by a rigid rubber
shell, was firmly attached to the skin overlying the belly of
the VL muscle, parallel to the major axis of the thigh and at
14–20 cm from the knee, by a double-sided adhesive sheet.
The rigid rubber shell, in turn, was secured by a soft andelastic bandage (Tensoplast, BSN Medical, South Africa).
For identification of the VL muscle belly, on the day before
the measurements, each subject was asked to perform apreliminary leg press isometric contraction. The identified
area was carefully shaven before the experimentation. A
pen mark was used to indicate the correct position of theprobe holder shape for the next day. Pen marks were also
made on the skin to check for any sliding of the rubber shell
during the exercise. No sliding of the probe was observedat the end of the measurements in any subject. The NIRS
data were recorded with a sampling rate of 6 Hz. Eventswere marked on the NIRO-300 to indicate the start/stop ofeach trial and the onset/end of each exercise. The measured
NIRS data by the NIRO-300 were 1) SmO2 as TOI(expressed as a percentage), 2) concentration changes in
O2Hb and HHb (expressed in micromoles per liter per
centimeter), and 3) the derived changes in tHb (expressed in
micromoles per liter per centimeter). These measurements
can be affected by the contribution of Mb oxygenation
changes (9,12). TOI reflects the local balance between O2
supply and O2 consumption. The tHb volume changes,
being strictly related to blood volume changes, can beconsidered an indirect measure of changes in local blood
flow. After fixing the probe holders on the subjects, an
initialization procedure was carried out. The latter sets eachlaser power automatically, establishing the optimum
measurement condition. The zero-set procedure (carriedout just before the beginning of each baseline condition)
was adopted to return the O2Hb, HHb, and tHb parameters

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10 untrained subjects were university students who did not
spend any time on specific physical exercise. The twogroups were not statistically different by unpaired t-test forage (P = 0.97), height (P = 0.30), or weight (P = 0.07).
Mean (T SD) age, height, and body mass of all the subjects
were 28.0 T 6.3 yr, 1.8 T 0.1 m, and 77.8 T 9.9 kg,
respectively. After receiving a complete explanation of the
purpose and the procedures of the study, subjects gave theirwritten consent; none of them reported recent thigh injuries.
The study was approved by the university ethics committee
and conformed to the regulations laid out in the Declarationof Helsinki on the use of human subjects in research.
Experimental design. All subjects performed five
trials on a modified leg press machine (Leg Press,
TechnoGym, Italy). Every trial consisted of 1) a 1-min rest
period, 2) a leg press exercise of approximately 2–4 s, and
3) a 2-min recovery period. The leg press exercise consistedof a static maximal voluntary contraction (MVC), for which
the subjects were instructed, on verbal command, to act
against the footplate Bas forcefully and as fast as possible[
using only their dominant leg, and to maintain the MVC fora time period of approximately 2–4 s while the other leg
was resting. The dominant leg was determined by the
Edinburgh dominance test (32), to which specific items
were added regarding foot preference. During the trial
duration, volunteers were positioned on the seat of the leg
press with a knee angle of 110- (full extension being 180-).
Knee joint angle was determined with a handheld
goniometer. The subject waist was fixed in position bybands; during the exercise, the subjects were allowed tostabilize their upper body by holding the handles of the leg
press machine. NIRS recording was interrupted at the endof the 2-min postexercise recovery period of each trial.
Subjects then remained seated, moving freely and relaxing
their legs, for the next 2 min. The fifth minute of recovery
corresponded to the rest period of the subsequent trial.
During the intertrial periods, cardiac frequency wasmonitored by a pulse oximeter (N-200; Nellcor, Pleasanton,
CA), with the sensor attached on the forehead. Cardiac
frequency returned back to baseline values at the end of therest period (data not shown). Neuromuscular and metabolic
fatigue was considered to be minimal because of 1) the
small number of repetitions performed, 2) the sufficient rest
interval between trials, and 3) the good health of all thesubjects. The sufficient rest interval between trials was
confirmed by post hoc analysis, which demonstrated thatthe mean tissue oxygenation index (TOI) values, evaluatedfrom j4 to j1 s before each MVC, returned to the baseline
values (data not shown). Subjects were familiarized with theprotocol before the beginning of the study. The first trial
was preceded by a 10-min warm-up performed on anelectronically braked cycle ergometer (Ergocard II, OTE
Biomedica, Italy; 50 W, 50–60 rpm).
Force instrumentation. Leg press strength wasrecorded using a calibrated load cell (UU-K300, Dacell,
Korea) inserted into the mechanical vinculum that fixed the

BASIC SCIENCES

to the zero value. This procedure does not affect the TOI
value, because TOI is measured as an absolute value insteadof a change with respect to the arbitrary initial zero value.
The adipose tissue thickness overlaying the VL muscle wasmeasured with a skinfold caliper (British Indicators
Harpenden, UK). An unpaired t-test established that there
was no difference between the two groups (P = 0.11). The
adipose tissue thickness was 3.1 T 0.8 mm (mean T SD).
Considering that the adipose tissue thickness was relatively
low, and the penetration depth of the NIRS signal is almost
half of the source-detector separation (4.5 cm in the opticalprobe of the NIRO-300), the changes in TOI and tHb
reflected mainly muscle metabolic and hemodynamicchanges of VL (12).
Data analysis. Strength and NIRS data were exported
in text format without filtration. Analysis was performed
with custom software developed in Matlab (version 5.3,
The MathWorks Inc.).
Force data analysis. Each force dataset was expressedin newtons (by the measured calibration factors) andsmoothed (Savitzky–Golay filter, polynomial order 2, frame

size 41). The resting mean and SD force values were
determined in the time interval from 1 to 4 s after the startof the recording of the force signals (Figs. 1 and 2A). This
interval terminated around 1 s before the MVC onset. The
MVC onset was identified as the force value higher than thethreshold and maintained for at least 1 s. The threshold wasconsidered the rest mean force value plus two times the rest
SD value. The rest 2-SD value range was 170–269 and100–243 N for trained and untrained subjects, respectively.
The mean and SD of the force expressed during each
exercise were calculated for 1.5 s of the exercise in the timeinterval from 0.5 to 2.0 s after the MVC onset. The exercise
end was identified as the time when the force value became
lower than the mean, minus 2 SD of the force expressed
during the exercise. For each trial, the following force
parameters were considered: 1) mean force output (Fm), 2)
force duration (TF), and 3) maximum rate of force
development (RFD). Fm was the mean force expressed
during the specified 1.5 s of exercise minus the rest mean
force. TF was the difference between the end and the onsetof exercise according to the force data. RFD was the first

FIGURE 1—Changes before, during, and after a 3-s static maximal voluntary leg press exercise of a trained subject. A) Leg force output (thick line)
and the corresponding first derivative (thin line); B) tissue oxygenation index (TOI, thin line) and total hemoglobin concentration changes (tHb, thickline); C) oxyhemoglobin (O2Hb, thin line) and deoxyhemoglobin changes (HHb, thick line). The two vertical dashed lines in panel A indicate the onset/
end of the exercise calculated by the force duration (TF = 3.13 s). The two vertical dashed lines in panels B and C indicate the onset/end of the exercise
calculated by the tHb concentration changes provoked by exercise (TtHb = 3.30 s). The dash-dotted vertical line in panel B indicates the time to theonset of TOI decrease (TTOI = 3.96 s). The rest and ex segments indicate the time intervals used for calculating the average and the SD of F, TOI, andtHb before and during the exercise. These segments are extended up to the threshold values used to identify the onset/end of the exercise and the
TTOI (see Methods).

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BASIC SCIENCESFIGURE 2—Changes before, during, and after a 3-s static maximal voluntary leg press exercise of a untrained subject. A) Leg force output (thickline) and the corresponding first derivative (thin line); B) tissue oxygenation index (TOI, thin line) and total hemoglobin concentration changes (tHb,thick line); C) oxyhemoglobin (O2Hb, thin line) and deoxyhemoglobin changes (HHb, thick line). The two vertical dashed lines in panel A indicate theonset/end of the exercise calculated by the force duration (TF = 3.21 s). The two vertical dashed lines in panels B and C indicate the onset/end of theexercise calculated by the tHb concentration changes provoked by exercise (TtHb = 3.14 s). The dash-dotted vertical line in panel B indicates the time tothe onset of TOI decrease (TTOI = 2.48 s). The rest and ex segments indicate the time intervals used for calculating the average and the SD of F, TOI,and tHb before and during the exercise. These segments are extended up to the threshold values used to identify the onset/end of the exercise and the
TTOI (see Methods).

derivative maximum of the force–time dataset. For eachsubject, the reported force and NIRS data are referred to thebest performance trial with regard to the maximal RFD
value.
NIRS data analysis. The mean and SD values ofresting tHb and TOI were calculated for the time intervalfrom j4 to j1 s (Figs. 1 and 2B and C) before the exerciseonset event marker. This rest interval terminated around 1 s
before the MVC onset. The onset of the exercise was
identified as the time at which the tHb values became, forat least 1 s, lower than the mean minus two times the SD of
the resting tHb. The rest 2-SD value range was 9–46 and
8–37 KMIcm for trained and untrained subjects, respectively.
The mean and SD values of tHb and TOI occurring during
each MVC were calculated for the time interval from 0.5 to
2.0 s after the identified onset of the exercise. The exercise
end was identified as the time at which the tHb values
became, for at least 1 s, higher than mean plus two times theSD value of the tHb expressed during the exercise. The onset
of TOI decrease was identified as the time at which the TOI
values became, for at least 1 s, lower than the mean minus

two times the SD of the resting TOI. The rest 2-SD value
range was 1.2–2.4% and 1.9–2.5% for trained and untrained
subjects, respectively. For each analyzed trial, the following
NIRS parameters were considered: 1) mean tHb and TOIchanges during exercise ($tHb mean and $TOI mean ,respectively), 2) contraction duration based on NIRS data
(TtHb), 3) time to the onset of TOI decrease (TTOI), 4)
maximum postexercise TOI decrease ($TOImin), 5) time tomaximum postexercise TOI decrease (TTOImin), 6) halfrecovery time of TOI (T1/2TOI), 7) maximum postexercise
tHb increase ($tHb max ), and 8) time to maximum
postexercise tHb increase (TtHbmax). $tHbmean and $TOImean
were the tHb and the TOI values, respectively, calculated asmeans for the specified 1.5 s of exercise minus thecorresponding mean rest values. TtHb was the difference
between the end and the onset of the exercise based on tHb
signal. TTOI was the onset of TOI decrease minus the onset ofthe exercise for NIRS data. The $TOImin was the difference
between the minimum TOI value reached during thepostexercise phase and the corresponding mean resting value.
TTOImin was the time at which TOI reached its minimum

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value during the postexercise phase. The T1/2TOI was the timeat which TOI recovered 50% of $TOImin from minimum
TOI. The $tHbmax was the difference between the maximum
tHb value reached during the recovery phase and thecorresponding mean resting value. TtHbmax was the time atwhich tHb reached its maximum value during the recovery.
TTOImin, T1/2TOI, and TtHbmax were counted from the onset ofthe exercise as identified by using the tHb values.
Statistics. Statistical analyses were performed using the
SigmaStat 3.5 package (Systat Software Inc., Richmond,
CA). The average values were expressed as means T SD. A
one-way analysis of variance (ANOVA) was used tocompare the data between the two groups of subjects(training effect). A two-way ANOVA was used to compare
the data between groups and the order trial selected (trial
effect). A two-way repeated-measures ANOVA was used
for comparisons within subjects (signal or exercise effect)and groups, followed by the Student_s t-test whenappropriate. Results were considered statistically different
at P G 0.05. Bland and Altman_s limits-of-agreement plot(6) was employed to assess the level of agreement between
the exercise duration determined using the force–time curve
and the tHb–time curve.

other hand, in the trained subject TOI was almost stable
during the exercise period (force duration, 3.13 s) andstarted to decrease 3.96 s after the beginning of the exercise,
whereas in the untrained subject (force duration, 3.21 s)
TOI started to decrease at 2.48 s. After the end of the short
exercise bout, in both subjects TOI consistently andprogressively decreased, reaching actual minimum valuesof 63.4 and 51.6% in 11.39 and 9.74 s in the trained anduntrained subject, respectively; then, TOI progressively
returned to the preexercise level in about 1–1.5 min.
Table 1 reports the leg force and VL muscle oxygenation/hemodynamic parameters for the best performed trial
with regard to the highest RFD value. No relationshipbetween the two groups was found regarding the chronological order of the trial associated with the highest RFD
value (P = 0.73). The analysis of variance revealed asignificant difference in RFD between the exercises performed by the trained and untrained subjects (P G 0.05). In
contrast, Fm and TF were not significantly different between
the two groups (P = 0.28 and 0.14 for Fm and TF, respectively). The duration of the exercise, according to tHbchanges, was not significantly different between the twogroups (P = 0.25). Moreover, TtHb was significantly higher
than TF within each group (P G 0.001). However, theBland–Altman plot between TtHb and TF (Fig. 3) shows 1)
no trend in the data as the mean time duration increases, 2)
a 95% confidence interval from j0.14 to + 0.42 s, and 3) abias of +0.14 s. The latter can be explained by the different
sampling times of the NIRO-300 and the force transducer(0.16 s and 0.01 s, respectively).
At rest condition, a significant interindividual variation in
the TOI percentage was found in both groups (73.5 T 5.1
and 71.4 T 4.4% in the trained and untrained groups,
respectively). The maximum TOI achieved during exercise
with respect to the rest condition was not different between
the two groups (2.5 T 1.3 and 2.8 T 1.3% in the trained anduntrained groups, respectively; P = 0.60). During theexercise, tHb and TOI values changed significantly withrespect to the rest condition (P G 0.001 and P G 0.01 for tHb
and TOI, respectively). The amplitude of these changes was
similar in both groups (P = 0.95 and 0.35 for tHb and TOI,RESULTS
Figures 1 and 2 show a typical time course of leg force
and TOI, as well as O2Hb, and HHb changes (used to
calculate tHb changes) measured on a trained subject(Fig. 1) and an untrained subject (Fig. 2). These subjects
were chosen as representative of the difference between thetwo groups. The diverse force performance between the
trained and untrained subjects is shown by the dissimilar
RFD values (about 7800 and 5000 NIsj1 in the trained anduntrained subject, respectively). The onset of the exercise
clearly provoked an abrupt drop of tHb, which could be
attributable mainly to venous compression. tHb was almost
stable for the exercise duration and promptly started toincrease after the exercise end; then, a transient tHb
overshoot was observed. tHb returned slowly to its
preexercise level within 1–3 min (data not shown). On the
TABLE 1. Leg force and vastus lateralis muscle oxygenation/hemodynamic parameters.
Force duration (s)Mean force output (N)Maximum rate force development (NIsj1)
Contraction duration calculated by tHb changes (s)Mean tHb changes during exercise (KMIcm)
Mean TOI changes during exercise (%)
Time to the onset of TOI decrease (s)Maximum postexercise TOI decrease (%)
Time to maximum postexercise TOI decrease (s)Half-recovery time of TOI (s)Maximum postexercise tHb increase (KMIcm)
Time to maximum postexercise tHb increase (s)Trained (N = 10)

Untrained (N = 10)

2.75 T 0.39 (1.93 to 3.34)LL
2086 T 497 (1735 to 3232)LL
6897 T 1654 (5020 to 10137)LL
2.94 T 0.44 (1.98 to 347)LL
j229 T 103 (j325 to j33)LL+1.1 T 0.9 (+0.0 to +2.7)LL
3.91 T 0.67 (3.13 to 4.95)LL
j15.4 T 6.9 (j29.0 to j7.4)
15.0 T 3.8 (9.6 to 21.1)
29.6 T 8.5 (21.8 to 51.8)+94.0 T 39.2 (+39 to +175)
26.8 T 7.1 (13.5 to 34.8)

2.94 T 0.45 (1.89 to 3.51)L
1983 T 455 (1272 to 3032)L
5515 T 1434 (2951 to 8258)*L
3.04 T 0.42 (2.14 to 3.63)L
j261 T 198 (j594 to j19)
+0.8 T 1.5 (j1.1 to +3.6)
2.81 T 0.40 (2.31 to 3.30)**L
j22.1 T 7.4 (j39 to j14)*
10.1 T 1.3 (8.8 to 12.9)**
21.8 T 5.1 (15.7 to 32.7)+72.6 T 32.3 (+15.8 to +115.6)
32.6 T 12.5 (13.0 to 54.6)

Values are means T SD with range (minimum to maximum).
tHb, total hemoglobin volume; TOI, tissue oxygenation index.
Significant difference between groups (two-way ANOVA, training effect): * P G 0.05; ** P G 0.01. Significant difference within groups for TF vs TtHb and for TtHb vs TTOI (paired
Student_s t-test): # P G 0.05; ## P G 0.01.

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FIGURE 4—Time to the onset of TOI decrease vs the exercise
duration (identified on tHb changes) for trained (full dots, N = 10)
and untrained subjects (open squares, N = 10). The symbol size
corresponds to the NIRO-300 sampling time (0.16 s). Solid line, identity
line. Five data points are overlapped. ) Three overlapping data points(two trained and one untrained); * two overlapping data points (onetrained and one untrained).

DISCUSSION
These results are consistent with our hypothesis that, on abrief and fast maximal isometric voluntary contraction, VL
muscle of heavy-resistance strength-trained subjects would
have, with respect to the VL muscle of untrained subjects, adelayed beginning of the use of the aerobic oxidative
metabolic system (evaluated as muscle O2Hb desaturation).
In particular, the SmO2 of the VL muscle of the trainedgroup started to decrease only after the end of the exercise
in 9 of 10 subjects, and just at the end of the MVC in theremaining subject (Fig. 4). In the case of the untrainedgroup, SmO2 started to decrease before the end of theexercise in 8 of 10 subjects only. To the best of ourknowledge, this is the first time that the characteristics of
NIRS of high temporal resolution and low sensitivity tomotion artifacts have been exploited to investigate the timecourse of SmO2 during an explosive intense exercise.

FIGURE 3—Bland–Altman representation of exercise duration determined by using the force–time curve (as TF) and tHb–time curve (asTtHb). Full dots, trained subjects; open squares, untrained subjects.

FIGURE 5—Maximum postexercise TOI decrease (as $TOImin) vs thehalf-recovery time of TOI (as T1/2TOI) for trained (full dots, N = 10) anduntrained (open squares, N = 10) subjects.

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respectively). The time to the onset of TOI decrease wasconsistently shorter in the untrained subjects than in the
trained ones (Table 1; P G 0.01). This difference is better
illustrated by Figure 4, which shows the time to the onset of
the TOI decrease versus the exercise duration measured in all
the subjects. Nine measurements collected on trained subjects are above the identity line (with two data points
overlapping), and one is coincident with the identity line.
Six measurements collected on untrained subjects are below
the identity line, two are coincident with the identity line, andtwo are above, though very close, to the identity line.
Maximum postexercise TOI decrease was consistently
greater in the untrained subjects, and the time to maximum
postexercise TOI decrease was consistently longer in the
trained subjects (Table 1; P G 0.05 and P G 0.01 for$TOImin and TTOImin, respectively). Half-recovery time of
TOI was similar in both groups (P = 0.06). Figure 5 reports
the maximum postexercise TOI decrease ($TOImin, %)versus half-recovery time of TOI (T1/2TOI, s) for trained anduntrained subjects. Maximum postexercise tHb increase andtime to maximum postexercise tHb increase were notsignificantly different between trained and untrained subjects (P = 0.96 and 0.37 for $tHbmax and TtHbmax,
respectively).

BASIC SCIENCES

The maximum rate of force development is an importantstrength parameter because it incorporates the aspect ofcontraction time, which is neglected using the Fm (1). RFD
describes the ability to rapidly develop muscular force andreflects the ability of a subject to realize the contraction Bas
forcefully and as fast as possible.[ So, the maximum RFD
value can be considered one of the most reliable muscle
force–dependent tests of explosive force production (27).
According to previous studies (2,27), in the present study
all five trials were used for the assessment of the RFD
reliability, whereas the trial associated with the highest
RFD value served for the data analysis. The relatively large
SD of the RFD values found in the present study (Table 1)
is in agreement with values reported in recent similar
studies (2,27,38). Although the rapid exertion of maximum
force requires more practice than exerting force per se, thisintersubject variability of RFD values could be explained by
the diversity of one or more of the following physiologicalfactors: muscle fiber type and myosin heavy-chain composition, muscle cross-sectional area, viscoelastic properties ofthe muscle–tendon complex, and neural drive to the muscle(2). Strength and endurance training produce widely
diversified adaptations, with little overlap between them(29). Strength training typically results in increases ofmuscle mass and muscle strength. In contrast, endurance
training induces increases in maximal O2 uptake andmetabolic adaptations that lead to an increased exercise
capacity. Training induces gains in RFD (1,34), so, as
would be expected, in the present study the heavyresistance strength-trained subjects developed an RFD
higher than that produced by the untrained subjects.
The mean force output was not significantly greater in the
trained versus untrained subjects (Table 1) and was highly
correlated with the maximum force achieved during MVC(P G 0.001, R = 0.97; data not shown). Similar results were
found by others when the force output was collected fromdifferent groups of subjects (active vs sedentary) (38).
Therefore, because the Fm of the two groups was similar(at least for the time period between 0.5 and 2 s of MVC),
and assuming that the exercise energetic cost was notsubstantially different between the two groups (21), thedelayed time to onset of TOI decrease in the trained groupsuggests that the VL muscle of the trained subjects, during avery short and fast high-intensity isometric contraction, uses
other metabolic systems rather than the aerobic oxidative
one. The delayed activation of the aerobic oxidative metabolic system (evaluated as muscle O2Hb desaturation) in the
trained subjects could be a consequence of a larger proportion of type II fibers and a higher PCr concentration on
the average, or greater PCr breakdown and anaerobic glycolytic ATP provision in trained than in untrained subjects.
Our results are also in agreement with a recent 31P-NMR
study (21) that demonstrates marked differences in force
production, aerobic as well as anaerobic gastrocnemiousmuscle metabolism, between endurance-trained, sprinttrained, and untrained subjects during four maximal

1956

isometric contractions of 30-s duration each. No difference
was found in resting PCr/ATP among the three groups. The
groups differed with respect to PCr breakdown; sprintersdemonstrated about 75% breakdown in each contraction
compared with about 60 and 40% for untrained andendurance-trained subjects, respectively. In particular, during the first 5 s of MVC, PCr decreased by about 10% and
pH increased by about 0.1 units in sprint-trained subjects.
Conversely, PCr and pH were unchanged during MVC in
the untrained subjects, suggesting that the aerobic systemstarted to be used.
A delayed VL muscle desaturation has also been
observed at the onset of cycling exercise by Grassi et al.
(14). The authors consider PCr hydrolysis and anaerobic
glycolysis responsible for the delay or the attenuation of theincrease in ADP concentration within the cell after rapid
increase in ATP demand, thereby Bbuffering[ a more rapid
activation of oxidative phosphorylation. In isolated singlefrog myocytes, it was found that at the contraction onset, amonoexponential decrease in intracellular PO2 was preceded by about 10 s in which PO2 remained constant(23,39). The results of those studies suggest that there wasplenty of O2 available at the mitochondrial level in thesecells during the first seconds of contraction (39). Therefore,
in the subjects of the present study, the exploitation of the
aerobic oxidative metabolism, which uses O2 available inthe mitochondrial matrix, could not be excluded during thevery short exercise. If stored oxygen is greater in the trained
subjects, this may partly explain a later onset of TOI
decrease.
In human skeletal muscle, the role of Mb and its
relationship with factors such as muscle perfusion andmetabolic capacity are not yet well understood (40).
Unfortunately, NIRS is unable to differentiate between thesignal attenuation attributable to Hb and Mb, because theabsorbency signals of these two chromophores overlap in
the near-infrared range. Mb is a confounding factor at 10%of the whole NIRS signal (12). Considering the poor
temporal resolution of 1H-MRS, no data are available on
Mb desaturation during very short MVC (9). The present
NIRS results collected on trained subjects suggest that
although VL muscle blood flow was interrupted, Hb and
Mb did not desaturate during the 2–4 s of high-intensity
exercise. During the recovery of high-energy phosphatelevels after exercise, Mb is expected to be fully saturated
and does not affect the whole NIRS signal. Recently, leg
Mb concentrations, measured by NMR, were shown to be
25% greater in endurance-trained athletes as compared withsprinters, and to correlate with mitochondrial oxidative
production of ATP (9). We could speculate that in our study
the heavy-resistance strength-trained subjects might also
have higher Mb concentration compared with untrained
subjects. Combined 1H-MRS and NIRS studies are needed
to clarify not only the issue of the contribution of Mb to the
NIRS signal, but also the kinetics and the amount of Mb
desaturation during exercises with different workloads (9).

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the increase of the maximum postexercise tHb and its
corresponding time between trained and untrained subjects(Table 1), the differences in postexercise TOI decreasecannot be attributable to differences in postexercise muscle
blood flow. The differences in the VL muscle oxygenation
recovery after maximal cycling exercise found between
sedentary and active subjects (20) could be explained bydifferences in postexercise muscle blood flow on prolonged
exercise and/or muscle capillarization. In our study, thevery short duration of the VL muscle isometric exercise (3 svs several minutes) was not capable of generating significant postexercise muscle blood-flow differences, as indirectly indicated by the tHb changes. Conversely, Towse
et al. (38) have recently found, by 1H-MRI, a postexercise
transient hyperemia more than threefold greater in active
compared with sedentary subjects after a 1-s ankle dorsiflexion of the anterior tibialis muscle. Nevertheless, any
assumptions done concerning the training-induced adaptations that would have influenced the results between thetwo groups remain to be verified in future studies byinvasive or other measurements.
The major advantage of NIRS is represented by thepossibility to perform tissue oxygenation measurement
repeatedly. The main NIRS results in sports science havebeen reported and discussed in several recent reviews(5,30). Despite the advantages of NIRS, there are limitations of this study that warrant discussion. Some of thelimitations are related to the general assumptions made in
NIRS. 1) Absorbing compounds: Hemoglobin is considered the main absorbing component in the tissue volumeinterrogated. 2) Sample volume: The use of NIRS allows
the investigation of only a few cubic centimeters of superficial VL muscle. Therefore, it is assumed that the investigated portion of a given muscle is recruited in proportion
to the work performed. 3) The accuracy of TOI measurement relies on the assumption that muscle tissue is macroscopically homogeneous: This is not certainly true for invivo measurement, because of the skin-fat layer separating
the NIRS probe from the muscle. However, the multidistance method strongly reduces the effect of the superficial layer on the determination of TOI (35). 4) The
difference in the time intervals of the force and the NIRS
recordings: In this study, the force and the NIRS data wererecorded at 100 and 6 Hz, respectively. Although other
NIRS instruments have a higher time resolution (up to
50 Hz) than that of the NIRO-300, they measure concentration changes in O2Hb and HHb only (12). 5) The range
in contraction duration between subjects and between
trials: It was quite difficult to standardize the duration ofa very short MVC. Future studies should be designed toinclude a variable duration of MVC and intertrial interval.
6) The lack of muscle biopsies or alternative, noninvasive
methods to substantiate either metabolic claims or inferences regarding fiber type and recruitment: In the present
study, it was not possible to take muscle biopsy samples. 7)
Other methods for measuring muscle activity such as

MUSCLE DESATURATION DURING CONTRACTION

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1957

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335

BASIC SCIENCES

An accurate determination of the beginning/end of the
MVC as well as the stability of the blood volume (measured
as tHb changes) during the exercise are both necessary toclaim the validity of our results. It is well known that themuscle contraction pinches the arteries/arterioles and veins/venules along the fascicular lines, whereas the capillaries
are relatively uncompressed (15). A VL muscle maximal
isometric voluntary contraction provokes a complete
obstruction of muscle blood flow (3,4). This is witnessedby the fact that tHb, after an immediate initial drop, wasstable during the exercise period. The exercise duration wasdetermined either on force or tHb time courses (Figs. 1 and
2). The beginning of the exercise evaluated on the basis ofboth force and tHb tracings was coincident for theimmediate effect of the muscle contraction pinch on themuscle blood volume. Although TtHb was higher than TF,
the Bland–Altman plot shows a small bias attributable tothe different sampling times of the NIRS instrumentationand the force transducer (Fig. 3).
A diverse postexercise TOI decrease (less intense in the
trained subjects) was found (Table 1 and Fig. 5). Figure 5
clearly illustrates the large data-point dispersion in$TOImin, which is also confirmed by the high SD reported
in Table 1. The half-recovery time of TOI was not different
between trained and untrained subjects. The presence of adata point with a prolonged recovery time (about 50 s)
might be explained by the subject_s difficulty to relax theVL muscle immediately after the exercise. A similar SmO2
time course was also found in the finger flexor muscle aftera 10-s MVC (22). In that study, a significant positive
correlation between postexercise SmO2 recovery rate(measured by NIRS) and the time constant for PCr resynthesis (measured by 31P-MRS) was found. The postexercise
SmO2 recovery rate closely correlated with muscle O2
consumption, but not with forearm blood flow. A delayed
SmO2 recovery has recently been reported in the tibialis
anterior muscle after a 3-s MVC (24).
Glycolytic and oxidative ATP synthesis allows PCr
recovery after MVC. The recovery is faster in slow thanin fast fibers for the first minute after maximal exercise (7).
The factors affecting the rate of PCr resynthesis after
intense exercise have been recently reviewed (26). In ourstudy, the O2 supply is limited during the early phase of
post-MVC metabolic recovery in the VL muscle of trained
and untrained subjects, because TOI transiently decreased
after the MVC. On the other hand, it has been reported that
PCr recovery is limited by O2 availability in trained subjects(18) and by mitochondrial oxidative capacity in untrained
subjects (19). In fact, it has been demonstrated in exercisetrained subjects that PCr recovery occurred more rapidly
when inspired oxygen fraction was 1.0 than when it was
0.21 (18).
The time course of the TOI recovery depends also on the
post-MVC muscle blood-flow increase. It is generally
accepted that tHb changes are related to blood-flow changes(12). Taking into account that no differences were found in

BASIC SCIENCES

EMG would have been beneficial. However, the simultaneous measurement of EMG and NIRS would havebeen very difficult in the measured muscle because of thesize of the optical probe, and it would have required extra
trials to be performed by the subjects, to collect EMG
information separately. Given the above-mentioned considerations, we are careful to not extend our finding
beyond the limitations of the NIRS technology that has
been used.
In conclusion, the data from this study suggest that the
VL muscle of heavy-resistance strength-trained subjects
could have a late activation of the oxidative metabolic
system, or greater availability of stored oxygen, during avery fast and short isometric maximal contraction. Considering that leg press exercise 1) is a common exercise used byathletes to enhance performance in sport, 2) is responsiblefor development of the largest and most powerful muscles ofthe body, and 3) mimics, from the neuromuscular point ofview, many athletic movements, the results of this study
could give a valuable contribution to exercise science. For
instance, NIRS and leg press exercise could be used to
identify, noninvasively, in single muscle groups, the contribution of the aerobic energy system during very short andfast intense exercise, and, secondly, to observe the effects ofspecific aerobic or anaerobic training programs on thestarting time of the aerobic energy system activation.
This research was supported in part by PRIN 2005 andHamamatsu Photonics K.K. (Japan). The authors wish to thankthe two anonymous reviewers for their stimulating comments. The
authors also thank Dr. S. Crisostomi and Dr. L. Fallavollita, who
assisted the NIRS measurements, and TechnoGym (Italy) for theloan of the leg press machine.

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36. TAKAHASHI, H., M. INAKI, K. FUJIMOTO, et al. Control of the rate ofphosphocreatine resynthesis after exercise in trained and untrained
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APPLIED SCIENCES
Biodynamics

Gastrocnemius Medialis and Vastus
Lateralis Oxygenation during Whole-Body
Vibration Exercise
MARCO CARDINALE1,2, MARCO FERRARI3, and VALENTINA QUARESIMA3
Olympic Medical Institute, Northwick Park Hospital, Harrow, UNITED KINGDOM; 2University of Aberdeen, Collegeof Life Sciences and Medicine, Aberdeen, UNITED KINGDOM; and 3University of L`Aquila, Department of Sciences
and Biomedical Technologies, L`Aquila, ITALY

1

ABSTRACTCARDINALE, M., M. FERRARI, and V. QUARESIMA. Gastrocnemius Medialis and Vastus Lateralis Oxygenation during WholeBody Vibration Exercise. Med. Sci. Sports Exerc., Vol. 39, No. 4, pp. 694–700, 2007. Purpose: The aim of this study was toinvestigate the effects of different whole-body vibration (WBV) frequencies on oxygenation of vastus lateralis (VL) andgastrocnemius medialis (GM) muscles during static squatting in sedentary and physically active healthy males. Methods: Twenty
volunteers (age: 24.6 T 2.9 yr; body mass: 80.6 T 11.8 kg; height: 178.1 T 7.6 cm) participated in this study. Ten subjects weresedentary individuals and 10 were athletes practicing different sports. All subjects completed four trials (control, and 30-, 40-, and
50-Hz WBV) in a randomized controlled crossover design. The trials consisted of static squatting on a vibrating platform for a total
duration of 110 s. Muscle-oxygenation status was recorded with near-infrared spectroscopy. Results: The data analysis revealed nosignificant treatment-by-time interactions in tissue-oxygenation index (TOI) or $ total hemoglobin volume (tHb) in VL and GM
muscles. A significant main effect of time in TOI of both VL and GM muscles was identified (P G 0.001). VL TOI significantly
decreased by 2.8% at 90 s in the control condition and by 3.3% at 110 s in the 30-Hz condition; VL TOI significantly increased by 2.1
and 3.0% at 30 s in the 40- and 50-Hz conditions, respectively. GM TOI significantly decreased by 3.2% at 60 s, by 4.1% at 90 s, andby 4.3% at 110 s in the control condition, and by 5.5% at 110 s in the 30-Hz condition. Conclusion: This study showed that WBV
exercise with frequencies of 30, 40, and 50 Hz and small amplitudes does not affect muscle oxygenation of VL and GM muscles to ahigher degree than a nonvibration condition. Key Words: VIBRATION EXERCISE, MUSCLE OXYGENATION, NEARINFRARED SPECTROSCOPY, OXIDATIVE METABOLISM

W

hole-body vibration (WBV) has been promoted
as an alternative exercise intervention able toaffect neuromuscular performance (4,6) inyoung and old individuals. This new neuromuscular training method consists of squatting on specially designed
plates producing sinusoidal oscillations of different frequencies and amplitudes (6). It has been suggested that thesinusoidal vibration generated by the plate oscillations

elicits reflex muscle activity in the lower limbs (5,9,26),
mainly via monosynaptic pathways.
Muscle activation during squat exercise on vibrating
surfaces is still a controversial topic. In fact, although
recent work from De Ruiter et al. (8) indicates thatvibration elicits only low levels of muscle activation inleg extensor muscles, Rittweger et al. (25,24) have shownthat both frequency and amplitude of vibration increase
specific oxygen uptake and thus muscle activity. Veryrecently, Yamada et al. (34) have reported that squatting
exercise with low-frequency, small-amplitude vibration
performed on a tilting vibrating plate reduced muscleoxygenation levels of vastus lateralis (VL) more thansquatting without vibration as measured by near-infrared
spectroscopy (NIRS). An increase in oxygen use wasreported as the most likely cause.
Vibration exercise intensity can be determined bymanipulating two parameters: amplitude and frequency(4,6). In most of the vibrating plates currently available on

Address for correspondence: Marco Cardinale, Ph.D., Olympic Medical
Institute, Northwick Park Hospital, Watford Rd HA1 3UJ, Harrow, UK;
E-mail: Marco.Cardinale@boa.org.uk.
Submitted for publication August 2006.
Accepted for publication November 2006.
0195-9131/07/3904-0694/0
MEDICINE & SCIENCE IN SPORTS & EXERCISE�
Copyright � 2007 by the American College of Sports Medicine
DOI: 10.1249/mss.0b013e31803084d8

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338

the market, vibration frequency is the only parameter thatcan be changed, and notwithstanding manufacturers`
instructions, there is no real evidence to suggest the
optimal training frequency to be adopted. Therefore, thedetermination of the effects of different WBV frequencies
on muscle oxidative metabolism represents an important
aspect to be analyzed to provide guidelines for WBVtraining programs.
The possibility of noninvasively studying local muscle
oxidative metabolism during exercise has been enhanced in
the last few years, thanks to the use of NIRS (2,10,12,15,
21,31). For the quantification of muscle O2 saturation,different NIRS methods are available; so far, one of themost largely used in muscle studies is represented by nearinfrared, spatially resolved spectroscopy (NIRSRS). NIRSRS
provides an average (from small vessels, such as thecapillary, arteriolar, and venular bed) tissue O2 saturationand concentration changes in oxyhemoglobin (O2Hb),
deoxyhemoglobin (HHb), and total hemoglobin (tHb =O2Hb + HHb). Tissue O2 saturation represents a dynamicbalance between O2 supply and consumption in theinvestigated tissue volume.
During exercise, both blood flow and oxidative metabolism in skeletal muscle respond to meet increased oxygen
demand. For this reason, NIRS measurements can provide
an indication of localized muscle activities (21). Few
studies have been conducted using NIRS during WBV
exposure. In particular, recent work from Maikala et al.
(16) shows a decrease in lumbar erector spinae oxygenation and blood volume in healthy males during seated
WBV, independently of vibration dose. The authors showthat prolonged exposure to such a form of WBV could leadto fatigue in erector spinae, and they suggest this as apossible underlying factor for low-back pain. Considering
the lack of information regarding muscle oxygenation
during WBV exercise, we aimed to investigate the effects
of different WBV frequencies on oxygenation of VL andgastrocnemius medialis (GM) muscles during static squatting in sedentary and physically active healthy males. We
hypothesized that vibration would determine a decrease inmuscle oxygenation in GM and VL greater than in thecontrol condition, because of an increase in muscle
activation. Furthermore, we hypothesized that the oxygenation of GM muscle, because of its proximity to thevibration source, would be more affected than the oxygenation of VL during WBV.

different sports: road cycling (1), weight lifting (2),mountain biking (2), rugby (1), volleyball (2), full contact(1), and triathlon (1). All subjects gave their written
informed consent before participation. The study wasapproved by the ethics committee of the University of
L`Aquila.
Muscle-Oxygenation Measurements

METHODS
Subjects
Twenty volunteers (age: 24.6 T 2.9 yr; body mass: 80.6 T
11.8 kg; height: 178.1 T 7.6 cm) participated in this study.
Ten subjects were sedentary individuals (body mass: 78.6 T
7.1 kg; height: 177.1 T 6.9 cm), and 10 were athletes (bodymass: 83.6 T 16.7 kg; height: 179.4 T 9.0 cm) practicing

ACUTE EFFECTS OF WHOLE BODY VIBRATION

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APPLIED SCIENCES

Muscle oxygenation was assessed by NIRSRS using a
two-channel tissue oximeter (NIRO-300, Hamamatsu Photonics, Japan). The design and the features of this device
have been previously described (28). The theory behind the
NIRSRS approach and the reliability to measure tissue O2
saturation has been reported (28). The NIRO-300 provides
tissue O2-saturation data as tissue-oxygenation index (TOI,
expressed in percentage), which has been tested both invitro and in vivo (3,28). The TOI value reflects predominantly the mean of arteriolar, capillary, and venular O2
saturations, with a minor (less than 20%) contribution frommyoglobin (23). In addition, the NIRO-300 provides,
independently of TOI, changes in O2 Hb and HHb(expressed in $KMIcm) and the derived changes in totalhemoglobin volume ($tHb = $[O2Hb] + $[HHb]). The
tHb changes, being strictly related to blood volume
changes, can be considered an indirect measure of local
blood flow changes. After the probe test on a phantom toanalyze the total probe sensitivity and the sensitivity
difference between the three sensors of the detection probe,
the two optical probes (each consisting of an emitter and a
detector kept at a constant geometry and distance of 4.5 cm
by a rigid rubber probe holder) were firmly attached to theskin overlying the belly of the GM and VL muscle groupsof the right leg. In the case of hairy skin, the skin was
carefully shaven before the experimentation. The opticalprobes were further secured by an elastic band. No
downward sliding of the optical probes was observed at
the end of the measurements in any subject. After fixing
the probe holders on the subjects, an initialization
procedure was carried out. The latter sets each laser power,
automatically establishing the optimum measurement condition. The zero-set procedure (carried out just before thebeginning of each baseline condition) was adopted toreturn the O2Hb, HHb, and tHb parameters to the zero
value. This procedure does not affect the TOI value,
because TOI is measured as absolute value instead of achange with respect to the arbitrary initial zero value. TheNIRSRS data were recorded with a sampling rate of 6 Hz.
Adipose tissue thickness underlying the monitored VL
and GM area was measured with a Harpenden skinfold
caliper. Adipose tissue thickness of sedentary subjects was
4.6 T 1.2 and 3.4 T 0.7 mm for VL and GM, respectively.
Adipose tissue thickness of athletes was 3.6 T 0.9 and 2.9 T
0.9 mm for VL and GM, respectively.
For each subject, TOI and tHb data are reported as meanvalues for the last 5 s (30 data points) in each consideredAPPLIED SCIENCESFIGURE 1—Typical time course of vastus lateralis (left panels) and gastrocnemius medialis (right panels) muscle TOI (%) (thick black line) and tHb
concentration (gray thick line) changes measured on an athlete during the control condition (A, B), 30-Hz WBV (C, D), 40-Hz WBV (E, F), and 50Hz WBV (G, H). The vertical bars indicate the beginning and the end of the treatment.

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condition (vibration and control) and time (baseline and at
30, 60, 90, and 110 s).

Each condition was preceded by a 60-s baseline in halfsquat position. All subjects were able to hold the required
position for the duration of the condition throughout the
protocol. The vibration amplitude in all conditions was
T 4 mm (peak-to-peak displacement of the platform).
Twenty minutes of rest were observed between conditions
to allow for full recovery and to avoid the occurrence of
fatigue. The NIRO-300 recordings were interrupted 30 s
after the end of the randomized condition. Then, the subjects
were allowed to move freely and, eventually, to sit on achair. During the interval between the different conditions(rest period), the optical probes were not removed. During
the 20 min of rest, the cardiac frequency was monitored by apulse oximeter (N-200; Nellcor, Puritan Bennet, St. Louis,MO), with the sensor attached to the forehead. The cardiac
frequency was completely recovered to the baseline values
at the end of the rest period (data not shown).

Experimental Procedures
Subjects were asked to attend the experimental session
after 24 h of complete rest from any physical activity. The
subjects were familiarized with the protocol 1 d before thestudy. After the skinfold measurement, the two opticalprobes were positioned. Before each treatment, the subjects
performed a 10-min warm-up, cycling at 50 W on anelectronically braked cycle ergometer (QTE Biomedica
Ergocard II, Esaote Biomedica, Italy).
The subjects (wearing their socks) were then asked tostand in half-squat position (knee angle 110-) on a
vibration platform (Fitwave, Medisport, Italy), with theirarms on the front handlebar, their feet parallel, and theirfoot stance similar to the distance between shoulders. A
custom-made goniometer, fixed by velcro straps to thecontralateral leg, was used to maintain the joint angle. The
subjects were asked to maintain the squat position for 110 s(the maximum duration allowed by the vibrating platform)on the balls of their feet in the following randomized
conditions: no vibrations, and 30-, 40-, and 50-Hz WBV.

Statistical Analysis
Data are reported as mean T standard error of measurement of TOI and changes in tHb. A four-way analysis ofvariance (treatment (4) � time (5) � groups (2) � muscle(2)) was used to compare changes in TOI and in tHb. Whena significant interaction was found, a repeated-measures
ANOVA with Dunnet comparisons was used. Significancelevel was set at P G 0.05. The statistical analyses were
performed with SPSS (Chicago, IL).

Some typical tracings of TOI and $tHb are shown in
Figure 1. The statistical analysis revealed no differences
between treatments in the baseline values of TOI, indicating that full recovery occurred between the treatments(Fig. 2). The statistical analysis revealed no significant
differences in changes of TOI and tHb between groups(athletes and sedentary), suggesting that a short exposure to
vibration in isometric squat position affects muscle oxygenation independently of the training level of theindividual. Because no significant difference was identified
between trained and sedentary individuals, all data werepooled and statistical analyses were performed on all 20
subjects participating in the study.
The data analysis revealed no significant treatment-bytime interactions in TOI or $tHb in VL and GM muscles.
A significant main effect of time in TOI of VL as well as
GM muscles was identified (P G 0.001; Fig. 2). The
repeated-measures ANOVA with Dunnet comparisonsrevealed a significant decrease from baseline in TOI of
VL in control conditions after 90 and 110 s (P G 0.05 andP G 0.05, respectively), a significant decrease from baseline in TOI in the 30-Hz condition after 110 s (P G 0.01), a
significant increase in TOI after 30 s (P G 0.05) in the
40-Hz condition, and a significant increase in TOI after
30 s in the 50-Hz condition.

FIGURE 2—TOI (%) of vastus lateralis (A) and gastrocnemius
medialis (B) in different conditions over time. Data represent
measurements at baseline (first bar), 30 s (second bar), 60 s (thirdbar), 90 s (fourth bar), and 110 s (fifth bar) after the beginning of theexercise bout. No significant difference was identified between baseline values. Means T SEM (N = 20). * P G 0.05 from baseline; ** P G
0.01 from baseline.

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697

APPLIED SCIENCESRESULTS(7,8,29,30). Recent technological developments havemade it possible to noninvasively study local muscle
oxidative metabolism by means of NIRS (2,10,21). To
the best of our knowledge, only one study thus far has been
conducted using NIRS to investigate the oxygenation oflower-limb muscles during squatting exercise on a vibrating plate (34).
In the study by Yamada et al. (34), subjects
performed 3 min of continuous dynamic squatting in thecontrol and vibration conditions (15 Hz, T 2.5-mm
amplitude). The results of their study show that muscleoxygenation levels of VL were significantly reduced after
90 s. Our results did not show any significant difference
between the diverse vibration conditions and the control
condition. Differences in exercise modality and vibration
magnitude between the two studies could explain the
disparity. In fact, Yamada et al. (34) exercised theirsubjects on a vibrating plate while performing dynamic
squatting with a relatively large range of motion (from full
extension to 60-), whereas our subjects performed a static
squatting exercise. Different studies have shown thatdynamic muscle contraction generated by electrical stimulation causes greater energy turnover and fatigue than static
contractions performed at equal force levels (1,33). The
same can hold true for WBV exercise. Furthermore, theyused a similar amplitude (T 5 vs T 4 mm in our study), a
completely different frequency (15 vs 30 Hz in our study),
and a different vibration device (alternating vibration side
to side vs whole-plate oscillation). This suggests that WBV
performed on a platform oscillating side to side can be
more demanding for the lower limbs, because for brief
periods during the oscillations, the body is almost entirely
supported on one leg. It is also possible that the static
position used in our study produced a very low level ofmuscle tension, and for this reason, significant differences
probably would have been identified only after a much
longer duration than 110 s. Furthermore, considering that
Yamada et al. (34) used an incorrect statistical procedure(repeated Student`s t-tests with no Bonferroni adjustment),
it is possible that, even during dynamic squatting on a
vibrating plate for short periods of time, there is no
significant alteration of local oxidative metabolism,
because of the low level of muscle stimulation generated
by low-amplitude vibration.
As supportive evidence, recent work from Mileva et al.
(20) has shown that even after four sets of eight repetitions
with a load equal to 35 or 70% of the one-repetition
maximum of leg extension on a vibrating leg-extension
device (10-Hz vibration frequency; total duration approximately 80 s), no significant muscle-deoxygenation rate
could be observed. Muscle-oxygenation level is affected by
the balance between oxygen use and oxygen supply inhuman skeletal muscle. The lack of difference in muscleoxygenation response between WBV exposure for 110 s
and the control condition observed in our study seems tosuggest that when low-amplitude vibration is applied for a

APPLIED SCIENCESFIGURE 3—Concentration changes of tHb (KMIcm) of vastus
lateralis (A) and gastrocnemius medialis (B) in different conditions
over time. Data represent measurements at baseline (first bar), 30 s(second bar), 60 s (third bar), 90 s (fourth bar), and 110 s (fifth bar)after the beginning of the exercise bout. No significant difference was
identified between baseline values. Means T SEM (N = 20). * P G 0.05
from baseline.

GM TOI was found to be significantly lower thanbaseline at 60 s (P G 0.05), 90 s (P G 0.01), and 110 s(P G 0.01) in the control condition, and at 110 s (P G 0.05)
in the 30-Hz condition. The results suggest, again, thatvibration does not determine the same level of desaturation
observed in the control condition. A significant main effectwhen comparing VL and GM TOI was identified (P G
0.001). The repeated measure revealed significant differences at all time points between GM and VL, suggesting
different desaturation between plantar flexors and leg
extensors during the task.
No significant difference was identified in $tHb overtime in VL muscle. A significant increase for $tHb overtime was identified in GM (P G 0.001; Fig. 3). The
repeated-measures ANOVA with Dunnet comparisonsrevealed a significant increase in $tHb after 90 and 110 s
only in the control conditions.

DISCUSSIONWBV training is becoming a popular form of exercise
because it is relatively user friendly and does not require
advanced instructions or complicated movements. However, few studies have been conducted on this novel
exercise modality, and they all have shown contradicting
results, particularly when acute responses were identified

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lower intramuscular pressure measured during dynamic
exercise was responsible for the discrepancy between
muscle activation and oxygenation. No study has been
conducted so far on intramuscular pressure during vibration exercise, but other mechanisms such as a reduction inblood viscosity (14), an increase in total peripheral
resistance and opening of more capillaries (19), and anenhanced peripheral blood and lymphatic flow (27) could
be responsible for maintaining oxygen supply despite anincrease in motor unit recruitment.
The results of our study seem to suggest that shortduration WBV performed in static conditions with small
amplitudes does not cause the same level of muscle
desaturation that is observed from squatting without
vibration, and could also delay the desaturation observedin similar conditions without vibration. Considering thelack of desaturation observed in our study and the possibility for vibration to increase blood flow in the exercisingmuscles, we suggest that WBV exercises with a total duration shorter than 2 min could be used as a warm-up procedure in athletes. Needless to say, more studies are needed
to elucidate the vascular mechanisms and to evaluate what
happens when long-duration vibration exercise is performed, and also whether there is any value to using
vibration to increase muscle perfusion.
At the moment, it is not clear whether WBV represents a
training stimulus strong enough to influence force-generating capacity and/or muscle metabolism (6). However,
because many manufacturers are advertising the use ofvibration as an exercise tool capable of positively influencing the overall fitness of an individual, it is clear that morewell-controlled studies are needed to provide safe andeffective guidelines for its use. Considering that our study
and few other previous studies have shown that there areno potential limitations of using NIRS to analyze muscle
and cerebral oxygenation in WBV research (16–18), andconsidering the successful application of NIRS to sports
science research (21,22), future studies might be carriedout employing this technique to improve the understandingof muscle oxidative metabolism in response to different
vibration protocols.
In conclusion, this study has shown that WBV exercise
with frequencies of 30, 40, and 50 Hz and small amplitudes
does not affect muscle oxygenation of VL and GM muscles
to a higher degree than a nonvibration condition. Morestudies are needed to elucidate the physiological responses
to WBV exercise, with particular reference to the interactions between neuromuscular and metabolic demands ofthis novel and promising exercise intervention.
This research was supported in part by Hamamatsu Photonics
K.K, Japan. The authors wish to thank Medisport s.r.l. (Borgo
Podgora, Latina, Italy) for providing the vibration platform used in
the study (Fitwave); Dr. S. Crisostomi, Dr. A. Franco, and Dr. L.
Fallavollita, who assisted with NIRS measurement setup; and Ms. J.
Erskine for carefully reviewing the manuscript. The results of thepresent study do not constitute endorsement of the product by theauthors or ACSM.

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699

APPLIED SCIENCES

short duration, it is unlikely to alter local muscle
metabolism significantly.
However, it is interesting to remark on the different
effects of vibration on GM and VL over time. The resultsof our study show a significant desaturation in both GM
and VL after 60 and 90 s of static exercise in the control
condition. WBV exposure determined a significant desaturation only after 110 s in VL and GM. Considering also thesignificant increase in VL TOI% after 30 s at 40 and
50 Hz, and the lack of significant changes over time inGM, it seems that when vibration is superimposed to mild
levels of muscle activation, some alterations in muscle
metabolism and blood flow occur, delaying the hypothesized desaturation.
Previous studies have reported that muscular blood
circulation in the calf and thigh was significantly
increased after one bout of a 9-min WBV exercise on atilting plate (26 Hz, 3-mm amplitude; (14)). The authors
attributed the peripheral changes they observed to an
exercise-induced widening of small vessels. Because TOI
patterns reflect the balance between oxygen supply anddemand in the target muscles, it seems feasible to suggestthat the increased blood flow caused by vibration could
provide an adequate oxygen supply, delaying the desaturation observed when no vibration is applied. Furthermore,considering that plantar vibration has been shown toincrease supine blood flow in the calf measured by straingauge plethysmography by 20% (27), and that similar
increases were observed by the same authors in peripheral
lymphatic flow and venous drainage, it is possible that therelatively short duration of our vibration protocol might
have actually delayed muscle desaturation through an
improvement in muscle perfusion.
WBV exposure previously has been shown to determine higher levels of muscle activation by EMG in VL
and GM muscles as compared with standing on thevibrating plate with no vibration delivered to the body(5,9). Many authors have suggested that this neuromuscular response is similar to the tonic vibration reflex (11)previously observed with direct applications of vibration toeither muscles or tendons (5,6,9,13,26). The increased
muscle activation observed in previous studies was
hypothesized as able to produce a larger muscle desaturation. Furthermore, Rittweger et al. (25) have reported ahigher oxygen uptake while performing dynamic squattingin vibration conditions as compared with nonvibration
conditions, and a shorter time to exhaustion. Local muscle
oxidative metabolism with vibration exercise may besustained despite an increase in EMG activity that is
possibly attributable to changes in blood flow and intramuscular pressure, and this may change with dynamic andstatic WBV exercise. In this light, a recent study from
Vedsted et al. (32) shows no differences in the reduction ofmuscle-oxygenation tension between dynamic and static
muscle contraction despite a marked difference in EMG
and mechanomyography. The authors suggest that the

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Journal of Biomedical Optics 12�6�, 062105 �November/December 2007�

Near-infrared spectroscopy/imaging for monitoring
muscle oxygenation and oxidative metabolism
in healthy and diseased humans
Takafumi Hamaoka
National Institute of Fitness and Sports
Department of Exercise Science
Shiromizu 1
Kanoya, 891-2393 Japan
E-mail: kyp02504@nifty.com

Kevin K. McCully
University of Georgia
115 Ramsey Center
330 River Road
Athens, Georgia

Valentina Quaresima
University of L’Aquila
Department of Sciences
and Biomedical Technologies
L’Aquila, 67100 Italy

Abstract. Near-infrared spectroscopy �NIRS� was initiated in 1977 by
Jobsis as a simple, noninvasive method for measuring the presence ofoxygen in muscle and other tissues in vivo. This review honoring
Jobsis highlights the progress that has been made in developing andadapting NIRS and NIR imaging �NIRI� technologies for evaluating
skeletal muscle O2 dynamics and oxidative energy metabolism. Development of NIRS/NIRI technologies has included novel approaches
to quantification of the signal, as well as the addition of multiple
source detector pairs for imaging. Adaptation of NIRS technology has
focused on the validity and reliability of NIRS measurements. NIRS
measurements have been extended to resting, ischemic, localized exercise, and whole body exercise conditions. In addition, NIRS technology has been applied to the study of a number of chronic healthconditions, including patients with chronic heart failure, peripheral
vascular disease, chronic obstructive pulmonary disease, varying
muscle diseases, spinal cord injury, and renal failure. As NIRS technology continues to evolve, the study of skeletal muscle function withNIRS first illuminated by Jobsis continues to be bright. © 2007 Society of
Photo-Optical Instrumentation Engineers. �DOI: 10.1117/1.2805437�

Katsuyuki Yamamoto
Hokkaido University
Biomedical Systems Engineering Divisionof Bioengineering and Bioinformatics
Graduate School of Information Scienceand Technology
North 14 West 9
Sapporo 060-0814, Japan

Keywords: muscle; near-infrared spectroscopy; near-infrared imaging; oximetry;muscle oxygenation; muscle metabolism; exercise.
Paper 07157SSR received May 1, 2007; revised manuscript received Jul. 6, 2007;
accepted for publication Jul. 16, 2007; published online Nov. 16, 2007.

Britton Chance
University of Pennsylvania
Department of Biochemistry and Biophysics
Philadelphia, Pennsylvania 19104-6059

1

Introduction

The primary reason NIRS technology is so valuable for the
study of skeletal muscle is the strong dependence of skeletal
muscle on oxidative metabolism. During exercise, skeletal
muscle O2 consumption �VO2� can rise 50 fold with subsequent increases in O2 delivery �DO2� of up to 10 fold. Because of this, pathological impairments of either VO2 or DO2
will severely limit exercise and thus functional capacity. The
net oxidative energy pathway in muscles can be described by
the following equation:

The purpose of this review article is to highlight the mostrecent noninvasive near-infrared spectroscopy �NIRS� and
NIR imaging �NIRI� studies aimed at evaluating skeletal
muscle O2 dynamics and oxidative energy metabolism, inlight of historical studies that initiated this important and stilldeveloping technology. A brief background on the methodologies and approaches are presented, along with examples of
how these methodologies and approaches have been used tobetter understand muscle function in both health and disease.
A number of detailed review articles have previously described some aspects of the use of NIRS in muscle exercise
pathophysiology.1–6 A number of recent detailed review articles describing the principles, limitations, and applicationsof NIRS have appeared in the literature.7–13

3ADP + 3Pi + NADH + H+ + 1/2O2 = 3ATP + NAD+ + H2O,
where ADP is the adenosine diphosphate, Pi is the inorganic
phosphate, NADH is the reduced nicotinamide adenine dinucleotide, ATP is the adenosine triphosphate, and NAD+ isthe nicotinamide adenine dinucleotide.
Early developments of dual wavelength spectrophotometers set the stage for the development of NIRS in vivo.

Address all correspondence to Takafumi Hamaoka, National Institute of Fitness
and Sports Kanoya, Kagashima, Japan shiromizu 1-kanoya, kagoshima 8912393 Japan; Tel: 81 994 46 4935; Fax: 81 994 46 4935; E-mail:kyp02504@nifty.com

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062105-1

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November/December 2007�Vol. 12�6�Hamaoka et al.: Near-infrared spectroscopy/imaging for monitoring muscle oxygenation…

In-vitro studies by Chance14 and Chance and Connelly14,15
showed that the newly discovered mitochondrial signal of
NADH responded to electrical muscle stimulation in a fraction of a second, even at less than 10 ° C, coupling muscle
contraction to mitochondrial function. Jobsis,16 together withRamirez, Weber, and others, followed up with in-vitro opticalstudies of the bioenergetics of organs, heart, liver, brain, andadrenal and salt glands. Jobsis focused especially on skeletal
muscle and greatly improved the technique when he moved toDuke University, where he performed a series of outstanding
muscle physiology studies. These studies bridged the gap between bioenergetics and physiology and exploiting the relationship of the previous equation, that DO2 in combination
with the provision of other chemical substances, are the major
key players for mitochondrial VO2 or muscle oxidative
metabolism.
Prior to the development of NIRS, skeletal muscle oxygenation �a balance between DO2 and VO2� and metabolism
were evaluated in humans by conventional analytical biochemistry invasive methods after obtaining biopsy specimens.
The strength of the biopsy approach is that a wide array of
metabolites can be measured for studying specific metabolic
pathways. The disadvantage of the biopsy technique is thatbiopsies cannot be easily performed during muscle contractions and have limited repeatability, thus limiting the ability toobtain time course data. To overcome these disadvantages,
magnetic resonance spectroscopy �MRS�17 was developed tomeasure in-vivo free �active� forms of phosphate compounds
and intracellular pH, as well as intramyocelluar myoglobin�Mb� levels. MRS remains a valuable technology for the measurement of in-vivo energy status, oxygen saturations, andblood flow, but its high cost, large size, and limited availability reduce the usefulness of this method.
The continuing development of NIRS technology eventually leads to the study of intact organisms. The extension of
the optical technology to wider spectral and time regions was
epitomized by the elegant instrument of Lubbers and Thiefs
�rapid spectroscopy� and by the work of Kramer and others
who explored the NIR region, noting that the NIR light penetrated the hand, setting the stage for Jobsis’ brilliant
discovery18 that the skull is not a barrier to NIR light, as
recounted in his own words as follows.19 Very briefly, on 28
December 1976 his family enjoyed a grilled chuck roast witha part of the shoulder blade of the steer—a flat piece of bone
3 or 4 mm thick. When his son Paul held the object up against
the light, Jobsis noticed that the shadow of a finger could
easily be seen in the diffused red light coming through thebone. Then he speculated that NIR light at longer wavelengths
would penetrate the human skull and provide access to thetissue. His extraordinary scientific exploration started at atable with his family over a dinner with a very American cut
of beef �he used this expression himself�. In fact, the properties of the skull to enhance the NIR signals was later quantified in studies of the cat brain, where the removal of the skull
shortened the NIR photon migration pathlength. Thus Jobsis’
discovery opened the very active field of NIR studies of brain
and stimulated the studies of skeletal muscle in human subjects, a tradition carried on elegantly by his son, Paul Jobsis.
In the intervening years, numerous studies have developed
and refined the NIRS approach of studying skeletal muscle invivo. They have experimented with the wavelengths and arJournal of Biomedical Optics

rangement of light sources and detectors, as well as the portability of the devices.20–26 Equally variable have been the experimental approaches and subject populations used to takeadvantage of NIRS technologies.

2

Methodological Issues Related to theNoninvasive Evaluation of Muscle
Oxygenation and Metabolism Using
Near-Infrared Spectroscopy

The first issue related to the use of optics to study skeletal
muscle in vivo is the choice of wavelengths. Wavelengths
ranging from 700 to 3000 nm show much less scattering andthus better penetration into biological tissue than visible light.
However, light absorption by water limits the tissue penetration above 900-nm wavelength, leaving the 650- to 900-nm
range. The major absorbing compounds of this wavelength
region are intravascular hemoglobin �Hb�, intramuscular Mb,
skin melanin, and mitochondrial cytochrome c oxidase.18
NIRS measurements rely on O2 dependent absorption changes
that occur in the theme, and copper containing compounds.
The most common, commercially available NIRS devices
use single-distance continuous-wave light �NIRSDCWS�. To
calculate the changes in oxy-Hb/Mb, deoxy-Hb/Mb, or totalHb/Mb, the equation of a two- or multiple-wavelength
method can be applied according to the following BeerLambert law.

�OD = − logc�I/I0� = �PL��C� ,�1�

��C� = �OD/�PL,

�2�

where � is the extinction coefficient �OD / cm/ mM��=constant�, PL is the pathlength, �C� is the concentration ofabsorber �mM�, I is the detected light intensity, I0 is the incident light intensity, and OD is the optical density.
The major advantage of NIRSDCWS devices is in theirsimple design. The invention of laser diodes and LED lightsources in the NIR region, and of Si diode integrated chip
detectors, has made possible inexpensive and wearable NIR
detectors of muscle function.23,27 A major limitation to the
NIRSDCWS devices is that they currently provide only the relative values of tissue oxygenation. The main reason for a lackof quantification by NIRSDCWS is the unknown path of NIR
light through biological tissues. The pathlength of light willvary due to variations in tissue composition �adipose tissue
versus muscle, discussed later�, blood volume �can increase or
decrease heme concentrations over time�, and muscle shape�altered during muscle contractions�.
The pathlength of NIR light can be measured using otheroptical approaches, including time-resolved spectroscopy
�NIRTRS�20,24,28 and phase modulation spectroscopy
�NIRPMS�.29–31 NIRTRS uses expensive single photon detectors to measure the time the light spends in the tissue, while
NIRPMS uses the change in phase of coherent light to determine the time the light spends in the tissue. These approaches
provide absolute values of oxygenated and deoxygenated
Hb/Mb and Hb/Mb O2 saturation �SO2� in the skeletal
muscle. Spatially resolved NIRSRCWS �NIRSRCWS�32,33 provides relative changes in Hb/Mb and absolute values of SO2.
NIRSRCWS using multiple light sources coupled to one detec-

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tor solves multiple equations for pathlength. These approaches have been used in the study for skeletal muscle oxygenation and metabolism, and technological improvements
will make these approaches more practical in the future.
What is known about the pattern of the light path from thelight source to the detector is that it follows a banana-shaped
curve, in which the penetration depth into the tissue is approximately equal to half the distance between the lightsource and the detector.23 If light source-detector separation
was set to be 3 cm, penetration depth would be 1 to 2 cm andthe measured volume would be approximately 4 cm3.20 Usually, light source-detector distance ranges from12 to 50 mm.34–37 Subcutaneous adipose tissue thickness
greatly influences the light pathlength and makes it difficult toquantify tissue oxygenation, especially in the measurementsof muscle oxygenation from the skin surface.11,32,38–40 The
influence of adipose tissue thickness on the NIR spectra ofhuman muscle was studied by Monte Carlo simulations of a
two-layer structure and with phantom experiments.41 The
study suggested that subject-to-subject variation in the fat optical coefficients and thickness can be ignored if the fat thickness is less than 5 mm when the source-detector separation is
40 mm. Other studies indicated that for a fat thickness of
5 mm, the signal intensity reduces approximately by 0.2
�80% signal of zero fat thickness� with a light source-detector
separation being 30 to 40 mm, and further reduces by 0.3 to
0.6 with a separation of 15 to 20 mm, respectively.39,42 The
correction curve is presented for the influence of an adipose
tissue thickness ranging from 0 to 15 mm with a sourcedetector separation being 15 to 40 mm.39,42,43 The curve wasobtained from the results of both Monte Carlo simulation andin-vivo experiments.39,42

S = exp�− �h/A1�2� − A2G��, �� ,pathlength should be extensively examined in a wide range of
exercise mode/intensity and among varying subjects.
A technological limitation to the use of NIRS is the similar
absorption spectra for Hb and Mb. This makes it difficult todistinguish between the two by the optical properties alone. A
number of studies have taken advantage of 1H-magnetic resonance spectroscopy � 1H-MRS� measurements of Mb45–47 toestimate the relative contributions of Hb and Mb to the total
NIR signal. Combined 1H-MRS and NIRS studies of canine
muscle during exercise in normoxic and hypoxic conditions
concluded that the NIR signal came 65% from Hb and 35%
from Mb.48 As canine muscle contains more Mb than humanmuscle, this suggests more than 65% of the signal from human muscle comes from Hb during normoxic conditions. During ischemia, MbO2 levels appear to decline only after
4 min,49 while NIRS measured oxygen signals decline almost
immediately and reach near maximal levels at 4 min.50,51
From this, Ferrari, Mottola, and Quaresima suggested that
NIRS-measured SO2 values would reflect predominantly �atleast 80%� HbO2 saturation during exercise in humans.2 A
simulation experiment based on combined measurements of1
H-MRS and NIRS concluded that the overall NIR signal
would be greater than �50% Hb.52 In contrast, Tran et al.
reported a greater contribution of Mb signal than Hb to theoverall NIR signals in a study using 1H-MRS.53 The differing
conclusions from these studies highlight the need for additional studies to clarify not only the issue of the contributionof Mb to the NIR signal, but also the kinetics and the amountof Mb desaturation during exercises under different
conditions.54 To acknowledge this concern, many studies
present NIRS-measured oxygen saturation as HbO2 / MbO2.
For simplicity, this work presents oxygenated Hb/ Mb expressed as O2Hb, deoxygenated Hb/ Mb as HHb, and total
Hb/ Mb as tHb.
Recent advances in NIRS technology have included the
addition of multiple-source detector pairs to “image” skeletal
muscle. This has been done to take advantage of classicalstudies that have shown regional differences in skeletal
muscle oxygenation and metabolism in different locations
within a muscle.55 Several multiple-channel NIR imaging systems have been developed to detect regional differences inmuscle oxygenation.43,56–62 By simultaneously collecting datafrom multiple muscle regions, these devices avoid the variability caused by position dependent differences in muscle
oxygenation that plague all single location measurements. Imaging devices also allow the study of regional differences in
how skeletal muscle responds to exercise. The challenge of
NIR imaging systems is how to evaluate the much greater
amounts of information that are collected. The application of
NIR imaging technology to the study of exercising muscles is
illustrated in Fig. 1.

�3�

where S is normalized measurement sensitivity, h is adipose
tissue thickness, G�� , �� is a gamma distribution, and theconstants A1, A2, �, and � at a light source-detector separation of 15 mm are 6.9, 1.15, 7.86, and 0.80, respectively.
Considering that the value of S is determined in practice only
by h, then the corrected values are obtained by dividing themeasured values by S. A qualitative description of reduced
NIRS signal intensity by a larger adipose tissue thickness was
illustrated in a previous review.11
In NIRSDCWS measurements, there is the assumption thatpathlength does not show any significant change during exercise, recovery, and other intervention periods, otherwise thevalues obtained are either underestimated or overestimated, as
is shown in Eqs. �1� and �2�. During and after the end ofarterial occlusion, the changes in pathlength of the forearmmuscle ranged from −8.3 to −2.1% at 780 nm, and from −2.2
to 0.74% at 830 nm.28 Changes in pathlength were less than
10% during arterial occlusion with maximum voluntary contraction �MVC�.24 Differential pathlength factor �DPF� in thethigh muscle decreased slightly, but significantly from baseline �DPF at 690 nm= 5.22; DPF at 830 nm= 4.49 on average� to peak cycle exercise �DPF at 690 nm= 4.88; DPF at
830 nm= 4.27 on average� �−6.5% at 690 nm and −4.9% at
830 nm�.44 For an accurate evaluation of muscle oxygenation
during arterial occlusion, exercise, and recovery, changes in
Journal of Biomedical Optics

3

Types of Measurements Made on Skeletal
Muscle Using Near-Infrared Spectroscopy

3.1 Muscle Oxygenation
The most common measurement made with NIRS is muscle
oxygenation, or the fraction of Hb that is bound to oxygen.
Relative changes in O2Hb, HHb, and tHb are also reported.
Because of the difficulty in quantifying NIRSDCWS, muscle

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Fig. 1 Near-infrared �NIR� images from the quadriceps muscles before, during, and after intermittent isometric knee-extension exercise
�IKEx�. The NIR imaging system had 200 channels that covered a
45 cm� 15 cm2 area. The top left image indicates the approximate
location of specific muscles. Contractions 1, 3, and 5 indicate images
obtained during a series of 3-s duration contractions at 50% of maximum voluntary contraction �MVC�, with one second rest in between.
The 15-s contraction shows data at the end of a continuous 15-s
MVC. The recovery image was obtained 10 s after the last contraction. These images demonstrate the spatial differences seen withinmuscles during exercise and recovery. The detailed description of thesystem and the source-detector arrangement are described in a previous paper.42 O2Hb is oxygenated hemoglobin and myoglobin; HHb isdeoxygenated hemoglobin and myoglobin; and tHb is total hemoglobin and myoglobin.

Fig. 2 An example of how to quantitatively calibrate the NIRS signal.
Changes in phosphocreatine �PCr� and oxygenated hemoglobin andmyoglobin �O2Hb� in the forearm muscle were measured during
15 min of arterial occlusion by magnetic resonance spectroscopy andnear-infrared spectroscopy. The detailed description of the methods is
described in a previous paper.50 Copyright �c� The American Physiological Society. Reproduced by permission of the publisher.

A simple and common method of calibrating NIRSDCWS
signals is to use the range of muscle oxygenation caused byarterial occlusion followed by reactive hyperemia.23 The arterial occlusion method is based on the assumptions that
5 to 6 min of ischemia will result in the complete disappearance of O2Hb, and that the reactive hyperemia after occlusion
will almost completely eliminate HHb. So while O2Hb and
HHb in arbitrary units may vary between measurement sites
and individuals, the occlusion calibration will account forthese changes. Quantitative calibration of NIRSDCWS signal ispossible in a combination with MRS measurement by applying a 15-min ischemia to the muscles �Fig. 2�.50 The rate of
decline of muscle O2Hb during ischemia can be comparedwith that of muscle PCr in mM per second or a conversion tomMO2 per second. As a result, this method provides quantitative values of both muscle oxygen store and muscle VO2
�mVO2�.
Several studies reported the validity of NIRS-measured
O2Hb and HHb signals in animals and humans under steadystate conditions. Wilson et al. demonstrated a linear relationship between NIRS measurements and venous SO2 �SvO2�
using an in-situ canine muscle preparation.101 Shiga et al.
found a strong linear relationship �r = 0.934; P = 0.01� between the change in the HHb signal and arterial SO2 �SaO2�
in a hypoxic-dog model.27 Mancini et al. found muscle oxygenation and SvO2 of human forearm muscles to be closely
related during exercise.102 They also demonstrated that muscle
oxygenation level decreased with an intravascular norepinephrine administration, and increased with a vasodilator �nitroprusside� administration. Muscle deoxygenation was quantified during resting arterial occlusion in human skeletal

oxygenation is usually expressed in arbitrary units �opticaldensity �OD��, �M � cm or �M �using DPF� sourcedetector spacing� for O2Hb, HHb, and tHb. A wide variety ofskeletal muscles have been evaluated using this approach, including the back extensor muscles,63–66 gluteus maximus,67,68
vastus lateralis,44,69–72 vastus medialis,70 rectus femoris,70,71
biceps femoris,68 calf,72–76 dorsiflexors,77,78 respiratory
muscles,79 trapezius,34,80,81 deltoid,82 triceps,83,84 biceps
brachii,85,86 extensor carpi radialis brevis,87 forearm flexors,88
thenar muscles,89 brachioradialis,90 and masseter muscle.91
Some researchers have used NIRS at multiple sites, such as
vastus lateralis versus serratus anterior92 and vastus lateralis
versus rectus femoris,73,93 to obtain a clearer understanding ofphysiological changes in the various tissues during exercise.
Most studies have evaluated muscle oxygenation changes during aerobic types of exercise, but several studies have also
examined high intensity94,95 or resistance types of
exercise.96,97 While most of the information obtained pertains
to muscle oxygenation, there are several studies that havedocumented the changes in tHb during exercise.98,99 Whilemost studies have evaluated muscle oxygenation changes ofthe exercising limb some researchers have studied inactive
limb muscle oxygenation during dynamic exercise of theother limb.83,100
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3.2 Muscle Oxygen Consumption and Muscle Blood
Flow

muscles using NIRTRS. In a study using NIRTRS, muscle
deoxygenation �SO2-TRS� during arterial occlusion wascompared to SvO2 and interstitial partial pressure �PintO2�.28
At the end of occlusion, SO2-TRS �24.1± 5.6% � agreed with
SvO2 �26.2± 6.4�; and PintO2 �14.7± 1.0 Torr� agreed with
PvO2 �17.3± 2.2 Torr�. Thus, there are several studies thathave validated NIRS measurements relative to established invasive methods.
However, there have been a number of studies that havefailed to validate NIRS measurements. Both Costes et al. and
MacDonald et al. reported discrepancies between the NIR signal of the vastus lateralis and the femoral SvO2 during acycling exercise under normoxic conditions, while a correlation between the two parameters was reported under hypoxic
conditions.103,104 A possible explanation for the discrepancies
is that the NIRS signal contains information of arterioles, capillaries, venules, and intracellular Mb, and that the O2 gradient from an arteriole to venule is large in normoxic conditions, such that variations in blood volume from arteriole tovenule could alter the NIRS signal without change in venous
oxygen signals.11 The lower oxygen levels during hypoxic
conditions would reduce this effect. However, further researchis needed to clarify NIRS signal contribution from arterioles,
capillaries, venules, and Mb under varying oxygenation status
and in varying measurement protocols.
Recently, good association was found between regional
quadriceps oxygenation at three different measurement sites
and SvO2 during one-legged dynamic knee extension exercise, even under normoxic conditions.93 It may be that byusing multiple measuring locations, the NIRS signal shows
better agreement with the entire extremities SvO2. A good
relationship was also found between vastus lateralis oxygenation and femoral arterio-venous O2 difference �a-vO2D� during one-legged dynamic knee extension exercise under normoxic as well as hypoxic and hyperoxic conditions.7 Thus, itis broadly accepted that the NIRS-oxygenation/deoxygenation
signal has considerable agreement with the changes in SvO2
and/or a-vO2D under varying oxygenation status of the human muscles.
In nonsteady-state conditions, such as at the onset of exercise and in recovery after exercise, changes in muscle oxygenation determined by NIRS provide relevant information on
muscle oxidative function. The rate of deoxygenation at theonset of exercise,105 recovery time of muscle reoxygenation
after submaximal to maximal exercise,23,106–110 and the rate ofreoxygenation after brief high intensity MVC exercise111 areamong indicators for evaluating muscle oxidative capacity.
These studies have reported good agreement between fasterPCr recovery kinetics and faster oxygenation kinetics measured with NIRS. A different outcome was obtained after
maximal short-duration isometric exercise, where higher oxidative capacity muscle �faster PCr kinetics� was inversely related to the rate of muscle reoxygenation after the exercise.111
The result of this study was attributed to the hypothesis thatmuscle reoxygenation rate after this type of short high intensity exercise may be influenced more by VO2 than by DO2,
when O2 demand is still high and O2 supply is not fully
activated.
Journal of Biomedical Optics

3.2.1 Transient arterial occlusion method
Evaluation of muscle energy metabolism using NIRS is difficult, because the measured oxygenation levels do not specifically reflect mVO2; rather, they reflect the balance between
muscle DO2 in relation to mVO2. To dissociate mVO2 fromDO2 using NIRS, two approaches have been used; the transient arterial occlusion method and the venous occlusion
method. The transient arterial occlusion uses 10 to 30 s ofarterial occlusion provided by a pneumatic tourniquet to interrupt DO2 to the monitored muscle.26,50,112–116 Measurements of resting mVO2 using this approach in the forearmmuscles of young health males was found to have a small
amount of variability �23.0± 1.2% / min�,50 and to be consistent between studies by different investigators.51 NIRTRS has
also been used to measure resting mVO2, providing results inabsolute units �0.82 �M s−1�.28 The transient arterial occlusion method has also been used to measure forearm muscle
metabolism during exercise.50 Varying moderate intensities
were used to provide a range of mVO2 levels, and resulting
mVO2 values were compared to simultaneous MRS measurements of phosphorus metabolities. A significant correlation
was found between NIRS measured mVO2 and MRS measured PCr �r2 = 0.99, p � 0.01�, and ADP �r2 = 0.98, p � 0.01�
concentrations. The linear relationships between exercise intensity and the NIRS and MRS measured indicators of mVO2
supports both the thermodynamic117,118 and kinetic119 regulation models of mitochondrial respiration in skeletal muscle.
Validation of NIRS measurements of mVO2 have been
performed using MRS measurements of PCr kinetics, as wellas measurements of whole body VO2 performed by measuring expired gas concentrations. NIRS measured mVO2 using
the transient arterial occlusion method was significantly related to the rate of PCr recovery, a biochemical process of
ATP resynthesis via oxidative phosphorylation after muscle
contractions �r = 0.965�.115 Repeated transient arterial occlusions after exercise can provide successive mVO2 values, information that is basically similar to that determined from PCr
recovery kinetics,117,120–123 an indicator for muscle oxidative
capacity. Thus, the time constant for mVO2 recovery is anindicator for evaluating muscle oxidative capacity �Fig. 3�.124
NIRS measured muscle oxygenation was also compared topulmonary O2 consumption �pVO2� in 16 healthy males during an exercise tolerance test on a cycle ergometer.125 A significant positive correlation was observed between HHb andpVO2 �r = 0.893 to 0.986�, and a negative correlation between pVO2 and O2Hb �r = 0.726 to 0.978�. There are several reports indicating that: 1. oxygenation of forearm flexor
muscles closely reflected the exercise intensity and the metabolic rate determined by MRS during exercise112,126,127 andduring recovery,112,126 and 2. that muscle oxygenation level�percent of arterial occlusion� showed a linear relationshipwith mVO2, though in a limited range �3.2� mVO2 � 13.3
fold of resting�, during exercise �Fig. 4�128 and recovery.
These studies suggest that the initial rate of muscle deoxygenation during transient arterial occlusion is a direct measure of
mVO2, and that muscle oxygenation level itself is a reflectionof mVO2.

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Fig. 4 Relationship between muscle oxygenation level and muscle
oxygen consumption �mVO2� in the calf muscle during incremental
intermittent isometric plantar flexion exercise �IPFx�. Changes inmuscle oxygenation level and mVO2 in the calf muscle were measured during IPFx �6-s contraction/4-s relaxation�. The subjects performed IPFx, starting at 10% of maximum contraction �MVC� until
exhaustion. The value of mVO2 was measured by transient arterial
occlusion method. Muscle oxygenation level was normalized to theoverall changes during ischemia. The fall in oxygenation level reflected increases in exercise intensity, and the NIRS measurements
demonstrate the increased muscle oxygen consumption results fromincreased exercise intensity. There is a linear relationship between
muscle oxygenation level and mVO2 in a certain range �3.2
� mVO2 � 13.3, determined by the best fit by a piece-wise linear regression model� during this type of exercise.

Fig. 3 An example of the repeated transient arterial occlusion methodof measuring muscle oxygen consumption �mVO2�. �a� Transient arterial occlusion was applied at rest and then at various times after exercise. As highlighted by the arrows, the slope of desaturation of the
O2Hb signal was less rapid during rest than after exercise, consistent
with the higher rates of mVO2 after exercise. �b� Calculated mVO2
values after exercise show an exponential decline consistent withchanges in phosphocreatine levels from magnetic resonancespectroscopy.

3.2.2

mBF measured immediately after the end of the exercise reflect the mVO2 and mBF values during exercise.

3.2.3 Other methods for measuring muscle
oxygen consumption and blood flow
with near-infrared spectroscopy
A variation of the transient arterial occlusion method is to takeadvantage of the ischemia produced during high intensity isometric muscle contractions. Contraction-induced compression
and crimping of blood vessels produces ischemia without theneed for externally applied arterial occlusion. Using the ischemic exercise method, the rate of deoxygenation measured
at the onset of intermittent �5-s contraction/5-s relaxation�
isometric exercise at 50% MVC followed an exponential timecourse with a time constant of 42.0± 12.5 s �mean ±SD�.126
The NIRS measurements were in good agreement with thetime constant of the decrease in PCr measured simultaneously�48.2± 10.2 s�. Muscle blood flow can be quantitatively,
though invasively, measured using NIRS with an indocyanine
green �ICG� dye infusion.130 More recently, NIR diffuse correlation spectroscopy �NIRDCS� and diffuse reflectance spectroscopy �NIRDRS� have been developed for measuringchanges in muscle oxygenation and mBF, and are able tocompute mVO2.131 NIRDRS methodology uses the unique approach of monitoring mBF by measuring the optical phase

Venous occlusion method

The venous occlusion method can be used to determinemVO2 and muscle blood flow �mBF� by applying thesametechniqueusedinconventional
venousplethysmography.114,129 Briefly, transiently applied low cuff
pressures �typically 60 mm Hg� occlude venous outflow
while minimally obstructing arterial inflow. The increase indeoxygenated blood is then used to calculate mVO2 and mBF.
NIRS-determined measures of mBF and mVO2 by the venous
occlusion method have been shown to agree with traditional
measurements using plethysmography114,129 and the Fickmethod.114,116,129 The advantage of NIRS is that it is capableof providing information about mVO2 and mBF in a local
area of a muscle. One of the difficulties in validating NIRS
studies are that conventional methods such as plethysmograpy, Doppler sonography, and the Fick method cannot
provide localized measurements. The disadvantage of using
the venous occlusion method as well as the transient arterial
occlusion method is that exercise must be interrupted to makethe measurements. The assumption is that both mVO2 and the
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shift caused by moving blood cells. NIRDCS methodology isable to monitor tissue optical properties, such as the absorption coefficient ��a� and reduced scattering coefficient ��s��,
without applying arterial occlusion or venous occlusion to alimb. The ability to measure mVO2 and the mBF without
occlusion is a strong potential advantage, although an extensive validation study in humans is needed before broadly applying this technique to practical and clinical use.

exercise-training-induced adaptations in muscles can be determined by NIRS.182 Training did not change the pattern ofmuscle oxygenation, though a significant relationship was
found between blood lactate and muscle oxygenation at theend of exercise. Ichimura et al. examined the interaction ofage and habitual physical activity on recovery time of muscle
oxygenation following maximal cycling exercise.107 They
found that NIRS measured recovery time was prolonged withaging, regardless of habitual physical activity levels. However, habitual physical activity may prevent the age-related
prolongation in the recovery time of muscle oxygenation after
maximal cycling exercise. Changes in skeletal muscle oxidative function were measured by NIRS in immobilized forearmmuscles, evaluating the preventive effect of the endurance
training protocol on deterioration of skeletal muscle.124
Muscle oxidative function was determined by the time constant for the recovery of mVO2, applying repeated transient
arterial occlusions after exercise. This study suggested thatNIRS can be used clinically for noninvasive monitoring of
deconditioning and reconditioning of skeletal muscle oxidative functions.
NIRS has also been used for evaluating acute and chronic
�training� effects of exercise on muscle oxygenation for athletes such as endurance cyclists,13,149,152,183–186 sprinters,187 endurance runners,152,187 swimmers,188 triathletes,25,152,183 soccer
players,189 resistance-trained athletes,190 skaters,191 and crosscountry skiers.192 What has emerged from these studies is thatseveral NIRS derived indicators can be useful for evaluating
the effect of exercise training on muscle metabolism. These
include the recovery time for muscle reoxygenation and thetime constant for mVO2 recovery after exercise in healthy
subjects. However, most of the studies on the influence of
training have been performed using cross-sectional study design, and there is a need for more longitudinal studies on
exercise training that use NIRS measurements. Further, if
NIRS is to be used in examining the alteration of intervention
for longitudinal studies, it is imperative that the reliability ofthe technique be demonstrated. Currently there is limited
research193,194 that has documented the reliability of NIRS
during exercise.

3.3 Other Indicators
NIRS is able to provide other indicators than those mentioned.
SvO2 is estimated by measuring changes in O2Hb over tHb
during venous occlusion,132 and by the method based on the
respiration-induced oscillations of the NIR absorption in tissues, named spiroximetry.30 A method for measuring the compliance of the microvascular superficial venous system of thelimb using NIRS has been developed.133 More indicators havebeen proposed and used specifically in clinical science, whichis addressed in the following section.

4

Near-Infrared Spectroscopy in Combination
with Other Methodologies

NIRS has been used in combination with a large variety ofother invasive and noninvasive methodologies to evaluate
physiological and pathological changes in peripheral muscle
and/or whole body metabolism. The noninvasive methods
that have been used in combination with NIRS in recent studies �2000 to 2006�, include: MRS,88,128,134,135 magnetic resoelectromyographynance
imaging�MRI�,78,135–138
68,71,136,139–143
ultrasoundsonographyand�EMG�,
Doppler,35,144–147 plethysmography,76,148 respiratory gas
transcutaneous
oxygenpressure
analysis,98,149–159
measurement,160–162 laser Doppler skin blood flow and skinoxygenation measurements,163–167 pulse oximetry,152,168
mechanomyography,66,169,170 muscle force and powermusclefatigueindex
measurements,78,94,171–173
measurements,77 ankle-brachial �blood pressure� index
measurements,74,75 and sweat response measurements.174 The
invasive methods that have been used in combination with
NIRS
inrecentstudies
include:bloodgasmusclesympathetic
activity
measurement,93,175,176
measurement,145 blood biochemical measurements �including
lactate�,34,69,98,177 muscle biopsy,34,150,178 intramuscular presand
positronemissionsuremeasurements,169,179
tomography.180,181 Among them, substantial numbers of studies have been conducted to examine the relationship between
respiratory gas indicators and NIRS indicators.151–155,157 Recently, there have been several studies to evaluate oxygen
uptake kinetics during exercise using NIRS indicators such as
HHb delay, HHb mean response time, and HHb time constantat the onset of exercise.35,149,150,156

5

5.2 Patients
5.2.1 Peripheral vascular disease
A number of studies have used NIRS to evaluate patients with
peripheral vessel disease �PVDs�. Peripheral arterial disease
�PAD� involves partial occlusion of arterial flow, usually tothe legs, that impairs function. The impaired function can bequite severe, and is termed intermittent claudication. PAD has
been shown to produce impaired oxidative metabolism,195 despite observations of increased mitochondrial enzyme
content.196 The increase in mitochondrial volume indicates anadaptive response to the low DO2.
A consistent finding with NIRS measurements in PAD patients is slower rates of calf reoxygenation after
exercise.74,75,197–199 The magnitude of the impairment could bevery large, with recovery rates being up to five times slower
than healthy control subjects.109 Good correlation was foundbetween measurements of Doppler pressure waveforms andankle arm systolic pressures �AAI� and the NIRS recovery
time constant.109 An important aspect of this study was that

Examples of the Use of Near-Infrared
Spectroscopy in the Assessment of Human
Skeletal Muscle Function

5.1 Healthy Subjects
A number of different studies have evaluated the influence ofincreased activity as well as decreased activity on muscle
function using NIRS. Costes et al. examined whether
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acute deep vein thrombosis from 1 to 12 months after treatment. These indicators were able to distinguish between successfully treated patients and those remaining with deep veinthrombosis after a period of 12 months.

5.2.2 Heart diseases
A number of studies have used NIRS to evaluate skeletal
muscle in patients with heart disease. In addition to functional
deficits associated with impaired cardiac function, heart disease has also been shown to be associated with impaired
muscle metabolism.204 This decrease in muscle metabolism
has been linked to reduced exercise tolerance and decreased
pVO2, and increased risk of cardiovascular disease.205,206
NIRS measured muscle oxygenation kinetics have beenstudied in patients with congestive heart failure�CHF�.101,106,207–209 Wilson et al. concluded that CHF patients
exhibited greater deoxygenation compared with the controls,
due partly to the pump failure of the heart and the consequent
skeletal muscle hypoperfusion. A correlation between changes
in tHb and leg vessel conductance was found in patients withand without cardiac dysfunction during submaximal dynamic
exercise, but there was some discrepancy between the NIRS
and leg vessel conductance measurements at near maximal
exercise levels.148 Recently, skeletal muscle oxygenation was
evaluated in heart transplant recipients �HTR�.151 The changes
in HHb during submaximal exercise were steeper in HTR
than in the control subjects, while the peak value of HHb was
lower in HTR. The authors suggested that NIRS allows thedetection of an impairment of both DO2 and O2 extraction in
the HTR skeletal muscle.
To elucidate with heart failure, NIRS has been used toassess respiratory muscle deoxygenation in patients with CHF
or HTR during leg cycling exercise.159,210,211 The rationale forthese studies is that exercise-induced dyspnea is common inpatients with heart disease. The NIRS measurements wereconsistent with respiratory muscle hypoperfusion combinedwith the greater work of breathing in patients with CHF.

Fig. 5 An example of NIRS measurements of the rate of reoxygenation
after exercise in patients with peripheral arterial disease �PAD�. �a�Four measurements from one elderly male subject with PAD in only
one leg. Note that multiple trials on one leg produce very similar
results, while the diseased leg shows a much slower rate of recovery.
�b� The distribution of reoxygenation rates in a population of older
subjects with suspected PAD by self report. Note the wide and continuous range of responses. Subjects with faster recovery rates wereshown to be normal on clinical examination, while those with slower
recovery rates had PAD. �c� Recovery rates for healthy subjects forcomparison. Copyright �c� The Gerontological Society of America.
Reproduced by permission of the publisher.

5.2.3 Chronic obstructive pulmonary disease
Patients with chronic obstructive pulmonary disease �COPD�
frequently develop skeletal muscle and vascular abnormalities
as complications of their disease, similar to patients with heartdisease.212,213 These observations suggest that deteriorated
oxidative metabolism is related to lowered muscle oxidative
capacity, elicited both by chronic inactivity and abnormal
metabolic regulation, as well as reduced DO2 to muscles. Evidence for a peripheral mechanism for exercise intolerance issupported by studies that have shown that exercise capacity
was improved with endurance exercise training in patientswith COPD.213
NIRS measured recovery of oxygen saturation after exercise has been shown to correlate with expired air pVO2 off
kinetics in COPD patients.214 In a study measuring oxygen
saturation in skeletal muscle with NIRS during incremental
cycling exercise in 16 COPD patients and 10 age-matchedhealthy subjects, the slope of SO2 was significantly steeper in
COPD patients than in healthy subjects. The rate of the decrease in SO2 with increasing exercise intensity in COPD
patients significantly correlated with body mass index �BMI�,
suggesting that BMI contributes independently to the change

the degree of impairment appeared to be continuous, demonstrating that clear separation of healthy and diseased people isdifficult �Fig. 5�. Komiyama et al. successfully classified patients with a varied severity of PVD by using patterns of calf
oxygenation kinetics during treadmill exercise andrecovery.198 Impaired muscle O2 usage at the exercise onset
was also observed in PAD patients.200 Interestingly, Mohler
et al. reported an interaction between PAD and the presence orabsence of diabetes mellitus �DM� using changes in muscle
capillary blood expansion and reoxygenation recovery.75 Capillary blood expansion was reduced in patients with DM, regardless of the existence of PAD; therefore, this parameter
might be a good indicator for evaluating vascular impairment
in DM patients. Taking into account that not all studies haveshown positive results, NIRS appears to be able to identify
and quantify the severity of patients with PAD.
Several studies have evaluated peripheral venous occlusive
diseases using NIRS.201–203 A calf venous blood filling index
was tested on standing patients, and the calf venous retention
index was monitored after exercise testing in patients with
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of muscle SO2 with exercise.215 NIRS was used to obtain thetime constant of the deoxygenation recovery signal �HHb-Tc�
during three constant work exercise tests, one below and two
above the lactic acidosis threshold.110 This study found significant correlations between changes in oxidative enzyme activity and changes in HHb-Tc and endurance time. It was
concluded that leg training accelerates the speed of reoxygenation of the vastus lateralis muscle after exercise. This improvement is correlated to changes in the oxidative
enzymes.110

fered from normal controls. Six SCI patients underwent electrical stimulation training �45 min daily for 3 days per week
for 10 weeks� with different loads on muscle oxygenation of
the paralyzed lower limbs using NIRS.178 NIRS detected attenuated muscle deoxygenation after static training comparedwith prevalue.

5.2.6 Renal failure
NIRS has been used to evaluate the potential for vascular andmetabolic dysfunction in patients with renal failure. Forearm
vasodilator responses to 3-min arterial occlusion were measured by NIRS in patients receiving hemodialysis.171 Vasodilator responses estimated by the ratio of the maximum valueof O2Hb after release of arterial occlusion to its minimum
value before the release were significantly smaller in the renal
failure patients compared with those in the controls �132± 20
versus 161± 27%, p � 0.05�. No improvement in the vasodilator responses was observed after exercise training. Muscle
oxygenation and metabolism were examined by using NIRSin ten children with end-stage renal disease �ESRD� before
and after renal transplantation �ages 12.4± 3.1 years� and inten controls �ages 12.8± 2.6 years� during submaximal hand
grip.81 The rate of initial decrease in oxygenation during transient arterial occlusion after exercise relative to the value atrest �S2/S1� and recovery time �TR� after exercise was used as
an indicator of O2 delivery to the muscle and aerobic capacity.
S2/S1 and TR after exercise improved significantly after renaltransplantation �P � 0.01 and P � 0.05, respectively� andwere not significantly different from those of controls. Thesestudies show that NIRS is able to detect muscle hypoperfusion in patients with renal failure as well as the functional
alterations of muscle oxidative metabolism that occur after
renal transplantation. The noninvasive nature of the NIRS
measurements is an advantage in the study of children withrenal failure as well as children with other diseases.81,208,225

5.2.4 Muscle diseases
NIRS measurements have been used to study patients withneuromuscular disorders. Exercise intolerance and fatigue arecommon complaints in patients with neuromusculardisorders.216,217 Although neuromuscular disorders encompass
a variety of pathologies, physical deconditioning often contributes to the limited exercise capacity in these chronic disorders. Previous studies using MRS have shown the utility ofmeasuring muscle energetics in patients with cytochrome b
deficiency.218–220
Using NIRS, an increase in muscle oxygenation at the onset of treadmill exercise has been detected in patients withcytochrome c oxidase deficiency,221 in patients with mitochondrial myopathy caused by mitochondrial DNA
mutations,222 and in patients with Friedreich’s ataxia.223 This
paradoxical oxygenation is due to the combination of impaired mVO2 along with normal physiological increase ofDO2 �vasodilatation�, stimulated by muscle pump and/or
myogenic activity. Muscle hyperoxygenation measured withNIRS has been used as a diagnostic in many cases of suspected mitochondrial disease. Quite recently, patients withmitochondrial myopathies �MM� or myophosphorylase deficiency �McArdle’s disease, McA� were tested for changes in
the capacity for O2 extraction, maximal aerobic power, andexercise tolerance during cycle exercise using NIRS.69 HHb
peak �percent of arterial occlusion�, an index of O2 extraction,
was lower in MM �25.3± 12.0% � and McA �18.7± 7.3% �than in control subjects �62.4± 3.9% �. These results suggestthat NIRS is a promising tool for monitoring noninvasively
the metabolic impairment in the settings of follow-up and in
the assessment of therapies and interventions.

5.2.7 Diabetes mellitus
NIRS has been used to evaluate the potential for vascular andmetabolic disorders in skeletal muscle of patients with either
type-1138,225 or type-2 diabetes mellitus �DM�.138,225–227 After
exercise, NIRS measured muscle reoxygenation rates as wellas MRS measured PCr recovery rates were slower in patientswith type-2 DM. Exercise duration correlated negatively withdeoxygenation rates and HbAlc levels, while reoxygenation
times correlated positively with HbAlc levels.227 In patientswith type-1 DM, the NIRS measured muscle reoxygenation
rate correlated with percentage body fatness, visceral and abdominal subcutaneous fat volume, and dietary fat intake, but
not with the duration of diabetes nor HbAlc.138

5.2.5 Spinal cord injury
NIRS has also been used to evaluate the extensive changes
that occur to paralyzed muscles in the lower leg with spinal
cord injury �SCI�. Bhambhani et al. found a lower degree ofmuscle deoxygenation during maximal exercise and fasterchanges in muscle deoxygenation with respect to the pVO2
during functional electrical stimulation cycle exercise in SCI
patients when compared to healthy subjects.86 Olive et al.
found normal rates of reoxygenation after muscle stimulation
exercise and ischemia in SCI subjects, although the SCI subjects had to have their legs warmed prior to testing to control
for temperature.224 NIRS has been used to evaluate potential
therapies for SCI. Six motor-complete SCI subjects and fourneurologically normal controls were placed on a gait-training
apparatus that enabled the SCI subjects to stand and movetheir legs passively.142 The O2Hb level gradually increased,
whereas the HHb decreased in the patients. This response difJournal of Biomedical Optics

5.2.8 Other diseases
A number of other diseases and syndromes have been studied
with NIRS. Muscle metabolism in chronic fatigue syndrome
�CFS� was measured using NIRS and MRS.228,229 These studies suggested that CFS may have altered control of blood
flow, but this is unlikely to influence muscle metabolism. Patients with chronic compartment syndrome showed greater
maximum relative deoxygenation during exercise and slower
reoxygenation during recovery than the control patients.230
Patients with traumatic acute compartment syndrome had

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lower SO2 values relative to the control patients, which wasusually normalized after fasciotomy. NIRS evaluation may
offer a rapid, noninvasive method of assessing extremities atrisk for compartment syndrome.231 Muscle perfusion and oxygen consumption have been measured in septic-shock
patients232,233 and in digit replantation patients.234

6

5. H. Owen-Reece, M. Smith, C. E. Elwell, and J. C. Goldstone, “Nearinfrared spectroscopy,” Br. J. Anaesth. 82, 418–426 �1999�.
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Conclusion

There is an increasing need to develop noninvasive and realtime methods for evaluating skeletal muscle metabolism inhumans. NIRS has been developed to fill this need, and thiswork reviews some of the studies that have evaluated skeletal
muscle oxidative metabolism and blood flow. Special reference is taken to examine the validity of the indicators determined by NIRS, and the application of these indicators formonitoring training-induced changes in oxidative metabolism
in healthy and diseased muscles. For the most part, NIRS
indicators are shown to be useful for the detection of changes
in muscle metabolism and oxygen delivery in healthy subjects, as well as in patients with various organ diseases as wellas muscle-specific disorders. The advantage of using NIRS
over invasive techniques and MRS measurement is that theequipment itself is more portable and the procedure can bedone more simply. The use of NIRS is therefore suitable forpractical and clinical use. However, the variety of NIRS
equipment that is available as well as the addition of new
developed equipment will require continued validation studies. It can be argued that there are too many NIRS derived
indices, and that standardization of testing approaches isneeded to allow for greater ease of comparison between research studies. In addition, along with applied clinical studies,basic research is still needed, such as the origin of the NIR
signal �which fractions from arterioles, capillary, and venules,
as well as from Hb and Mb�, the NIR penetration depth ormeasurement area in tissue with varying source-detector arrangement �orientation� in the multilayer model, including theeffect of nonmuscular tissue, and changes in optical properties
during a wide range of tissue oxygenation status, varying subjects, and exercise modality. Thus, NIRS technology remains
a promising and continually development methodology. We
are grateful for Jobsis’ discovery of the NIR window into
biological tissues, and we are proud to be among those who
strive to continue his legacy by advancing the research ofhuman skeletal muscle function with NIRS.

Acknowledgments
This study was supported, in part, by a grant-in-aid from theJapanese Ministry of Education, Science, Sports, and Culture.
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Journal of Biomedical Optics 12�6�, 062104 �November/December 2007�

Progress of near-infrared spectroscopy and topography
for brain and muscle clinical applications
Martin Wolf
University Hospital Zurich
Clinic of Neonatology
Biomedical Optics Research Laboratory
8091 Zurich, Switzerland

Marco Ferrari
Valentina Quaresima
University of L’Aquila
Department of Sciences and Biomedical
Technologies
L’Aquila, 67100 Italy

Abstract. This review celebrates the 30th anniversary of the first invivo near-infrared �NIR� spectroscopy �NIRS� publication, which was
authored by Professor Frans Jöbsis. At first, NIRS was utilized to experimentally and clinically investigate cerebral oxygenation. Later it
was applied to study muscle oxidative metabolism. Since 1993, thediscovery that the functional activation of the human cerebral cortex
can be explored by NIRS has added a new dimension to the research.
To obtain simultaneous multiple and localized information, a further
major step forward was achieved by introducing NIR imaging �NIRI�
and tomography. This review reports on the progress of the NIRS andNIRI instrumentation for brain and muscle clinical applications 30
years after the discovery of in vivo NIRS. The review summarizes themeasurable parameters in relation to the different techniques, themain characteristics of the prototypes under development, and thepresent commercially available NIRS and NIRI instrumentation. Moreover, it discusses strengths and limitations and gives an outlook into
the “bright” future. © 2007 Society of Photo-Optical Instrumentation Engineers.
�DOI: 10.1117/1.2804899�

Keywords: brain; muscle; near-infrared spectroscopy; near-infrared imaging;oximetry; tissue oxygenation.
Paper 07101SSR received Mar. 15, 2007; revised manuscript received May 17,
2007; accepted for publication May 30, 2007; published online Nov. 15, 2007.

1

scope of clinical use of NIRS.29 A number of recent detailed
reviews describe the use of NIRS and NIRS imaging �NIRI�
for human brain mapping15,30–36 and muscle exercise
pathophysiology.37–43
This review reports on the progress of the NIRS and NIRI
instrumentation for brain and muscle clinical applications, 30
years after the discovery of in vivo NIRS. The review summarizes the measurable parameters in relation to the different
NIRS techniques, the main characteristics of the prototypes
under development, and the present commercially available
NIRS and NIRI instrumentation. Moreover, a discussion on
the strengths and limitations of NIRS and/or NIRI and an
outlook into the “bright” future are reported.

Introduction

This review celebrates the 30th anniversary of the first in vivo
near-infrared �NIR� spectroscopy �NIRS� publication,1 which
was authored by Frans Jöbsis, who described his discoveries
in two papers published in the Journal of Biomedical Optics
22 years after his original publication.2,3Starting with the pioneering work of Jöbsis, noninvasive
NIRS was first utilized to investigate cerebral oxygenation
experimentally and clinically and, later on, muscle oxidative
metabolism. In addition, since 1993, multichannel NIRS instruments have been largely applied to investigate the functional activation of the human cerebral cortex in adults4–7 andlater in newborns.8 A number of recent detailed reviews describing the principles, the limitations, and the applications of
NIRS have appeared in the literature.9–18 The same is true forreviews describing the applications of NIRS on cerebral oxygenation monitoring in newborns and adults.19–29
The most recently available NIRS technology for monitoring cerebral oxygenation can contribute to the identification of
deficits in cerebral oxygenation. Monitoring such deficits supports certain forms of therapy in reversing cerebral oxygenation issues and thereby preventing long-term neurologicalsequelae. Recently, it has been demonstrated that quantitative
thresholds for cerebral oxygenation led to the identification of
cerebral ischemia in the adult brain and thus increased the2Papers were retrieved by the authors through different strategies. First, a search on the two databases MEDLINE and INSPEC was performed using the keywords: “near infrared,”“near infrared oximetry,” “cerebral oximetry,” “muscle oxygenation,” “optical imaging,” and/or “instrument.” The references were screened and the full texts of relevant publications
were retrieved. Next, the references of reviews were handsearched. The research was restricted to literature on the
NIRS and/or NIRI instrumentation suitable for human muscle
and brain measurements published or made available up to
February 2007. Breast imaging instrumentation was not included, because its progress has recently been reviewed.44–46

Address all correspondence to Martin Wolf, Head of Biomedical Optics Research Laboratory, Clinic of Neonatology, University Hospital Zurich, Frauenklinikstr. 10, 8091 Zurich, Switzerland; Tel: +41–44–255–5346; Fax: +41–44–
255–4442; E-mail: martin.wolf@usz.ch

Journal of Biomedical Optics

Methods

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Wolf, Ferrari, and Quaresima: Progress of near-infrared spectroscopy and topography…

In addition, three-dimensional tomography was excluded, because it is covered by another paper in honor of Professor F. F.
Jöbsis. The very recent proceedings of conferences organizedby the following societies: Optical Society of America, The
International Society of Optical Engineering �SPIE�, Organization of Human Brain Mapping, American College of Sports
Medicine, and the Polish Academy of Sciences were also consulted. Research groups known to be active in the field were
contacted for gathering further information. The Web sites of
the commercial systems were searched and visited for exploring the specifications of the instruments. After collecting all
the documentation, a consensus was made by all authors toproperly select material eligible for inclusion in this review.
The material was sorted according to the type of NIRS andNIRI instrumentation and the parameters measured. Tables
were generated to report the origin and properties of each
instrument and all the measurable parameters.

3

cient, absolute values of the chromophore concentration canbe calculated. Generally, this requires measuring light intensity and the time of flight �i.e., the time the light takes to passthrough the tissue�.
Several techniques to physically carry out the measurements have been described and applied. Table 1 summarizes
the different types of instruments and indicates key features,
advantages, and disadvantages. The parameters that can bemeasured are outlined in Table 2.
Most of the parameters are based on the measurement of
O2Hb and HHb. In addition, NIRS’s measurement of thechanges in the redox state of oxidized cytochrome c oxidase
��oxCCO�, as first proposed by Jöbsis,1 has the potential toprovide a unique method for monitoring changes of intracellular O2 delivery.9,60 Although much work has been done on
the refinement of NIRS hardware and algorithms �utilized todeconvolute the light absorption signal�, recent years haveseen a vivid discussion in the literature on the possibility ofmeasuring �oxCCO by NIRS. To improve the accuracy ofthe measurement of this NIRS parameter, most of the recent
animal61,62 and human63,64 NIRS studies have been performed
using a broadband approach with a continuous white light
spectrum.
Continuous wave �CW� means that only changes in thelight intensity are measured. Usually at least two different
wavelengths are multiplexed to obtain spectral information.
The ambient light level is also measured and subtracted by the
NIRS instrument. CW can easily be used for imaging by using
many source-detector pairs, which are distributed on the tissue of interest.15,65–70 This method only allows the continuous
quantification of relative values �except for absolute values ofvenous oxygen saturation71,72� and usually relies on the DPF
method. Another disadvantage is represented by the fact that itis relatively sensitive to motion artifacts. The advantages arethat CW is inexpensive and can be miniaturized to the extent
of a wireless instrument,73 even for imaging �Fig. 1�. In addition, in many situations �e.g., studies of functional activity ofthe brain or intervention studies for testing reactions on drugs
or changes in treatment15,32,74� relative values are sufficient�Fig. 2�.
Spatially resolved spectroscopy �SRS� is also called multidistance spectroscopy and is based on light intensity being
measured at several different source-detector distances.75,76
One problem of NIRS and/or NIRI is that the light coupling
between the optodes and the tissue is unknown, difficult tomeasure, and sensitive to changes on the tissue surface overtime. SRS techniques assume that the coupling is the same forthe different source-detector distances and, by measuring theintensity as a function of the distance, determine a parameterthat is independent of the coupling.76 This allows the determination of ratios of O2Hb to total hemoglobin �O2Hb+ HHb�and thus tissue oxygen saturation. The application of cerebral
NIRS in adults has been hampered by concerns over contamination from extracerebral tissues. Using SRS,77 the brain was
identified as the anatomic source of the signal on adult patients undergoing carotid endarterectomy. A change in brain
oxygen saturation was predominantly associated with internal
carotid artery clamping. The reason is that using a SRS approach, the superficial layers of tissue affect all the lightbundles similarly and therefore their influence cancels out.

Results

NIR from the 650- to 950-nm wavelength penetrates tissue
relatively deeply. In this region of wavelength, chromophores
such as oxyhemoglobin �O2Hb in micromolar concentration�,
deoxyhemoglobin �HHb in micromolar concentration�, cytochrome oxidase, water, lipids, and indocyanine green absorb
light. Thus their concentration can in principle be measured
by NIRS and NIRI. However, besides the light absorption, thestrong light scattering of tissue in the NIR has to be taken into
consideration. To quantify the measurements, theoreticalmodels describing light transportation in tissue have beendeveloped.47 Because a general mathematical approach is not
feasible, all the mathematical models rely on assumptions andapproximations to simplify matters.47 It is important to ensurethat these assumptions are fulfilled, when applying NIRS andNIRI.
The most widely used approximations are the differential
pathlength factor �DPF� method48–50 and the diffusion
approximation.47,51–53 The DPF method is a relatively simple
model that enables us to quantify changes in chromophore
concentration. Absolute values cannot be obtained directly by
the DPF method. Only changes in light attenuation are measured, and it is assumed that these changes reflect changes in
the chromophore concentration. If geometrical or structuralchanges occur, they will be misinterpreted as changes in thechromophore concentration, which, for instance, might occur
during motion artifacts. In addition, the DPF method assumes
that the tissue and the change in chromophore concentration
are homogeneous. To obtain quantitative values, the DPF,
which accounts for the increased pathlength due to light scattering, has to be measured or taken from the literature.54–59
The diffusion approximation of the Boltzmann transport
equation is another widely used mathematical model. The diffusion approximation has analytical solutions under the following assumptions: �1� tissue is homogeneous, �2� scattering
is much larger than absorption, and �3� the tissue has a specific geometry—infinite, semi-infinite, slab, or two-layered.47
To obtain correct values, it is again vital to observe theseboundary conditions. The DPF method is in agreement withthe diffusion approximation. The diffusion approximation canbe used to measure absolute values of the absorption and scattering coefficients of tissue and from the absorption coeffiJournal of Biomedical Optics

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lown.r.

Instrument cost

Caution for eye exposure to coherent sources

feasible on
newborns

n.a.

availablenofeasible on
newborns

n.a.

n.a.

no

criticaln.r.

moderate

easy

n.r.

mediumn.a.

1

feasible on
newborns

feasiblen.a.

nocriticalrequiredhighfeasiblerequired.

mediumfeasible

�5

low

no

no

yes, relative

no

DWS
a

feasible on
newborns

n.a.

availablenonot criticaln.r.

moderate

easy

n.r.

small

n.a.

�6

low, but deep for
SO2

yes

no

no

yes, changes

SRS CWfeasible on
newborns

feasibledifficultnonot criticaln.r.

moderate

easy

n.r.

small

n.a.

feasible on
newbornsn.a.

difficultnocritical

n.r.

high

easy

n.r.

medium

n.a.

�1

low

deep

�100

yes

yes

no

yes, absolute value

PMS MF

yes

yes

no

yes, absolute value

PMS MD

1 or 2 Channels Oximeters

feasible on
newborns

feasibledifficultnonot criticalrequired

high

easy

requiredmedium

n.a.

�6

low

yes

yes

no

yes, absolute value

TRSafeasible on
newborns

n.a.

available

scarcecriticaldepends on
instrument

some low,some highsome easy,some feasiblen.r.

some bulky,
some small

�1

�100

low

no

no

no

yes, changes

CW

feasible on
newborns

feasibledifficultscarcenot criticalrequiredvery highfeasible

n.r.

bulky

�1

�50

deep

yes

yes

no

yes, absolute value

PMS

Imagers

feasible on
newborns

feasible

not easyscarcenot criticalrequiredvery highfeasiblerequired

bulky

�1

1

low

yes

yes

no

yes, absolute value

TRSaWhen the differential pathlength factor �DPF� is included to calculate the tissue pathlength �=DPF��source-detector separation��.
CSF=cerebrospinal fluid, CW=continuous wave, DWS=diffusing-wave spectroscopy or diffuse correlation spectroscopy, HHb=deoxyhemoglobin, MD=multidistance geometry, MF=multifrequency measurement, n.a.=notavailable, n.r.=not required, O2Hb=oxyhemoglobin, PMS=phase modulation spectroscopy, SRS=spatially resolved spectroscopy, tHb= O2Hb+ HHb, TRS=time resolved spectroscopy.

Possibility to measure deep brain structures

Discrimination between cerebral and extracerebral
tissue �scalp, skull, CSF�Telemetry

Precise anatomical localization

criticaleasy

Transportability

Stable optical contact

n.r.

Instrument stabilization

very smalln.a.

Spatial resolution �cm�Instrument size

�100

low

Penetration depth with a 4-cm source-detector
separation

Sampling rate �Hz�

yes

no

Tissue O2Hb saturation measurement �SO2,%�
lowyes, pathlengthnoScattering and absorption coefficient andpathlength measurement

noyes, absolute valuenoyes, changesaDiscrete
Broadbandwavelengths second derivative

Blood flow measurement

�O2Hb�, �HHb�, �tHb�

Parameters measured and instrument
characteristics

Single-Distance CW Photometers

Table 1 Near-infrared spectroscopy and imaging instrumentation: Characteristics and main parameters directly measured.

Wolf, Ferrari, and Quaresima: Progress of near-infrared spectroscopy and topography…

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Wolf, Ferrari, and Quaresima: Progress of near-infrared spectroscopy and topography…
Table 2 Parameters measured directly and indirectly by near-infrared spectroscopy and imaging instrumentation.

Parameter

Units

Applicability
�during muscle
exercise�Modality

Delpy 1997129

�O2Hb, �HHb, �tHb,
�oxCCO,a.u., �M � cm, �M

DYes

D �by SRS�Yes

Matcher 1995,75 De Blasi 1993,1994,104,105
Quaresima 2002,131 Cuccia 200580

D �by PMS�Yes

Fantini 199576

D �by TRS�Yes

Oda 1996132

D �by calibration�

Yes

Benni 2005133

Second differential

No

Matcher 1994, Cooper 199658,134

I �by VOM�No

Yoxall 1997135

D

No

Franceschini 2002136

�M

D �by PMS�YesFranceschini 1997126

a.u.

D �by DWS�No

Durduran 200395

mL/ 100 mL/ minI �by VOM�NoDe Blasi 1994105

I �by ICG�Yes

Boushel 2000137

�M / minI �by VOM�No

Wolf 2003106

mL/ 100 g / minI �by VOM�NoDe Blasi 1993, 1994104,105

Tissue O2 saturation%

Muscle SvO2%

Muscle tHb

Muscle Hb flow
Muscle VO2

Tisdall 200764
Grassi 1999130

OI

Muscle BF

Author�reference�I �by AOM�
Muscle recovery time

s

D

No

Chance 1992138

Muscle compliancemL/L/mmHg

I

No

Binzoni 2000139%

I �by VOM�No

Yoxall 1995140

D

No

Wolf 199772

D �by PMS�Yes

Choi 200478

I �by O2 swing�

No

Wolf 2002141

I �by O2 swing�

No

Wyatt 1990,101 Wolf 2002141

SRS and second differential

No

Leung 2006142

I �by ICG�No

Hopton 1999143

a.u.

D �by DWS�No

Durduran 2004,96 Li 200594

mL/ 100 mL/ minI �by O2 swing�

No

Edwards 1988100

Cerebral SvO2

Cerebral tHb

�M

Cerebral BV

Cerebral BF

mL/ 100 mL

Roberts 1993,144 Keller 2000145

I �by ICG�Cerebral VO2

mL/ 100 g / min

Combination cerebral
SvO2 and BF

No

Elwell 2005146

�=Relative changes from arbitrary baseline, AOM=arterial occlusion Method, a.u.=arbitrary units, BF=blood flow, BV=blood volume, DWS=diffusing-wave spectroscopy, D=directly, I=indirectly, ICG=indocyanine green, OI=oxygenation index ��O2Hb-�HHb�, oxCCO=cytochrome c oxidase redox state, PMS=phase modulation
spectroscopy, SRS=spatially resolved spectroscopy, SvO2=venous O2 saturation, tHb= O2Hb+ HHb, TRS=time resolved spectroscopy, VO2=oxygen consumption,
VOM= venous occlusion method.

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Fig. 2 A sample of a functional NIRs measurement with a 100-Hz
sampling rate in a healthy neonate. The upper trace �red� depicts
O2Hb, and the lower trace �blue� HHb and the straight line �black�
depict the duration of the visual stimulation. A number of physiological phenomena can be observed: �1� The arterial pulsations are visible
in the O2Hb tracing. The pulsations can be used to calculate the heart
rate and arterial oxygen saturation. �2� Approximately every 10 s,there are fluctuations in the blood circulation �the so-called slow vasomotion�. These changes are particularly evident in the O2Hb tracing. �3� The O2Hb increases and the HHb decreases during the stimulation. This corresponds to a typical functional cortical activation.
Although the slow vasomotion partially masks the activation, the measurement can be repeated several times and thus the functional activation can be revealed statistically. �Color online only.�

Fig. 1 Wireless imaging instrument attached to a newborn infant’shead. The squares �blue� represent the detector locations, while thecircles �red� depict source locations, each equipped with light emitting diodes at two wavelengths �730 and 830 nm�. The electronics tothe right includes a Bluetooth device for wireless transmission, drivers
for the light emitting diodes, filters, analog-to-digital converters, a microprocessor, and a power supply based on a battery. The instrument
weighs as little as 40 g, has a sample rate of 100 Hz, and the battery
lasts for approximately 3 h. The wireless technology is comfortable towear, easy to apply, and enables measurements in moving subjects
and everyday situations. �Color online only.�

tive and can penetrate relatively large tissues �e.g., the head ofa neonate�. However, due to the low number of photons, TRS
measurements are also characterized by a relatively high levelof noise. From a clinical point of view, the disadvantages are
represented by the physical size of the instrumentation, theuse of glass fibers, and the photomultiplier tubes �i.e., thedanger of destroying these detectors by excess ambient light�.
In the near future, technological advances in this field, in particular the miniaturization and reduction in cost of the instrumentation, will promote this technology.
Phase modulation spectroscopy �PMS� is also called intensity modulated or frequency domain spectroscopy. This technique is in principle equivalent to TRS except that it operates
in the Fourier domain. This means that the light sources areintensity modulated at radio frequencies �50 MHz to 1 GHz�.
After passing through the tissue, the mean intensity �DC�,
amplitude �AC�, and phase of the emerging wave are measured. The phase contains information about the time of flight.
To obtain the same information as TRS, PMS requires scanning through all frequencies from 50 MHz to 1 GHz.76,87–92
The result is a Fourier transform of the time point spreadfunction of TRS. Only a few instruments are operated in scanning mode �also called multifrequency mode�89–92 because thetime resolution is relatively low. Most of the instruments are
single frequency instruments and use a multidistance or SRS
geometry.76,87,88 It has been shown that the latter type of instrument is technically much simpler than TRS and provides
measurements with a good signal-to-noise ratio and a hightime resolution. In addition, unlike TRS instruments, SRS instruments can deal with a higher number of photons at thedetector and thus with a higher signal-to-noise ratio. From aclinical point of view, the advantages are represented by theeasier transportability and the commercial availability. How-

Only deeper tissue layers have an effect on the values.78,79
Using a single source-detector distance, however, the influence of the superficial tissues on the signals is relatively large.
It depends on the source-detector separation. It can be minimized using large separations and a correction for an extracranial sample volume or both.9
The enhanced type of SRS, called spatial frequency domain measurements,80 projects several bar patterns of different distances between bright bars and dark bars on the tissue.
This type of imaging is able to determine absolute values.
Time resolved spectroscopy �TRS�, also known as time
domain spectroscopy,49,81–85 is a technique that measures thetime of flight in addition to the light intensity. It does so by
emitting a short ��100 ps� pulse of light into the tissue andmeasuring the time point spread function of the light after itpasses through the tissue. Due to the scattering process, thepulse will broaden and, due to absorption, the intensity will be
reduced. The result of such a measurement is a histogram of
the number of photons on the y axis and their arrival times on
the x axis. The histogram also contains information about thedepth of the photonic path, because photons that arrive later
have a higher probability to have traveled deeper. The absorption and the reduced scattering coefficients are calculated
from the histogram and the absorption coefficients are utilized
to calculate the absolute values of the chromophores concentration. This technique is also used for three-dimensional imaging and tomography.14,85,86 Thus, from the physicist’s pointof view, TRS is an excellent method because it yields a lot of
information relatively rapidly and with a high dynamic range.
However, it requires sophisticated instrumentation that is so
far commercially unavailable. Because the instrumentation
usually operates in photon counting mode, it is highly sensiJournal of Biomedical Optics

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ever, compared to TRS, if only one frequency is used, PMS
provides less information about the tissue. In addition, from aclinical point of view, the disadvantages are represented by
the use of the glass fibers and the sensitivity of the photomultiplier tubes to excess light. In the near future, this technology
might profit from technological advances and developmentsin the mobile communications industry, which lead to theminiaturization, optimization, and dramatic reduction in costof crucial components such as synthesizers or demodulators.
Broadband
imaging,orseconddifferential
spectroscopy,89–93 means that white light is used instead of
discrete wavelengths and, at the detection site, a spectrometermeasures the whole range of wavelengths. The advantage isthat a whole spectrum is available, which allows the discrimination of chromophores within the tissue with higher accuracy
and less crosstalk. Using the second differential, even absolute values can be obtained if a certain water concentration
can be assumed.58 One disadvantage of second differential
spectroscopy is that taking the derivative magnifies the noiselevel and thus measurements have a lower signal-to-noise ratio. Some groups also use a combination of broadband and
PMS to be absolutely quantitative.92 The disadvantage is thatto utilize all wavelengths, the power of the light source needs
to be higher and tissue warming may be a dangerous consequence.
Diffusing-wave spectroscopy �DWS�, also called diffuse
correlation spectroscopy, allows using lasers with a long coherence length and the speckle pattern that is created in thetissue.94–98 Speckles, a pattern of bright and dark spots, are a
result of the interference of light. This interference occurs
when light with large coherence length �laser light� is going
through the tissue by different paths, which may lead to constructive or destructive interference. Because in a tissue there
is also movement, mainly of the blood, this interference pattern changes in time. The autocorrelation of the speckle pattern contains information about the blood flow. This technique
is related to laser Doppler flowmetry, which measures superficial blood flow and is not included in this review. DWS is
the fruit of a relatively recent development and the technology
is relatively expensive. In the future, efforts for understanding
the factors that affect the autocorrelation must be made tocompletely quantify blood flow.
NIRI, also called diffuse optical imaging �DOI� or topography, reconstructs two-dimensional images of the chromophore concentrations in tissue. The term “diffuse” in DOI
refers to the fact that the theory is based on the diffusion
approximation. This type of instrumentation operates usuallyin reflection mode. The resolution of the images achieved today is on the order of 1 cm.
Table 3 includes the main commercially available instruments, and Table 4 provides an overview of the most important recent noncommercial prototypes.

4

ministration. Therefore, their distribution has been limited toJapan and/or the European Community. Considering the highcost and the restricted clinical applications of the imagers,
more oximeters than imagers have been sold particularly formonitoring adult brain oxygenation during heart surgery. It is
not possible to report the exact number of the oximeters soldbecause the companies do not release such figures. However,
it is possible to estimate that more than 2000 clinical oximeters are presently operating for different clinical applications.
The development of instrumentation and methodology has
been proceeding in steps. At first, only CW instruments with
one channel were available. These instruments allowed measurement of relative values only �i.e., changes in chromophore
concentration�. They provided useful information in many instances, particularly in intervention studies in which, for instance, the safety of drugs was tested �e.g., Ref. 99� or functional brain activity was investigated. In brain studies,absolute values of hemoglobin concentration or blood flow
can be obtained using changes in oxygenation.100–103 In
muscle studies, the combination of relative concentration
changes with a venous or arterial occlusion provides absolute
quantitation of the oxygenation and blood flow.104–106 In asecond step, instrumentation based on spatially resolved ortime resolved �TRS or PMS� methods led to the measurementof absolute values of concentration.76 This considerable evolution enhanced the value of the NIRS measurements, because
it allowed the comparison of concentration and oxygen saturation values among patients without any interventions. This
paves the way for monitoring patients during treatment �e.g.,
in intensive care�. In a third step, the use of multichannel
instruments enhanced the scope of the measurements fromsingle locations to two or three dimensions. This was anotherbig step, because the single location measurements usuallyassumed that the values at a given location were representative for the whole area or organ. Imaging studies however
showed that �1� this assumption is not true and �2� there may
be considerable local variability in volume and/or flow andoxygenation.106–109
This leaves us with new problems that have to be solved toenhance NIRI advancement, for example, the placement ofmultiple channels, the handling of large amounts of data, andthe algorithms for reconstructing images. However, NIRS
and/or NIRI instrument development can be considered constant as witnessed, for instance, by the fact that every 2 to 3
years new models have been replacing the previous ones, particularly as far as oximeters are concerned. Usually, the newmodels are characterized by lower dimensions, weight, andcost, as well as improved data presentation, software, andprecision. In addition, new techniques have been proposed
and are under evaluation for improving the quantitation ofoximeters �Table 4�.
A large effort refers to the development of imaging instrumentation and image reconstruction algorithms. The main
problem of imaging relies on the existence of the strong scattering of light in the NIR range and the very low number oflight bundles. Most of the commercial imagers are based on
CW light sources and are still very bulky and expensive
�Table 3�. The fact that several prototypes have been developed by industries and academic institutions using TRS andPMS approaches could suggest that these techniques would be
utilized by the next generation of commercial clinical imagers

Discussion

Table 3 shows that quite a number of oximeters and imagers
are commercially available. The presence of three big Japanese companies developing such devices underlines the consistent efforts made by this country in the field of NIRS andNIRI development. Unfortunately, so far, very few instruments have the approval of the American Food and Drug AdJournal of Biomedical Optics

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Table 3 Main commercial near-infrared clinical instrumentation.

Instrument
Photometers

BOM-L1 TR
HEO-200a,b

Oximeters

Imagers

Technique

Number ofchannelsCompany

Web siteSingle-distance CW

1Omegawave, Japan

www.omegawave.co.jp

Single-distance CW

1

OMRON, Japan

n.a.

a

Micro-RunMan

Single-distance CW

1NIM, Inc., USA

n.a.

OXYMON MkIII

Single-distance CW

1 to 96

Artinis, The Netherlands

www.artinis.com

FORE-SIGHTc

Multidistance1

Casmed, USA

www.casmed.com

c

INVOS 5100C

Multidistance

2 or 4

Somanetics, USA

www.somanetics.com

InSpectra 325c

Multidistance1

Hutchinson, USA

www.htbiomeasurement.com

NIMO

Multidistance

1

NIROX, Italy

www.nirox.it

NIRO-100

Multidistance2

Hamamatsu, Japan

www.hamamatsu.com

NIRO-200

Multidistance2

Hamamatsu, Japan

www.hamamatsu.com

O2C

Broadband

2

LEA, Germany

www.lea.de

ODISseydMultidistance2

Vioptix, Inc., USA

www.vioptix.com

OM-220Multidistance2

Shimadzu, Japan

www.med.shimadzu.co.jp

OxiplexTS

Multidistance PMS

1 or 2

ISS, USA

www.iss.com

TRS-20Multidistance TRS

2Hamamatsu, Japan

www.hamamatsu.com

Dynot

CW

up to 32

NIRx, USAwww.nirx.net

ETG-4000c

CW

44

Hitachi, Japan

www.hitachimed.com

ETG-7000c

CW

72

Hitachi, Japan

www.hitachimed.com

Imagent

PMS

up to 128

ISS, USA

www.iss.com

LED IMAGERCW

16

NIM, Inc., USA

n.a.

nScan D1200

CW

16 to 32

Arquatis, Switzerland

www.arquatis.com

nScan W1200

Wireless CW

16

Arquatis, Switzerland

www.arquatis.com

NIRO-200

CW

8

Hamamatsu, Japan

www.hamamatsu.com

NIRS 4/58

CW

4 or 58

TechEn, Inc, USA

www.nirsoptix.com

OMM-2001

CW

42

Shimadzu, Japan

www.med.shimadzu.co.jp

OMM-3000

CW

64

Shimadzu, Japan

www.med.shimadzu.co.jpaWearable instrument.
b
No longer commercially available.
c
USA Food and Drug Administration’s approval.
d30-min battery backup.
CW=continuous wave, n.a.=not available, PMS=phase modulation spectroscopy, SRS=spatially resolved spectroscopy, TRS=time resolved spectroscopy.

�Table 4�. But why are there so many different instruments?
One reason is that, unlike the other well-established imaging
modalities such as magnetic resonance imaging �MRI� or
computerized tomography �CT�, the setup of NIRS and/or
NIRI is highly dependent on the application performed andthe tissue measured. Thus, each of the instruments optimizes acertain aspect. For example in neonatology, it is less imporJournal of Biomedical Optics

tant to utilize high sensitivity detectors, because neonatal tissue is relatively transparent, and neonatal measurements require soft and flexible probes to prevent lesions of thesensitive skin. An instrument, which optimally incorporates
all the physical aspects of the technique �such as highly sensitive detectors� and therefore is capable of providing all themeasurable parameters, might be impractical for any kind of

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Table 4 Main recently developed near-infrared prototypes.
Name of the instrument or town of
the university
Oximeters

Imagers

Technique

Number ofchannels

University or firm

Author �reference�

IrvineBroadband PMS

1Irvine Univ., USA

Pham 2000,147 Lee 2006148

Keele

PMS

1

Keele Univ., UK

Alford 2000149

Koblenz

Broadband SRS

1Koblenz Univ., Germany

Geraskin 2005150

NeoBrain

CW

8Helsinki Univ., Finland

Nissila 2002151

Philadelphia

Multidistance SRS

1

NIM, Inc., USA

Nelson 2006152

IRIS-3CW

1

INFM, Italy

Giardini153

TSNIR-3

Multidistance SRS

1Tsinghua Univ., China

Teng 2006154

ZurichPMS

1Univ. Hospital Zurich, Switzerland

Brown 2004155

Arlington

CW

64

Univ. of Texas, Arlington, USA

Kashyap 2007156

BerlinCW

22

Charité, Germany

Boden 2007157

LondonCW

20

Univ. College London, UK

Everdell 2005158

NIROXCOPE 201

CW

16

BoğaziÇi Univ., Turkey

Akin, 2006159

Nanjing

CW

16Southeast Univ., China

Li 2005160

New York

CW

var.

Columbia Univ., USA

Schmitz 2002161

Philadelphia

CW

16

Drexel Univ., USA

Leon-Carrion 2006162

St. Louis

CW

300

Washington Univ., USA

Culver 2006163

ZurichaCW

16

Univ. Hospital Zurich, Switzerland

Mühlemann 200673

BerlinTRS

16

Physikalisch Technische Bundesaustalt, Germany

Liebert 200682

BostonTRS

32Harvard Univ., USA

Selb 2006164

Hamamatsu

TRS

16

Hamamatsu, Japan

Ueda 2005165

Milan

TRS

16

Politecnico of Milan, Italy

Contini 2006166

Monstir

TRS

32

Univ. College London, UK

Schmidt 2000167

Strasbourg

TRS

8Strasbourg Univ., France

Montcel 2004168

Warsaw

TRS

16

Academy of Sciences, Poland

Liebert 2005169

Helsinki

PMS

16

Helsinki Univ., Finland

Nissila 2005170

Seoul

PMS

16

Yonsei Univ., South Korea

Ho 2007171

Hokkaido

SRS

64

Hokkaido Univ., JapanKek 2006172

IrvineSRS

CCD

Irvine Univ., USA

Cuccia 200580

aWearable instrument.
CCD=charge coupled device, the instrument uses a noncontact camera; CW=continuous wave; PMS=phase modulation spectroscopy; SRS=spatially resolved spectroscopy; TRS=time resolved spectroscopy; Univ.=university; var.=variable.

clinical application because, for instance, the detector is too
sensitive to excess light and could therefore be easily destroyed.
The possibility to map the whole cerebral cortex convinced
many cognitive neuroscience research groups to utilize NIRI
Journal of Biomedical Optics

instrumentation for human brain mapping studies. In thisframework, sophisticated data processing methods have recently been investigated and applied to the analysis of NIRI
data. Principal component analysis has been utilized for analyzing the spatial and spectral features of diffuse reflectance

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data from brain tissue110 and for suppressing systemic physiological contributions to the evoked hemoglobin-related
signals.111 Independent component analysis112 and the continuous wavelet transform113 have been proposed to detect
activated cortical areas, whereas lagged covariance methods
have been proposed to explore functional brain connectivity
from event-related optical signals.114 In the attempt to characterize the contributions of systemic parameters, such as theheart rate and the mean arterial blood pressure to the lowfrequency oscillations in cerebral oxygenation,115 researchers
applied information transfer analysis. The recent and quickly
growing emphasis placed on data processing procedures for
NIRI data shows the importance that the NIRI field is attributing to the development of powerful and reliable data analysis tools. However, no standardized approach for NIRI data
analysis has been established yet, laying further emphasis on
the development of standard data processing schemes to elevate NIRI into a well-established human cortical imaging
modality.116
One measured but not widely explored variable is the lightscattering, which is related to tissue structure, cell membranes, and mitochondria. Unfortunately scattering and scattering changes are often disregarded when the focus is on theabsorption. One example showing the potential value of scattering changes is their association with the neuronal
activity.117 The latter leads to small changes in light scattering
at the neuronal level. Because the changes are small, they are
difficult to detect. Although several groups report the detection of such changes,118–122 there are some controversies.123
New algorithms able to better separate the other physiologicalsignals from the scattering changes might help to resolve thisissue. Light scattering has also been investigated in NIR
mammography for breast cancer detection.124
The progress of NIRS and/or NIRI is not as rapid as expected and hoped for.22,125 There are several reasons for this.
In fact, NIRS and NIRI have many pitfalls and limitations.
Some typical examples can be summarized as follows. �1� For
correct measurements, it is necessary to precisely know theassumptions in the physical models and to make sure that they
are fulfilled �e.g., the boundary conditions assumed in thealgorithms have to correspond to the geometry of the tissue
under investigation�. �2� An incorrect attachment of the sensor
might lead to light piping and consequently large errors. �3�
Heterogeneous tissue cannot be measured if the physicalmodel assumes a homogenous tissue. �4� The different NIRS
and NIRI approaches show a different degree of susceptibility
to movement artifacts, single distance measurements arehighly sensitive while multidistance geometries are relatively
inert.126 Often these pitfalls lead to errors that in turn are
wrongly used to disqualify NIRS and/or NIRI results. A
strong interdisciplinary collaboration between clinicians andscientists could facilitate the correct use of NIRS and NIRI.
Another explanation for the slow progress is that there is nota unique ideal NIRS and NIRI instrument. Instead, different
instruments could be optimal for a given clinical application.
Another problem is that the clinical studies for understanding
the meaning of a new parameter �such as tissue oxygen saturation�, for establishing its normal values, and for determining
limits requiring therapeutic or corrective actions �e.g., the administration of oxygen� call for time-consuming, extensive,and very expensive clinical studies.
Journal of Biomedical Optics

There is considerable technical progress that, leading to ahigher precision of the measurements and resolution of theimages, could partly overcome the limitations of the technique. Also from the clinical perspectives there is considerable progress in view of the first clinical applications entering
routine.21,22,25–28,127 It can be predicted that the evolution ofthis progress will consist of an increasing variety of clinicalapplications in which NIRS and/or NIRI will become established techniques in hospitals.

5

Conclusion

Thirty years after NIRS’s discovery, NIRS and NIRI are currently at a stage of transition from basic clinical research to an
adjuvant in clinical applications. On average, two to threepapers per day about the clinical applications of NIRS andNIRI are reported on MEDLINE and “Current Contents Connect” �Thomson Scientific, USA�. In addition, several technical papers are published in journals not included in MEDLINE. In the next 5 years, additional efforts are expected intechnology developments, commercialization, and clinicalvalidation of oximetry and imager instrumentation. In particular, oximeters are expected to become capable of measuring
absolute values, and this will give a consistent contribution
for the expansion of their clinical applications. Multimodality
imaging systems will be developed to integrate NIRI withvarious other well-established brain imaging techniques suchas MRI and positron emission tomography.128 Structural information of brain tissue that is obtained from conventional imaging tools, such as CT, MRI, and ultrasound, will provide
highly useful coregistration and guidance that will ultimately
improve the accuracy of NIRI image reconstruction. Because
NIRS and/or NIRI have an inherently high contrast, technological and computational advances will enable image reconstruction with higher spatial resolution and sensitivity. NIRI
techniques show a tremendous potential for noninvasive brain
imaging by providing functional and metabolic maps of theactivated brain cortex. The complementary information provided by changes in O2Hb and HHb; the coregistration withelectroencephalography and systemic parameters such as theheart rate, blood pressure, and respiratory rate; and the development of dedicated data processing algorithms are criticallyimportant for the analysis and interpretation of NIRI data.
In summary, although NIRS and NIRI have been growing
slowly but constantly, NIRS and NIRI are on the verge ofentering clinical everyday applications and have alreadybrought many valuable insights in clinical research. There aregood prospects that NIRS and/or NIRI will light up in the
future, shed light on many physiological issues, and brighten
the perspectives of many illnesses.

Acknowledgments
The authors, in particular Marco Ferrari, wish to thank Professor Frans Jöbsis for inspiring their scientific research careers. This research was supported in part by PRIN 2005 �VQ,
MF� and the county of Zurich, Switzerland �MW�. The authors thank Mark Adams for revising the English language.
We thank the parents for the consent to publish the picture of
their infant, who was not harmed in this process.

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Wolf, Ferrari, and Quaresima: Progress of near-infrared spectroscopy and topography…

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BioMed Central

Research

Open Access

Exercise-induced blood flow in relation to muscle relaxation period
Fumiko Ohmori*1, Shizuyo Shimizu2 and Atsuko Kagaya3
Address: 1National Institute of Fitness and Sports in Kanoya, 1 Shiromizu, Kanoya, Kagoshima 891-2393, Japan, 2Institute of Physical Education,
Keio University, 4-1-1 Hiyoshi, Kohoku, Yokohama, Kanagawa 223-8521, Japan and 3Research Institute of Physical Fitness, Japan Women'sCollege of Physical Education, 8-19-1 Kitakarasuyama, Setagaya, Tokyo 157-8565, Japan
Email: Fumiko Ohmori* - fumiko_235_0731@yahoo.co.jp; Shizuyo Shimizu - shimizu@hc.cc.keio.ac.jp; Atsuko Kagaya - kagaya@jwcpe.ac.jp* Corresponding author

Published: 9 May 2007
Dynamic Medicine 2007, 6:5

doi:10.1186/1476-5918-6-5

Received: 5 November 2006
Accepted: 9 May 2007

This article is available from: http://www.dynamic-med.com/content/6/1/5© 2007 Ohmori et al; licensee BioMed Central Ltd.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0),
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract
Background: Dynamic exercise is characterized by relaxation periods between contractions. The
relaxation period should be considered as a causal factor for determining the magnitude of bloodflow during dynamic exercise. The purpose of this study was to investigate the effect of muscle
relaxation periods determined by the response of each subject on the exercise-induced blood flow
response.
Methods: Seven healthy female subjects performed dynamic plantar flexions twice in succession;
the duration of each flexion was 1- s and they were performed at an intensity of 15%, 30% and 50%of the maximal voluntary contraction (MVC). Based on the blood flow response after a single
contraction, we set up intervals between two successive contractions; the intervals corresponded
to 50% (pre-Tpeak), 100% (Tpeak), and 150% (post-Tpeak) of the time required to reach peak bloodflow.
Results: In all the conditions, upon cessation of the contraction, there was a progressive, beat-bybeat increase in the blood flow through the popliteal artery that peaked by the 5th cardiac cycle.
Peak values of blood flow achieved after exercise were significantly higher at pre-Tpeak than at Tpeak
and post-Tpeak (p < 0.05).
Conclusion: The result indicate that at three intervals based on the time taken to reach the peakvalue, the highest blood flow value was obtained at the pre-Tpeak interval.

Backgroundwhich an exercise protocols increases the blood flow during the relaxation phase of dynamic exercise needs to beclarified.

The blood flow to an active muscle changes depending on
the exercise intensity, contraction frequency, contractionto-relaxation duty cycle, etc [1-9]. The blood flow
increases markedly during the relaxation phase of
dynamic exercise, whereas it remains at a lower level during the contraction period [10-14]. Thus, the magnitudeof the blood flow during the relaxation phase of the
dynamic exercise determines the magnitude of blood supply to the exercising muscles. Further, the manner in

An earlier study on contraction-to-relaxation duty cycle
indicated that the blood flow to an active muscle during
dynamic exercise reflects the influence of alteration in the
duration of the relaxation phase, rather than the effect ofaltering the contraction rate [9]. It was also reported thata second contraction of the same intensity during the375

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period of increased blood flow due to the first contraction
induced a greater increase in the blood flow than thatcaused by the first contraction alone [15]. Therefore, therelaxation time between successive contractions should bea causal factor for the determination of blood flow during
dynamic exercise. Hence, the time courses of changes inthe blood flow immediately after dynamic contraction
should be clarified.

relaxed their foot to return the ankle joint to 90°.
Dynamic plantar flexion was performed against the loads
adjusted to 15%, 30%, and 50% of the maximal voluntary
contraction (MVC). The MVC of the plantar flexors wasdetermined isometrically and the average of 3 of 5 trials,
i.e., excluding the highest and lowest values, was used as
the representative MVC to standardize the load. The duty
cycle comprised 0.5-second lifting, 0.5-second hold, and
0.5-second unloading. The cadence was determined using
an auditory metronome. Prior to the experiments, theexperimental approach was explained to all the subjects;
the subjects practiced the exercise to ensure that they
could maintain the contraction-relaxation schedule andcadence. The experiment was conducted in a room withthe temperature and relative humidity set at 24°C and60%, respectively.

The immediate post-exercise flow was approximately
analogous to an interpolated blood flow during relaxation [10,13]. Moreover the blood flow early in recovery
after exercise differed between subjects, including athletes
and non-athletes [16]. Based on these findings, it is reasonable to hypothesize that exercise-induced hyperemia
may vary between the subjects depending on the time
taken to reach peak blood flow. To elucidate the changes
in blood flow induced by the contraction-to-relaxation
duty cycle, the relationship between the changes in the
blood flow during relaxation phase and augmentation ofblood flow during exercise should be clarified. However,
the effect of relaxation time on the time course of changes
in the blood flow has never been assessed previously.

Determination of the relaxation time
Two experimental protocols were tested in this study (Figure 1). In the first experiment, we investigated the popliteal artery blood flow after a single contraction during
plantar flexion exercise to determine the time at which
peak blood flow was achieved, i.e., the time taken to reachthe peak value of blood flow after contraction.

Therefore, the aim of this study was to elucidate the effectof muscle relaxation periods that were determined fromthe blood flow response of each subject on the exerciseinduced blood flow. The following approaches were
employed. The three intervals were chosen based on thetime taken to reach peak value of blood flow after a single
contraction of plantar flexion exercise. Alternations in the
blood flow after contractions were studied by comparing
the 3 different time durations between contractions–thetime corresponding to peak value of blood flow, before
reaching the peak value, and after the peak value of bloodflow was reached.

In the second experiment, two successive plantar flexor
contractions were performed at three intervals that werebased on the results of the first experiment. The intervals
Protocol1:
Single contraction
BF(ml㨯
㨯min-1)

700

The time taken to reach the peak value ofblood flow

600
500
400
300
200
100
Time(sec)

Protocol2:
Two successive contraction

Methodst (sec)pre-Tpeak: t - 1/2 t(s)Subjects
Seven physically active women participated in the study
after giving their informed consent. The age, body heightand body mass (means ± SD) of the subjects were 21.9 ±0.7 years, 162.5 ± 5.8 cm and 55.4 ± 5.3 kg, respectively.
All the subjects were free of medical problems.

Tpeak : t(s)post-Tpeak : t + 1/2 t (s)
0

50%

100%

150%

: First contraction: Second contraction

Figure 1protocol
Exercise
Exercise protocol. We set up the time intervals based on
the time taken to reach the peak value of blood flow. In thefirst experiment, we investigated popliteal artery blood flow
after a single 1-second contraction of plantar flexion exercise. Immediately after the cessation of contraction, theblood flow began to increase markedly and reached its peakvalue. The intervals between the contractions used in thisstudy were 50%, 100%, and 150% of the time taken to reachthe peak value.

Experimental protocol
Exercise protocol
All the experiments were performed in the supine position. To fix the entire distance between shoulder and foot,the subjects were stabilized in a fixed position by a usinga padded support plate. Each subject placed their respective right foot on the pedal of the ergometer with ankle
and knee joints angle at 90° and 180°, respectively. The
subject pressed the pedal with the ball of the foot toextend the ankle joint to 100°, and then the subject

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between contractions used in this study correspondedwith the following time durations: to 1) The time taken toreach the peak blood flow (Tpeak), 2) the interval preceding Tpeak (pre-Tpeak), and 3) the interval following Tpeak(post-Tpeak). The time corresponding to pre-Tpeak and postTpeak were calculated as follows: pre-Tpeak = t – 1/2t, postTpeak = t + 1/2t, where t was the time taken to reach thepeak value of blood flow.

however, there were significant differences in the peak
blood flow achieved, at different exercise intensities, andthose obtained during exercise at 30% and 50% MVC
were significantly higher than that obtained at 15% MVC(p < 0.05: Table 1).
The average of the beat-by-beat blood flow after a single
contraction in the 7 subjects at all intensities is illustrated
in Figure 3. The blood flow reached its peak value by the
4 th or 5 th cardiac cycle.

Physiological measurement
The mean blood velocity and the vessel diameter of the
popliteal artery were measured by using a Doppler and Bmode ultrasound method (HP SONOS 1000, USA). A 7.7
MHz linear array transducer was placed approximately 1
cm above the bifurcation of the popliteal artery into theanterior and posterior tibial arteries. The sampling volume was maintained at 8.9 mm and the angle of the beam
to determine the direction of flow of blood was adjusted
automatically to 60°.

The relaxation time calculated using the time to reachpeak blood flow after single contraction is listed in Table
2.
Blood flow and time to reach the peak blood flow after
two successive contractions
The beat-by-beat blood flow after contractions at all contraction frequencies and intensities are illustrated in Figure 4. At all contraction frequencies and intensities, thepeak value of blood flow was observed during the third
cardiac cycle after two successive.

The diameter of blood vessel based on the relative time
periods of the systolic (1/3) and the diastolic (2/3) phasesof the cardiac cycle was assumed to be the most representative of the diameter size for each cardiac cycle, and it was
utilized for determining the cross-sectional area of the vessel (A = πr2, where r is the radius of the vessel); this wasused to calculate the blood flow.

The peak value of blood flow immediately after two successive contractions are shown in Figure 5. A comparing of
the three different intervals reveals that the highest bloodflow values were obtained after the second contraction at
the pre-Tpeak interval at all intensities (p < 0.05). In contrast, the blood flow value was the lowest during the postTpeak interval further, the blood flow after the contractionin the post-Tpeak interval was lowers than that after a single
contraction at 15% and 30%MVCs.

Beat-by-beat popliteal artery blood flow was calculated bymultiplying FI, HR, and πr2, where FI is the flow integral
during each cardiac cycle and HR is the heart rate obtained
from the R-R interval of the electrocardiogram (ECG).
Statistical analysis
The group values are expressed as mean ± SE. Differencesamong means obtained from the 3 intervals were evaluated by using a one-way ANOVA with post hoc comparison using Fischer's PLSD. Difference between the bloodflow during the relaxation period and post-contraction
were analyzed using t test for paired samples. A p value ofless than 0.05 was considered statistically significant.

GONIO
ECG

Ԙ ԙ Ԛ

Results

Blood flow and time to reach peak blood flow after a single
contraction
Following the initiation of a decrease in tension after the
0.5-s hold, the blood flow began to increase immediately.
Moreover, it continued to increase even after the developed tension returned to baseline and reached the peakvalues in 3.8 – 4.7 seconds (mean: 4.0 ± 0.2) (Figure 2).
Table 1 shows the time taken to reach the peak blood flow
and the coefficients of variation of the time to reach thepeak blood flow for each subject at 3 intensities. There
were no significant differences in the time taken to reachthe peak value of blood flow among the 3 intensities;

Doppler
spectrumԘ: lifting the load ԙ: maintaining the load Ԛ: lifting off the load

traction
Blood
Figurevelocity2
signal before, during and after a single conBlood velocity signal before, during and after a single contraction.

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Table 1: Peak blood flow and the time taken to re ach the peak
blood flow after a single contraction

Peak BF (ml/min Mean ± S
The time taken to reach thepeak BF (s)The coefficients of variation (%)

15%MVC

30%MVC

50%MVC

149 ± 153.8 ± 0.3

416 ± 414.7 ± 0.2

488 ± 55
3.9 ± 0.2

23

12

14

Table 2: Determination of the relaxation time

2.0 ± 0.2
2.3 ± 0.1
2.1 ± 0.1

3.9 ± 0.4
4.6 ± 0.3
3.9 ± 0.2

5.7 ± 0.4
6.7 ± 0.3
5.8 ± 0.4
(Mean ± SE)

Tschakovsky et al [19]. Although all subjects required asimilar number of cardiac cycles to reach the peak blood
flow, the time taken to reach peak blood flow differed
between subjects because of differences in the R-R intervals of the subjects.

The major finding of this study was that the blood flow
was augmented to a greater extent when the second contraction occurred prior to the time of the peak hyperemic
response. The contraction interval in this study was basedon using the time taken to reach peak blood flow after asingle contraction. We set up at three intervals using thetime duration reaching peak value; the time shorter andlonger the time reaching peak value after a single contraction. As a result, the highest blood flow value wasobtained from interval using the time before reaching
peak value after a single contraction.

In this study, immediately after the tension in the muscle
began to decrease during unloading, the blood flow began
to increase and continued to do despite the return of thetension to resting levels. This rapid increase is most likely
a consequence of the mechanical effects of the muscle
pump on alterations of the perfusion pressure gradientacross the capillary bed [20]. The rapid vasodilation after
a single contraction was detectable within approximately
0.5 – 2 s [15,19]. Considering from the time taken toreach the highest blood flow (3.8– 4.7 s), we cannot
exclude the possibility of vasodilation mechanism due tothe local release of any vasodilators [15,17].

As reported by previous studies, the blood flow after a single contraction began to increase markedly immediately
after contraction [15,17,18]. After a single contraction, abeat-by-beat increase in the blood flow was observed, andthe peak value was obtained between the 4 th and 5 th cardiac cycles. At all contraction intervals and intensities,
after two successive contractions, the blood flow showeda progressive, beat-by-beat increase peaked by the 3rd cardiac cycle. These results are similar to those reported by

A novel featuring of this study was that the relaxation
times for each subject were set up by using relative timeǍ$( ONOKP/8%
/8%
/8%

30%MVC

15%MVC






TGUV 



















TGUV 



















ECTFKCEE[ENGU

ECTFKCEE[ENGU50%MVCǍ$( ONOKP

Ǎ$( ONOKP

post-Tpeak (sec)

Data are the relaxation time calculated using the time to reaching
peak blood flow after a single contraction.

Discussion



Tpeak (sec)

15% MVC
30% MVC
50% MVC

Data are obtained from after single contraction. Peak value of bloodflow at 30% and 50% MVC were significantly higher than that at 15%
MVC. Peak BF: Peak value of blood flow.
*p < 0.05 as compared to 15% MVC











pre-Tpeak (sec): pre-Tpeak: Tpeak: post-Tpeak





Ǎ: change from the rest value

TGUV 



















TGUV    ECTFKCEE[ENGU









Figure 4
Beat-by-beatblood flow after two successive contractions
Beat-by-beat blood flow after two successive contractions. At all contraction frequencies and intensities, abeat-by-beat progressive increase in the popliteal arteryblood flow was observed following the cessation of contraction, and the peak value was obtained during the third cardiac
cycle.

ECTFKCEE[ENGUCHVGTCUKPINGEQPVTCEVKQP
Ǎ: change from baseline

Figure 3
Beat-by-beatblood flow after a single contraction
Beat-by-beat blood flow after a single contraction.

378

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Dynamic Medicine 2007, 6:5

BF (ml/min)

700
600
500
400
300
200
100
0

frequency of 19–20 contractions per min (cpm), 11–13
cpm, and 8–9 cpm at the pre-Tpeak, Tpeak, and post-Tpeak
intervals, respectively. Several studies have indicated thatan increase in the blood flow and contraction frequency
was paralleled at lower contraction frequency [8,21-23].
With regard to higher contraction frequencies, the results
obtained were inconsistent with those of some studied
that showed it increased blood flow [21,22] and the others showing decreased blood flow [9]. The contraction frequency used in this study was lower than that used in theprevious studies. The effect of contraction intervals shorter
than that used in the present study on the blood flow
remains to be studied.

30㧑
30㧑MVC

15㧑
15㧑MVC
700
600
500
400
300
200
100
0

http://www.dynamic-med.com/content/6/1/5

㧖
㧖

50㧑
50㧑MVC 㧏: peak blood flow after
a single contraction: pre-Tpeak: Tpeak: post-Tpeak: peak blood flow after
a single contraction

With respect to the exercise intensities (15%, 30%, and
50% MVC) used in this study, the peak blood flows after
contraction increased with the increase in the exercise
intensity. This might be either due to the number of muscle fibers recruited [24] or the increased tension produced
due to the increase in the exercise intensity [3]. Moreover,
Hamann et al [25] indicated that the blood flow response
to a single muscle contraction is not solely determined by
the rate at which work is performed; muscle fiber recruitment also contributes independently to the changes in the
blood flow.

timesblood
Peak
Figure5 flow in exercise at three different relaxation
Peak blood flow in exercise at three different relaxation times. The pre-Tpeak interval showed the highest
blood flow value and the value decreased as the relaxation
period increased. *p < 0.05 pre-Tpeak compared with Tpeak
and post-Tpeak at 15% MVC and during the three relaxationintervals at 30% MVC. #p < 0.01 during the three relaxation
period at 50% MVC.

based on the time taken to reaching peak value of bloodflow after a single contraction. The advantage of the use of
relative time is that the timing of the second contraction
was adjusted for change in the blood flow changes of eachsubject. As a result, it indicates that the blood flow will
markedly increase during two successive contraction
model used in this study if the second contraction comes
50% of time for reaching peak blood flow. Corcondilas etal [15] reported that amount of blood flow increase wasdifferent when second contraction was performed four
seconds and ten seconds after a single contraction. It is
possible to suppose that the effect of the exercise stimulus(mechanical or metabolic stimulus, central command etc)
to the vessel caused by a single contraction may be summated when the second contraction comes before postcontraction blood flow reaches the peak. On the other
hand, the summation may not occur when the second
contraction comes at or after the time for the peak postcontraction hyperemia. Further physiological mechanism
remains to be studied.

Conclusion

Dynamic plantar flexion contractions were performed
twice successively at three different intervals, which were
determined based on the time taken to reach peak valueof blood flow after a single contraction. We demonstrated
if the second contraction occurs before the peak value ofblood flow is reached subsequent to the previous contraction, the increase in the blood flow is higher as comparedto the case if the second contraction occurs after the peak
blood flow is reached.

Acknowledgements
The authors are grateful to all the volunteers who participated in this study.

References
1.
2.

3.

The three relaxation times that were used in this study corresponded to 2.1– 2.3 s (pre-Tpeak), 3.9– 4.6 s (Tpeak) and
5.7– 5.6 s (post-Tpeak). Among the three relaxation times,
the highest blood flow was obtained at the pre-Tpeak contraction interval. This is in agreement with the results of
Byström and Kilbon [7] who demonstrated that the bloodflow during exercise with short intervals were higher thanthat during exercise with long intervals. The contractionto-relaxation duty cycle in this study corresponded to a

4.
5.
6.

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Humphreys PW, Lind AR: The blood flow through active andinactive muscle of the forearm during sustained handgrip
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Lind AR, McNicol GW: Local and central circulatory responses
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Byström SEG, Kilbom Å: Physiological response in the forearm
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Barcroft H, Dornhost AC: The blood flow through the humancalf during rhythmic exercise. J Physiol 1949, 109:402-411.
Wesche J: The time course and magnitude of blood flowchanges in the human quadriceps muscles following isometric contraction. J Physiol 1986, 377:445-462.
Walløe L, Wesche J: Time course and magnitude of blood flowchanges in the human quadriceps muscle during and following rhythmic exercise. J Physsiol 1988, 405:257-273.
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Hughson RL: Effect of acetylcholine and nitric oxide on forearm blood flow at rest and after a single muscle contraction.
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Eur J Appl Physiol (2008) 103:509–514
DOI 10.1007/s00421-008-0740-8

O RI G I N A L A R T I C L E

Transient increase in femoral arterial blood flow
to the contralateral non-exercising limb during
one-legged exercise
Mutsuko Yoshizawa Æ Shizuyo Shimizu-Okuyama Æ
Atsuko Kagaya

Accepted: 31 March 2008 / Published online: 19 April 2008
� Springer-Verlag 2008

Introduction

Abstract We studied the effect of exercise intensity andduration on blood flow to the non-exercising leg during
one-legged dynamic knee extension. Femoral arterial bloodflow (FBF) to the non-exercising leg, blood pressure (BP),and heart rate (HR) were monitored during one-legged
dynamic knee extension exercise at 15, 30, and 45%
maximal voluntary contraction (MVC) in seven healthy
females. There was an interaction between exercise intensity and duration for FBF and FVC (P \ 0.01). During theinitial phase of contralateral leg exercise at all intensities,
FBF and femoral vascular conductance (FVC) of nonexercising leg increased, and the increase was larger athigher intensities (P \ 0.01). After initial vasodilatation,
FBF and FVC decreased to baseline, which suggests thevasoconstriction. However, FBF and FVC gradually
increased during exercise at 15% MVC. We conclude thattransient vasodilatation at the onset of exercise is followed
by gradual change to vasoconstriction in non-exercisinglimb during dynamic one-legged exercise and these changes are exercise intensity- and duration-dependent.

Exercise induces redistribution of blood flow by elevating
sympathetic nerve activity mainly by local accumulation ofvarious metabolites in the active muscles (the muscle
pressure reflex) and this reflex contributes to increase bloodflow to the exercising muscles. Thus, flow to non-exercising muscles and especially the splanchnic area decreases(Hohimer et al. 1983; Osada et al. 1999; Saito et al. 1990;
Sinoway et al. 1989). Recent findings regarding blood flow
to nonworking limbs are, however, controversial. Several
studies indicate that blood flow to the inactive forearm
increases during leg cycling exercise (Ahlborg et al. 1975;
Kagaya and Homma 1997; Tanaka et al. 2006; Taylor et al.
1989). Increased shear stress to the vessels in the nonworking limb was considered a possible mechanism. On
the other hand, Green et al. (2002a, b, c) found that leg
cycling exercise at least at a low intensity decreases bloodflow in the inactive forearm.
In regard to blood flow to the nonworking leg, bloodflow in the calf is reduced during handgrip exercises (Saito
et al. 1990). In contrast, Tanaka et al. (2005) demonstrated
that femoral arterial blood flow (FBF) increases during arm
cranking exercises and Gaffney et al. (1990) reported an
initial elevation in blood flow to the inactive contralateralleg during static exercise.
Considering these findings, it may be that forearm andleg vasculatures are differentially controlled during exercise (Taylor et al. 1989). Also different types of exercisespresent different hemodynamic stimuli to the endothelium,
which may result in differential effects of shear stress on
the vasculature (Green et al. 2005). However, the mechanism by which exercise induces an increase, or a decrease,in blood flow in non-exercising limbs has not been determined. Additionally, muscle sympathetic nerve activity

Keywords Ultrasound Doppler � Exercise intensity �
Exercise duration � Heart rate � Blood pressure
M. Yoshizawa (&)
Institute of Health and Sport Sciences, University of Tsukuba,
Ibaraki, Japane-mail: myoshizawa@med.taiiku.tsukuba.ac.jp
M. Yoshizawa � A. Kagaya
Research Institute of Physical Fitness,
Japan Women’s College of Physical Education,
Tokyo, Japan
S. Shimizu-Okuyama
Institute of Physical Education, Keio University,
Kanagawa, Japan

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Eur J Appl Physiol (2008) 103:509–514

over the femoral artery. The measurements were performed
below the inguinal ligament at *2 cm proximal to thebifurcation of the common femoral artery in order tominimize artifacts from turbulent flow. B-mode ultrasoundsonography was used to measure the diameter of the arteryand Doppler-mode was used to measure blood flow
velocity. Blood flow was obtained every 15 s for 90 s
during exercise and at exhaustion.
Blood flow was calculated as:(MSNA) that induces vasoconstriction depends on theintensity and duration of the exercise (Saito 1995; Saito
et al. 1997; Seals 1993). Therefore, the exercise intensity(Taylor et al. 1989) and its duration (Gaffney et al. 1990)
should be considered as important factors in modifying thecirculatory response to exercise. However, no data are
available regarding the effects of exercise intensity and its
duration, or the interaction between these factors on the
blood flow to the non-exercising leg.
The purpose of this study was to determine the effect of
exercise intensity, duration of leg exercise, and the interaction between these two variables on the blood flow in thecontralateral leg during dynamic knee extension exercises.
The time course of changes in the blood flow to the femoral
artery of the non-exercising contralateral leg was studied
during one-legged knee extension exercise conducted atvarious intensities and continued to exhaustion.

Q_ ¼ flow integral for each cardiac cycle� 60=RR interval � pr2 ; where Q_ is the blood flow
ðml min�1 Þ and r is the radius of the artery (cm).

Heart rate was determined from the RR intervals of theelectrocardiogram, and blood pressure (BP) was measured
on beat-by-beat basis throughout the experiment (Finapres
model 2300, Ohmeda, USA). The blood pressure monitoring device was attached to a finger of the right hand andsupported at the heart level. Mean arterial pressure (MAP)
was calculated as: diastolic pressure +1/3 (systolic pressure–diastolic pressure).

Methods
The participants of this study were seven healthy femaleswith a mean (±SD) age, height, and body mass of 23 (±2)
years, 166 (±3) cm, and 61 (±7) kg, respectively. Voluntary
consent was obtained from all the participants after they were
informed of the purpose of the experiment, the procedure,
and the possible risks involved. The study was approved by
the Ethics Committee of the Japan Women’s College ofPhysical Education in accordance with guidelines of the
Declaration of Helsinki of The World Medical Association.

Data acquisition and analysis
To determine the femoral vascular conductance (FVC),
MAP was adjusted to the level of the femoral artery (Keller
et al. 2003):_
FVC ¼ Q=½MAP
þ 0:75 mmHg

� ðheight difference between the heart
and femoral artery in cmÞ�:

Experimental protocol

Statistics

Right leg maximal voluntary contraction (MVC) of knee
extension was assessed by an ‘‘Action meter device’’ (VINE,
Tokyo, Japan), which changes the resistance electrically. An
average of three attempts was considered as the subject’s
MVC. On separate days, the subjects performed one-legged
dynamic knee-extension exercise of the right leg in the
upright position with the knee joint angle extended from 90�
to 120� (180� = full extension). The exercise comprised
contraction and relaxation for 1 s each, as indicated by ametronome. The exercise intensities corresponded to 15, 30,
and 45% of the MVC. Following a 10-min rest period, thesubjects performed the knee extension exercise at a given
load until exhaustion. However, the activity was stopped
after 15 min if the subjects could continue to exercise.

Values are presented as mean ± SEM, unless indicatedotherwise. In order to assess exercise intensity and duration, comparisons of the time courses of the parameters
during exercise were assessed by one- or two-way ANOVA
for repeated measures. Post hoc analysis was performed by
Fisher’s least significant difference (LSD) test Statisticalsignificance was set at P \ 0.05.
Results
The exercise durations were 900 ± 0, 217 ± 21, and
135 ± 8 s for exercise at 15, 30, and 45% MVC,
respectively.

Physiological measurements
FBF
Common FBF in the left leg was determined using a
Doppler instrument (HP 8500-GP, Hewlett-Packard, USA).
A 7.5 mHz linear array transducer was placed on the skin

At 15 s, FBF increased at all the intensities, and thechanges in blood flow reached a maximum at 45% MVC

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511

Discussion(Table 1; Fig. 1). After 15 s in the 15% MVC session, theFBF returned to the resting level; however, it increased
again at the end of exercise. At the 30 and 45% MVC, FBF
remained elevated until 45 s (30% MVC) and 60 s (45%
MVC). At the end of the exercise at 15% MVC, blood flow
was higher than that at the end of the 30 and 45% MVC
sessions (Fig. 3). Interaction was observed between theexercise intensity and duration (P \ 0.01).

This study examined the influence of exercise intensity andduration besides the interaction between these factors on
blood flow in the femoral artery of the non-exercising leg.
The major finding was that blood flow and vascular conductance of the leg vessels in the contralateral nonexercising leg demonstrated biphasic time-dependentchanges, in that they increased at the onset of exercise to
decrease during continued exercise.

Mean blood pressure and heart rate

Vasodilation in the non-exercising leg during the initial
phase of exercise

An increase in the MBP was observed after 30 s of exercise
at 15% (P \ 0.01) and 30% MVC (P \ 0.01), whereas it
was observed after 45 s of exercise at 45% MVC(P \ 0.01) (Table 1). The HR increased immediately at theonset of exercise and continued to increase throughout
exercise.

Blood flow and vascular conductance in the non-exercisingleg during dynamic contralateral leg exercise exhibited anincrease for the first 15–30 s, and the increase dependent
on exercise intensity. The initial increase in the blood flowin the contralateral leg and vascular conductance were inagreement with the results reported for static leg exercise(Fisher and White 2003; Fisher et al. 2005; Gaffney et al.
1990). These studies on static leg exercise indicate thatblood flow to the contralateral leg increases momentarily.
The explanation for these results may include two possible
mechanisms: changes in neural control and changes inblood flow stimuli to the vessel walls. In contrast to arm
exercise, during leg exercises, both static and dynamic,muscle sympathetic activity decreases during the earlystages of exercise (Ray et al. 1992, 1993) and returns to thebaseline with time. Therefore, a reduction in MSNA is a

FVC
At the onset of the exercise at all intensities, FVC increased(P \ 0.01) (Table 1). The change in FVC was the highest
at 45% MVC (Fig. 2). At 15% MVC, the FVC increased
again after having being reduced to the resting level, andhigh FVC values were observed at the end of exercise(Fig. 3). At 30 and 45% MVC, FVC remained elevateduntil 30 s (30% MVC) and 60 s (45% MVC), and it
thereafter decreased with time. At the end of exercise, adecrease was observed in FVC at 45% MVC as comparedto the resting level.

Table 1 Average values of femoral blood flow (FBF), femoral vascular conductance (FVC), mean blood pressure (MBP), and heart rate (HR)determined at rest and during exercise
MVC

Time
Rest

15 s

30 s

45 s

60 s

75 s

90 s

Exhaustion or 900 s-1

FBF (ml min )15% MVC

251 ± 32362 ± 34**

300 ± 28259 ± 27258 ± 36233 ± 35269 ± 46452 ± 94**

30% MVC
45% MVC

237 ± 28260 ± 31393 ± 55**458 ± 45**347 ± 34**468 ± 52**335 ± 54*531 ± 82**

312 ± 48
501 ± 92**278 ± 34341 ± 57

256 ± 28277 ± 32219 ± 20220 ± 26

15% MVC

2.4 ± 0.3

3.4 ± 0.4**

2.6 ± 0.3

2.2 ± 0.3

2.2 ± 0.4

1.9 ± 0.3

2.2 ± 0.5

3.8 ± 1.0*

30% MVC

2.2 ± 0.3

3.6 ± 0.7**

2.9 ± 0.3*

2.7 ± 0.5

2.5 ± 0.4

2.1 ± 0.3

2.0 ± 0.3

1.5 ± 0.1

45% MVC

2.4 ± 0.3

4.4 ± 0.6**

4.1 ± 0.5**

4.4 ± 0.7**

4.0 ± 0.8**

2.6 ± 0.5

2.0 ± 0.3

1.5 ± 0.2

95.2 ± 5.8**

96.8 ± 5.7**

98.5 ± 5.9** 102.5 ± 9.4**

MBP (mmHg)
15% MVC 81.5 ± 5.1 82.8 ± 5.3

89.9 ± 4.9** 91.4 ± 5.5**

30% MVC 85.8 ± 4.6 86.5 ± 5.0

94.7 ± 4.1** 98.6 ± 4.2** 102.6 ± 3.9** 104.9 ± 4.2** 106.3 ± 5.9** 117.0 ± 6.0**

45% MVC 84.0 ± 5.0 80.2 ± 4.8

90.4 ± 3.1

97.3 ± 3.3** 102.7 ± 4.2** 108.6 ± 3.3** 111.0 ± 3.4** 118.7 ± 5.3**

HR (bpm)
15% MVC 64.3 ± 3.0 76.6 ± 2.9** 81.0 ± 2.5** 81.0 ± 2.9**

77.8 ± 4.1**

80.0 ± 3.8**

82.3 ± 3.0**

85.4 ± 4.2**

30% MVC 69.3 ± 5.6 82.4 ± 4.1** 84.9 ± 4.8** 86.0 ± 5.2**

87.4 ± 4.6**

89.9 ± 4.2**

91.3 ± 4.9**

94.6 ± 5.5**

45% MVC 70.4 ± 4.5 85.7 ± 3.5** 91.2 ± 4.4** 93.1 ± 4.9**

91.2 ± 4.9**

92.9 ± 5.1**

94.4 ± 5.3**

97.6 ± 6.9*** P \ 0.05, ** P \ 0.01 versus rest

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Eur J Appl Physiol (2008) 103:509–514

**
300

**

200

**

900sec

**

100

**

**

*

0

-100

**
2

**

**

30%MVC

45%MVC

3.0

*

**

1

15%MVC**FVC (ml•min-1•mmHg-1)

FVC (ml/min/mmHg)

100

0

**
0

-1

**

2.5
2.0
1.5
1.0
0.5

-2

0.0

50

**

40

MBP (mmHg)

150

50

Exhaustion
Exhaustion

3

**

200

**

**

FBF (ml•min-1)

FBF (ml/min)

250

Exhaustion or 900sec

400

**

30

**
**

10

**

0

**
** **
** ** ** **
**

**

0

15

30

45

60

75

45%MVCet al. 1993) and it is, therefore, unlikely that lowering of
MSNA is the only factor underlying the intensity-dependent increase in blood flow to the non-exercising leg.
Fisher et al. (2005) found that increased vascular conductance during contralateral isometric exercise is unrelated tothe decrease in MSNA.
In the active muscles, blood flow increased immediately
and remarkably upon initiation of exercise, and thisincrease was related to exercise intensity (Rådegran andSaltin 1998). As blood flow to the femoral artery passes
through the abdominal aorta, which branches into femoral
arteries of active and non-active legs, an increased FBF to
the active limb during exercise induces increase in
upstream blood flow of the abdominal aorta in an intensitydependent manner (Osada et al. 1999). If MSNA is reduced
but the vasoconstriction of the contralateral leg vessels is
not yet augmented, the gradient of flow resistance to thefemoral arteries on both sides may not be high enough toprevent blood flow to the non-exercising regions. Furthermore, accelerated blood flow due to exercise may stimulate
the endothelium and lead to the release of nitric oxide

**

**

-10

30%MVC

Fig. 2 Mean changes in the femoral arterial blood flow (DFBF) andfemoral vascular conductance (DFVC) of the resting leg at 15 s ofdynamic knee extension exercise of the contralateral leg. *P \ 0.05,**P \ 0.01 versus 15% MVC

**

**
20

15%MVC90

Keep on Time (sec)Fig. 1 Changes in the femoral arterial blood flow (FBF), femoral
vascular conductance (FVC) of the resting leg, and mean bloodpressure (MBP) during one-legged dynamic exercise with thecontralateral leg. For 30% (open circle) and 45% (filled square)
MVC exercise, the values at exhaustion are illustrated, and for 15%(filled circle) MVC, values at the very right are those obtained at
15 min. Main effect for exercise duration was observed (P \ 0.01).
Interaction was observed between exercise intensity and duration(P \ 0.01). *P \ 0.05, **P \ 0.01 versus rest

probable mechanism for increased blood flow and vascular
conductance in the non-exercising leg at the early stages of
exercise. However, the reduction in the MSNA at the onsetof exercise does not increase with exercise intensity (Ray

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Eur J Appl Physiol (2008) 103:509–514

513

300

temperature increases during exercise and blood flow to the
cutaneous vasculature increases proportionately (Kolka andStephenson 1997).
At 30 and 45% MVC, blood flow to the non-exercising
leg remained elevated until 45 and 60 s from the onset of
exercise and FBF and FVC thereafter decreased to below
the baseline level. The results of this study were consistent
with the finding by Taylor et al. (1989) who reported that
vascular resistance in the calf of the non-exercising leg
increased in a time- and intensity-dependent manner. Thesechanges may be caused by augmented MSNA via metaboreflex from the exercising muscles (Ray et al. 1993). Saito(1995) demonstrated that MSNA is markedly activated byexercise at intensities above 30% MVC. Considering this,the SNA occurring in the late phase of exercise at 30 and
45% MVC in the present study may be mediated by anincrease in metabolites in the exercising muscles. The
consequent activation of muscle metaboreflex may haveresulted in reduction of vasoconstriction and blood flow in
the non-exercising leg.
Another mechanism to explain the late vasoconstriction
observed in this study could be the release of endothelin-1(ET-1), which is the most potent endothelium-derived
constricting factor and it contributes to regulation of
peripheral vascular tone. Maeda et al. (1997) showed that
the ET-1 concentration increased in the circulation of the
nonworking muscle after one-legged dynamic exercise.
Dynamic leg exercise induces intensity-dependenttransient increase in the blood flow and vascular conductance in the contralateral limb. The explanation of ourresults might involve an increase in shear stress due topassively increased blood perfusion to the non-exercisinglimb, although other explanations are possible. After initial
vasodilation, vasoconstriction manifests during exercise at
higher intensities (30 and 45% MVC) but not at lower
intensities (15% MVC). Time- and exercise intensitydependent responses of the vasculature were indicated in
the contralateral non-exercising limb during leg exercise.

FBF (ml•min-1)

200

100

0

-100

*

*

30%MVC

45%MVC**

30%MVC

45%MVC-200

15%MVCFVC (ml•min-1•mmHg-1)

3
2
1
0
-1
-2
-3

15%MVC

Fig. 3 Mean changes in the femoral arterial blood flow (DFBF) andfemoral vascular conductance (DFVC) of the resting leg at the end of
dynamic knee extension exercise of the contralateral leg. *P \ 0.05,**P \ 0.01 versus 15% MVC(NO), which is a strong vasodilatator (Green et al. 2002a;
Gilligan et al. 1994). The intensity-dependent vasodilation
at the initial phase of leg exercise in the contralateral nonexercising leg could be explained by the reduced MSNA
and increased shear stress to the vessel due to the passively
increased perfusion.

Acknowledgments This research was supported by ‘‘Academic
Frontier Project,’’ 2004, at Japan Women’s College of Physical
Education (project leader, A. Kagaya).

Time-dependent vasoconstriction in the non-exercisingleg during contralateral leg exercise

References

After the initial phase of exercise, we observed differentchanges in blood flow depending on the exercise intensity.
At 15% MVC, flow to the non-exercising leg returned to
the resting level and then increased again after 900 s. One
mechanism for this increase in flow could be the release of
NO. Green et al. (2002a, b, c) demonstrated that brachialarterial blood flow increased during cycling exercises, but
intra-arterial infusion of a NO synthase inhibitor decreased
brachial arterial blood flow. Another possibility is that core

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Fisher JP, White MJ (2003) The time course and direction of lower
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Fisher JP, Sander M, MacDonald I, White MJ (2005) Decreased
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and nitric oxide function. Am J Physiol Heart Circ Physiol
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G, Walsh JH (2005) Comparison of forearm blood flow
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the inactive forearm. Adv Exerc Sports Physiol 3:29–34
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Kolka MA, Stephenson LA (1997) Effect of luteal phase elevation incore temperature on forearm blood flow during exercise. J Appl
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DOI 10.1007/s00421-008-0893-5

O R I G I N A L A RT I CL E

Resistance exercise training enhances sympathetic nerve activity
during fatigue-inducing isometric handgrip trials
Mitsuru Saito · Satoshi Iwase · Tesshin Hachiya

Accepted: 1 October 2008 / Published online: 22 October 2008
© Springer-Verlag 2008

Abstract Muscle sympathetic nerve activity (MSNA)
was investigated 1 week before (pre-training), 1 week after,and 4–6 weeks after strength training using fatigue-inducing handgrip exercises and post-exercise forearm occlusion.
Eighteen volunteers underwent forearm training, which
consisted of 30 maximal eVort, 10-s-duration static handgrips, 4 days per week for 4 weeks. A second group of 18 volunteers served as a control. MSNA was recorded from thetibial nerve by microneurography. Maximal handgrip force
increased at 1 week post-training. The MSNA response
during fatigued handgrip also increased at 1 week posttraining, as compared to pre-training (52.6 § 5.8 vs.
40.6 § 4.4 bursts min¡1 (mean § SEM), respectively).
However, at 4 weeks post-training, MSNA activity returnedto the pre-training level (44.0 § 5.2 bursts min¡1;
p < 0.0001 by ANOVA), while the control group showedno changes throughout this period. The MSNA response
during post-exercise forearm occlusion was constantthroughout the experiment in both groups. Our results indicate that an increased MSNA response after strength training is likely to be the result of central neural factors rather
than the muscle metaboreXex.

Introduction
The modulating eVect of exercise on the cardiovascularresponse to muscular exercise is well documented (Fisher
and White 1999), and these adaptive changes have been
attributed to the autonomic sympathetic nervous system.
Muscle sympathetic eVerent nerve activity (MSNA) during
exercise is attenuated by muscle training via the attenuationof muscle reXexes (Ray 1999; Sinoway et al. 1996; Somers
et al. 1992), including the decreased stimulation of muscle
metaboreceptors (Somers et al. 1992) and mechanoreceptors (Sinoway et al. 1996). However, resistance exercise
training does not alter the MSNA response during muscular
contractions (Carter et al. 2003; Ray and Carrasco 2000).
This discrepancy may be the result of the training mode
used; endurance training improves muscle oxidative metabolic activity (Kent-Braun et al. 1990), whereas resistancetraining improves mainly the muscle strength associatedwith increased central neural activity, rather than metabolic
potentials (Kraemer et al. 1996; Narici et al. 1989). MSNA
during muscle contraction is controlled by both central
command and the reXexes from contracting skeletal muscles (Mitchell 1990). The relative contributions of endurance or resistance training eVects on central command andmuscle reXexes, such as the metaboreXex, may underlie theconXicting results obtained for the MSNA response during
exercise.
Many studies on strength exercises have indicated thatstrength training develops muscle force and delays theonset of muscle fatigue, which is associated not only with
peripheral factors (i.e., muscle reXexes), but also with central neural factors (i.e., central command) (Gandevia 2001;
Rube and Secher 1990; Sale 1988). Increased muscle force
after short-term resistance training (i.e., less than 6 weeks)
is due primarily to increased central motor command, rather

Keywords Muscle sympathetic nerve activity ·Central command · Muscle metaboreXex ·Muscle mechanoreXex

M. Saito (&) · T. Hachiya
Applied Physiology Laboratory, Toyota Technological Institute,2-12 Hisakata Tmpaku-ku, Nagoya 468-8511, Japane-mail: msaito@toyota-ti.ac.jp
S. Iwase
Department of Physiology, Aichi Medical University,
21 Yazako, Nagakute 480-1195, Japan

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Eur J Appl Physiol (2009) 105:225–234

Handgrip exercise test

than muscle properties (Sale 1988). After the cessation ofresistance training, muscle force decreases in line withdecreased motor neural activity (Houston et al. 1983, Narici
et al. 1989). Therefore, we hypothesised that if high-intensity resistance training increases central motor command,followed by a decrease after cessation of training, thiswould, in part, modulate the MSNA response during muscular exercise. Central command is one factor that stimulates MSNA during static handgrip, although this eVect was
only observed during a strong contraction or eVort (Victor
et al. 1989, 1995). Indeed, the MSNA response during
fatigued isometric handgrip was found to be greater in athletes than in sedentary subjects (Ng et al. 1994), and physical inactivity, such as bed rest, attenuated the MSNA
response during muscle contraction (Kamiya et al. 2000,
2003).
We re-examined whether resistance exercise training
inXuences the MSNA response during muscle contraction. The exercise test was carried out after strength training and at 4 weeks after halting training (i.e., detraining).
However, since both the central motor command andmuscle reXexes act simultaneously during voluntary contraction, it is impossible to separate their contributions to
MSNA modulation during exercise. For this reason, thefollowing exercise tests were conducted to activate diVerentially the central motor command and muscle receptors: (1) a standard 2-min isometric handgrip performed
at 33% of maximal voluntary force (MVC); (2) a rhythmic handgrip with forearm ischaemia performed at maximal eVort, to stimulate forearm muscle metaboreceptors
and mechanoreceptors with high-intensity contraction;and (3) a fatigued isometric handgrip performed at 33%
of maximal handgrip force, to stimulate central motor
command.

For the exercise tests, three diVerent static handgrips were
performed in a supine position: (1) a 2-min isometric handgrip performed at 33% of maximal voluntary contraction(MVC); (2) a rhythmic handgrip (40 contractions per min)with forearm ischaemia performed at maximal eVort; and(3) a fatigued isometric handgrip performed at 33% of
MVC, until the subject could no longer maintain grip force.
Each handgrip was followed by a 2-min post-exercise forearm occlusion. Nine of the trained subjects performed theisometric exercise Wrst, followed by the fatigued handgrip
after an interval of 20 min on the same day; the remaining
nine subjects performed the rhythmic handgrip, and one ofthese subjects also performed the isometric handgrip test.
The subjects were asked to breathe as normally as possible
and to not hold their breath or contract any muscles otherthan those directly involved in the handgrip contraction. All
subjects were introduced to the routine 1 day prior to theexperiment, to become familiar with the equipment andprocedures.
Measurements
MSNA was recorded from the tibial nerve at the popliteal
fossa, using an inserted tungsten microelectrode with ashaft diameter of 0.1 mm (Saito et al. 1989). The nerve
action potential (ampliWed by a factor of 100,000) was
Wltered at 500–3000 Hz, rectiWed, and integrated (timeconstant, 0.1 s) to obtain a mean voltage neurogram.
MSNA was identiWed as a MSNA burst rhythm that corresponded to the heartbeat rhythm. The Valsalva manoeuvre
was used to enhance MSNA, and the burst rhythm andactivity were unchanged by arousal stimuli. The burst
amplitude of the original mean voltage neurogram was
normalised against the highest MSNA burst amplitude
during baseline recording, which was set at an arbitraryvalue of 20. The MSNA burst was inspected by the experimenter, and the data are expressed as the burst frequency(BF; bursts per min) and percent change in total activity(TSNA; sum of the burst area in arbitrary units). MSNA
and other physiological data were recorded from 3 to
1 min before exercise (i.e., a 2-min window of baselinedata) and for each 30-s period of exercise and post-exercise forearm occlusion in the isometric and rhythmic
handgrip exercises. In the fatigued handgrip test, MSNA
was determined in the same manner as in the isometrichandgrip; a 2-min handgrip was used as the common nonfatiguing point, and the last 30 s of the exercise were used
for the fatigue data.
Heart rate was determined using the R–R interval of anelectrocardiogram (ECG), which was performed using
bipolar electrodes positioned on the chest (AB118;

Methods
Subjects
All 36 subjects were volunteers and provided written
informed consent before participating. This study wasapproved by the Human Subject Ethics Committee of the
Toyota Technological Institute. Participants were provided
with information about the study and were randomly
assigned to the resistance training group (TG, n = 18) or thecontrol group (CG, n = 18). The subjects were aged
22 § 2 years (mean § SD), with a mean height of
172 § 4 cm and mean body mass of 65 § 9 kg. One of the
trained subjects was left-handed and 17 were right-handed.
All subjects were in good health and had recently participated in leisure sports, but none had engaged in any activity
that speciWcally used the arms, such as racket sports.

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227

Results

Nihonkhoden, Tokyo). Blood pressure was measured
using a Finapres blood pressure monitor (Ohmeda Englewood, CO) with the Wnger cuV on the middle Wnger of theresting hand. Heart rate and blood pressure were determined in the same segments as the MSNA analysis.
Respiratory movements were monitored using a facemask
attached to a Xow meter with a hot wire (RT-6; Minato
Medical, Tokyo). Handgrip force was monitored using astrain gauge attached to a hand dynamometer(TKK5710b; Takei Co., Tokyo), and maximal handgrip
force was calculated as the highest value among three trials of a 3-s maximal eVort performed over 2–3 min in astanding position. Work performance of the handgrip
exercise was represented by the integration of the handgrip force curve.
Exercise tests were performed 2 weeks prior to training(pre-training), 1 week after the cessation of training(1 week post-training), and between 4 and 6 weeks from theend of training (4 weeks post-training). All signals weredigitised at 200 Hz through an analogue-digital converter(MP100; Biopac Systems, Goleta, CA) for later processing
on a personal computer that was equipped with an online
data acquisition programme.

EVects of training
Resistance training increased maximal handgrip force by
6.6% in the TG, whereas the CG showed no change overthe same time period (Fig. 1). Total handgrip work during
the fatigued handgrip increased by 17.6% after training in
the TG. Although endurance time tended to increase after
training, the diVerences among the values for pre-training,
1 week post-training, and 4 weeks post-training (171 § 32,
190 § 30, and 185 § 18 s, respectively) were not signiWcant. No changes were observed in the CG (Fig. 1). Total
handgrip work was unchanged for the rhythmic and isometric handgrip exercises in both groups.
MSNA increased from the basal control during the handgrip exercises, and higher activity persisted during post-exercise forearm occlusion in the isometric, rhythmic, and fatigued
handgrip exercises (Tables 1, 2, 3, respectively). In the TG,
the increase in MSNA was greater during the fatigued handgrip exercise at 1 week post-training (Fig. 2), whereas nochange occurred during the isometric or rhythmic handgrip
exercise. In the CG, no signiWcant change was noted during
any exercise (Fig. 2). The MSNA response did not change
during forearm occlusion after any exercise in the TG or CG.
The mean blood pressure was elevated during exercise, andremained high during post-exercise forearm occlusion. No signiWcant diVerence was observed in the mean blood pressure
response at pre-training versus 1 or 4 weeks post-training forthe three diVerent handgrip exercises, and the magnitude of the
response was identical in the TG and CG. In the TG, the heart
rate increased during the handgrip exercises, but no diVerencein heart rate was observed between the control resting stateand during post-exercise forearm occlusion (Tables 1, 2, 3). In
the CG, the blood pressure and heart rate responses were identical before and after the experimental period.

Training
Although strength training could be reveal any speciWc
strength the gain the important factors initial strength
gain attributable to neural factors is very high intensity(Kraemer et al. 1996). Thus, intermittent handgrip exercise with maximal eVort was used for resistance training,
to enhance central motor activity and the number ofactivated motor units, which correlates with the intensityof muscle force (Grimby 1977). We tested the nondominant arm, as it is used less frequently in daily activities
than the dominant arm and is expected to show a greater
physiological response to training and at 4 weeks posttraining. The training regimen involved 10-s isometrichandgrip contractions performed at maximal eVort,
repeated 10 times at 10-s intervals for three sets per day,
4 days per week for 4 weeks. Subjects in the control
group were asked to maintain their normal daily activities.

EVects of halting resistance training
In the TG, training resulted in an 8% increase in maximal
handgrip force, which persisted throughout the subsequent
4 weeks of detraining (Fig. 1). Handgrip force remained
stable in the CG throughout the study period. The integrated handgrip force during the rhythmic and fatigued
handgrip exercises did not diVer in comparison to thatobserved pre-training (Fig. 1).
At 4 weeks post-training, the MSNA response during thefatigued handgrip exercise decreased compared to the
1 week post-training response and was similar to the pretraining response (Fig. 2). No signiWcant diVerence in
MSNA was noted during the isometric versus rhythmic
handgrip exercise. After the detraining period, the MSNA
response during post-exercise forearm occlusion did not

Statistics
The signiWcance of the main eVect was tested by one-way
analysis of variance (ANOVA) using time (resistance training) and handgrip exercise, followed by a Tukey-Dunnet
post hoc test to detect signiWcant diVerences (Prism 5;
Graph Pad Software, CA). Values are expressed as themean § standard error (SEM). A value of P < 0.05 indicates statistical signiWcance.

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Maximal Handgrip Force
TG

n=18

∗

∗

CG

n=18
600

(Nm)

Ma x H G F

400

200

400

(Nm)

600

Ma x H G F

Fig. 1 Maximal handgrip forces (Max HGF) and integrated
handgrip forces (iHGF) in the
training (TG) and control (CG)groups during the rhythmic andfatigued handgrip exercises at
pre-training (B), 1 week posttraining (A) and 4 weeks posttraining (D). * p < 0.05 compared to the pre-training values,n number of data points

Eur J Appl Physiol (2009) 105:225–234

200

0

0

B

A

D

B

A

D

Integrated Handgrip Force in RHG
TG

n=9(x10 2 )

100

80

80

60

60

40

( N)

100

iHGF

( N)

iHGF

(x10 2 )

CG

n=8

40

20

20

0

0

B

A

D

B

A

D

Integrated Handgrip Force in FTG(x10 3 )n=930(x10 3 )

TG

CG

30

∗

( N)
10

( N)

20

iHGF

20

iHGF

n=8

10

0

0

B

A

diVer from the pre-training or 1 week post-training
response, irrespective of exercise mode. In the CG, no signiWcant change in MSNA was observed during any handgrip exercise or post-exercise forearm occlusion.
In both the TG and CG, the responses in heart rate andmean blood pressure during exercise and post-exercise
forearm occlusion did not diVer signiWcantly at 4 weeks
post-training compared to the pre-training or 1 week posttraining values (Tables 1, 2, 3).

D

B

A

D

MSNA is restored to the pre-training levels after training is
stopped for 4 weeks (i.e., detraining). However, sympathetic activity during post-exercise circulatory occlusion
did not change at 1 or 4 weeks post-training. Furthermore,maximal handgrip force increased after strength training,and persisted at this level at 4 weeks post-training.
Training eVects on performance
Four weeks of high-intensity resistance training increased
the maximal handgrip force. In previous studies, resistancetraining for less than 6 weeks was typically associated withimproved force of muscle contraction, which was produced
primarily by increased motor unit recruitment with little
muscle hypertrophy or muscle Wbre alteration (Lewis et al.

Discussion
Our results demonstrate that strength training increases
MSNA during fatiguing static handgrip exercise, whereas

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229

Table 1 Burst frequency (BF), total sympathetic nerve activity (TSNA), heart rate (HR), and mean blood pressure (MBP) during the handgrip exercise and post-exercise forearm occlusion (OCL) for theisometric handgrip exercise at pre-training, 1 week post-training, and4 weeks post-training in the training and control groups

n

Base

IHG1

IHG2

OCL1

OCL2

19.3 § 3.5

24.2 § 1.4

36.2 § 4.4*

29.7 § 3.0*

31.5 § 2.7*

67 § 179 § 3*85 § 2*72 § 269 § 229.8 § 4.3*

Trained group
Pre-training

1 weekPost-training

BF

Bursts min¡1

9

TSNA

Unit

9

HR

bpm

9

MBP

mmHg

8

BF

Bursts min¡1

9

TSNA

Unit

9

HR

Beats/min

9

MBP

mmHg

9

4 weeks

BF

Bursts min¡1

9

Post-training

TSNA

Unit

9

HR

bpm

9

MBP

mmHg

8

BF

Bursts min¡1

8

TSNA

Unit

8

HR

bpm

8

MBP

mmHg

Control group
Pre-training

8
¡1

8

1 weekBF

Bursts min

Post-training

TSNA

Unit

8

HR

bpm

7

MBP

mmHg

8

BF

Bursts min¡1

8

4 weeks
Post-training

TSNA

Unit

8

HR

bpm

8

MBP

mmHg

8

45 § 359 § 479 § 3100 § 6*111 § 21*108 § 6*91 § 13*98 § 6*18.2 § 3.4

19.3 § 3.6

33.2 § 5.2*

30.0 § 2.9*

67 § 176 § 2.7*

82 § 2*72 § 243 § 948 § 976 § 495 § 8*94 § 19*105 § 8*92 § 11*104 § 5*20.3 § 3.1

26.7 § 4.4

36.8 § 6.4*

30.3 § 4.2*

65 § 275 § 2.1*

82 § 2.6*

73 § 2*49 § 858 § 1295 § 23.4*

76 § 1696 § 16.1*

95 § 7*88 § 13.9*
73 § 3101 § 6*35.3 § 4.7*

92 § 18.6*
72 § 2.2*

77 § 394 § 6*104 § 4*99 § 4*100 § 4*14.8 § 1.1

23.2 § 2.6*

34.3 § 2.4*

25.1 § 2.2*

26.7 § 2.9*

64 § 176 § 2*82 § 2*70 § 2.4*

72 § 2.4*

34 § 563 § 8.3*

78 § 2103 § 4*122 § 13.2*

114 § 4*92 § 10*105 § 4*13.5 § 2.7

22.0 § 2.4*

37.7 § 3.6*

23.3 § 2.8*

61 § 274 § 1.3*

81 § 2.4*

67 § 3.4*

31 § 748 § 675 § 2105 § 4*122 § 15.7*

114 § 4*75 § 10.9*

103 § 4*18.8 § 1.9

23.6 § 2.9

42.3 § 4*

29.2 § 3.8*

65 § 277 § 2*85 § 3*71 § 246 § 759 § 1082 § 2108 § 4*113 § 11.9*
120 § 5*80 § 13.5*

106 § 3*91 § 12*107 § 4*24.2 § 4.3*

80 § 18.5*
67 § 3*103 § 4*30.6 § 4.1*

85 § 15.2*
73 § 3*106 § 4*

Values represent the mean § standard error (SEM)
IHG1 and IHG2 represent the Wrst and second minute of the isometric handgrip, respectively, OCL1 and OCL2 represent the Wrst and second minuteof the post-exercise forearm occlusion, respectively, n, number of data points* p < 0.05 compared to the control base

1984; Narici et al. 1989; Rube and Secher 1990; Sale 1988).
Increased central motor nervous activation after training was
also reported (Aagaard et al. 2002; Gandevia 2001). Thisphenomenon may explain the increase in maximal handgrip
force observed in the present study. Force output during thefatiguing handgrip exercise increased by 17% after training,whereas the increase in force output during the rhythmic
handgrip exercise was insigniWcant (7%). These Wndings
suggest that short-term strength training improves endurance
for isometric contraction, but has only a small eVect onanaerobic performance, similar to that seen during an ischaemic rhythmic handgrip (Hansen 1961).

observed during the isometric or rhythmic handgrip exercise. In contrast, Ray and Carrasco (2000) found no signiWcant diVerence in MSNA response during fatiguing
isometric handgrip exercises between pre- and post-training. This discrepancy may be attributable to diVerences intraining regimen. The previous study used a 3-min submaximal isometric handgrip at a tension of 30% MVC. In
contrast, to activate high-threshold motor neurons, weused an intermittent handgrip performed at maximal
eVort. The involvement of a greater number of motor units
than that involved in a submaximal isometric contraction(Grimby 1977) may stimulate sympathetic muscle eVerent
activity to a greater extent. In cross-sectional studies,whole-body resistance training decreased the MSNA
response (Sinoway et al. 1992) or MSNA remained
unchanged (Carter et al. 2003) during fatiguing static
handgrip trials, as compared to controls. This discrepancy

EVect of resistance training on MSNA
Training increased MSNA during contraction in thefatiguing handgrip exercise, whereas no change was

123
391

230

Eur J Appl Physiol (2009) 105:225–234

Table 2 Burst frequency (BF), total sympathetic nerve activity (TSNA), heart rate (HR), and mean blood pressure (MBP) during the handgrip exercise and post-exercise forearm occlusion (OCL) for thenrhythmic handgrip exercise at pre-training, 1 week post-training, and4 weeks post-training in the training and control groups

Base

RHG1

RHG2

OCL1

OCL2

17.7 § 2.2

30.2 § 1.5*

38.2 § 2.8*

23.1 § 2.2

28.6 § 2.4*

73 § 391 § 3*94 § 2*76 § 376 § 3Trained group
Pre-training

1 weekPost-training

BF

Bursts min¡1

10

TSNA

Unit

10

HR

bpm

10

MBP

mmHg

10

BF

Bursts min¡1

10

TSNA

Unit

10

HR

bpm

10

MBP

mmHg

10

4 weeks

BF

Bursts min¡1

7

Post-training

TSNA

Unit

7

HR

bpm

7

MBP

mmHg

7

BF

Bursts min¡1

9

TSNA

Unit

9

HR

bpm

9

MBP

mmHg

9

1 weekBF

Bursts min¡1

9

Post-training

TSNA

Unit

9

HR

bpm

9

MBP

mmHg

9

BF

Bursts min¡1

8

Control group
Pre-training

4 weeks
Post-training

TSNA

Unit

8

HR

bpm

8

MBP

mmHg

8

43 § 599 § 389 § 8*119 § 4*135 § 10*127 § 4*17.1 § 2.2

31.0 § 3.5*

42.2 § 5.3*

67 § 292 § 2.8*

96 § 3.5*

40 § 692 § 318.4 § 1.2
48 § 467 § 2104 § 15*116 § 6*31.4 § 3*

108 § 6*88 § 3.2*

83 § 3157 § 19*122 § 7*66 § 6114 § 5*28.4 § 3*

82 § 8*76 § 3.9*

118 § 6*72 § 7*115 § 5*32.2 § 2.7*
93 § 12*76 § 3.8*

114 § 7*44.8 § 4*

28.1 § 2.2*

28.7 § 2.8*

92 § 3*74 § 3.2*

74 § 3.3*

152 § 13*79 § 10*82 § 7*98 § 8*108 § 8*103 § 4*104 § 3*11.2 § 1.7

23.5 § 2.2*

35.7 § 3.4*

22.2 § 2.7*

22.9 § 3*

68 § 282 § 2.1*

86 § 3.2*

72 § 228 § 584 § 274 § 10*95 § 2*141 § 16*108 § 2*80 § 17*106 § 4*12.8 § 2.2

22.4 § 2.4*

37.1 § 3.3*

30.6 § 3.1*

66 § 291 § 2.3*

96 § 3.1*

76 § 4*31 § 678 § 268 § 999 § 3*16.7 § 2.6

24.0 § 2.1

67 § 288 § 2.5*

41 § 778 § 385 § 9*97 § 3*142 § 17*108 § 4*40.7 § 2*

167 § 11*92 § 2.6*

107 § 3*100 § 16*107 § 5*76 § 21*71 § 2107 § 4*26.7 § 3.3*
86 § 17*76 § 4.2*

108 § 5*29.2 § 2.6*

28.1 § 3.1*

73 § 3.5*

74 § 2.9*

92 § 10*105 § 4*84 § 11*104 § 4*

Values represent the mean § standard error (SEM)* p < 0.05 compared to the control base
RHG1 and RHG2 represent the Wrst and last 30 seconds of the rhythmic handgrip, respectively, OCL1 and OCL2 represent the Wrst and second
minute of the post-exercise forearm occlusion, respectively, n Number of data points

post-exercise arterial occlusion after the fatigued handgrip
exercise remained unchanged throughout the study period,
despite the increase in total handgrip force and a non-signiWcant trend toward increased endurance time (11%) at
1 week post-training. These results suggest that no alteration of metaboreXex intensity reached the maximal level.
Therefore, our subjects were thought to be naïve to training
and showed sustained central activity during fatigue compared to pre-training (Bigland-Ritchie et al. 1978; Gandevia 2001). Therefore, we propose that an increase in central
activity after resistance training contributes to an increased
MSNA response.
The MSNA response during rhythmic handgrip performed at maximal eVort was not altered post- training,although it increased during the fatigued handgrip exercise.
This diVerence in response may be due to the pattern of

may reXect diVerences in subjects or the training of diVerent muscle groups.
When constant handgrip exercises are performed until
fatigue, motor nerve activity increases with the onset ofmuscle fatigue (Sale 1988), and the concomitant increase inperceived exertion and the surface electromyogram areboth correlated with increased MSNA (Saito et al. 1989;
Seals and Enoka 1989). However, the development of
fatigue during sustained muscle contraction decreases after
resistance training (Gandevia 2001; Lewis et al. 1984;
Rube and Secher 1990), signifying that not only peripheral
factors, but also central fatigue factors are involved. In thecurrent study, using the standard 2-min isometric handgrip
test, the MSNA response during the handgrip exercise
remained unchanged during the subsequent post-exercise
arterial occlusion. Furthermore, the MSNA response during

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Eur J Appl Physiol (2009) 105:225–234

231

Table 3 Burst frequency (BF), total sympathetic nerve activity (TSNA), heart rate (HR), and mean blood pressure (MBP) during the handgrip exercise and post-exercise forearm occlusion (OCL) for thefatigued handgrip exercise at pre-training, 1 week post-training, and4 weeks post-training in the training and control groups

n

Base

FTG1

FTG2

OCL1

OCL2

17.1 § 2.2

37.8 § 4.2*

40.6 § 4.4*

24.0 § 2.5*

28.6 § 3*

68 § 289 § 2*94 § 3.4*

73 § 2.4*

72 § 2Trained group
Pre-training

1 weekPost-training

BF

Bursts min¡1

9

TSNA

Unit

9

HR

bpm

9

MBP

mmHg

9

BF

Bursts min¡1

9

TSNA

Unit

9

HR

bpm

9

MBP

mmHg

9

4 weeks

BF

Bursts min¡1

9

Post-training

TSNA

Unit

9

HR

bpm

9

MBP

mmHg

8

BF

Bursts min¡1

9

TSNA

Unit

9

HR

bpm

9

MBP

mmHg

9

1 weekBF

Bursts min¡1

9

Post-training

TSNA

Unit

9

HR

bpm

9

MBP

mmHg

8

BF

Bursts min¡1

7

Control group
Pre-training

4 weeks
Post-training

TSNA

Unit

7

HR

bpm

7

MBP

mmHg

7

34 § 4127 § 26*85 § 4122 § 8*18.0 § 3.4

42.2 § 5*

39 § 6122 § 14*69 § 288 § 2.3*

82 § 2113 § 6*163 § 32*
133 § 9*81 § 11*111 § 5*52.6 § 5.8*

30.0 § 4.2*

94 § 3.2*

78 § 2.1*

294 § 147*
123 § 5*96 § 19*103 § 5*

20.6 § 1.9

39.1 § 4.4*

44.0 § 5.2*

33.1 § 4.3*

67 § 288 § 6.1*

93 § 5*77 § 2.9*

49 § 4109 § 16*145 § 34*

84 § 1298 § 16113 § 5*32.2 § 4.2*
92 § 18*79 § 2*100 § 6*

32.6 § 3*

84 § 1473 § 382 § 2115 § 5*123 § 5*106 § 4*105 § 5*16.8 § 2.6

34.7 § 3.8*

41.3 § 3.4*

27.2 § 3.4*

26.2 § 3*

64 § 283 § 2.8*

90 § 3*72 § 241 § 5101 § 10*84 § 398 § 5+148 § 14*111 § 484 § 12*106 § 515.5 § 2.7

34.7 § 4.2*

41.1 § 4.3*

26.1 § 2.6*

63 § 381 § 2*88 § 3.4*

72 § 336 § 695 § 13*84 § 3105 § 4*147 § 20*121 § 6*90 § 10*108 § 6*17.4 § 1.4

30.5 § 3.6*

37.1 § 3.7*

23.8 § 2.9

65 § 180 § 3.4*

91 § 5.7*

73 § 443 § 581 § 6*82 § 4106 § 4*129 § 19*120 § 6*73 § 13106 § 6*80 § 12*72 § 2106 § 530.1 § 2.7*
89 § 14*73 § 3108 § 6*28.2 § 1.9*
81 § 1173 § 3106 § 6*

Values represent the mean § standard error (SEM)* p < 0.05 compared to the control base
FTG1 and FTG2 represent the second minute and last 30 s of the handgrip exercise, respectively, OCL1 and OCL2 represent the Wrst and second
minute of the post-exercise forearm occlusion, respectively, n number of data points

muscle contraction. Even if the activity of higher-thresholdmotor units increases during the post-training rhythmic
handgrip exercise, central motor activity is periodicallyassociated with rhythmic muscle contraction, meaning that
one half of the exercise duration corresponds to a pause incentral motor neuron activity. Thus, the extent of theimpinging central sympathetic neurons at a given time during rhythmic handgrip should be small in comparison to thecontinuous central motor command during fatigued isometric contraction, which may result in an insigniWcant change
in the MSNA response. In addition, maximal rhythmic
handgrip with forearm ischaemia was used to stimulate
maximally the muscle receptors for a given duration, andthe metaboreXex MSNA response was identical to that during the fatigued handgrip. Thus, the strong but relatively
small eVerent volley from central motor neurons duringrhythmic handgrip versus static contraction may have beenmasked by the central command-induced MSNA increaseby enhanced muscle reXexes.
EVects of halting training
Maximal handgrip force remained high at 4 weeks posttraining, whereas the MSNA response during the fatigued
handgrip exercise decreased after training was stopped andeventually returned to the pre-training level. If an increasein central motor activity after training is a factor inincreased maximal handgrip force, a higher MSNA
response should be maintained after detraining; however,this was not the case. The observed dissociation may havebeen caused by the diVerence in the duration of muscle
contraction (e.g., contraction for several seconds in the

123
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232

Trained Group

n=9

Handgrip

∗

40
30

dBF

dBF

PEFO
50

20

(bursts min -1)∗

50(bursts min -1)

Fig. 2 Comparisons of thechanges in burst frequency(dBF) and total sympathetic
nerve activity (TSNA) during
fatiguing handgrip exercises(Handgrip) and post-exercise
forearm occlusion (PEFO) at
pre-training (B), 1 week posttraining (A), 4 weeks post-training (D) in the training and control groups. * p < 0.05 comparedto the pre-training or post-training values; n, number of data
pointsEur J Appl Physiol (2009) 105:225–234

10

40
30
20
10
0

0

B

A

D

∗

1500

B

A

D

B

A

D

1000

500

600

(% )

TSNA

(% )

TSNA

800
1000

400
200

0

0

B

A

D

Control Group
Handgrip

40

dBF

30
20
10

40
30
20
10
0

0

B

A

D
1000

800

800

600
400

(% )

1000

TSNA

(% )

PEFO

50

(bursts min -1)

dBF(bursts min -1)

50

TSNA

n=7

0

0

D

maximal handgrip exercise versus contraction for several
minutes in the test exercise). Cessation of training may
cause a decrease in central motor activity and a subsequent
increase in the development of central fatigue during prolonged contraction (Gandevia 2001). Thus, it is believedthat neural eVerent activity from the central nervous system
to the sympathetic nervous centre decreases rapidly after
training is halted. At 4 weeks post-training, the MSNA
responses during handgrip exercises returned quickly to thepre-training level, even though the metaboreXex MSNA

D

B

A

D

400
200

A

A

600

200

B

B

response during post-exercise forearm occlusion was
unchanged.
Dissociation of MSNA and blood pressure
The pre-training blood pressure response during fatiguing
contraction was similar to that after resistance training,
despite the observed increase in MSNA. This dissociation
may be explained by diVerences in sympathetic outXow tothe various organs, such as muscle, skin, kidney, and

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Eur J Appl Physiol (2009) 105:225–234

233

viscera (Saito et al. 1990). Alternatively, the training ofsympatholysis may enhance the modulation of vasodilatation in not only trained skeletal muscle, but also in restingmuscle vessels (Green et al. 1994), by increasing the nitrite
level. Several studies have demonstrated that the nitrite
concentration correlates with the extent of MSNA in resting
humans (Skarphedinesson et al. 1997) and with the plasma
norepinephrine levels during strenuous exercise (Nodeet al. 1996).
In summary, short-term high-intensity resistance training resulted in an increased MSNA response during
fatigued isometric handgrip, which returned to the pretraining level at 4 weeks after training was ceased, althoughno signiWcant changes were observed for the metaboreXex
responses throughout the experiments. In the standard isometric and ischaemic rhythmic handgrip exercises, the
MSNA response was constant throughout the study. Neither the heart rate nor the blood pressure changes at pretraining compared to 1 or 4 weeks post-training, irrespective of the exercise performed. The enhanced MSNA
response to exercise after strength training probably
involves activation of the central nervous system rather
than alteration of the metaboreXex, which indicates that
central motor command plays an important role in determining MSNA during exercise and may vary with strength
training or eVort.

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BR A I N R ES E A RC H 1 2 1 0 ( 2 00 8 ) 1 4 2 –14 7

a v a i l a b l e a t w w w. s c i e n c e d i r e c t . c o mw w w. e l s e v i e r. c o m / l o c a t e / b r a i n r e s

Research Report

Quantification of delayed oxygenation in ipsilateral primary
motor cortex compared with contralateral side during
a unimanual dominant-hand motor task usingnear-infrared spectroscopy
Kenichi Shibuya a,⁎, Tomoko Sadamoto a , Kohei Sato a ,Mayumi Moriyama a , Masako Iwadate a,baResearch Institute of Physical Fitness, Japan Women's College of Physical Education, 8-19-1 Kita-karasuyama,
Setagaya-ku, Tokyo 157-8565, Japanb
College of Humanities and Sciences, Nihon University, 3-25-40 Sakurajyosui, Setagaya-ku, Tokyo 156-8550, JapanA R T I C LE I N FO

AB S T R A C T

Article history:

Using near-infrared spectroscopy (NIRS) techniques, it is possible to examine bilateralAccepted 7 March 2008

motor cortex oxygenation during a static motor task. Cortical activation was assumed to be

Available online 19 March 2008reflected by increased oxygenation. The purpose of the present study was to examine thetime course of oxygenation in the bilateral motor cortex during a low-intensity handgrip

Keywords:task. Six healthy, right-handed subjects participated in the study. The near-infrared

Motor task

spectroscopy probes positioned over the bilateral motor cortex were used to measure theFatiguecortical activation throughout a handgrip task carried out. The subjects performed a 3-min

Primary motor cortex

handgrip task with increasing intensity in a ramp-like manner [10–30% of the maximal

Hemispherevoluntary contraction (MVC) at 6.67% MVC.min− 1]. Contralateral motor cortex oxygenation
increased significantly from 100 to 180 s after the start of the motor task compared withthe baseline value ( p < 0.05). Ipsilateral motor cortex oxygenation also increased
significantly from 130 to 180 s after the start of the motor task ( p < 0.05). The onset ofincrease in oxyhemoglobin ([HbO 2 ]) and decrease in deoxyhemoglobin ([Hb]) in
contralateral motor cortex area (M1) were significantly earlier than in ipsilateral M1(respectively, p < 0.05). These results show that there is a delayed oxygenation in ipsilateral
primary motor cortex area compared with contralateral side during a unimanual
dominant-hand motor task.
Crown Copyright © 2008 Published by Elsevier B.V. All rights reserved.

1.

Introduction

Booth and Thomason, 1991; Nybo and Nielsen, 2001; Gandevia,2001).
Cortical activation was assumed to be reflected by increased oxygenation (Colier et al., 1997, 1999; Kleinschmidt
et al., 1996; Obrig et al., 1996). It was recently reported that theMusce fatigue is characterized by an exercise-induced loss of
power- and force-generating ability of the muscle during thecourse of or after exercise (Bigland-Ritchie and Woods, 1984;⁎ Corresponding author. Research Institute of Physical Fitness, Japan Women's College of Physical Education, 8-19-1 Kita-karasuyama,
Setagaya-ku, Tokyo 157-8565, Japan. Fax: +81 3 3300 5825.
E-mail address: kshibuya@jwcpe.ac.jp (K. Shibuya).
0006-8993/$ – see front matter. Crown Copyright © 2008 Published by Elsevier B.V. All rights reserved.
doi:10.1016/j.brainres.2008.03.009

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bilateral primary motor cortex area (M1) reaches a point of
deoxygenation during an exhaustive motor task, which suggested the existence of an interhemispheric connection
during a motor task (Shibuya and Kuboyama, 2007). An
increase in voluntary effort during the prolonged performanceof a low-intensity motor task is indicated by an increase inelectromyographic (EMG) signals recorded from the contracting muscle (Fuglevand et al., 1993, 1995; Loscher et al., 1996;
Yue et al., 1997). These signals indicate that the nervous
system attempts to recruit additional motor units to compensate for the decrease in force. Along with the increase in motor
recruitment during a fatiguing motor task, there should also
be an increased activation of the motor cortex, which sends
then efferent commands to the contracting muscle groups.
Previous studies have shown that activation in the contralateral M1 increases gradually during motor task and thendecreases as exhaustion approaches (Shibuya and Kuboyama,2007). In our previous study (Shibuya and Kuboyama, 2007),
however, oxygenation in the ipsilateral M1 could not be
confirmed. Oxygenation in the bilateral M1 decreased at
exhaustion simultaneously, which indicates that a connection
between bilateral hemispheres was formed during the motor
task. The connectivity between bilateral M1 might concern inthe familiarization with the motor task, because the familiarization would be plasticized the intercortical neural connectivity. If the subjects in that study (Shibuya and Kuboyama,2007) would have been more familiar or less familiar with thepinching motor task, or if the intensity of pinching task werelower than that protocol, oxygenation in the ipsilateral M1
might be found. It is needed to confirm the existence ininterhemispheric connection during general low-intensity
motor task.
Dai et al. (2001) reported bilateral M1 activation during ahandgrip task lasting approximately 30 s. This indicates thepossibility of the existence of an interhemispheric interaction
at or before the start of the motor task. In that case, there
should be simultaneous bilateral M1 oxygenation along withincreasing intensity of the motor task without reaching
exhaustion. If there is delayed oxygenation in the ipsilateral
M1 compared with the contralateral M1, it can be consideredthat the interhemispheric interaction is activated during thecourse of the motor task. It is important to know when theinterhemispheric interaction occurs during the course of a
motor task. This can be inferred by observing the increase inbilateral M1 oxygenation during a low-intensity motor taskusing high temporal resolution techniques (e.g., near-infrared
spectroscopy: NIRS).
NIRS allows for noninvasive monitoring of regionalchanges in cortical tissue oxygenation in response to various
stimuli (Colier et al., 1999; Kleinschmidt et al., 1996; Mehagnoul-Schipper et al., 2000; Obrig et al., 1996, 2000). It also
permits monitoring of changes in the oxyhemoglobin ([HbO 2])
and deoxyhemoglobin ([Hb]) levels with high temporal
resolution. The NIRS method is based on absorption changes
that depend on concentration changes of [HbO2] and [Hb] inthe tissue under investigation. In addition, NIRS can monitorchanges in cerebral oxygenation during dynamic motor taskwith high temporal resolution. Using NIRS techniques, it ispossible to examine bilateral M1 oxygenation during a static
motor task. The purpose of the present study was to examine

143

Fig. 1 – Oxygenation in contralateral motor cortex. Changes
from baseline values in oxyhemoglobin concentration(cHbO2), deoxyhemogrobin (cHb) and total-hemoglobin (ctHb)
in the contralateral motor cortex during a motor task. Values
are means ± SD. Asterisks show significant differences,p < 0.05.

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Fig. 3 – Example of the oxygenation response to motor task.
Arrows indicate the onset of response to motor task.

bilateral M1 oxygenation during a low-intensity unimanual
handgrip task.

2.

Results

2.1.

Contralateral (left-sided) M1 oxygenation

The kinetics of oxygenation in the contralateral M1 during thecourse of the motor task are shown in Fig. 1. The contralateral[HbO2] levels changed significantly during the motor task
(F = 6.5172, p < 0.0001). Compared with the baseline value, thecontralateral [HbO2] levels increased significantly in all subjects, from 100 s (equivalent to 21.1% of the maximal voluntary
contraction (MVC)) to 180 s (equivalent to 30% MVC) after thestart of the motor task ( p < 0.05).
The contralateral [Hb] levels also changed significantly
during the motor task (F = 3.734, p < 0.0001). In all the subjects,
the contralateral [Hb] levels decreased from 60 to 180 s after
the start of motor task compared with the baseline value,
more significant from 65 s onward (equivalent to 17.2% MVC)
( p < 0.05).
The contralateral total hemoglobin ([tHb]: [HbO2] + [Hb])level changed significantly during the motor task (F = 4.087,
p < 0.0001). The contralateral [tHb] levels significantly increased from 100 (equivalent to 21.1% MVC) to 180 s after thestart of motor task compared with the baseline value ( p < 0.05).

2.2.
Fig. 2 – Oxygenation in ipsilateral motor cortex. Changes
from baseline values in oxyhemoglobin concentration(iHbO2), deoxyhemogrobin (iHb) and total-hemoglobin (itHb)in the ipsilateral motor cortex during a motor task. Values aremeans ± SD. Asterisks show significant differences, p < 0.05.

Ipsilateral (right-sided) M1 oxygenation

The kinetics of oxygenation in the ipsilateral M1 during thecourse of the motor task are shown in Fig. 2. The ipsilateral[HbO2] levels changed significantly during the motor task
(F = 14.799, p < 0.0001). In all the subjects, the ipsilateral [HbO2]

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Table 1 – The time for oxygenation after the start of motor
task

HbO2
Hb
tHb

Contralateral

Ipsilateral50.8 ± 35.4
32.5 ± 15.7
45.0 ± 17.3

60.0 ± 31.3
94.2 ± 38.1
64.2 ± 9.2

M1, which sends efferent commands to contracting muscle
groups, should increase its activity to compensate for thedecrease in force. Then, it can be easily conceived that theipsilateral M1 is recruited during the fatiguing motor task incompensation for the contralateral M1 (Ghacibeh et al., 2007).
Actually, a few studies have reported that ipsilateral motor
activity increases as a response to a greater voluntary effort toperform a motor task (Dai et al., 2001). However, there are noreports about the time lag between contralateral and ipsilateral M1 activation and/or oxygenation during a motor task asassessed using high temporal resolution techniques. The timelag between activation of the contralateral and ipsilateral M1
allows us to study the interhemispheric connection, hemispheric dominancy. In the present study, ipsilateral M1 oxygenation was delayed for approximately 30 (in [HbO2] changes)
to 90 s (in [Hb] changes) compared with contralateral M1 oxygenation. As shown in Table 1, the onset of change in [tHb] incontralateral M1 was faster than [HbO2] and [Hb] in contralateral M1, while the onset of change in [tHb] in ipsilateral M1
was slower than [HbO2]. These might reflect the relative delayof blood volume distribution to the activation in ipsilateral M1compared with in contralateral M1. These findings suggest theexistence of an interhemispheric connection and the delayed
oxygenation in ipsilateral primary motor cortex comparedwith contralateral side during a motor task. NIRS permits measurement of cerebral oxygenation (Jobsis, 1977) and has beenused to assess brain activation (Chance et al., 1993). While
BOLD-fMRI is based on the magnetic field distortions producedby the cerebral blood oxygenation changes, NIRS detects more
direct hemodynamic parameters such as changes in [HbO2]and [Hb]. An increase in neural activation typically produces anincrease in [HbO2] and occasionally a decrease in [Hb] in NIRS
measurements (Vilringer and Chance, 1997; Mochizuki et al.,2006). The delayed kinetics in [Hb] in the present study would
be due to the lower sensitivity of [Hb] changes than [HbO2] or[tHb] changes in NIRS measurement (Madsen and Secher,1999). This is an issue for future study using NIRS and fMRI.
The mechanisms of this phenomenon remain unclear.
However, these changes might reflect the interhemisphericmodulation of motor activity, perhaps through transcallosal
connections or secondary to other cortical projections to themotor cortex on both sides. The increasing oxygenation in theipsilateral motor cortex shown in the present study suggests
the presence of a real-time interaction between bilateral hemispheres during the course of the motor task. The pathways
mediating the ipsilateral responses and their relationship tothe contralateral corticospinal projections have not been fully
defined (Chen et al., 2003). Further research is needed to clarify
the interaction between bilateral hemispheres.
NIRS is not a direct measure of synaptic activities or action
potentials of cortical neurons. An increase in neural activity ina cortical region increases the local blood flow. On the other
hand, the consumption of oxygen in the region does notincrease or increases only slightly (Fox and Raichle 1986; Fox
et al., 1988). Consequently, the increased blood volume might
have a greater proportion of venous relative to arterial blood in
the illuminated area. As a result, oxygenation is increased in
the area where the uncoupling of the changes in blood flow andoxygen consumption occurs. Nevertheless, the meaning ofdata obtained from NIRS is still under discussion. In particular,⁎⁎⁎

Asterisks show significant differences between the response on
hemispheres ( p < 0.05).

levels increased from 125 s to 180 s after the start of motor task
compared with the baseline value, more significantly from130 s onward (equivalent to 24.5% MVC) ( p < 0.05).
The ipsilateral [Hb] levels also changed significantly during
the motor task (F = 3.738, p < 0.0001). In all the subjects, theipsilateral [Hb] levels decreased from 135 to 180 s after thestart of motor task compared with the baseline value, moresignificantly from 155 s onward (equivalent to 27.2% MVC)
( p < 0.05).
The ipsilateral [tHb] level changed significantly during the
motor task (F = 3.950, p < 0.0001). The ipsilateral [tHb] levels
significantly increased from 115 (equivalent to 22.8% MVC) to
180 s after the start of motor task compared with the baseline
value ( p < 0.05).

2.3.

The kinetic analysis in bilateral M1 oxygenation

The hemodynamics ([HbO2], [Hb] and [tHb]) during the earlyphase of motor task did not change compared with the restingvalue (cf. Fig. 3). Then, the oxygenation increased or decreased
from the baseline values. The onset of increase in [HbO2] and[tHb] and decrease in [Hb] was shown in Table 1. The onset ofincrease in [HbO2] in contralateral M1 was significantly earlier
than in ipsilateral M1 (t = 2.803, p < 0.05). The onset of decreasein [Hb] in contralateral M1 was significantly earlier than in
ipsilateral M1 (t = 3.323, p < 0.05). The onset of decrease in [tHb]in contralateral M1 was significantly earlier than in ipsilateral
M1 (t = 3.781, p < 0.05).

3.

145

Discussion

Changes in cerebral oxygenation reflect cerebral functional
activation (Colier et al., 1997, 1999; Kleinschmidt et al., 1996;
Obrig et al., 1996). In the present study, we observed a bilateralincrease in M1 oxygenation during the course of a lowintensity static motor task. The increase in ipsilateral M1 oxygenation was delayed compared with the increase in contralateral M1 oxygenation. To the best of our knowledge, this is thefirst report showing that ipsilateral M1 oxygenation is delayedcompared with contralateral M1 oxygenation during thecourse of a motor task.
It is a well-known fact that EMG signals increase with thepassage of time during low-intensity fatiguing exercises. Thisis because of the recruitment of additional motor units
to compensate for the decrease in muscle force production(Bigland-Ritchie and Woods, 1984; Fuglevand et al., 1993, 1995;
Yue et al., 1997). The increase in EMG signals during themaintenance of a target force is an indication of fatigue. The

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it is debated whether the NIRS signals reflect the intracerebral
blood volume of pial circulation or the blood volume of a more
superficial circulation. For example, hyperventilation at rest
induces a reduction in [HbO2] levels, not because of decreased
cerebral oxygenation but because the circulating blood volume
is reduced as a result of peripheral vasoconstriction (Rostrup
et al., 2002).
The NIRS signal changes may be due to excitatory or inhibitory neuronal activity. However, it is impossible to prove
whether the NIRS signal changes in the present study are due
to excitatory of to inhibitory activity on M1. Therefore, theresults of the present study might suggest that ipsilateral M1
activates inhibitory transcallosal systems to inhibit intracortical inhibitory interneurons, leading to increased facilitationof the contralateral M1 in an adaptive mechanism. Further
studies are needed to clarify the meanings of the changes ofoxygenation in M1 during motor task that derived in thepresent study, as proposed by the recent previous studies(Benwell et al., 2006).
In the present study, the intensity of voluntary contraction
was increased in a ramp-like manner. Contralateral M1 oxygenation increased with the passage of time, which reflected
the elevation of required force production. Dettmers et al.
(1995) and Dai et al. (2001) reported a linear regression between
force production and M1 activation. The results of the present
study are consistent with the results of these previous studies.
This could be an evidence for monitoring the M1 oxygenationin the present study and that the NIRS signals reflect the
cerebral activities.
In conclusion, the results of the present study show adelayed oxygenation in the ipsilateral primary motor cortex
during the course of a unimanual low-intensity motor task.
The increasing oxygenation in the ipsilateral motor cortex
suggests a real-time interaction between bilateral hemispheres during a motor task.

4.

Experimental procedures

4.1.

Subjects

consisted of one emitter and one detector (comprising three
separate sensors). These probes were guided on the subjects'
heads using glass fiber bundles and positioned over the bilateralmotor cortex areas. The distance between the transmitting andthe receiving probes was 3.0 cm. The probes were positioned
over bilateral motor cortex areas for hand enclosing C3, according to the modified international EEG 10–20 system (American
Electroencephalographic Society, 1994), which was checked
during a handgrip motor task of the right and left hands to
induce functional oxygenation. If no oxygenation changes weredetected in response to the task, the probes were moved over
several millimeters by trial and error until a consistent oxygenation response was found (Colier et al., 1999; Shibuya andTachi, 2006; Shibuya and Kuboyama, 2007).
The probes were then fixed to the motor cortex areas. A
description of room luminance and any procedures implemented to reduce light interference with the measurements.
For quantification of changes in [HbO2] and [Hb] and totalhemoglobin concentrations ([tHb] = [HbO2] + [Hb]) levels (Delpy
et al., 1988), a modified Lambert–Beer law was used, which
describes optical attenuation in a highly scattered medium.
The NIRS data were collected with a sample frequency of
10 Hz. The baseline values of [HbO2] and [Hb] were calculated
as an average of 900 data points (90 s) taken during rest at
3 min before the start of the motor task. The values of [HbO2]and [Hb] during exercise were calculated as an average of 50
data points (5 s).

4.3.

Before the start of the study, the subjects were familiarized withthe protocol. They performed a static 3-min right-handgrip taskwith a ramp-like increase in intensity from 10% MVC to 30%
MVC (6.67% min− 1). The subjects were seated and were given a
handgrip meter (Meiko-sha, Co. Japan) which was held at heartlevel. During the NIRS experiment, the subjects gripped thedevice by right hand to match the target force provided by avisual feedback system. The force applied by pinching wassensed and converted to a voltage signal by the pressuretransducer in the hydraulic system. The laboratory was airconditioned and the temperature was maintained at 19–22 °C.

Six right-handed, healthy volunteers (age: 21.4 ± 0.2 y, height:
159.1 ± 1.3 cm, weight: 56.3 ± 1.9 kg, MVC: 315.6 ± 11.8 N) participated in the present study. Informed consent was obtained
from each subject after a full explanation of the nature of thestudy procedure and its noninvasiveness. Throughout the
study, the subjects were seated on a comfortable chair in aquiet room. All subjects had no remarkable medical history
with sign of cardiovascular, pulmonary, renal, endocrinological,
and neurological disorders. The subjects were told not to train
hard on the day before the testing and not to exercise on the dayof testing. They were also asked to refrain from consuming foodor beverages containing caffeine before the test.

4.2.

Protocol4.4.

Statistical analysis

To assess for the presence of changes in oxygenation with thepassage of time, a repeated ANOVA was applied. Post-hoc
analysis using Dunnett's correction was performed on the timeseries of oxygenation changes in [HbO2], [Hb] and [tHb] levels.
To assess the difference in oxygenation kinetics between
hemispheres, it was compared the onset of increases in [HbO2]and [tHb], and decrease in [Hb] from the baseline values asshown in Fig. 3, then Student's paired t-test was performed. A pvalue <0.05 was considered statistically significant.

Near-infrared spectroscopy

Acknowledgment
NIRS techniques have been described elsewhere (Elwell et al.,1994). We used a three-wavelength NIRS apparatus (780, 805,
and 830 nm; NIRStation, OMM3000, Shimadzu Co., Kyoto, Japan)
for measuring motor cortex oxygenation. The optical probe

The study was supported by the “Academic Frontier” Projectfor Private Universities: matching fund subsidy from Ministryof Education, Culture, Sports, Science and Technology in Japan.

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147

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Fuglevand, A.J., Zackowski, K.M., Huey, K.A., Enoka, R.M., 1993.
Impairment of neuromuscular propagation during humanfatiguing contractions at submaximal forces. J. Physiol.
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Fuglevand, A.J., Bilodeau, M., Enoka, R.M., 1995. Short-term
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cerebral blood flow and oxidative metabolism during

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Muscle reoxygenation difference between
superficial and deep regions of the muscles
during static knee extension
Chihoko Ueda and Atsuko Kagaya
Research Institute of Physical Fitness, Japan Women's College of Physical Education, Tokyo
157-8565, Japan; E-mail: cueda@jwcpe.ac.jp.

Abstract The purpose of this study was to test the hypothesis that differences invertical spatial difference in reoxygenation after exercise exists, reflecting heterogeneity of muscle oxygenation during exercise might be due to the difference indominantly recruited muscle fiber type. Methods: Ten healthy female subjects performed 1 minute static knee extension exercise at low (30%) and high (60%) fraction of maximal voluntary contraction (MVC). Muscle oxygenation in the vastus
lateralis (VL) was monitored using multi channel near-infrared spectroscopy. Halftime reoxygenation (T1/2reoxy) after exercise was calculated from oxygenatedhemoglobin in the eight channels which changed the distance between light sourceand detector distances at 2,3,4,5cm. Blood flow (BF) in the femoral artery wasmeasured by Doppler ultrasound. Mean arterial blood pressure (BP) at the end of
the each exercise was assessed by a Finometer device. Results: BF during exercise
did not differ significantly during exercise at low and high intensity, whereas BP
was elevated at high intensity. T1/2reoxy tended to be prolonged at high intensity.
It would be due to a transition of muscle fiber recruitment from type I toward typeII fiber dominance, and/or insufficient oxygen supply for increased demand in themuscle. T1/2reoxy in different light source and detector distances was not different among them. Conclusion: This study demonstrated that the reoxygenation in
the superficial region did not differ from that in the deeper region, including superficial, even when exercise intensity was high.

1 Introduction
Recent studies indicated a spatial heterogeneity in lateral direction of deoxygenation and reoxygenation in a single muscle [6,7,9,10]. One of the studies demonstrated that plantar flexion resulted in more deoxygenation during exercise andan earlier reoxygenation during recovery in the distal portion compared with the

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proximal portion in gastrocremius muscle [9]. Another study also reported that reoxygenation in VL after cycling exercise was progressively delayed from distal
sites to proximal site at the same submaximal intensities [6]. Possible reasons forsuch regional differences in muscle oxygenation between the proximal and distal
portion are differences in muscle fiber composition, intramuscular pressure, andcapillary density and so on [9]. A previous study in human demonstrated that
distribution of different fiber type varied within a muscle, with a predominance totype II fibers at surface and type I fibers in deeper regions of the muscle [11].
Based upon the non-uniformity of muscle fiber composition from superficial to
deeper portions of muscle, we assumed that muscle reoxygenation should be different depending on the depth of the region studied in the muscle. Additionally thedifference in intramuscular pressure between the superficial and deep regions [12]should be considered, because it results in the difference in oxygen delivery andtherefore reoxygenation difference.
Recently, muscle oxygenation during exercise has been measured noninvasively by near-infrared spectroscopy (NIRS). Recovery time of muscle oxygenation following the completion of exercise is used as an index of deficits ofoxygen delivery to the muscle in relation to oxygen demand of working muscle[1,2,4,8]. Therefore we supposed that surface regions of muscle have a prolonged recovery time of muscle oxygenation as compared with deeper regions.
The purpose of this study was to test the hypothesis that vertical spatial difference
in recovery time of muscle oxygenation exists, reflecting heterogeneity of muscle
oxygenation during exercise is probably caused by non-uniform fiber composition
distribution.

2 Methods
Ten healthy females [age: 22.0 ± 1.2 (means ± SD) yr, body height: 160.4 ±
4.6cm, body mass: 55.3 ± 5.7kg] participated in this study. The subjects were fully
informed of the purpose, nature, and potential risks of the experiments and gave
their written, informed consent to participate in this study. This study was approved by The Ethical Committee of the Japan Women’s College of Physical
Education.
Static knee extension was adopted in this study. Before the experiments, all subjects were familiarized with the exercise equipment and the protocol. Maximal voluntary contraction (MVC) of knee extension was measured on the right leg. The
exercise was performed in upright position with the knee joint angle set at 90 degrees. The exercise comprised 1 minute static contraction at low (30%MVC) andhigh (60%MVC) intensities. The order of the contractions was random, and separated by at least 5 minutes.
Femoral arterial blood velocity in the right leg was measured by Doppler ultrasound method (Vivid7 pro, GE Yokokawa Medical Systems, Japan) with a

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7.5MHz transducer. The systolic and diastolic diameters in the femoral arterial
were also measured using B-mode ultrasonography. The mean diameter was calculated based on the relative time periods of the systolic (1/3) and the diastolic(2/3) phases of the cardiac cycle: ([systolic diameter value × 1/3] + [diastolic diameter value × 2/3]). Mean blood velocity (Vmean) was obtained from angle corrected, time averaged, and integrated velocity of whole consecutive cardiac cycles
of Doppler signals within the approximately last 5 seconds of each exercise. Femoral artery blood flow (FBF) was calculated by multiplying the cross-sectional
area (area = π × [diame-ter/2]2) (CSA) of the femoral artery with Vmean ; FBF(L/min) = Vmean (cm/sec) × CSA (mm2) × 6 × 10-4.
Mean arterial blood pressure (BP) was measured non-invasively by photoelectric plethysmogaraphy with Finometer (Finapres Medical Systems BV, Netherlands). The beat-to-beat values were averaged over the last 5 seconds of exercise
at each intensity.
Muscle oxygenation in the VL was monitored by near infrared continuous wave
spectroscopy (NIRS, OMM-3000, Shimadzu, Japan). The NIRS probe was placed
over the thickest site of VL, and 3cm distal part from there. The distance lightsource and detector distances was set at 2, 3, 4, and 5 cm. Tissue thickness overthis position was 8.6±0.6 mm for the subcutaneous adipose tissue, 20.7±0.9 mm
for VL and 16.2±0.8 mm for Vastus intermedius (VI) muscle. The NIRS signals at
wavelengths of 780, 805, 830nm were used for calculation of changes in the concentration of oxygenated hemoglobin (oxyHb), deoxygenated hemoglobin (deoxyHb), and total hemoglobin (totalHb). Half time reoxygenation (T1/2reoxy) was
determined as the time required to reach the value halfway between the oxyHb
level immediately after exercise and that at peak hyperemia during recovery.
Values are represented as means ± SE, unless indicated otherwise. Differencesin BF, BP, and T1/2reoxy between the low and high intensities were analyzed using the t test for paired samples. One-way ANOVA for repeated measurements
was used to compare T1/2reoxy for different light source detector distances. A pvalue of less than 0.05 was considered statistically significant.

3 Results
FBF at 30%MVC (0.45±0.04 L/min) was not different from that at 60% MVC(0.50±0.06 L/min) (Fig. 1.).
BP was significantly higher at 60%MVC (95±3 mmHg) compared with
30%MVC (106±6 mmHg) (p<0.05) (Fig. 2.).
T1/2reoxy tended to be prolonged at 60%MVC as compared with 30%MVC(p<0.10). However there were no differences among T1/2reoxy values in different light source detector distances (Fig. 3.).

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4 Discussion
The present study examined muscle reoxygenation from the superficial to deep region of the VL in static knee extension exercise at low and high intensities. Results showed that T1/2reoxy tended to be prolonged at the high-intensity exercise.
This would be explained by a transition of muscle fiber recruitment from type I
toward type II fiber dominance, and/or due to insufficient oxygen supply for increased demand in the muscle supposed from pre-sent result of BF. BF during exercise was constant, and means that the blood supply condition was not different
between low and high intensities. This result on BF is supported by previous studies [3, 5]. The values of T1/2reoxy in this study were smaller than that in previous
references [6, 8]. It might be due to different exercise. We used static one-legged
knee extension exercise and they used cycle ergometer exercise. Dynamic cycle
exercise should induce recruitment of larger muscle mass and increase oxygen
demand of working muscle.
We could not find differences in T1/2reoxy among different light source anddetector distances. Following three possible reasons are considered; the first is that
recruited muscle fibers in this exercise are not different in proportion of types between superficial and deep regions of the muscle. The second is that wider lightsource and detector distance has included not only deep region information but also superficial information of muscle oxygenation. The third is that the heterogeneity of intramuscular pressure could affect on T1/2reoxy in the opposite direction to
the heterogeneity of muscle fiber distribution. The question remains unresolved ifheterogeneity of muscle fiber composition and blood flow distribution will cause
different recovery time of muscle oxygenation between superficial and deep regions of the muscle.
In conclusion, this study demonstrated that recovery time of muscle oxygenation in deep and superficial regions did not differ from that in the region limited tothe superficial one after exercise even at high intensity.
Acknowledgments This work was supported by “Academic Frontier” Project of Japan Women’s College of Physical Education. We thank Prof. T. Sadamoto, Dr. K. Sato, and Dr. K. Shibuya for their thoughtful suggestions and advice, and Ms. A. Hirasawa for her skilful assistance.

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2. Hamaoka T, Albani C, Chance B, Iwane H. A new method for the evaluation of muscle aerobic capacity in relation to physical activity measured by near-infrared spectroscopy. Med
Sport Sci. 1992; 37: 421-9.

425

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3. Homma S, Kagaya A. Oxygen delivery and utilization in working muscle during 1-min static
handgrip exercise at varied intensity. J Exerc Sci. 1998; 8: 30-37.
4. Ichimura S, Murase N, Osada T, Kime R, Homma T, Ueda C, Nagasawa T, Motobe M, Hamaoka T, Katsumura T. Age and activity status affect muscle reoxygenation time after maximal cycling exercise. Med Sci Sports Exerc. 2006; 38: 1277-81.
5. Kagaya A, Homma S. Brachial arterial blood flow during static handgrip exercise of short duration at varying intensities studied by a Doppler ultrasound method. Acta Physiol Scand.
1997; 160: 257-65.
6. Kime R, Im J, Moser D, Lin Y, Nioka S, Katsumura T, Chance B. Reduced heterogeneity ofmuscle deoxygenation during heavy bicycle exercise. Med Sci Sports Exerc. 2005; 37: 412-7.
7. Koga S, Poole DC, Ferreira LF, Whipp BJ, Kondo N, Saitoh T, Ohmae E, Barstow TJ. Spatial heterogeneity of quadriceps muscle deoxygenation kinetics during cycle exercise. J Appl
Physiol. 2007; 103: 2049-56.
8. McCully KK, Iotti S, Kendrick K, Wang Z, Posner JD, Leigh J Jr, Chance B. Simultaneous invivo measurements of HbO2 saturation and PCr kinetics after exercise in normal humans. J
Appl Physiol. 1994; 77: 5-10.
9. Miura H, McCully K, Hong L, Nioka S, Chance B. Regional difference of muscle oxygen saturation and blood volume during exercise determined by near infrared imaging device. Jpn J
Physiol. 2001; 51: 599-606.
10. Mizuno M, Tokizawa K, Iwakawa T, Muraoka I. Inflection points of cardiovascular responses and oxygenation are correlated in the distal but not the proximal portions of muscle
during incremental exercise. J Appl Physiol. 2004; 97: 867-73.
11. Lexell J, Henriksson-Larsén K, Sjöström M. Distribution of different fibre types in humanskeletal muscles. 2. A study of cross-sections of whole m. vastus lateralis. Acta Physiol
Scand. 1983; 117: 115-22.
12. Sejersted OM, Hargens AR, Kardel KR, Blom P, Jensen O, Hermansen L. Intramuscular fluid pressure during isometric contraction of human skeletal muscle. J Appl Physiol. 1984; 56:
287-95.

Fig. 1. Femoral artery blood flow (FBF) during knee extension exercise at low (30%MVC) andhigh (60%MVC) intensities. Values are mean±SE, n=9. NS.
Fig. 2. Mean blood pressure (BP) during knee extension exercise at low (30%MVC) and high
(60%MVC) intensities. Values are mean±SE, n=9. *Significant difference between intensities(P<0.05).
Fig. 3. Half time reoxygenation (T1/2reoxy) during knee extension exercise at low (30%MVC)
and high (60%MVC) intensities in different light source detector distances. Values are mean±SE,
n=10. P<0.1, 30%MVC vs. 60%MVC corresponding values.

426

3. Homma S, Kagaya A. Oxygen delivery and utilization in working muscle during 1-min static
handgrip exercise at varied intensity. J Exerc Sci. 1998; 8: 30-37.
4. Ichimura S, Murase N, Osada T, Kime R, Homma T, Ueda C, Nagasawa T, Motobe M, Hamaoka T, Katsumura T. Age and activity status affect muscle reoxygenation time after maximal cycling exercise. Med Sci Sports Exerc. 2006; 38: 1277-81.
5. Kagaya A, Homma S. Brachial arterial blood flow during static handgrip exercise of short duration at varying intensities studied by a Doppler ultrasound method. Acta Physiol Scand.
1997; 160: 257-65.
6. Kime R, Im J, Moser D, Lin Y, Nioka S, Katsumura T, Chance B. Reduced heterogeneity ofmuscle deoxygenation during heavy bicycle exercise. Med Sci Sports Exerc. 2005; 37: 412-7.
7. Koga S, Poole DC, Ferreira LF, Whipp BJ, Kondo N, Saitoh T, Ohmae E, Barstow TJ. Spatial heterogeneity of quadriceps muscle deoxygenation kinetics during cycle exercise. J Appl
Physiol. 2007; 103: 2049-56.
8. McCully KK, Iotti S, Kendrick K, Wang Z, Posner JD, Leigh J Jr, Chance B. Simultaneous invivo measurements of HbO2 saturation and PCr kinetics after exercise in normal humans. J
Appl Physiol. 1994; 77: 5-10.
9. Miura H, McCully K, Hong L, Nioka S, Chance B. Regional difference of muscle oxygen saturation and blood volume during exercise determined by near infrared imaging device. Jpn J
Physiol. 2001; 51: 599-606.
10. Mizuno M, Tokizawa K, Iwakawa T, Muraoka I. Inflection points of cardiovascular responses and oxygenation are correlated in the distal but not the proximal portions of muscle
during incremental exercise. J Appl Physiol. 2004; 97: 867-73.
11. Lexell J, Henriksson-Larsén K, Sjöström M. Distribution of different fibre types in human5skeletal muscles. 2. A study of cross-sections of whole m. vastus lateralis. Acta Physiol
Scand. 1983; 117: 115-22.
12. Sejersted OM, Hargens AR, Kardel KR, Blom P, Jensen O, Hermansen L. Intramuscular flu3. Homma S, Kagaya A. Oxygen delivery and utilization in working muscle during 1-min static
id pressure during isometric contraction of human skeletal muscle. J Appl Physiol. 1984; 56:
handgrip exercise at varied intensity. J Exerc Sci. 1998; 8: 30-37.
287-95.
4. Ichimura S, Murase N, Osada T, Kime R, Homma T, Ueda C, Nagasawa T, Motobe M, Hamaoka T, Katsumura T. Age and activity status affect muscle reoxygenation time after maximal cycling exercise. Med Sci Sports Exerc. 2006; 38: 1277-81.
5. Kagaya A, Homma S. Brachial arterial blood flow during static handgrip exercise of short duration at varying intensities studied by a Doppler ultrasound method. Acta Physiol Scand.
1997; 160: 257-65.
6. Kime R, Im J, Moser D, Lin Y, Nioka S, Katsumura T, Chance B. Reduced heterogeneity of
deoxygenation
duringMed Sciexercise
Sports Exerc.
37: 412-7.
Fig.muscle
1. Femoral
artery blood
flowheavy(FBF)bicycle
duringexercise.
knee extension
at low 2005;(30%MVC)
and
7. Koga
S, Pooleintensities.
DC, Ferreira
LF, areWhipp
BJ, Kondo
high(60%MVC)
Valuesmean±SE,
n=9. N,NS.Saitoh T, Ohmae E, Barstow TJ. Spatial heterogeneity of quadriceps muscle deoxygenation kinetics during cycle exercise. J Appl
Physiol. 2007; 103: 2049-56.
Fig.
2. MeanKK,
blood(BP) K,
duringextension
exerciselow (30%MVC)
and high
8. McCully
Iottipressure
S, Kendrick
WangkneeZ, Posner
JD, LeighJ Jr,atChance
B. Simultaneousin(60%MVC)
intensities. of
Valuesmean±SE,*Significant
intensitiesJ
vivo measurements
HbO2aresaturation
andn=9.
PCr kinetics
after difference
exercise inbetween
normal humans.
(P<0.05).
Appl Physiol. 1994; 77: 5-10.
9. Miura H, McCully K, Hong L, Nioka S, Chance B. Regional difference of muscle oxygen saturation and blood volume during exercise determined by near infrared imaging device. Jpn J
Fig.Physiol.
3. Half 2001;
time reoxygenation
51: 599-606. (T1/2reoxy) during knee extension exercise at low (30%MVC)
andhigh (60%MVC)
intensities
in different
sourcedistances.
Valuesare mean±SE,
10. Mizuno
M, Tokizawa
K, Iwakawa
T, light
MuraokaI. detector
Inflection
points ofcardiovascular
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P<0.1,and
30%MVCvs. 60%MVC
corresponding
values.
sponsesoxygenation
are correlated
in the distal
but not the proximal portions of muscle
during incremental exercise. J Appl Physiol. 2004; 97: 867-73.
11. Lexell J, Henriksson-Larsén K, Sjöström M. Distribution of different fibre types in humanskeletal muscles. 2. A study of cross-sections of whole m. vastus lateralis. Acta Physiol
Scand. 1983; 117: 115-22.
12. Sejersted OM, Hargens AR, Kardel KR, Blom P, Jensen O, Hermansen L. Intramuscular fluid pressure during isometric contraction of human skeletal muscle. J Appl Physiol. 1984; 56:
287-95.

Fig. 1. Femoral artery blood flow (FBF) during knee extension exercise at low (30%MVC) andhigh (60%MVC) intensities. Values are mean±SE, n=9. NS.
Fig. 2. Mean blood pressure (BP) during knee extension exercise at low (30%MVC) and high
(60%MVC) intensities. Values are mean±SE, n=9. *Significant difference between intensities(P<0.05).
Fig. 3. Half time reoxygenation (T1/2reoxy) during knee extension exercise at low (30%MVC)
and high (60%MVC) intensities in different light source detector distances. Values are mean±SE,
n=10. P<0.1, 30%MVC vs. 60%MVC corresponding values.

427

5
3. Homma S, Kagaya A. Oxygen delivery and utilization in working muscle during 1-min static
handgrip exercise at varied intensity. J Exerc Sci. 1998; 8: 30-37.
4. Ichimura S, Murase N, Osada T, Kime R, Homma T, Ueda C, Nagasawa T, Motobe M, Hamaoka T, Katsumura T. Age and activity status affect muscle reoxygenation time after maximal cycling exercise. Med Sci Sports Exerc. 2006; 38: 1277-81.
5. Kagaya A, Homma S. Brachial arterial blood flow during static handgrip exercise of short duration at varying intensities studied by a Doppler ultrasound method. Acta Physiol Scand.
1997; 160: 257-65.
6. Kime R, Im J, Moser D, Lin Y, Nioka S, Katsumura T, Chance B. Reduced heterogeneity ofmuscle deoxygenation during heavy bicycle exercise. Med Sci Sports Exerc. 2005; 37: 412-7.
7. Koga S, Poole DC, Ferreira LF, Whipp BJ, Kondo N, Saitoh T, Ohmae E, Barstow TJ. Spatial heterogeneity of quadriceps muscle deoxygenation kinetics during cycle exercise. J Appl
Physiol. 2007; 103: 2049-56.
8. McCully KK, Iotti S, Kendrick K, Wang Z, Posner JD, Leigh J Jr, Chance B. Simultaneous invivo measurements of HbO2 saturation and PCr kinetics after exercise in normal humans. J
Appl Physiol. 1994; 77: 5-10.
9. Miura H, McCully K, Hong L, Nioka S, Chance B. Regional difference of muscle oxygen saturation and blood volume during exercise determined by near infrared imaging device. Jpn J
Physiol. 2001; 51: 599-606.
10. Mizuno M, Tokizawa K, Iwakawa T, Muraoka I. Inflection points of cardiovascular responses and oxygenation are correlated in the distal but not the proximal portions of muscle
during incremental exercise. J Appl Physiol. 2004; 97: 867-73.
11. Lexell J, Henriksson-Larsén K, Sjöström M. Distribution of different fibre types in humanskeletal muscles. 2. A study of cross-sections of whole m. vastus lateralis. Acta Physiol
Scand. 1983; 117: 115-22.
12. Sejersted OM, Hargens AR, Kardel KR, Blom P, Jensen O, Hermansen L. Intramuscular fluid pressure during isometric contraction of human skeletal muscle. J Appl Physiol. 1984; 56:
287-95.

Fig. 1. Femoral artery blood flow (FBF) during knee extension exercise at low (30%MVC) andhigh (60%MVC) intensities. Values are mean±SE, n=9. NS.
Fig. 2. Mean blood pressure (BP) during knee extension exercise at low (30%MVC) and high
(60%MVC) intensities. Values are mean±SE, n=9. *Significant difference between intensities(P<0.05).
Fig. 3. Half time reoxygenation (T1/2reoxy) during knee extension exercise at low (30%MVC)
and high (60%MVC) intensities in different light source detector distances. Values are mean±SE,
n=10. P<0.1, 30%MVC vs. 60%MVC corresponding values.

428

Accepted for Adv. Exp. Med. Biol.

Blood flow and arterial vessel diameter change
during graded handgrip exercise in dominant
and non-dominant forearms of tennis players
Atsuko Kagaya1, Fumiko Ohmori1, Shizuyo Okuyama2, Yoshiho Muraoka3,
and Kohei Sato1
1Research Institute of Physical Fitness, Japan Women's College of Physical Education,
Tokyo 57-8565, Japan. 2Institute of Physical Education, Keio University, Kanagawa 2238521, Japan 3Faculty of Humanities and Social Sciences, Meisei University, Tokyo 1918506, Japan

Abstract The training effect on exercise-induced maximal blood flow remains
unclear. The purpose of this study was to clarify the difference of exerciseinduced blood flow, blood flow velocity and vessel diameter of brachial artery indominant and non-dominant forearms of tennis players during graded hand-grip
exercise. Ten female tennis players aged 20.1±0.1 yrs. (mean±SD) performed 30-s
static handgrip exercise in the supine position with either the dominant or nondominant hand by increasing load at 30-s intervals until exhaustion. Brachial arterial blood flow velocity (Doppler ultrasound method) did not differ between both
limbs, whereas the vessel diameter (2-D method) was significantly larger in thedominant limb during diastole both at baseline (P<0.01) and after exercise(P<0.05), but no difference was found during systole. As a result, the blood flow
was significantly higher (P<0.05) in the dominant limb during post-exercise condition. Muscle thickness of the forearm muscles and maximal handgrip strength
were significantly higher in the dominant limb. Thus, the effect of training on exercise-induced blood flow specific to the dominant limb was confirmed during
post-exercise due to the enlarged vessel diameter during diastole of cardiac cycle.
The dimensional change in the vasculature specific to the dominant side will be
included in the training effects associated with the dimensional muscular changes
in the dominant forearm.

1 Introduction
Maximal metabolic vasodilation capacity is enhanced due to training [2,3,14].
Cross-sectional study on blood flow in the dominant and non-dominant limbs oftennis players also indicated an increased blood flow in dominant limb used in

429

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tennis [7,14]. However, it is unclear if these training effects are applicable to exercise-induced maximal blood flow, because the sympathetic vasoconstriction occurred during exercise and the blood flow during exercise did not reach a level ofmaximal metabolic vasodilation[9,16] .
Blood volume per unit time is determined by the cross-sectional area of vessel
and blood flow velocity. Previous studies indicated that muscle vasculature wasadjusted to training or disuse of the muscle [3,4,8,13]. Despite that structural adaptation of vasculature has been reported at baseline, a training effect on vasculardimension during exercise remains to be studied.
The purpose of this study was to clarify the effects of training on blood flow
and structure of the conduit artery during static exercise (muscle action). For thispurpose, the blood flow velocity and vessel diameter of the brachial artery were
determined in dominant and non-dominant forearms of tennis players during andafter each load of graded handgrip exercise.

2 Methods
Subjects; Ten female tennis players aged 20.1±0.1(mean±SD) years old participated in the study. They were recruited from the collegiate tennis team, which
won 4th place in the national inter-collegiate tennis tournament that year. The
study was approved by the Ethical Committee on Human Subjects Research at theJapan Women’s College of Physical Education. All subjects provided written informed consent after being informed about all experimental procedures, the exercise protocol, and possible risks associated with participation in the study.
Experimental protocol and physiological measurements; Following 3-minutebaseline measurements, the subject performed 30-s static handgrip exercise in asupine position with either the dominant (right side) or non-dominant hand on different days. The static handgrip exercise was repeated at 30-s intervals with increasing load by 2kgw until exhaustion. Total work index was calculated as a sumof each work load multiplied by duration. Brachial arterial blood flow velocity (V)and diameter (D) were obtained continuously using ultrasound Doppler and 2-D
methods (GE, Vivid7 Pro) and determined for 10 (baseline), 5 (during exercise) or
2-3 cardiac cycles (immediate post-exercise) each at diastole (Dd) and systole(Ds). Brachial arterial blood flow was calculated as V*π(D/2)2 (D=2Dd/3+Ds/3).
Blood pressure (BP) was measured on the contralateral finger on beat-by-beat basis throughout the experiment (Finapres model 2300, Ohmeda, USA). Maximal
voluntary contraction (MVC) of forearm muscles, and radial and ulnar forearm
flexor muscle thickness were measured (Aloka, SSD1000).
Data Analysis and Statistics; The group data were expressed as mean±SE,
unless otherwise indicated. Differences among the means obtained from 7 loads
and 2 limbs (dominant and non-dominant) were evaluated using two-way analysis
of variance (ANOVA). When significant differences (major effect, interaction)

430

3

were observed, a post hoc comparison was performed using Tukey’s HSD. A Pvalue less than 0.05 was accepted as significant.

3 Results
Muscle thickness of Rad and UL, MVC, highest load attained by each subject
and total work index performed until exhaustion were significantly higher in thedominant limb.
The blood flow velocity during exercise and immediately after exercise increased significantly (P<0.01) with loads both in dominant and non-dominant
limbs. No significant differences were found between both limbs. The diastolicand systolic vessel diameters, during exercise and immediate post-exercise, gradually increased with time and increasing loads. A significant major effect on diastolic diameter was obtained only for load during (P<0.01) and post (P<0.05) exercise. Interaction was significant (P<0.01) for the means of diastolic diameters,
which were significantly larger in the dominant limb at baseline (dominant;3.4±0.1, non-dominant; 3.0±0.1mm) and after exercise at the highest load (dominant; 3.5±0.1, non-dominant; 3.2±0.1mm) (Figure 1a). In contrast, systolic diameter did not differ either during exercise or post-exercise between both limbs (Figure 1b). The brachial arterial blood flow in both limbs increased linearly related toexercise load both during (P<0.01) exercise and post-exercise (P<0.01). Interaction was significant (P<0.05) and higher post-exercise blood flow was obtained in
the dominant limb after exercise at the highest load (P<0.05) (Figure1c).

4 Discussion
The first finding of this study was that the lateral difference in blood flow intennis players was detected post-exercise when muscle contraction was terminated, which is consistent with the study of Sinoway et al. [15] on tennis players.
However, the blood flow during exercise did not differ between both arms in thisstudy. Therefore, the exercise training will induce an increase in exercise-induced
blood flow during post-exercise phase, (or relaxation phase of dynamic exercise)and metaboreceptor mediated vasodilation [7,14,15]. However, this functional adaptation would not increase blood flow during static muscle action, probably because an elevated intramuscular pressure due to muscle contraction [17] impedes avasodilation in the contracting muscles.
Cross-sectional studies on vasculature demonstrated that diameters of the conduit artery were positively associated with the level of physical activity. Larger

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vessel size was observed in trained people of various sports, limited to the trained
region of the body [8, 13], whereas smaller dimension of vessel diameter was reported in sedentary and paraplegic subjects, and in healthy people after bed-rest or
limb suspension [3, 4, 8,13]. Longitudinal study confirmed the vessel expansion
due to training in various arteries [6, 11,12]. However, those studies measured thevessel diameters at baseline, and no studies, to our knowledge, compared dimensional adaptation during exercise. Furthermore, no study except the study ofSchmidt-Trucksäss et al. [13], considered the vascular size fluctuation with cardiac cycle; systole or diastole. Our second new finding, therefore, was that theluminal vessel diameter of the brachial artery during systole did not change significantly between limbs, whereas the diameter during diastole was larger in thedominant limb. The latter finding is consistent with the study of Huonker et al.
[8], who studied thoracic, abdominal, subclavian and common femoral arteries intrained athletes including professional tennis players, but not with the study ofSchmidt-Trucksäss et al. [13]. They demonstrated that the vessel diameters weresignificantly larger in athletes for both systolic and diastolic phases. The discrepancy might be due to the difference of subjects compared in the respective studies;dominant vs. non-dominant (this study) limbs, or professional athletes vs. sedentary and paraplegic subjects [13].
The mechanism to explain an increased blood flow with training has not yet
been completely elucidated, but structural remodeling of the vasculature might be
one of the most potent mechanisms [6, 12]. As the muscle thickness of the dominant forearm was significantly larger compared to that of the non-dominant one inthis study, the dimensional change in muscle due to training will be considered toinfluence vascular remodeling. Other underlying mechanisms for the increased
blood flow with training will include a change in vasoactivity because of an increased flow-mediated dilation after training [1, 5]. Considered from the role ofnitric oxide (NO) in exercise hyperemia [10], one potent mechanism will be an increase in NO production or sensitivity to NO. However, the contribution of NO tothe effect of exercise training on vascular responses in human subjects remains
undecided [7]. This study suggests that the training effect on NO-dependent vasodilation, if any, might be masked during muscle contraction.
In conclusion, larger brachial arterial vessel diameter and muscle thickness intennis players will probably be included in training effects. However, the effect oftraining on exercise-induced blood flow specific to the dominant limb was notconfirmed during exercise but was detected during post-exercise due to theenlarged vessel diameter during diastole of the cardiac cycle. The dimensionalchange in the vasculature specific to the dominant side will be included in the
training effects associated with the dimensional muscular changes in the dominantforearm.

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Acknowledgments This work was supported by the “Academic Frontier” project of Japan
Women’s College of Physical Education. The authors are grateful to Ms A. Mori (Graduate
School of Humanities and Sciences, Ochanomizu University) for her help in analyzing data.

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15) Sinoway LI, Shenberger J, Wilson J, McLaughlin D, Musch T, (1987) A 30-day forearm
work protocol increases maximal forearm blood flow. J Appl Physiol. 62:1063-1067.
16) Sinoway L and Prophet S (1990) Skeletal muscle metaboreceptor stimulation opposes peakmetabolic vasodilation in humans. Circ Res.66:1576-1584.
17) Sjφgaard, G, Kiens, B., Jorgensen, K. and Saltin, B.(1986) Intramuscular pressure, EMG andblood flow during low-level prolonged static contraction in man. Acta Physiol Scand
128:475-484.

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Figure legend
Figure 1 Diastolic (a), systolic (b) vessel diameter and brachial arterial blood flow(c) at baseline, during, and after exercise at the highest loads in dominant（■)
and non-dominant（□）limbs.
*, **; P<0.05, P<0.001 between limbs.

6

Figure legend
Figure 1 Diastolic (a), systolic (b) vessel diameter and brachial arterial blood flow(c) at baseline, during, and after exercise at the highest loads in dominant（■)
and non-dominant（□）limbs.
*, **; P<0.05, P<0.001 between limbs.

434

Cerebrovascular response during heavy upper
body exercise: effect of mode of ventilation on
blood flow velocity in the middle cerebral artery
K. SATO, A. HIRASAWA, N. TSUNODA, Y. TANIGUCHI, and T.
SADAMOTO
Research Institute of Physical Fitness, Japan Women’s College of Physical Education,
Tokyo 157-8565, Japan. E-mail: ksato@jwcpe.ac.jp

Abstract Heavy resistance exercise may be associated with a small risk of cerebral aneurysm rupture, subarachnoid hemorrhage, and symptoms of dizziness oroutright weight-lifters’ blackout, which may be induced by a rapid change in the
cerebral blood flow. We hypothesized that these changes during heavy exercise
could be associated with the mode of ventilation. The purpose of the present study
was to elucidate the effect of the mode of ventilation on cerebral blood flow response during heavy upper body exercise. Subjects performed 15-s static exercises
at 80% maximum voluntary contraction (MVC) under different modes of ventilation. In this study, we observed that heavy exercise with breath holding induced
marked and rapid changes in the cerebral blood flow velocity in the middle cerebral artery during and after exercise as compared with that with continued normal
ventilation. We also observed that hyperventilation before exercise could largely
contribute to a lower cerebral blood flow velocity during exercise and extending to
the recovery phase. Our data suggested that even during heavy upper body exercise, the mode of ventilation is very important for maintaining cerebral circulation.

1 Introduction
Heavy resistance exercise is associated with a pronounced increase in the arterialpressure and cerebral blood flow, which may occasionally result in bleedingaround the brain. On the other hand, symptoms of dizziness or outright weight lifters “black out” could be linked to decrease in the cerebral blood flow during andafter heavy exercise. Despite the benefits of resistance exercise on skeletal morphology and function, heavy resistance exercise may be associated with a small

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2

risk of rupture of cerebral aneurysm, subarachnoid hemorrhage, and weight lifters“black out” [2, 6, 7].
Change in the cerebral blood flow during heavy exercise could be associatedwith the mode of ventilation, including the forced expiration against a closed glottis (breath holding induced a Valsalva-like maneuver) and hypocapnia induced byhyperventilation before and during exercise [1, 6, 7, 10]. A previous study reported marked change in the mean cerebral blood flow velocity in the middle cerebral artery (MCA Vmean) during heavy two legged extension with concomitant
Valsalva-like maneuver [7]. More recently, Romero and Cooke [10] demonstrated
that hyperventilation before exercise exacerbates the reduction in MCA Vmean during leg-press resistance exercise. These studies suggested that during heavy exercise the associated mode of ventilation may be of deterministic importance for cerebral circulation. However, these investigations focus on cerebral blood flow
regulation during lower-body exercise involving a large muscle mass. To date,there is no information regarding the effect of the mode of ventilation on the cerebral blood flow response during upper body heavy exercise involving a small
muscle mass. In addition, the individual effects of breath holding during exercise
and of hyperventilation before exercise on cerebral blood flow remain unclear.
Therefore, the purpose of the present study was to elucidate the effect of themode of ventilation on cerebral blood flow response during heavy upper body exercise. We hypothesized that hypocapnia induced by hyperventilation before exercise and by breath holding during exercise may cause greater reduction in the cerebral blood flow as compared with that during continued normal ventilation.

2 Methods
Subjects A total of 10 male field athletes (7 shot putters and 3 hammer throwers;
mean age ± SD: 21.2 ± 1.2 years) volunteered to participate in this study after
providing informed consent to the protocol, as approved by the ethics committeeof Japan Women’s College of Physical Education.
Exercise and mode of ventilation In this study, single arm elbow flexion exercise
was performed with the use of a multifunctional dynamometer device. The exercise load selected was 80% of the maximal voluntary contraction (MVC) force.
After a 3-min resting period, the subjects performed 15-s static exercises at 80%
MVC with the following 3 different modes of ventilation (in random order): 1)
continued normal ventilation (EX), 2) exercise with concomitant breath holding(EX+BH), and 3) pre-exercise hyperventilation till an end tidal partial pressure of
CO2 (PET CO2) of 3.5% was achieved (HV). In HV, after a 2-min rest, the subjects
were instructed to perform voluntary hyperventilation for 1-min in order to

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achieve a PET CO2 of ~3.5% [10]. After the 1-min hyperventilation, the subjects
performed 15-s static exercises with continued normal ventilation.
Measurement MCA Vmean measurement was performed with an ultrasound system(Vivid 7pro; GE Yokogawa Medical Systems) equipped with a 2.0 MHz sectortransducer. The MCA Vmean was defined as the time-averaged mean velocity obtained in automatic calculation mode. Mean arterial pressure (MAP) was measured non-invasively by photoelectric plethysmography with Finometer (Finapres
Medical Systems BV). Furthermore, we determined the stroke volume (SV), andcardiac output (CO), from the blood pressure wave form by using the Modelflow
method. Respiratory parameters were determined with an online system for thebreath-by-breath method. The ratio of MAP/ MCA Vmean was calculated as an index of cerebrovascular resistance (CVR).
Statistics To confirm whether the parameters had actually changed as a result of
exercise as compared with the resting values, two-way analysis of variance(ANOVA) with repeated measurements and Dunnett’s t-test were conducted.

3 Results
The MCA Vmean and CVR responses at rest, during, and after exercise are illustrated in Figure 1. In EX, MCA Vmean decreased (not significantly) from 36.8 to
34.9 cm·s-1 and significantly (P < 0.05) decreased further to 32.4 cm·s-1 at 1–5 safter the end of exercise. The CVR gradually increases at the onset of exercise,and returned to resting levels immediately after the end of exercise. The PET CO2
rapidly decreased during exercise in EX.
In EX + BH, MCA Vmean dropped sharply to below the resting revel (from 38.2
to 31.9 cm·s-1) with a subsequent overshoot to 43.4 cm·s-1 at 1–5 s after the end of
exercise. The CVR significantly (P < 0.05) increased at the onset of exercise, andrapidly returned to resting levels immediately after the end of exercise. The COsignificantly (P < 0.01) decreased until just after the end of exercise (from 9.2 to
5.6 l·min-1), with a subsequent overshoot until 10 s after the end of exercise (to10.4 ·min-1).
Hyperventilation before exercise reduced the MCA Vmean from 35.2 cm·s-1 at rest
to 28.4 cm·s-1 at 5 s before the start of exercise. In contrast to both the EX and
EX+BH, the MCA Vmean gradually increased until the end of exercise (from 28.4
to 33.0 cm·s-1) and subsequently decreased to 30.9 cm·s-1 at 1–5 s after the end of
exercise. During hyperventilation, the CVR significantly (P < 0.05) increased andthis increasing continued and ex-tending to during and after the end of exercise.
Before exercise, PET CO2 significantly (P < 0.05) decreased to 27.7 mmHg withhyperventilation and was 27.5 l/min immediately before the start of exercise. PET

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4

CO2 values during exercise were significantly (P < 0.05) lower than the restingvalues. After the end of exercise, PET CO2 gradually returned to the baseline.
The results can be summarized as follows: (1.) the magnitude of reduction in the
MCA Vmean during exercise was larger in EX+BH than in EX, (2.) EX+BH also
caused a rapid overshoot of MCA Vmean after exercise, and (3.) in HV, the hyporcapnia induced by hyperventilation before exercise produced a marked reductionin the MCA Vmean before and during exercise, and extending to after exercise.

4 Discussion
It is well known that Pa CO2 is important for the regulation of cerebral blood flow
and CVR [4, 9, 10]. We suggested that the decrease in MCA Vmean during and after the end of exercise in EX might be related to Pa CO2, which may reflect PET
CO2. The time constant for MCA Vmean responses to a step decrease PET CO2 is ~6s, whereas the response to a step increase in CO2 takes ~14 s [8]. This seems tosuggest that the observed time delay between MCA Vmean and PET CO2 may havecontributed to the lowest MCA Vmean during the recovery period in the EX.
The expiratory strain during a Valsalva-like maneuver might reduce blood flow
to the brain [6, 7]. Forced expiration against a closed glottis increases intrathoracic
pressure and central venous pressures and marked reduces in SV and thus CO.
Previous studies indicated that CO is an important determinant of cerebral bloodflow during exercise [3, 5, 7, 9]. However, our data suggested relationship between CO and MCA Vmean was not simply under this situation. Furthermore, therapid increase in the CVR at the onset of exercise may also contribute to thechange in MCA Vmean and the increase in the CVR may be induced by sympathoexcitation due to heavy exercise and/or the reduction in CO and Pa CO2. The increase in the CVR during EX+BH suggested vasoconstriction of the peripheral
branches of the MCA. On the other hand, over shooting of the MCA Vmean immediately after the end of exercise may be induced by rapid decrease in CVR, with
rapid recovery of CO and Pa CO2.
In the HV trials, reduced MCA Vmean occurred in conjunction with increased
CVR. This reduction in MCA Vmean before, during, and after exercise was attributable to the reduction in Pa CO2. These results indicate that the increase in CVR
was probably associated with vasoconstriction of the cerebral blood vessels.
In summary, our data suggested that even during upper body heavy exercise involving small muscle mass, the mode of ventilation was very important for maintaining cerebral circulation. We think that the combination of hyperventilation before heavy exercise and breath holding during exercise is the worst scenario fromthe perspective of cerebral circulation. It may be that continued normal ventilation
during heavy upper body exercise may be safer, in that it helps to avoid rapid

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5

changes in the cerebral blood flow and CVR that may in turn cause symptoms of
dizziness or outright weight lifter’s “black out” and intracranial hemorrhage [7].

5 Acknowledgement
We especially thank Hiroyuiki Yamamoto (GE Yokogawa Medical Systems, Tokyo, Japan) for his expert technical assistance. This study was supported by a research grant from the Academic Frontier Project, Japan Women’s College ofPhysical Education, and Yamaha Motor foundation for sports.

6 References
1. Edwards MR, Martin DH, Hughson RL (2002) Cerebral hemodynamics and resistance exercise. Med Sci Sports Exerc 34: 1207–11
2. Haykowsky MJ, Findlay JM, Ignaszewski AP (1996). Aneurysmal subarachnoid hemorrhage
associated with weight training: three case reports. Clin J Sport Med 6: 52–55
3. Ide K, Boushel, R, Sorensen HM et al (2000) Middle cerebral artery blood velocity during
exercise with β-1 adrenergic and unilateral stellate ganglion blockade in humans. Acta Physiol Scand 170: 33–38
4. Jørgensen LG (1995) Transcranial Doppler ultrasound for cerebral perfusion. Acta Physiol
Scand (Suppl ) 625: 1–44
5. Ogoh S, Brothers RM, Barnes Q et al (2005) The effect of changes in cardiac output on midle
cerebral artery mean blood velocity at rest and during exercise. J Physiol (Lond) 569: 697–
704
6. Pott F, van Lieshout JJ, Ide K et al (2000) Middle cerebral artery blood velocity during a Valsalva maneuver in the standing position. J Appl Physiol 88: 1545–1550
7. Pott F, Van Lieshout JJ, Ide K et al (2003) Middle cerebral artery blood velocity during intense static exercise is dominated by a Valsalva maneuver. J Appl Physiol 94: 1335–1344
8. Poulin MJ, Liang PJ, Robbins PA (1996) Dynamics of the cerebral blood flow response to
step changes in end-tidal PCO2 and PO2 in humans. J Appl Physiol 81: 1084–1095
9. Querido JS, Sheel AW (2007) Regulation of cerebral blood flow during ex-ercise. Sports
Med 37: 765–782
10. Romero SA, Cooke WH (2007) Hyperventilation before resistance exercise: cerebral hemodynamics and orthostasis. Med Sci Sports Exerc 39: 1302–1307

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(cm.s-1)

MCA Vmean

50

Exercise

Rest

Recovery

A

45
40
35
30
25

hyperventilation

20-90 -75 -60

-45

-30

-15

0

15

30

45

60

90 105 120 135 150 165 180 195 210 225 240(mmHg/cm.s-1)

Cerebrovascular
Resistance(CVR)

4.5

EX

B

4

EX+BH
HV

3.5
3
2.5
2

-90 -75 -60

90

-45

-30

-15

0

15

30

45

60

105 120 135 150 165 180 195 210 225 240

Time (s)Fig. 1. Cerebrovascular responses at rest, during, and after heavy exercise. (A) MCA Vmean ,Mean middle cerebral artery blood flow velocity and (B) CVR, Cerebrovascular resistance index.

440

学術フロンティア発足シンポジウム

日本女子体育大学体育学部附属基礎体力研究所開所 15 周年記念シンポジウム−学術フロンティア推進事業「運動時の循環調節研究」の学術拠点形成を目指して−日

時：2004年 10 月23 日（土）基調講演：運動時の循環調節−基礎体力研究所 15 年の成果と学術フロンティア「運動時の循環調節」共同研究プロジェクトの発足について−
加賀谷淳子（研究代表者；日本女子体育大学学長）

研究発表：学術フロンティア推進事業；運動時における循環調節機構の統合的解明−スポーツによる健康・体力づくりプログラムの構築に向けて−「運動時の腹部内臓の血流動態」

定本朋子「Effects of muscle exercise on prefrontal cortex oxygenation monitored bynear infrared spectroscopy」

Valentina Quaresima「Technical developments of near-infrared devices for studying oxygenationand hemodynamics in brain cortex and skeletal muscle」

Marco Ferrari「運動時の腹部内臓の血流動態」

斉藤

満「運動単位の動員状態からみた運動特性」

加茂

美冬「運動時の心拍出量の変化と各種血管への血流分配」

清水靜代

「心臓血管系患者の血流プロファイル」

長田卓也

特別講演：Future perspectives in the study of circulatory regulation during exercise
Richard L. Hughson（University of Waterloo, Canada）

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日本女子体育大学附属基礎体力研究所
第 17 回研究フォーラム・学術フロンティア研究成果中間報告会
日時： 2006 年 11 月 25 日

13 ： 30 〜 16 ： 40会

場：日本女子体育大学本館

E102

プログラム
13 ： 30

開会の挨拶

13 ： 40 〜 15 ： 00

永島

惇正（日本女子体育大学学長）

研究成果（中間）報告
座長

中村泉（日本女子体育大学教授）「プロジェクト全体の説明」
定本

朋子（日本女子体育大学教授）清水靜代（慶應義塾大学体育研究所講師）「中心循環と末梢循環のマッチングとミスマッチング」「骨格筋への血流配分と筋からの血液還流」

加賀谷淳子（日本女子体育大学名誉教授）
大森芙美子（鹿屋体育大学大学院）「運動時の内臓器官および脳の血流動態とその調節機構」
定本

朋子（日本女子体育大学教授）「運動時の筋交感神経活動からみた中枢指令および反射性制御の調節機構」
斉藤

満（豊田工業大学教授）「運動準備期のセントラルコマンドの働き」
岩館

雅子（学術フロンティアポスドク研究員）「運動時の呼吸循環系変化に対する中枢性・末梢性の神経調節」
佐藤耕平（日本女子体育大学助手）「有疾患者における運動および筋虚血に対する血流調節プロファイル」
長田
15 ： 00 〜 15 ： 30

コーヒーブレイク

15 ： 40 〜 16 ： 30

特別講演卓也（東京医科大学講師）〈研究成果ポスター発表〉司会高橋

和之（日本女子体育大学基礎体力研究所所長）「脳を正しく使おう」
金澤

一郎先生

（国立精神・神経センター総長，日本学術会議会長，宮内庁長官官房・皇室医務主管）
16 ： 40

閉会

453

日本女子体育大学附属基礎体力研究所
第 17 回研究フォーラム・学術フロンティア研究成果中間報告会「運動時における循環調節の統合的解明−スポーツによる健康・体力づくりプログラムの構築に向けて−」学術フロンティア推進事業「運動時における循環調節の統合的解明−スポーツによる健康・体力づくりプログラムの構築に向けて−」は，日本女子体育大学附属基礎体力研究所を拠点として，国内外の研究者中心に（表 1参照），平成 16 年度から実施されている事業である．平成 18 年度はその 5 年間にわたる研究期間の中間年にあたり，基礎体力研究第 17 回研究フォーラムを兼ねた，学術フィロンティア研究成果中間報告会を平成 18 年 11 月 25日に開催した．
永島惇正学長（日本女子体育大学）の開会挨拶では，私学助成学術フィロンティア推進事業の経緯と本学における学術的意義に対する期待の言葉が述べられた．また成果の中間報告会という節目にあたり，多忙にも関わらず，特別講演をしてくださる金澤一郎先生への感謝が述べられた．研究成果中間報告会では，中村泉教授（日本女子体育大学スポーツ健康学科長）の司会により，プロジェクト全体の概要（図 1）およびこれまでの主な研究成果が報告された．発表された報告の要旨は以下のとおりである．
また，当日の午前中に開催された本プロジェクトの「外部評価委員会」においても，以下の要旨を含む研究成果についての報告がなされ，評価を受けるとともに，多くの示唆と教示を頂いた．その外部評価委員としてご尽力をいただいた浅見俊雄先生（東京大学名誉教授・元国立スポーツ科学センター長），松田

学名誉教授，流通経済大学教授），田村光生先生（筑波大

照子先生（文化女子大学大学院研究科長・教授）に心より感謝を申し上げる次第である．また研究成果中間報告会の開催，外部評価委員会の実施にあたりご支援をいただいた学校法人
二階堂学園理事長ならびに教職員の皆さまに重ねて感謝申し上げる次第である．

本プロジェクトの概要
現代社会においては日常的な身体活動の機会が減少し，すべての人々にとって意図的運動の実施が極めて重要である．しかし，「動く」ことに対する身体適応のメカニズム，特に「安全性」確保に不可欠であり，かつ多数の因子が複雑に作用する運動時の循環調節機序は十分明らかにされているわけではない．そこで本プロジェクトでは，さまざまな特性を持つ運動時の循環調節機構を明らかにすると同時に，多様な特性を持つ健康人および有疾患者に適用して検証し，科学的根拠を持つ「安全で有効な運動プログラム」の構築に向けた提案を行うことを目的としている．本プロジェクトは科学的な新知見をもたらすと同時に，国の重要かつ喫緊の課題となっている国
民の健康のための運動推進にも貢献するという大きな意義がある．
平成 16 〜 20 年度にわたる 5 年間の研究期間のうち，最初の 3 年間（平成 16 〜 18 年度）は，運動時の循環調節の研究基盤を確立するために，様々な運動様式（動的と静的運動），種々の運動強度と運動時間，身体各部位の運動を実施させて，循環の中心である心臓からの血液の拍出量（心拍出量）と身体各部位・臓器（活動筋，非活動筋，腹部内臓，脳など）への血流の分配，筋組織での酸素動態，血圧応答，交感神経活動の変化を測定し，循環調節に関与する生理学的因子の解明とその調節機構を実験的に明らかにする計画である．続く 2 年間（平成 19 〜
20 年度）は，それらの調節機構が，発育や加齢に伴ってどのように変化するか，疾患の有無，競技者と非競技者との体力差，男女の相違といったさまざまな身体特性をもった対象者において明らかにする．最終的には，これらの成果を総合して，循環調節の観点から安全で有効なスポーツ運動プログラムについて提案する．
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図1

表1
研究者氏名

本プロジェクトの研究デザイン

プロジェクトの研究体制（平成 18 年現在）

所属・職名

加賀谷淳子
日本女子体育大学
研究代表者
名誉教授（平成 16 〜 18 年度）

プロジェクトでの研究課題

プロジェクトでの役割

骨格筋への血流分配と筋からの 運動特性と骨格筋への血流分配への関
血液還流係解明，研究全体の統括と推進．
非活動組織血流からみた運動時の循環
運動時の内臓器官および脳の血調節の解明，研究の実施に関する統括
流動態とその調節機構と推進．
運動様式，運動強度，運動時間
筋疲労発現，運動特性，筋代謝との相および筋代謝からみたモーター
互連関の解明ユニットの動員特性

定本朋子

日本女子体育大学教授

加茂美冬

日本女子体育大学
助教授

清水

靜代

慶應義塾大学体育研究 運動時の心拍出量の変化と各種 中心静脈と末梢循環のマッチングとミ所講師
血管への血流分配
スマッチング佐藤耕平

日本女子体育大学助手

岩館

雅子

斉藤

満

長田

卓也

運動時の呼吸循環系変化に対す
呼吸循環応答に関わる調節因子の解明
る中枢性・末梢性の神経調節セントラルコマンドと循環応答の対応
学術フロンティア支援ス 運動準備期のセントラルコマン
関係の解明，各研究プロジェクト実施
タッフ，ポスドク研究員 ドの働きのための補助や調整
運動時の筋交感神経活動からみ自律神経による運動時循環調節メカニ
た中枢指令および反射性制御の豊田工業大学教授
ズムの解明
調節機構
有疾患者における運動および筋
低体力者や有疾患者の循環調節メカニ
虚血に対する血流調節プロファ
東京医科大学講師
ズムの解明と運動療法の基盤構築
イル

Marco Ferrari

University of L’Aquila（Italy）教授

脳循環・代謝測定用近赤外線分研究装置の開発
光法の開発

Valentina
Quaresima

University of L’Aquila（Italy）教授

近赤外線分光法による運動時の 脳への血流分配にかかわる調節機構の脳循環・代謝の変化解明455

■ 研究成果（中間）要旨

骨格筋への血流分配と筋からの血液還流
加賀谷淳子（日本女子体育大学）

大森芙美子（鹿屋体育大学大学院）
Abstract

Re-distribution of blood flow to skeletal muscles was studied to clarify 1) an interaction between
arterial and venous flow, 2) exercise time- and intensity-dependent blood flow changes to no-exercising limb, and 3) time course of changes in post-exercise blood flow. Three studies were conducted,
The first study indicated that the brachial venous outflow due to muscle action accelerated brachialarterial blood flow when a prolonged handgrip exercise increased muscle blood volume. The second
study observed blood flow and vascular conductance of non-exercising forearm and leg during handgrip exercise. Vascular conductance of non-exercising limb increased or decreased depending on exercise intensity, exercise duration, and the limb used and vessels studied. The third study was conducted
to find the time course of blood flow changes immediately after exercise to find an optimal exercise
interval (frequency). As a result, The largest occurrence of the cardiac cycle for peak blood flow after
exercise was at the 3rd cardiac cycle in all contraction intervals and exercise intensities,（1）活動中の骨格筋への血流供給は，筋内血液量や静脈血流出量によって修飾されると考えられてきたが，静脈血流量測定の困難さから，その仮説が実証されてはいなかった．本研究プロジェクトにおいて実施された掌握
運動時の動静脈血流の研究から，時間経過に伴う両者の関係は必ずしも一致していないこと，筋ポンプ作用（筋収縮によって筋内から押し出される血液量）が動脈側に影響を与えるのは，運動開始直後の極く短時間と，運動持続後の筋内血管床が拡大する時期においてであることが明らかになった．
（2）筋活動中の非活動体肢血流量は，血管拡張作用によって減少するとする報告と，血圧依存で増加するとする報告があり，議論の対象となっている．すでに，アームクランキング（上肢回旋運動）とサイクリング運動では強度依存で増加すること，それは，血管に対するシアストレスによるものであることを示したが，本プロジェ
クトでは，掌握運動時の非活動上下肢の血管コンダクタンスは運動の強度だけでなく，持続時間にも依存した変化を示すこと及び部位特異性のあることを明らかにし，この論争に新たな知見を加えた．
（3）骨格筋への血流量が運動後，一過性に低下するのか，増加するのか，増加するとすれば時間はどれくらいかは明らかでなかった．本プロジェクトでは，下腿運動後の膝窩動脈血流量は運動後増加し，それは 3 心拍目に，最高値に達するとの新知見を得た（アジアスポーツ医学会賞受賞）．

運動時の内臓器官および脳の血流動態とその調節機構
定本

朋子（日本女子体育大学）（1）内臓器官の血流動態とその調節機構
Abstract
Since visceral regions are consisted of functionally different organs such as kidneys and gastrointestinal tracts. It was hypothesized that blood flow regulation induced by the autonomic activation

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during exercise is different among arteries supplying to specific organs. To verify the hypothesis. We
studied blood flow responses in renal artery (RA) and the superior mesenteric artery (SMA) during static handgrip exercise and the postexercise muscle ischemia (PEMI). Ten healthy female volunteers performed a sustained static handgrip exercise at 30 % of maximum voluntary contraction for 2 min followed by a 6-min recovery period (control condition). Subjects also underwent the occlusion condition. In which arterial blood flow in the upper arm was arrested immediately after the handgrip exercise. Mean arterial blood pressure (Finapres), heart rate (ECG), and blood flow in RA (RABF) and SMA(SMABF) were measured by Doppler ultrasound technique. Vascular resistance in RA and SMA (RAVR
and SMAVR) were calculated. During handgrip exercise, RAVR significantly increased and sustained at
the higher level during PEMI in occlusion condition. Whereas RAVR in control condition returned to
the resting level. On the contrary, SMAVR in both conditions slightly increased during exercise andreturned to the resting level during PEMI. These results supported the hypothesis that blood flow regulation among different visceral organs is differential during exercise and PEMI. RA appeared to be
more sensitive to exercise stimulus and the reflex signals arising from muscle metaboreceptors than
SMA. The artery supplying to the digesting gastrointestinal tract such as SMA might be to some degree
exempt from flow-reducing participation during exercise．

先行研究では「運動時には腹部内臓の血流減少が起こる」と一括されてきたが，本研究では，臓器によって運
動時の内臓血流調節が異なるとの知見を得た．静的運動時（30 ％ MVC 負荷）には腎動脈血流が低下し，腎の血管抵抗が著しく上昇した．一方，消化器官へ連絡する動脈（上腸間膜動脈）では，同一運動であっても腎動脈のような血流減少がみられず，血管抵抗の上昇も低いことが示された．このような腎動脈と上腸間膜動脈の血流反応の違いをもたらす要因として，筋代謝受容器反射（活動筋中に蓄積された代謝産物に由来する反射性制御）の働きが腎動脈と上腸間膜動脈では異なることが示された．腎動脈は上腸間膜動脈に比べ，筋代謝受容器反射による血管収縮作用を受けやすいことが示唆された．

（2）運動時の脳血流動態とその調節
Abstract
To elucidate the cerebral blood flow responses to static exercise, we measured arterial blood flow
responses in three sites of "the carotid artery root" and one site of "the vertebral artery root". Ten
healthy female volunteers performed a 3-min sustained static handgrip exercise with ramp loadincreasing from 10% to 30% of maximum voluntary contraction followed by a 3-min postexercise muscle ischemia (PEMI). The blood flow (BF) in left common carotid artery (CCABF), the left internal
carotid artery (ICABF), and the left vertebral artery (VABF) was measured by ultrasonography. Meanflow velocity in the left middle cerebral artery (MCAV) was also recorded. Mean arterial blood pressure (MAP; Finapres) and heart rate (HR; ECG). The vascular resistance (VR) was calculated from theratio of MAP to the CCABF, ICABF, VABF, or MCAV. During static exercise the vascular resistance inall arteries increased from the resting level in parallel with the increase in MAP，but the magnitude ofincrease was greater in the "carotid artery root" than the "vertebral artery root". During PEMI, CCABFVR, ICABF-VR, and MCA-VR were significantly higher than the resting level, whereas VABF-VR
returned to the resting level. These data suggested that the static exercise produced greater vasoconstriction in the "carotid artery root" than the "vertebral artery root" and that the muscle metaboreflex
played an important role in vasoconstriction in the "the carotid artery root" but not in the "vertebral
artery root"

脳への血流は左右の内頸動脈経路（主に大脳皮質側頭葉，前頭葉，頭頂葉，島皮質へ潅流）と椎骨動脈経路（主に延髄，小脳，後頭葉へ潅流）の 2 経路により供給されるが，この 2 経路における運動時の血流動態およびその調節機構に相違があることが示された．内頸動脈経路では，血圧が上昇するような運動時には顕著な血管抵抗457

の増大，つまり血管収縮作用がみられ，これにより流入血液を制限することが示唆された．一方，椎骨動脈経路
では血管抵抗の増大が少なく，血流の制限が少ないことが示された．またこのような血管抵抗増大の要因として，
頸動脈経路では筋代謝受容器反射が果たす役割が大きいが，椎骨動脈経路では筋代謝受容器反射の関与が殆どみられないことも示された．

運動時の筋交感神経活動からみた中枢指令および反射性制御の調節機構
斉藤

満（豊田工業大学）

Abstract
This project attempted to investigate the effect of central command (CC) and peripheral reflex on
regulation of exercise circulation. Since sympathetic nervous system has crucial role to regulate cardiovascular system, muscle sympathetic nerve activity (MSNA), which is modulated by CC and reflex
input from periphery, was recorded during and following isometric handgrip. MSNA, blood pressure(BP) and perceived excretion as an index of CC increased gradually during exercise while inhibitory
effect of baroreflex on MSNA decreased gradually until exercise end. However, during post exercise
ischemia (PEI) its effect increased again compared with during exercise indicating that CC might influence baroreflex effect. In the second study, MSNA response during high intensity handgrip exercise
and metaboreflex MSNA during PEI was compared between dominant (DA) and non-dominant arm(NDA) exercise. MSNA response during high intensity handgrip was the same in both arms，while
metaboreflex MSNA response during PEI was greater in DA than in NDA. In addition，effect of fourweeks resistance training of NDA on metaboreflex MSNA response was investigated and the response
was still greater in DA compared to NDA exercise. These results demonstrate that no difference in CC
between DA and NDA, but metaboreflex was different and the difference could not cancel with shortterm resistance training．

運動時の圧反射調節にはセントラルコマンド（運動努力）が常時関わり，その強さに依存して変化することが示され，運動努力の重要性が確かめられた．利き腕と非利き腕をトレーニング，非トレーニング肢モデルとしてセントラルコマンドの効果を検討した結果，セントラルコマンドの左右差は認めなかったが，代謝受容器反射の差を認め，この結果に基づいて，代謝受容器反射がレジスタンストレーニングで解消できるかどうか検討した．
その結果，短期間の高強度レジスタンストレーニングは最大筋力やパフォーマンスを向上させるが，MSNA 反応の左右差を解消することはできず，代謝受容器反射への効果は認められなかった．したがって，代謝受容器反射に対する効果は 4 週以上のトレーニングが必要と考えられた．

運動様式，運動強度，運動時間および筋代謝からみたモーターユニットの動員特性
加茂美冬（日本女子体育大学）
Abstract

The first new finding of this study was that a constant discharge rate of motor units does not maintain constant force development, and "rate coding" is considered to be necessary for keeping a constant force. This finding was based upon following experiments. The evoked force of muscle fibers wasobserved during repetitive electrical stimulation for 3min on m. vastus medialis. The stimulus frequency was 0.2 Hz, 10 HZ and 20 Hz. The changes in the evoked force did not represent a constant but
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were complex at 10 Hz and 20 Hz stimulations. At 10 Hz the evoked force showed an initial transient
increment, then an abrupt decrement followed by a gradual increase and then a gradual decrease. The
initial transient peak did not appear at 20Hz stimulation. The magnitude of potentiation was not necessarily large at 20 Hz. The second finding of this study was that the mechanism to induce changes in
AMP during muscle exertion was not explained by the previously proposed hypothesis, because a significant positive correlation coefficient was obtained between CV and AMP.

筋力は骨格筋の運動単位（motor unit）の振る舞いにより決定されている．本プロジェクトでは，随意的に一定張力を発揮し，それを維持する静的運動（関節角度が変化しない状態で筋力発揮をする運動様式）を多く用いている．また運動負荷をさまざまに変化させる運動様式も多用している．このような運動時の運動単位の特性について，まず一定筋力の保持時について次のような知見を得た．一定頻度の電気刺激により誘発張力は初期に増大するが，この初期における張力増大を抑えるように，運動単位の活動頻度（放電間隔）を延長させる仕組みがあることが明らかとなった．また随意筋力発揮時の運動単位活動電位の波形（振幅）が，一定筋力を維持した場
合や強度を変化させた場合といった筋力発揮様式により異なることを運動単位活動電位の波形解析から明らかにした．そして筋力発揮様式により波形振幅を変化させる仕組みとして，従来の説明（Na+-K+ ポンプの増強）が当てはまらず，新たな説明が必要であることを指摘した．このような運動単位の活動変化は，筋線維間を走行する
血管にも影響を与える重要因子であり，運動時の循環を考える上で貴重な知見である（第 60 回日本体力医学会学会賞受賞）．

有疾患者における運動および筋虚血に対する血流調節プロファイル
長田卓也（東京医科大学）
Abstract

The present study examined the femoral arterial blood flow response in each leg during intermittent
isometric knee extension at incremental exercise intensities in patients having peripheral vascular disease. Changes in blood flow during exercise tend to be higher in the more-affected leg (PVD side) thanthe control healthy leg. Hyperemic response in the working skeletal muscle may be different in bothlegs. It is speculated that peripheral vascular disease may influence the blood flow response in muscle
contractions during a state of exercise.

閉塞性動脈硬化症保有者は，下肢動脈血管の動脈硬化による血行障害のために運動歩行時に間歇性跛行を認める．しかしながら，疾病下肢運動中の血流動態についての報告は少ない，そこで本研究では一過性運動時における血流動態を検討する事を目的とした．閉塞性動脈硬化症保有者を対象に，両下肢それぞれにおいて多段階負荷
等尺性片側膝伸展運動中の下肢血行動態を検討した．安静時において，疾病下肢血流量は，その反対側である対照下肢と比較して少ない傾向を示した．しかしながら，運動強度に対する下肢血流増加は，対照下肢側に比べ疾病下肢側において大きい傾向が認められた．運動に伴う疾病側下肢血流反応は，対照下肢と比べ異なることが考えられ，末梢循環障害が安静時のみならず運動中の骨格筋循環に与える影響が示唆された．

459

中心循環と末梢循環のマッチングとミスマッチング清水靜代（慶應義塾大学）
Abstract

The purpose of this study was to determine cardiac output and active limb blood flow responses toknee extension exercises. Two physically active women performed knee extension exercises with the
one-legged. Exercise intensities were 20%, 30% and 40% of the subjects' maximum voluntary contraction (MVC) and the exercise frequency was 50 contractions per minute. The 20% MVC exercise duration was 10 min, while the 30% and 50% MVC exercise conditions were performed to exhaustion.
During exercise, stroke volume (SV) and heart rate (HR) were measured using Doppler ultrasound andelectrocardiogram (ECG)，respectively. Cardiac output (Qsys) was calculated as the product of SV and
HR. Blood flow to the femoral (Qfa) was measured by Doppler ultrasound methods. The Qsys about
increased 1.4-2.0 times, when Qsys and Qfa were compared in the change from the resting level. In
contrast, Qfa during exercise were about 6-18 times. That it, compares the Qsys with Qfa did notchanges from the resting level. In addition, during muscle contraction phase of knee extension exercise, the effect of muscle contraction and relaxation on blood flow differs between Qsys and Qfa.

循環の中枢である心臓の拍出量と末梢の血流量は互いに影響しあい，末梢循環のみで調節できる場合と，中心循環を増加させて調節する場合がある．したがって，中枢と末梢の循環を同時に測定し，両者の相互作用を明らかにすることは重要である．本研究は，活動筋量の相違，及び筋の活動期および活動休止期の大腿動脈血流量が，心拍出量とどのような関係にあるのかを明らかにすることを目的とした．その結果，いずれの強度においても心拍出量は，大腿動脈血流量と比較し安静時からの変化は少ないことが示された．また，大腿動脈血流量は筋活動時には抑制，筋活動休止期には亢進されるが，心拍出量は筋活動及び休止の影響を受けないことが示された．

運動時の呼吸循環系変化に対する中枢性・末梢性の神経調節佐藤耕平（日本女子体育大学）
Abstract

The purpose of the present study was to evaluate the role of central command and muscle
mechanoreflex on the cardiorespiratory and cerebral blood flow responses at the onset of dynamic
exercise. Eleven young women were studied during no-load voluntary exercise (central command/muscle mechanoreflex) and passive movement (muscle mechanoreflex). Voluntary exercise consisted ofsingle arm elbow flexor-extensor exercise for 2-min with no-load. Passive movement was achieved
using a motor-driven lever arm and performed with the same range of movement, angular velocity,and frequency as voluntary exercise. In the present study, the following results were obtained: 1)
・Middle cerebral artery blood velocity (VMCA) and common carotid artery blood flow (QCCA) increased
significantly (P < 0．05) at the onset of voluntary exercise in parallel with increases in the circulatory
responses such as heart rate (HR) and cardiac output (CO). 2) During passive movement, no changes
in circulatory and cerebral blood flow responses were observed. These results suggested that central
command, but not muscle mechanoreflex, may significantly contribute to the immediate increase incirculatory and cerebral blood flow responses at the onset of dynamic exercise. Moreover, it is possible that the increase in HR and CO at the onset of voluntary exercise may directly affect on cerebral

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blood flow responses at the onset of voluntary exercise．

本研究課題では動的運動開始時における呼吸循環応答及び脳血流応答に対するセントラルコマンドと筋機械受
容器反射の役割を検討する．被検者は 11 人の健康な女子大学生とし，2 分間の安静後，無負荷での随意肘伸展屈曲運動（VOL）と，受動的に VOL と同じ動作を行なう受動的動作（PAS）をそれぞれ 2 分間行い，呼吸循環応答に加え，総頸動脈血流量，中大脳動脈血流速度を連続的に測定した．VOL 開始時における総頸動脈血流量および中大脳動脈血流速度の増加は心拍数や心拍出量の増加と同期した．しかしながら，PAS 開始時には毎分換気量といった呼吸応答に増加が見られたものの，循環応答及び脳血流応答には変化が認められなかった．この結果は，
筋機械受容器反射由来の神経反射は主に呼吸系の応答に影響を与える可能性と，随意運動に伴うセントラルコマ
ンド由来の心拍数，心拍出量の増加が脳血流応答に直接的に影響を与える可能性が示唆された．

運動準備期のセントラルコマンドの働き
岩館

雅子（日本女子体育大学基礎体力研究所ポスドク研究員）
Abstract

To study the relation between cardiovascular variables and the activation in the sensorimotor cortex(SM), we measured heart rate (HR), mean arterial blood pressure (MAP) and the oxygenation in SM
area and in the forearm flexor muscles by near-infrared spectroscopy (NIRS) during preparatory phaseof handgrip exercise. Eleven young healthy females participated in the three sessions with exercise
task (ET), a load of 5%, 30%, or 80% of maximum voluntary contraction，and one session without
exercise task (Con). In all sessions, subject was asked to count a number continuously from 1 to 50 inaccordance with 1-Hz sound signal provided 10 sec before the number counting, and thereafter a 10sec handgrip exercise was performed in ET but not in the Con. During the preparatory phase，the levels of oxyHb and totalHb in left SM area were higher in ET than those in Con. HR and oxyHb in theactive muscle showed similar responses as seen in the oxyHb and totalHb in SM area in spite of different responses seen in mean arterial blood pressure and cardiac output. These results suggested there
are a close linkage between the activation of cortical motor cortex and heart rate and the oxygenationin active muscle during preparatory phase.

循環調節におけるセントラルコマンド仮説によると，大脳皮質運動野の皮質活動は循環応答と対応した変化を生じている可能性が考えられるが，未だ不明な点が多い．本研究では，大脳皮質運動野周辺における脳酸素動態の変化が同部位の皮質活動を反映するのではないかと考え，運動準備期の脳酸素動態と循環応答の対応を検討した．その結果，脳の酸素化ヘモグロビンおよび総ヘモグロビン，心拍数，活動肢の酸素化ヘモグロビンは 30 ％MVC 強度以上の運動負荷において類似した反応を示した．このことから，運動準備期において運動関連領野に生じる皮質活動と心拍数および活動筋酸素動態は，比較的高い強度の運動時に対応した変化を生じるものと考えら
れた．

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■特別講演「脳を正しく使おう」
金澤

一郎

先生

（国立精神・神経センター総長，日本学術会議会長，
宮内庁長官官房・皇室医務主管）
第 17 回基礎体力研究所公開フォーラムでは，学術フロンティア推進事業「運動時における循環調節機構の統合的解明−スポーツによる健康・体力づくりのプログラムの構築に向けて−」の研究成果中間報告会の後に，金澤一郎先生をお迎えし，「脳を正しく使おう」という大変興味深い題目で特別講演をしていただいた．講演に先立って，高橋和之副学長（兼基礎体力研究所長）から金澤一郎先生の紹介が次のようにあった．
金澤一郎先生は，悠仁親王殿下が誕生された折に，笑顔で記者会見に臨まれた皇室医務主管としてメディアを通してご存知の方も多いが，先生は国立精神・神経センター総長，そして日本の科学者 77 万人を代表する第 20期日本学術会議の会長でもあり，脳科学における臨床医・研究者でもあるという先生の経歴がまず紹介された．
また金澤先生は，厚生労働省の医道審議会医道分科会長，特定疾患対策懇談会座長，難病財団企画委員会委員長
といった数々の委員会において，専門家の立場から優れた指導力を発揮されているリーダーであることも紹介された．
当日の講演は，立見が出るくらい多人数であり，先生のユーモアとウィットに富んだ語り口により，そしてタ
イミングよく挿入されるジョークとクイズにより，会場全体が金澤先生を中心に一体となり，熱気に満ち溢れた講演となった．その講演の中で，先生はどの年代においても，脳に刺激を与え脳を上手く使うことの大切さについて，次のように繰り返し話された．
最初の話は，講演会場に学生が多いことに配慮さてれて，脳細胞の話から大脳皮質における左右の機能局在などであり，脳機能に関する基礎知識の初歩的なところから丁寧に説明された．また馴染みやすい例を挙げられて，さまざまな脳の不思議さについて概観された．たとえば，右脳の機能が日本人と西洋人で違うため，われわれ日
本人は，秋の夜に鈴虫の声を聞くと「ああ，情緒があるな」と感慨深く思うが，西洋人には，単なる雑音にしか聞こえないということ等であった．
本題の話に移り，脳には巨大な学習機能と許容量があるが，そのような脳に幼児期から高齢者にいたるまで，適切に働きかけることの重要性を説明された．「雀百まで踊り忘れず」，「三つ子の魂百まで」という諺が示すように，乳幼児期の経験・学習がとりわけ重要であると話された．人間社会から阻害・隔離されて育てられた子ども
は，知的機能，感情表現，発話機能，言語理解といった発育が不十分となり，人間生活に不可欠な脳機能が獲得できないということを，次のような実験例をもとに説明された．成人したサルでは脳の変性は起こらないが，幼児期のサルの左目を遮蔽した生活をさせると，左目からの情報が入らないため，脳の構造・機能に変性がおこるということであった．
一方，成人後の学習や経験の重要性についても話された．認知症にみられるように，加齢とともに脳機能低下という健康問題も生じるが，成人後であってもさまざまな学習や経験によって脳細胞の新生がみられ，シナプス間の伝達効率も良くなるといった「脳機能向上」を示す研究成果が，日本の研究者により明らかにされていることを紹介された．脳機能を脆弱化させないよう，何事にも無反応な生活を続けるのではなく，さまざまな興味をもって生活することが肝要であるということであった．
続いて，認知症の予防に関する話をされた．カナダの研究者による 20 年間の追跡研究によると，ボードゲーム
やトランプなどを頻繁に行っている高齢者と行なわない高齢者では，認知症発症率が違い，トランプやゲームを行うグループの方が，明らかに認知症発症率が低いということを話された．また，身体運動やダンスをしている
462

人の方がしない人よりも認知能力が高いので，身体運動やスポーツが脳の健康に重要な役割を果たすのではないかというコメントも付け加えられた．脳も筋肉と同じで，使わなければ鈍るといえ，いろいろな刺激を与え，脳を目覚めさせて活性化させ，柔軟な脳をつくる必要性があることを強調された．
このような加齢と脳機能認低下予防に関わる話題の中で，年齢が高くなっても低下しない能力があることについても触れられた．専門的用語では「Crystallized ability（結晶化された能力）」とよばれるそうであるが，物事をカテゴリーに分類して記憶する，あるいは物事の共通点を見つけて，それを一区切りにまとめるといった能力であると説明された．文化的・社会的な経験を通して身に付ける能力だそうである．若いうちはこの能力が育成されていないため，「木を見て森を見ない」ということがあるが，経験を積むことによって「木も見て森も見る」ということが可能になる，ということである．同様に，状況判断能力なども，年齢とともに醸成される能力であるということを追加された．
最後に，脳を正しく使うための実例として，「脳をやわらかくする体操」を，会場の参加者全員で実施してみることになった．先生が提示されるスライドの写真・絵を見ながら，私たちの脳がいかに錯覚し，また誤判断をす
るのかについて，クイズ形式で体験した．金澤先生の明快でユーモアたっぷりの説明に，会場では幾度と無く驚きの歓声と笑いが渦巻くことになり，はっと気づいた時には講演終了の時間となっていた．そして，講演終了後も次々と質問が続き，参加者全員が金澤査先生に魅了された，実に充実した時間であった．
このような素晴らしい講演会をしてくださった金澤一郎先生に，あらためて深く感謝を申し上げたいと思います．また学術フロンティア推進事業の研究成果の中間報告会を含めて，公開フォーラムに参加していただいた学内外多くの研究者および学生・大学院生の方々にも感謝の意を表します．
（文責

463

佐藤

耕平，定本

朋子）

日本女子体育大学附属基礎体力研究所 第 19 回公開研究フォーラム
学術フロンティア推進事業 （平成 16 〜 20 年度）
公開国際シンポジウム
運動時における循環調節機構の統合的解明−スポーツによる健康・体力づくりのプログラム構築に向けて−日

時： 2008 年 11 月 29 日（土） 13 時 30 分〜 17 時 10 分

会

場：日本女子体育大学本館

E101

プログラム
開

会

13 ： 30

Session 1

高橋和之（日本女子体育大学学長）

13 ： 35 〜 14 ： 55

座長

加賀谷淳子

学術フロンティア成果「運動時の血流再配分ー運動特性と関連させてー」
加賀谷淳子（日本女子体育大学客員教授）
招待講演
Changes in vascular structure and function following exercise training
Daniel J. Green, Ph.D., Professor.
（Cardiovascular Physiology, School of Exercise and Sports Sciences,Liverpool John
Moores University, Liverpool, U.K.）
講演要旨説明ポスター発表＆ブレイク
Session 2

14 ： 55 〜 15 ： 25

座長

長田卓也（東京医科大学講師）

西田ますみ（日本女子体育大学教授）

15 ： 30 〜 16 ： 50

座長

定本

朋子

学術フロンティア成果「運動時の循環調節機構−神経調節を中心に−」
定本

朋子（日本女子体育大学教授）

招待講演
The role of central command in the cardiovascular regulation during exercise
Jon W. Williamson, Ph.D., Professor, Associate Dean.
（Health Care Sciences, UT Southwestern School of Health Professions,The University ofTexas Southwestern Medical Center at Dallas, U.S.A.）
講演要旨説明

笹原千穂子（東海学園大学講師）
佐藤

Session 3

16 ： 50 〜 17 ： 10

耕平（日本女子体育大学助教）
座長

定本

朋子

定本

朋子

学術フロンティア成果「運動時の循環調節機構の統合的解明へ向けて」
斉藤
閉

会
464

満（豊田工業大学・教授）

■招待講演 I

CHANGES IN VASCULAR FUNCTION AND STRUCTURE FOLLOWING
EXERCISE TRAINING
Daniel J Green
Research Institute for Sport and Exercise Sciences,
Liverpool John Moores University, UK;
School of Sport Science, Exercise and Health,
The University of Western Australia, Australia
SummaryThis presentation will address questions such as:●

Does risk factor modification explain the risk reduction associated with exercise?

●

What could account for the positive effects of exercise beyond traditional risk factors?

●

How does exercise training affect the vascular wall?

●

What is the relationship between change in artery function and structure with training?

●

Are the benefits of exercise training evident at all levels of the arterial tree?

●

Are changes in artery function and structure clinically relevant?

●Can we use information about the direct vascular effects of exercise to optimise interventions aimed
at decreasing cardiovascular risk?

Exercise is associated with an approximate 30% benefit in terms of decreased cardiovascular (CV) risk
(Thompson et al. 2003), a magnitude similar to that associated with antihypertensive and lipid loweringinterventions. The impact of exercise on traditional cardiovascular risk factors is, however, relatively modest. Indeed, a recent analysis of 27,000 subjects reported that around 50% of the cardiovascular risk
reduction associated with exercise cannot be explained by changes in CV risk factors (Mora et al. 2003).
Clearly, other explanations for the cardioprotective benefits of exercise must exist.

Exercise is associated with acute changes in central haemodynamics, arterial blood pressure and flow.
The vascular endothelium, which forms the interface between the circulating blood and the artery wall,
produces numerous paracrine hormones (eg nitric oxide NO) which are anti-atherogenic. Endothelial dysfunction can be considered an early and integral manifestation of vascular disease (Green et al. 2004). An
important physiological stimulus to endothelium-mediated vasodilation is arterial shear stress. Exercise
exerts direct effects on the vasculature via the impact of repetitive increases in shear stress on theendothelium.

There is strong evidence that exercise training of small and large muscle groups is associated withimprovement in endothelial function (Green et al. 2004), which can occur in the absence of changes inlipid levels (Green et al. 2003), blood pressure (Green et al. 2003; Higashi et al. 1999), glucose tolerance(Green et al. 2003) and BMI (Watts et al. 2004). The mechanisms responsible may involve shear stressmediated increases NO-synthase protein expression/phosphorylation or impacts of exercise on oxidative465

stress. Exercise training also induces changes in artery lumen diameter, arterial remodelling, which may
contribute to decreased atherothrombotic risk (Dinenno et al. 2001; Green et al. 1996; Naylor et al. 2006).
Studies of the relationship between changes in artery function and structure in humans are now emerging(Tinken et al. 2004), as is information relating to the impact of exercise training in microvessels (Black et al.
2008).

A direct effect of exercise on the vasculature therefore provides a plausible explanation for the reduction
in cardiac events associated with exercise training. Since different forms of exercise are associated with
distinct patterns of shear stress, it is likely that exercise prescription may be optimised if the direct effects
of exercise on vascular shear stress are taken into consideration.

References
1.

Black MA, Green DJ, Cable NT: Exercise training prevents age-related decline in nitric oxide (NO)-mediatedvasodilator function in human microvessels. J Physiol (Lond), In Press, 2008.
2. Dinenno FA, Tanaka H, Monahan KD, Clevenger CM, Eskurza I, DeSouza CA, and Seals DR: Regular
endurance exercise induces expansive arterial remodelling in the trained limbs of healthy men. J Physiol, 534:
287-295, 2001.
3. Green DJ, Fowler DT, O’Driscoll JG, Blanksby BA, Taylor RR: Endothelium-derived nitric oxide activity in forearm vessels of tennis players. J Appl Physiol, 81: 943-948, 1996.
4. Green DJ, Maiorana AJ, O’Driscoll G, Taylor R: Topical Review: Effects of exercise training on vascularendothelial nitric oxide function in humans. J Physiol (Lond), 561: 1-25, 2004.
5. Green DJ, Walsh JH, Maiorana A, Best M, Taylor RR, O’Driscoll JG: Exercise-induced improvement in endothelial dysfunction is not mediated by changes in CV risk factors: a pooled analysis of diverse patient populations.
Am J Physiol, 285: H2679-H2687, 2003.
6. Higashi Y, Sasaki S, Kurisu S, Yoshimizu A, Sasaki N, Matsuura H, Kajiyama G, Oshima T: Regular aerobic
exercise augments endothelium-dependent vascular relaxation in normotensive as well as hypertensive subjects. Circulation, 100: 1194-1202, 1999.
7. Mora S, Cook N, Buring JE, Ridker PM, Lee IM: Physical activity and reduced risk of cardiovascular events:
Potential mediating mechanisms. Circulation, 116: 2110-2118, 2007.
8. Naylor L, O’Driscoll G, Fitzsimons M, Arnolda L, Green DJ: Effects of training resumption on conduit arterial
diameter in elite rowers. Med Sci Sports Exerc, 38: 86-92, 2006.
9. Thompson PD, Buchner D, Pina IL, Balady GJ, Williams MA, Marcus BH, Berra K, Blair SN, Costa F, Franklin
B, Fletcher GF, Gordon NF, Pate RR, Rodriguez BL, Yancey AK, Wenger NK: Exercise and physical activity inthe prevention and treatment of atherosclerotic cardiovascular disease. A statement from the Council on
Clinical Cardiology (Subcommittee on Exercise, Rehabilitation, and Prevention) and the Council on Nutrition,
Physical Activity, and Metabolism Circulation, 107: 3109-3116, 2003.
10. Tinken TM, Thijssen DHJ, Black MA, Cable NT, Green DJ: Conduit artery functional adaptation is reversible
and precedes structural changes to exercise training in humans. J Physiol (Lond), 586: 5003-5012, 2008.
11. Watts K, Beye P, Siafarikas A, Davis EA, Jones TW, O’Driscoll G, and Green DJ: Exercise training normalises
vascular dysfunction and improves central adiposity in obese adolescents. J Am Coll Cardiol, 43: 1823-1827,
2004.

招待講演講師略歴
Daniel J. Green, Ph.D., Professor.
Daniel J. Green 氏は，身体活動がどのようにして心臓血管系疾患に対するリスクを軽減するかという視点から研究を進めれられている．氏の数多くの業績のなかでも，1993 年に Journal of Applied Physiology 誌に発表された

Modification of forearm resistance vessels by exercise training in young men

Journal of Physiology 誌に発表されたや，近年では 2005 年にComparison of forearm blood flow responses to incremental hand-

grip and cycle ergometer exercise: relative contribution of nitric oxide

は運動中の活動筋・非活動筋への血流を研究するものに大きな影響を与えた．また，これまでに国際誌に投稿された 80 編以上の論文を査読しており，
運動中の循環調節に関する研究をリードしている研究者の一人である．

466

■招待講演 II

THE ROLE OF CENTRAL COMMAND IN THE CARDIOVASCULAR REGULATIONDURING EXERCISE
Jon W. Williamson
Health Care Sciences,
UT Southwestern School of Health Professions,
The University of Texas,

Southwestern Medical Center at Dallas, USA.

Summary
The goal of this talk is to provide an update of current concepts on the role of central command in
humans with a particular emphasis on the regions of the brain that may be involved in cardiovascular regulation during exercise. Central modulation of the cardiovascular system via descending signals from thecerebral cortex has been well recognized for over a century, yet the specific regions of the human brain
involved in this exercise-related response have remained speculative. The concept of central command
during exercise has been classically defined as "a feed forward mechanism involving parallel activation of
motor and cardiovascular centers". The primary focus of many central command-related investigations has
involved the modulation of motor effort and the resulting alterations in cardiovascular responses.
However, most researchers would concur that the magnitude of central command during exercise can belargely dictated by an individual ’s perception of effort during actual or even attempted physical exertion,
independent of the actual work load or force production. This suggests that the magnitude of a central
command mediated cardiovascular response during exercise can be independent of force production (e.g.
imagined exercise) and dictated more by an individual’s perception of effort. Therefore, we would propose
the use of the term "central command" to imply a central neural mechanism that can function as a feedback system, responding to an individual's sense of effort, to elicit proportional changes in cardiovascularresponses, which does not require a parallel motor activation to exert its influence. However, during actual
exercise, neural networks involving both "motor" and "cardiovascular" systems would be activated, yetthese individual networks have not been well defined. Studies investigating the functional anatomy of central command-induced changes in regional cerebral blood flow (rCBF) have identified a network of structures activated in the human brain. These regions include the insular cortex and anterior cingulate cortex
or the medial prefrontal region, as well as thalamic regions. These findings are consistent with findings
from studies in animals. The structures involved appear to be activated in response to an increased perception of effort during exercise when heart rate and blood pressure are elevated. The cardiovascular andhemodynamic adjustments to exercise are primarily mediated by alterations in parasympathetic and sympathetic neural activity. These exercise-induced changes in autonomic neural outflow are designed to help
meet the metabolic demands of the exercising muscle. Central command appears to initiate autonomic
adjustments during exercise which involve a resetting of the arterial baroreflex during exercise. Morespecifically, central command input appears to be responsible for the relocation of the operating point(pre-stimulus blood pressure) away from the centering point (point at which there is an equal depressor
and pressor response to a given change in blood pressure) and closer to the threshold of the cardiac
baroreflex stimulus response curve. This effect of central command on the operating point appears to be467

mediated via vagal withdrawal associated with increases in exercise intensity. It has been shown to occur
in order to allow the arterial baroreflex to adapt to and potentially modify the increases in blood pressure
induced by activation of the exercise pressor reflex. A clear understanding of the role of central commandand defining the regions involved in centrally-mediated cardiovascular modulation is of critical importancein furthering our understanding of this concept and may have important clinical implications related tovarious types of autonomic dysfunction (e.g. emotional syncope, white coat hypertension, etc.). Future
investigations must be performed in humans to more clearly define the specific sites within these regions
responsible for changes in autonomic function and how they interact to effectively modulate cardiovascular responses during exercise as well as during non-exercise conditions.

招待講演講師略歴
Jon W. Williamson, Ph.D., Professor Associate Dean.
Jon W. Williamson 氏はこれまで Central Command が脳においてどのように発信されているかについて研究を進めてきた．氏の輝かしい研究業績の中でも 2002 年に Journal of Applied Physiology 誌に発表された
activation by central command during actual and imagined handgrip under hypnosis
Journal of Applied Physiology 誌に発表された
insular cortex during exercise

Brainや，2003 年に同じくEvidence for central command activation of the human

は，全身の血流調節という意味での Central Command が脳の Insular cortex の活動に起因することを明らかにしたことで有名である．

468

■学術フロンティア成果報告（Session 1）「運動時の血流再配分−運動特性と関連させて−」
加賀谷淳子（日本女子体育大学）

運動は，活動する骨格筋への血流量を増加させると同時に，運動指令を出す脳，運動を支援する心臓や肺の筋への血液供給を適切に調節することが必要である．しかし，血液を循環させる心臓の拍出能力には限界があること，生命維持に必要な調節が不可欠であることなどから，これらの臓器への血流調節だけでなく，これ以外の臓器や組織への血流の再分配が必要になる．逆に言えば，運動時の各器官・組織への血流量変化は，それら調節の結果として起こったものであるので，それらを把握することは，その背後にある調節機構を解明する有力な手がかりになる．一方，循環経路の動脈側と静脈側をつなぐ間に介在する骨格筋の活動は，循環に対して物理的ある
いは代謝性に干渉する．したがって骨格筋の活動特性が循環応答を修飾する極めて大きな要因である．そこで，
本プロジェクトでは，運動特性と関連させながら，運動時の血流再分配を明らかにし，その背後にあ る循環機構の解明に役立てようとした．得られた成果の概要をまとめると以下の通りである．
1．骨格筋，脳，腹部内臓への血流分配
一般的に心拍出量は運動強度や活動筋量の増加に連動して変化するとされている．しかし，本プロジェクトでは，局所的な小筋群の運動の場合は，両者が必ずしも連動した変化を示さず，骨格筋の血流需要に対して末梢的な対応をすることもあることが示された 4）．
運動指令を出す脳への血流再分配を，内頸動脈と椎骨動脈の二つの経路から調べたところ，内頸動脈経路では
静的および動的運動時に動脈血圧および心拍出量が著しく上昇しても，血流量の変化は見られないのに対して，
椎骨動脈経路では運動による心拍出量の上昇に伴い血流量が増加することが明らかになった 6）．
活動筋への動脈血流は筋収縮時には阻害され，筋の弛緩期に増加する．一方，活動筋からの静脈血の流出は筋活動期に加速され，筋弛緩期には減速し，両者は，筋内圧の局所的変化により相互に関連しているが，一義的ではない 3）．また，筋の発揮張力が極めて低い場合であっても，ストレッチングのように筋線維が伸長すると，動脈側からの血流の逆行成分が増えて血流は減少し，ストレッチング終了後には動脈側での加速，それに連動した静脈側の流出増加が起こることがわかった 2）．
骨格筋の血流がどこまで増えるかについてはなお議論が続いている問題である．この問題は主として代謝性の血管拡張能を調べたものであったが，酸素運搬系としての血流量の役割と考えると，運動中にどこまで増加するかが重要になる．本プロジェクトでは運動時最高値がどれくらいに達するかを知る前提条件として，最高血流量に達する運動条件を明らかにしようとした．その結果，動的運動時筋弛緩期の血流量については，運動強度とテンポの増加に伴って増加し，両者の組み合わせによって運動時血流量が最高になるのではないかとの知見を得た 3）．
また，活動筋での血流増加は酸素需要に応えて酸素輸送を高めるためであるが，閉塞性動脈硬化症保有者に多段階負荷運動を実施した結果では，安静時には患側での血流量が低いのに対して，運動時には患側の血流量が健側より増加して，虚血に伴う骨格筋酸素消費量を代償する現象が見られた 5）．運動の物理的特性と代謝性特性の両面から，酸素供給系としての血流動態を捉えることが重要であることが示された．
運動に直接関与しない臓器である腹部内臓への血流量は，運動時に骨格筋へ血流を優先的に分配するために減少するとされてきた．しかし，静的運動時の腎動脈と上腸間膜動脈の血流速度を調べると，腎動脈では血流速度減少が見られたが，上腸間膜動脈では顕著な変化は見られなかった．すなわち，運動時の腹部内臓器官への血流再分配は，一律の変化ではなく，本プロジェクトで調べた運動の範囲では，消化器官血流量は腎動脈血流量のように減少しないことが示された 6）．
2．運動の時間経過に伴う循環・代謝応答の変化
静的筋活動開始直後には筋内圧の上昇により，動脈側からの流入が低下し，静脈側からの血液流出は加速される．また，運動開始初期（約 30 秒程度）の動的運動では，心拍出量の増加に先行して活動筋への血流量が急速に増

3）

469

加するとされている．一方，運動開始初期の非活動肢の血流量変化をみると，強度依存で一過性の血流量の増加が見られ，それに続いて強度依存の血流減少が起こった（Yoshizawa et al. 2008）．すなわち，筋収縮開始と同時に起こる動静脈血流勾配の増加 3）等の作用によって，運動開始初期から活動筋での血流増加が素早く起こるものの，全身性の血管収縮作用は高まらずに，この時期には血流再分配は適切になされていないことが示唆される．非活動肢での血流量増加や，総末梢血管抵抗の減少により血圧が低下 1）はそれを支持する結果であると考えられる．
律動的な運動が持続すると，活動筋での血管拡張により動脈血流量の増加が起こり，筋血液量が増加する．そうなると，筋活動による静脈側の血液流出が続いて起こる動脈血流入量と密接な関係を保つようになることがわ
かっている 3）．
運動が終了すると，静的筋活動後は急激な血流増加が起こり，運動後の血流は約３拍目の心周期で最高値に達する（Ohmori et al. 2006）．この時期には静脈血流は安静時以下に減速し，動脈血流量が最高値に達し，筋の血
管床への血液再充満が起こってから静脈血流が安静レベルに復帰した 3）．
運動後の筋の酸素化動態の回復の速さは運動中の筋の代謝を反映しているので，筋線維組成の異なる深部と浅部において回復の速さ（T 1/2）が異なるかどうかを検討したが有意な差は見られなかった 7）．
3．運動強度と血流再分配
運動プログラムを考える上で，運動強度は極めて重要な運動条件である．本プロジェクトでは運動強度を筋収
縮強度と収縮頻度から検討した．筋収縮強度がある強度を超えると筋交感神経の亢進が起こる（Saito et al. 1986）
ことが知られているが，その結果，強度変化に対する血圧上昇が顕著になる（Kagaya et al. 2001）．そこで，血圧上昇が高くなる負荷（血圧変移点負荷）を基準として強度をとらえ，本研究の血流再分配の成果をまとめた．
活動筋への血流量が運動負荷強度の増加に伴って増加し，頭打ちになるかどうかは議論のあるところである．本
プロジェクトでは動的膝伸展運動・足底屈運動や間欠的な静的掌握運動において検討し，前者では頭打ちが観察され，後者では筋弛緩期血流が負荷の増加と共に増加するという結果を得た 1, 3）．動的・静的運動共に，運動後血流量に対する運動中血流量の比は，血圧変移点負荷とほぼ類似の負荷強度で急激に低下し，運動中の血流需要を満たす割合が低くなることが確認された 1）．また，強度が高くなると，運動持続に伴う筋の電気活動漸増の割合が高くなり，筋疲労耐性の低い筋が動員されるようになることが示唆されたが，その強度は血圧変移点と類似であった 1）．
筋の酸素代謝をみると，運動中の活動肢筋酸素化動態が負荷強度に対して低負荷とは異なる対応をする 1）ようになるのは，血圧変移点負荷よりやや低い負荷からであった 3）．さらに，運動中の有酸素性エネルギー機構関与の度合
いを，運動後の筋酸素動態（再酸素化時間 T1 / 2）からみると，強度に対して指数関数的な延長を示し，有意な延長を示すようになるのは血圧変移点よりさらに高い強度においてであった 7）．
次に，運動中，活動筋での変化を中心に身体の様々な変化を統合して感知する主観的筋疲労感覚（10 段階）は，
血圧変移点より低い負荷（38 ％ MVC）から急上昇した．血圧変移点に対応する値は 4.0 であった 3）．
骨格筋への血流量が心臓の拍出量とどう対応するかをみると，局所的な運動（足底屈運動）では，活動筋への
動脈血流量が低負荷から増加を開始し始めるが，心拍出量（中心循環）は中等度負荷にならないと増加しなかった 4）．すなわち，低負荷では，心拍出量の増加を伴わずに活動筋への血流再分配が起こり，強度が高くなると心拍出量を増加させて骨格筋への血流再分配を行っていることが明らかになった．
血圧が上昇するような強度の高い負荷では，脳への血液を供給するひとつの経路である椎骨動脈の血流増加が見られた．それに対して，腹部内臓においては腎動脈での血流減少が確認された 6）．
4．運動時の循環に対する重力の影響
本プロジェクトでは，循環系に対する重力の影響を，活動体肢の位置を変化させて検討した 3）．掌握運時の前腕を心臓より下にすると，筋活動中止期の血流量が有意に変化し，上腕動脈では増加，静脈では減少を示した．近赤外線分光法の総ヘモグロビン濃度変化からみた筋血液量は垂下で増加した．また，重力負荷を一定にして，血液貯留状態を変えた下肢の運動条件では，動脈静脈血流量には相違が見られず，30 分程度では，貯留血液量レベルの差は影響しないことが示された．
上記知見の得られた研究課題「再分配」共同研究

1）水）担当個別課題

2）

若手研究者受け入れ「ストレッチング」共同研究

長田担当個別課題

5）

定本担当個別課題

6）470

加賀谷担当個別課題

3）

笹原（上田）担当個別課題

7）

奥山（清

4）

■学術フロンティア成果報告（Session 2）「運動時の循環調節機構−神経調節を中心に−」
定本

朋子（日本女子体育大学）

1．運動発現に関わる仕組み
骨格筋の運動単位は神経系により運動指令が与えられることにより収縮する．筋に運動指令を直接伝えるのは運動神経であるが，脳や脊髄に実行したい運動を計画し，統合する中枢がある．このような運動に関わる脳・神経系の働きと運動単位の動員特性について理解することは，運動時の循環調節機構の統合的解明に不可欠である．
本プロジェクトでは運動発現に関わる仕組みに関して，次のような成果を得ている．
Ferrari は機能的近赤外線分光法装置の開発に携わり，その装置を用いて Quaresima と共同して前頭皮質の酸素化動態を検討している．その結果，力発揮を維持させること，そして正確で巧みな力発揮をするためには前頭前野の働きが重要な役割を担うことを明らかにしている．また澁谷は，運動指令を出す一次運動野の働きを調べ，運動時には一次運動野が左右半球間で相互連絡をもち，両側間の結合が生じることを示唆している．このような半球間結合は，対側一次運動野のみでは不十分な力発揮しか行えない場合に，それを補完する役割を担うと考えられている．さらに，加茂は，運動指令に基づいて生起する運動単位の活動参加およ び放電間隔変化と循環系応答の関係について検討している．その結果，一定筋力発揮時には運動単位の放電間隔時間の延長が観察されることを報告している．

2．運動時の循環調節−主にセントラルコマンドとの関わりから−運動の準備および運動の発現とともに，循環応答も刻々と変動する．このような運動発現と循環応答を連結させる仕組みとして，活動筋からの反射性制御や圧受容器反射の働きが重要である．本プロジェクトでは，反射性制御については，メンバーが個別課題においてさまざまな検討を加えている．たとえば，斉藤は，利き腕と非利
き腕における運動時の筋交感神経活動を各々調べ，利き腕運動後の筋虚血時における交感神経活動が非利き腕の場合よりも高いことを報告し，筋代謝受容器反射が利き腕運動時に高くなることを指摘している．定本は，腎動脈および上腸間膜動脈（主に消化器官へ連絡）の血流動態に対する筋虚血の影響を調べ，腎動脈血流量に比べ，上腸間膜動脈血流量が筋代謝受容器反射の影響を受けにくいことを報告している． さらに内因性反射である圧受容器反射と循環調節との関わりについても，個別課題において考察がなされている．
このような反射性制御に加えて，本プロジェクトでは高位中枢からの指令であるセントラルコマンドの働きに力点をおいた検討を行ってきた．セントラルコマンドの定義と解剖学的経路は未解決な部分が多いが，本プロジ
ェクトでは，運動の準備，運動直前の予測制御，運動開始直後の制御，運動の意志や努力感・頑張り（主観的運動強度）に関わるセントラルコマンドという側面において，次のような知見を得ている．
岩館は運動準備期（約 1 分前から）の大脳皮質運動野周辺の脳酸素動態と心拍数，血圧および前腕屈筋の酸素動態を同時計測し，掌握運動の準備に関連した皮質活動と循環応答の対応性を検討した．その結果，運動準備のための大脳運動野周辺の活動と心拍数および前腕屈筋の酸素化ヘモグロビンの上昇が共に生起することを観察し，運動の準備に付随する皮質運動野周辺の活性と循環応答との対応関係を示唆した．定本と佐藤は，随意運動と受動運動に伴う頸動脈経路（総頸動脈，中大脳動脈: 主に大脳皮質への血液供給路）とおよび椎骨動脈経路（椎骨動脈，後大脳動脈: 主に脳幹，小脳，脊髄などへの血液供給路）の血流変化を比較した結果，随意運動の開始前には動作に先 行する血管拡張が椎骨動脈経路に生じることを報告し，この経路が潅流する脳部位にはセントラルコマ
ンドによる予測制御が働くことを示唆した．また，定本は，腎動脈および上腸間膜動脈（主に消化器官へ連絡）
471

の血流速度の応答についても同様の検討を行ったが，腎動脈および上腸間膜動脈には予測制御の影響が及ばないことを指摘した．さらに，血流分配に関する共同研究の成果から，佐藤は動的運動開始直後（30 秒以内）の活動
筋では急激な血管拡張が起こり，総末梢血管抵抗が減少するため，運動開始直後の平均血圧が一過性に低下することを報告した．そしてこの応答はセントラルコマンドおよび圧受容器反射による調節が関わると報告した．斉藤は，ハンドグリップ運動時の筋交感神経活動の記録から，筋疲労にいたるような運動持続時には筋代謝受容器
反射の働きも重要であるが，運動の意志・頑張り（すなわちセントラルコマンド）が筋交感神経活動を上昇させ，それにより筋力が維持されることを明らかにした．さらに，短期間のハンドグリップレジスタンストレーニング
がセントラルコマンドを増大させ，筋交感神経活動を亢進させることを示唆した．
運動時のセントラルコマンドに関する国内メンバーの共同研究において，次のような検討がなされた．一定負荷保持時の活動筋への振動刺激（バイブレーション） により，運動指令を低下させる実験条件を設定し，バイブ
レーションを伴わない通常の運動条件における循環応答を比較した．特に，前頭前野の酸素化動態，中大脳動脈
血流速度，椎骨動脈血流量，腎動脈血流速度に及ぼす影響を中心に検討した．これらの実験の結果，セントラル
コマンドの低下条件である「振動＋運動」条件では，振動刺激を伴わない通常の「運動」条件に比べ，筋疲労感
覚と心拍数が低くなり，セントラルコマンドの低下に対応した変化が示された．同様に，セントラルコマンドの低下に対応した変化が椎骨動脈血流量の応答においても示された．しかし，前頭前野の酸素化動態，中大脳動脈
血流速度，腎動脈血流速度の応答には，セントラルコマンドの低下に対応した変化はみられなかった．このような結果から，先行研究で示されている心臓および皮膚組織といった組織・器官に加えて，セントラルコマンドは
椎骨動脈経路の脳血流調節にも働く可能性が示唆された．

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■学術フロンティア成果報告（Session 3）「運動時の循環調節機構の統合的解明へ向けて」
斉藤満（豊田工業大学）

1．循環調節機構解明の意義
スポーツを楽しむには必要な酸素を取り込み，活動筋は勿論酸素を必要とする部位に十分酸素を供給しなければならない．この役割は循環系が担い，その調節を誤ると楽しいスポーツも台無しとなる．このことは健康や体力にもあてはまる．たとえば健康を脅かす循環系疾患の多くは不適切な循環調節に起因することが少なくないし，体力の向上や低下も循環系機能と密接に関係することが明らかにされている．
循環系はポンプとしての心臓と血液を運ぶ血管系から構成され，構造的には極めて単純な系として捉えることができる．しかし，運動開始とともに活動筋は多量の血流を必要とするが非活動筋はほとんど必要としない．このとき両方へ同じように血流を配分していては活動筋に血液が十分行き渡らないだけでなく，無駄にもなる．また，血流調節のために血管を収縮しすぎると過剰な昇圧反応が生じ，心臓ポンプに負担をかけることになる．このように，どのような運動条件において適切な，あるいは不適切な循環調節が生じるか明らかにすることは，安全に運動を実行し，健康 ・体力の維持増進を目指す上で重要である．さらに，日常的に運動を続けることが循環調節機構にどのような影響を及ぼし，改善をもたらすのか明確にしておくことは運動プログラム構築にとって必須のことといえる．

2．運動時の循環調節機構解明と課題
運動時の循環調節が安静時と明確に異なることは，運動が意志に基づいて特定の筋を収縮し，ここに優先的に血流を配分することである．この調節は幾つもの調節系で構成され，統合的に実行されるが，系全体を一度に捉えることは出来ないため以下に示す観点から解析を進めた．
観点 1 ：循環調節機構に与える運動の意志（セントラルコマンド） の効果を的確に把握すること．本プロジ

ェクトでは循環調節機構に及ぼすセントラルコマンドの影響を，交感神経活動反応と血圧及び脳血流反応を指標に，運動強度，時間，さらに末梢体性感覚受容器刺激を用いセントラルコマンドに外乱を与えた際の解析を行った．この成果から， 運動の意志が循環調節に大な影響を及ぼすことが明らかとなった．本研究では小筋群の静的運動での実験解析が多かったことから，次の課題は大筋群の動的運動で検証をすすめることである．
観点 2 ： 600 余りあるからだの筋のうち特定の筋が運動に動員され，しかも発揮 する力や様式，リズムも様々である．また，筋活動をミクロにみると単一筋内でも代謝や血管拡張に不均一がみられ，血液循環も時間的，空間的に大きく異なる．他方，中枢調節とは独立した筋活動に伴う代謝が血管拡張を引き起こし，さらに筋収縮にともなう筋ポンプ作用が活動筋血流を決定する重要な因子となる．これらの生理的，物理的因子を区分けしながら筋血流反応の解析をすすめた．この結果，運動の様式やテンポ，収縮強度，さらに脈管構造（疾病含む）や筋形状の違いにより血流反応が大きく変わることが明らかとなった．
観点 3 ：酸素運搬に欠かせない血液を拍出する心臓，運動及び自律神経活動の指令中枢をもつ脳，体温調節器としての皮膚，さらに血液供給器官となる内臓のように運動発現には直接関与しないが重要である組織の血流と骨格筋血流がどのような仕組みで調節され，違いがみられるか明らかにすること．この調節の仕組みは交感神経による遠心性の全身調節と末梢における局所調節に大別される．ここでは，交感神経効果器としての血圧（血管）反応と 局所の個別臓器血流の反応を指標に活動筋の代謝受容器反射，体性感覚受容器刺激（Ia 求心性神経刺激）
時の脳，内臓器官，さらに骨格筋の血流変化から解析した．交感神経による血管収縮は臓器毎に異なるだけでな
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く，例えば脳内への血流供給には部位差がみられ，運動と脳活動との連関を考える上での新しい成果が得られた．
皮膚血流調節についての検討は今後の課題である．
観点 4 ：ポンプとしての心臓，すなわち心拍出量と末梢循環調節の調和はスポーツパフォーマンスを考える上で重要なテーマである．運動に必要な血流は心臓ポンプに加えて筋ポンプによる静脈還流が重要な役目を果たしており，両者は車の両輪の関係にある．ここでは心拍出量と活動筋血流の相互関係が運動強度や運動テンポの影響を受けるか否かを検討した．その結果，両者の定量関係は常に一定であるとは限らないことが確かめられた．
観点 5 ：継続的な運動は循環調節機構にどのような影響を及ぼすか確かめる．トレーニングに伴う運動時の交感神経活動反応から検討を試み，強い運動の意志は運動時の交感神経活動反応を高める効果をもつことを明らかにした．しかし，身体トレーニングは，有酸素運動，レジスタンス運動のように運動の特性や種類，運動強度・時間など組み合わせは無数にあり，さらに，運動実施者の特性や運動の目的を十分考慮した研究成果の蓄積が望まれよう．

3．今後に向けて
本プロジェクトでは運 動時循環調節機構を統合的に捉えることを目的に，上記に示す多面的な循環応答解析をすすめ，多くの成果を生み出すことができた．今後はさらに実際的な運動，例えば全身運動での検証を加え，本研究で得られた多面的な成果を統合し，より安全で効果的な運動プログラム構築向けて努力を続ける．また，本プロジェクトでは，複雑な循環調節システムを多面的に捉えるために血流の連続測定法（ドップラー血流計），組
織の酸素動態観察法（近赤外分光法），交感神経活動観察（微小神経電図法）などの新しい手法を導入して研究をすすめたが，さらに統合的な循環調節機構の解明を発展させるには循環に関わる血管拡張・収縮因子やホルモン，
関連遺伝子解析など，最新の生化学的解析の導入が望まれる．特に，継続的な運動と循環調節機構の長期的適応の解明にとって重要である．

474

■学術フロンティア個別課題概要

骨格筋への血流分配と筋からの血液還流
加賀谷淳子（日本女子体育大学）

運動時活動筋への血流増加は，体循環システムの整合性を保ちながら，局所的な調節がなされた結果である．
その調節は，遂行される運動の特性によって異なる．運動時の活動筋への血流量に関する報告は近年増えている
が，運動特性との関係から調節機序を明らかにするには至っていない．特に，運動時に到達し得る血流量は，代謝性の最大血管拡張時に比べて抑制されていることが報告されているものの，最高血流量を得る運動条件については明らかにされていない．
本プロジェクトでは，運動中の骨格筋への血流増加が，どのような運動条件（運動強度・テンポなど）によって最高値に達するか，静脈からの血液流出（主として筋ポンプ作用）と動脈側からの血液供給がどのように関わっているかについて明らかにしようとした．

1． 筋活動及び筋形状変化による動脈と静脈血流変化の関係
1） 筋が短縮する時期の動脈血流量は一旦安静時より低下するが，この時期の静脈血流は加速される．筋活動が一定の張力を保っている間は，動静脈血流速度は一定値を保ち，筋収縮中止直後は，動脈血 流量が顕著に増加し，その時期の静脈血流量は顕著に低下する．代謝性の血管拡張の関与が少ない短時間（5 秒）の静的掌握運動で検討した結果，活動開始初期の静脈血流速度は，5 0，70 ％ MVC 強度で有意に高く，活動中
止後の動脈血流速度と有意な相関関係のあることがわかった．運動後，動脈血流量は，徐々に高くなり，
ほぼ 3 心周期で最高値に達する（Ohmori et al. 2006; Ohmori et al. 2007）が，この時期の静脈血流速度は安静時以下に低下し，復帰するのは血流量が最高値に達してからであった．
以上の運動条件下では，筋ポンプ作用が血流増加に効果的であることが示された．
2） 筋活動が繰り返される動的運動の時間経過を追ってみると，運動開始直後（〜 20 秒）は，動脈血流量が漸増するのに対し，静脈血流量は減少する．そして，時間経過につれて両者とも徐々に増加する．両者の関係は，運動開始時には動脈血の流入が静脈血流出に，運動が 1 分持続した時点では静脈血流の変化が動脈側の血流増加に影響していることが明らかになった．また，筋活動による静脈血流速度の変化が顕著になるのは，体肢が心臓レベルより下にある場合であり，筋ポンプ作用の影響は重力の影響で血液貯留が起こる状況下で顕著であることが確認された．
3） 筋形状の変化は筋内血管形状を変化させる．筋が力を発揮しない下腿の受動的 ストレッチングでは，ストレッチング中に膝窩動静脈血流速度がやや低下した．動脈血流速度の減少要因は，血流の順行成分の変化
ではなく，ストレッチングによる逆行成分の増加によることが明らかになった．また，ストレッチングによる筋−腱複合体の伸長率が異なり，そのためストレッチングが筋血液量を減少させる筋と増加させる筋とがあることが示された．ストレッチング終了後には動脈血流の増加に続いて静脈血流速度の増加が起こり，動脈側依存で静脈血流の加速が起こることが明らかになった．
以上の結果から，筋活動時及び筋形状変化時の動静脈血流は相互に作用し合あうことが示され，その運動
条件（時間・強度）の具体例が得られた．

2． 運動誘発性の血流量最高値発現の運動条件
運動強度の変化と循環パラメータとの関係は一次関数ではなく，血圧は急上昇する変移点があり，血流量475

は，論議があるものの本研究で対象とした範囲ではレベリングオフを示す．血圧変移点強度付近では，主観的な筋疲労感覚の上昇，筋酸素動態の加速的変化がみられ，それ以上の強度から筋ポンプ作用による静脈流出が有意になる．そして，血流量が最高値に達する運動条件を運動頻度・強度から検討したが，最終結論を得るには至っていない．しかし，運動頻度，運動強度が高くなるほど血流量の増加が起こり，両者の組み合わせが，最高血流量を発現させる可能性が示唆されている．

3． 運動時の非活動肢の血流量の変化に関しては「増加」する，「減少」するなど，見解が分かれていた．本プ
ロジェクトでは，アームクランキングと下肢サイクリング運動はどちらも，非活動肢の血流量を強度異存で増加させること （Tanaka et al. 2006），動的膝伸展時の対側の大腿動脈変化をみると運動開始直後は，一過性に強度依存の増加が起こるが，時間経過にしたがって，血流減少の起こることが明らにされた（Yoshizawa et al. 2008）．この結果は，運動開始直後（˜30 秒）は，活動筋以外の活動肢においても血流増加が起こり，筋交感神経の亢 進が起って血管収縮が起こってくると非活動肢の血流量が減少し，血管拡張物質による血管拡張作用の高まる活動筋では血流増加が起こるという血流再分配がなされることを示したものである．これらの知見は，G r e e n らと Hopman らのグループによる論争に対して，運動時間，強度，
活動体肢の位置などにより，非活動肢の血流量は増加，減少のどちらもあり得ることをコメントし，この論争に方向を示す重要な知見を得た （Kagaya et al. 2008）．

4． トレーニングによって代謝性血管拡張能が向上し，活動筋への血流量が増加するとの報告はいくつか見られるが，運動誘発性の血流最高値に効果があるか否かについての報告は少ない．また，それが血管径と血流速度のどちらに効果があるかは明らかにされていなかった．本プロジェクトでは，テニス選手の利き手と非利き手の血流量を比較し，筋活動中止期の血流量に差のあること，それは，血流速度の相違ではなく，拡張期の血管径の差によっていることが明らかにされた（Kagaya et al. 2008）．

476

運動時の心拍出量の変化と各種血管への血流分配−中心循環と末梢循環のマッチングとミスマッチング−
奥山靜代（慶應義塾大学）

中心循環と末梢循環の関連について，血流速度から検討した研究はこれまでにみられていない．本プロジェク
トにより，次のような知見が得られた．第一に，活動筋近位の末梢動脈における血流速度は筋の活動期に低く休止期には高いというように，筋活動による大きな変動が起きるが，中心動脈の血流速度は筋の活動期と休止期により大きな影響を受けないがことが示された．すなわち，筋活動は，中心循環ではなく末梢循環の変動を起こす
ことが示された．その結果，中心動脈および末梢動脈の血流速度の関係は筋の活動期と休止期で異なり，活動期
では中心動脈血流速度が活動筋へ血液を供給する末梢動脈血流速度を上回り，休止期では逆に末梢動脈血流速度が中心動脈速度より早くなるという関係にあることが示された．第二に，運動強度に対する中心と末梢の循環応
答が異なることが示された．運動負荷の増加とともに心拍出量と活動筋血流量が増加することは既に知 られているが，両者が同期して生じるのかどうかは未解決な課題であった．本研究の結果において，末梢動脈血流量は低負荷運動時から増加し始めるが，心拍出量（中心循環）は中等度負荷にならないと増加しないことがわかった．
このことから，運動時の中心循環と末梢循環は関連して変化するものの運動負荷強度によって両者の対応は異なることが示唆された．

有疾患者における運動および虚血に対する血流調節プロファイル
長田卓也（東京医科大学）

閉塞性動脈硬化症保有者は，下肢動脈血管の動脈硬化による血行障害のために運動歩行時に間歇性跛行を認める．そのため Quality of life の低下が問題とされている．閉塞性動脈硬化症は，下肢血行障害に関わる要因が関与するとされているが，疾病下肢における運動時の血流動態を検討した報告は少なく，不明な点が多い．そこで，
本研究では閉塞性動脈硬化症保有者における一過性運動時の血流動態を検討することにした．両下肢（健側と患側）それぞれにおける多段階負荷等尺性片側膝伸展運動中の下肢血行動態を比較検討した．その結果，安静時において，患側の下肢血流量が反対側である健側下肢血流量よりが低い傾向 がみられた．しかし，運動時の運動強度に対する血流増加反応をみると，患側において健側よりも大きな血流増加が観られることが明らかとなった，
このような患側の血流増加は虚血に伴う骨格筋酸素消費量の代償や局所血管拡張を促す代謝産物の影響が推測される．このように末梢循環障害が安静時のみならず運動中の骨格筋循環に与える影響が示唆された．

筋の酸素代謝特性と運動時循環応答との連関
笹原（上田）千穂子（東海学園大学）

随意最大筋力（M V C）の 30 〜 50 ％の運動強度で，筋放電量が増加し，筋疲労感覚も上がり，そして血圧が急477上昇する血圧変移点が出現すると報告されている（本プロジェクト「再分配共同研究」成果）．この変移点を境に有酸素系から無酸素系へとエネルギー供給機構のシフトが起こるのかどうかについて，筋再酸素化時間（運動後
回復期に酸素動態が元に戻るまでの時間，この時間が延長すると筋の有酸素性代謝貢献が低いという関係性が示されている）の指標を用いて検討した．その結果，血圧変移点よりも高い 70 ％ MVC 強度になるまで筋再酸素化
時間は延長しないことが明らかとなった．したがって，活動筋では，血圧変移点を超えた高強度負荷に至るまで
有酸素性代謝の貢献度が高く保たれていることが明らかとなった．また，深部では遅筋線維が多く，浅部では速筋線維が多いとい報告から，酸素化動態が筋の深さにより異なることが十分に仮定された．この点を筋再酸素化
時間を用いて検討した結果，どの強度においても筋再酸素化時間は浅部と深部で差がみられなかった．筋の有酸
素性代謝貢献度が深さによって相違ないことが明らかとなった．

運動時の内臓器官および脳の血流動態とその調節機構
定本

朋子（日本女子体育大学）

1． 運動時には活動筋への血流が増大すると同時に，腹部内臓器官への血流が減少するとされている．しかし，個々の器官への血流応答については十分な検討がされてはいない．本研究において，静的運動時および運動後筋虚血時における腎動脈と上腸間膜動脈（主に小腸へ連絡）における血流速度を比較検討した結果，同一負荷の運動に対する血流減少は，上腸間膜動脈よりも腎動脈の方が大きいことが示された．また多段階の動的運動時にも同様の結果を得た．さらに腎動脈の方が筋代謝受容器反射による血管収縮作用を受けやすいことも示された．これらの結果から，腹部内臓器官には，腎動脈のように運動刺激および反射性入力に顕著に反応する組織（器官）と上腸間膜動脈のように反応の低い組織（器官）があり，そのために，運動時の血流調節に関わる機構も組織間で異なると考えられた．
2． 脳へ連絡する血管は，左右の内頸動脈経路（主に大脳皮質側頭葉，前頭葉，頭頂葉，島皮質へ潅流）と椎骨動脈経路（主に延髄，小脳，後頭葉へ潅流）の 2 経路がある．内 頸動脈血流量や中大脳動脈血流速度に関する研究は多いが，運動時の椎骨動脈経路の血流変化をみた研究はない．本研究では，静的および動的運動時における両経路の血流動態を比較検討した結果，運動に対する経路間の血流応答に次のような相違が示された．①内頸動脈経路では， 運動開始に先行した血管拡張（血流増加）はみられないが，椎骨動脈経路では見込み制御による顕著な血流増加がみられた．②運動時の動脈血圧および心拍出量の上昇に対して，内頸動脈経路では血管収縮が生じ，血液流入が制限されるが，椎骨動脈経路ではそのような血流制限が殆どみられな
かった．③呼気終末二酸化炭素分圧の変化に対して，内頸動脈経路の血流量はそれに対応した変化を示すが，
椎骨動脈経路ではその対応がみられなかった．④振動刺激操作によるセントラルコマンドの増減に対して，
内頸動脈経路は対応した変化を示さないが，椎骨動脈経路ではセントラルコマンドの増減に応じた血流変化がみられた．このような相違は，自動調節や潅流部位の脳代 謝に由来する調節および神経制御が経路間で異なることを示唆すると考えられた．

478

運動時の呼吸循環系変化に対する中枢性・末梢性の神経調節佐藤耕平（日本女子体育大学）

1．運動開始期の循環調節について
運動開始直後（30 秒以内）には，酸素需要の増加に応えるために心拍数（H R）や心拍出量（C O）が急激に増加することが知られている．一方，活動筋では急激な血管拡張が起り，総末梢血管抵抗（T P R）が減少するため，運動開始直後の平均血圧（MAP）は一過性に低下する．この MAP の低下は，運動開始時の酸素供給においては不利であると考えられる．しかしながら，その後の CO の増加が TPR の減少を上回り MAP は回復・上昇を始め，活動筋での酸素供給に応えようとする．本研究では，このような運動開始期における循環調節と，運動強度の関連性について検討した．その結果，運動開始直後における一過性の MAP 低下は，運動強度の増加に伴い抑制させることが明らかとなった．この結果は，運動強度に応じた開始期の HR ・ CO の増加と，運動強度に依存しない
TPR の減少によるものであり，この応答の調節因子はセントラルコマンドおよび圧受容器反射の作用であると考えられる．また，運動開始期における TPR は，活動肢での血管抵抗レベルを必ずしも反映しないことが明らかとなった．本研究より，運動 開始期においても，運動強度の増加に応えるために，「システマティックな循環調節」が行われていることが示唆できる．
2．高強度運動開始時における脳血流調節と呼吸法の関連性について
運動実践の場面では，過換気を伴う運動や，逆に息こらえをしながら力発揮をすることは頻繁にみられることであり，時には意識を喪失するといった場面も起こりうる．安全で効果的な運動を考えるにあたり，このような運動時における呼吸法の違いがもたらす「限界に近い状況時」の脳血流変化を描記することは不可欠である．呼吸法と脳血流調節の観点から検討した先行研究は 2 本であり極く限られている．本研究では，アスリート（陸上投擲選手大学トップレベル）が，短時間の高強度レジスタンス運動を，通常呼吸（持続呼吸）で行った場合，呼吸を止めて行った場合，運動前に過呼吸を行った場合における脳血流反応を比較した．その結果，呼吸を止めた
場合には運動開始時の脳血流減少が著しく，運動終了と同時に急激で過剰な血流増加（オーバーシュート）がおこる．過呼吸の場合に おいては，運動前から脳血流量は著しく低下し，その低下が運動終了後の回復期にまで持続することが明らかとなった．以上のように，トレーニング経験を積んだアスリートであっても，呼吸法によりレジスタンス運動時の脳血流反応が大きく変動する．このことから，意識喪失といった危険を回避するためにも，「呼吸のコントロールの重要性」が示された．

自律神経による運動時循環調節メカニズムの解明−運動時の交感神経活動からみた中枢指令及び反射性制御の調節機構−
斉藤

満（豊田工業大学）

運動を続けるためには活動筋に十分な血流が必要で，この調節には中枢指令と活動筋反射が重要な働きをする．
この調節に対し「運動の意志・頑張り」や「レジスタンストレーニング」がどのような影響を与えるのか検討した．
1．運動の意志・頑張り
ハンドグリップ運動を用い，最大ハンドグリップの 33 ％張力を疲労困憊まで維持する運動（E x 1）と，1 5 秒間

479

の静的最大努力ハンドグリップ運動を 15 秒の休憩を挟んで左右 10 回繰り返す運動（E x 2）を行った．この時の心拍，血圧，筋交感神経活動，及び活動筋疲労感覚を測定した．Ex1 では，活動筋疲労感覚の増強に比例して交感神経活動が高まった．この要因には筋疲労に伴う運動の意志・頑張り（中枢指令）の増強と運動時間とともに活
動筋代謝産物が増加し筋からの反射を強めたことが考えられる．Ex2 では，発揮筋力は運動回数とともに低下したが，交感神経活動は運動の 1 回目から有意に高まり，運動回数に関係なく 10 回目まで高い活動がみられた．発
揮筋力が低下したにもかかわらず高い交感神経活動がみられた背景には筋反射より運動の意志・頑張り，すなわ
ち中枢指令が大きく関係した可能性が考えられる．
2．レジスタンストレーニング
短期間のレジスタンストレーニングに伴う筋力向上には活動筋機能より中枢からの神経活動の増加が大きく関係するとされる．4 週間のハンドグリップレジスタンストレーニングを行い，トレーニング前，後，及び停止 4 週
後に，Ex1 と同様のハンドグリップ運動と運動後阻血時の心拍，血圧，筋交感神経活動を観察した．疲労困憊時
点の 筋交感神経活動はトレーニング前及び停止 4 週後に比べてトレーニング後有意に高まった．しかし運動後阻血時の代謝受容器反射による筋交感神経活動増加の差は認められなかった．トレーニング前，後，及び停止 4 週
後の心拍，血圧反応は疲労困憊時点，運動後阻血のいずれにおいても差は認められなかった．この結果から，短期間のレジスタンストレーニングは活動筋代謝受容器反射に影響しないが運動の疲労困憊時点では筋交感神経活動を増強することが明らかとなった．しかし，この適応反応はトレーニングを停止すると速やかに元に戻ることが明らかとなった．

運動様式，運動強度，運動時間および筋代謝からみたモーターユニットの動員特性（運動単位活動と循環系機能の相互関係）
加茂美冬（日本女子体育大学）

運動は，時間的，空間的に様々な組み合わせで起こる運動単位活動を基礎として成り立っている．運動単位（Motor unit; MU）における筋線維群（筋単位）の収縮は，種々の血管拡張シグナルを発し血管を拡張させ血液循環を促進する．また，十分でない酸素供給は MU 活動を変化させるなど，運動時の循環系機能と MU 活動は密接に関わっていると考えられる．一定筋力を持続的に発揮するとき，M U は放電間隔すなわち活動する間隔を時間とともに延長させる．この延長は全ての筋力レベルにおいて共通して観察される特徴的な現象であることから，筋力調節および筋疲労発現に関して重要な役割を担っていることが示唆されている．本実験では，この MU 活動様
式に焦点を当て，合目的性および発現メカニズムを探ろうとした．
その結果，次のような知見を得た．M U 放電間隔延長現象は骨格筋反復収縮初期の不完全強縮力増強に対して抑制効果をもつことを実験的に確かめ，さらに，低筋力発揮レベルではその効果は充分でないことを新たに見出し
た．また，放電間隔延長が必ずしも末梢感覚入力優位で生ずる現象とはいえない可能性を見出した．さらに，M Uの動員（r e c r u i t m e n t / d e c r u i t m e n t）のみならず放電間隔変化（rate coding）と循環系応答の関係についても検討を加えることができた．

480

運動時における一次運動野の酸素化動態澁谷顕一（日本女子体育大学）

運動指令を出す一次運動野の働きを理解することは，運動時の循環調節の解明には不可欠である．活動肢と同側半球における一次運動野は，活動肢の運動を直接制御することはないと考えられてきた．つまり対側半球一次
運動野の制御により行われていると考えられてきた．しかし，近年の研究では，左右半球間の一次運動野の相互作用が存在する可能性が示されている．本研究の近赤外線分光法を用いた脳酸素化動態の時系列的分析により，運動開始後の左半球の一次運動野と右半球一次運動野の酸素化動態に時間的差異が存在することが明らかとなり，運動開始後の左右半球間の一次運動野の相互作用形成の可能性が示された．このような両側半球間の結合は，対側半球の一次運動野だけでは力発揮が十分ではない場合に，それを補完するために同側半球一次運動野の活動が動員されると考えられる．また，トップアスリートと一般成人の一次運動野の活動比較から，疲労困憊に至る運
動時に一次運動野の酸素化動態に明確な相違があることも示された．

脳循環・代謝測定用近赤外分光法の開発
Marco Ferrari
Department of Health Sciences, University of L’Aquila,
67100, L’Aquila, Italy
His research activity has mainly been focused on the development and application of near infrared spectroscopy (NIRS) or imaging on different fields of medicine including sports medicine, cognitive neuroscience and psychiatry. In particular, his results have demonstrated the importance of reporting NIRS data
for single subject/patient rather than as averaged data. Moreover, he 1) designed and realized specificprobe holders for measuring oxygenation changes at cortical frontal lobe level of both hemispheres, and 2)
developed/tested a software for data handling and statistical analysis. Research efforts were also made on
the refinement of NIRS muscle measurements and data analysis.
本研究では，スポーツ医学や認知科学，精神医学を対象とした様々な医学分野へ近赤外線分光法（N I R S）およびその画像法を応用するために，主にそれらの開発を行ってきた．特に優れた点として，平均化されたデータよりも，個別の被験者・患者における NIRS データを用いることの重要性を指示してきた．さらに，1）両半球の前頭皮質における酸素化測定のための特別なプローブホルダーを設計・実現化に注力し，2）NIRS によって得られたデータの抽出や，その統計的な解析を行うためのソフトウエアの開発・試行を行ってきた．研究に対する試み
は NIRS による筋酸素化測定と解析にも注がれてきた．

481

近赤外分光法による運動時の脳循環・代謝の変化
Valentina Quaresima
Department of Health Sciences, University of L’Aquila,
67100, L’Aquila, Italy
Her research activity has mainly been focused on the study of the vascular and metabolic mechanism
regulating the cerebral and muscular oxygenation and metabolism by using near infrared spectroscopy(NIRS) and functional NIRS with a multidisciplinary approach. In particular, her results want to give a contribution for: 1) understanding the mechanism of the muscle fatigue during exercise and the kinetics of thetransition rest-exercise, and 2) supporting the hypothesis that prefrontal/frontal lobe plays a role in maintaining strength of the forearm muscles and ensuring a correct execution of motor tasks which require afine motor control and coordination.
本研究では，学際的な視点を取り入れ，主に，心臓血管系と代謝は脳と筋の酸素化および代謝に影響を及ぼす
心臓血管系および代謝機構を，近赤外線分光法（N I R S）と機能的 NIRS（fNIRS）を用いて検証してきた．特に，
1）運動中の筋疲労のメカニズムや安静から運動への移行期の酸素化動態のメカニズムの理解を進め，また，2）前腕筋の出力維持と，巧妙な運動の制御と協働を必要とする正確な動作遂行を可能なものとする上で，前頭前野・前頭野が重要な役割を果たすという仮説を支持する結果を発表してきた．

PROLONGED INTERMITTENT MAXIMAL HANDGRIP EXERCISEINDUCES LOSS IN MUSCLE FORCE AND PERSISTENT ACTIVATIONOF FRONTAL CORTEX AS MEASURED BY FUNCTIONAL
NEAR-INFRARED SPECTROSCOPY
V. Quaresima, T. Limongi, G. Di Sante, M. Ferrari
Department of Health Sciences, University of L’Aquila,
67100, L’Aquila, Italy

Introduction
Functional near-infrared spectroscopy (fNIRS) is a not harmful, non-invasive and safe optical techniqueallowing the simultaneous acquisition of oxygenated and deoxygenated hemoglobin concentration changes(Δ[O2Hb] and Δ[HHb], respectively) from an array of optical fibers on the scalp to construct maps of cortical activity (Wolf et al. 2007). The hemodynamic response typically observed over an activated corticalarea consists of a decrease in [HHb] accompanied by an increase in [O2Hb] of two or threefold of magnitude, resulting in an increased total hemoglobin concentration ([tHb]=[O2Hb] + [HHb]). This hemodynamic
pattern is representative of a localized increase in regional blood flow (rCBF).
The effect of fatiguing skeletal muscle exercise (involving small or large muscle groups) on brain, and inparticular on ipsi- and contralateral frontal cortex (FC) has not been fully clarified (Liu et al. 2005). The aimof this study was to investigate by fNIRS the FC oxygenation response to a prolonged fatiguing rhythmic482

handgrip exercise performed at the maximal voluntary contraction (MVC).

Methods
Twelve right-handed healthy volunteers completed two separate experimental sessions while lying
supine.
I session: subject performed 5 MVCs (2-s contraction with a 120-s interval).
II session: two rhythmic handgrip exercises at MVC were executed, one exercise for each hand. The task
consisted of a 5-min rhythmic exercise (100 MVCs, 2-s contraction at 100% MVC and 1-s relaxation) withthe first hand. The same task was performed with the other hand 15-min after the end of the first one.
Handgrip force was measured by a digital handgrip analyzer. Heart rate (HR) was measured by a pulse
oximeter. An 8-channel fNIRS system (NIRO-200 with multi-fiber adapter, Hamamatsu, Japan) was used toinvestigate the effects of this motor task on FC [O2Hb] and [HHb] changes.

Results
A significant progressive decline (up to about 60%) of force was observed over the exercise duration.
The so-called cortical activation of both FC areas (ipsi and contralateral) was observed in all subjects during rhythmic maximal handgrip exercise. The mismatched patterns of HR and [O2Hb] changes suggest thatthe observed FC oxygenation changes were task related. The amplitude of [O2Hb] changes was foundgreater in the FC ipsilateral to the exercising hand (p < 0.001).

Conclusions
Results confirm the previous ones obtained by functional Magnetic Resonance Imaging (Liu et al. 2005)
and provide further evidence that FC plays a role in maintaining strength of the forearm muscles andensuring a correct execution of motor tasks which require a fine motor control and coordination.

References
1.
2.

Wolf M, Ferrari M, Quaresima V: Progress of near-infrared spectroscopy and topography for brain and muscle
clinical applications. J Biomed Opt, 12: 062104, 2007.
Liu JZ, Zhang L, Yao B, Sahgal V, Yue GH: Fatigue induces greater brain signal reduction during sustained
than preparation phase of maximal voluntary contraction. Brain Res, 1057: 113-126, 2005.

483

日本女子体育大学附属基礎体力研究所
学術フロンティア推進事業 （平成 16 〜 20 年度）
最終研究成果報告会
運動時における循環調節機構の統合的解明−スポーツによる健康・体力づくりのプログラム構築に向けて−日

時： 2009 年 2 月 28 日（土） 13 時 30 分〜 17 時 10 分

会

場：日本女子体育大学本館

E101

プログラム
13 ： 00

開会挨拶

定本朋子（日本女子体育大学教授/プロジェクトリーダー）「本プロジェクトのねらい」

加賀谷淳子（日本女子体育大学名誉教授）

13 ： 05 〜 14 ： 15
Session 1 プログラム作成の基礎となる科学的エビデンス 1 −運動時の循環調節−
座長「運動準備や想起に伴う脳活性」

定本
岩館「運動を持続させる大脳皮質の働き」

澁谷朋子（日本女子体育大学教授）

雅子（日本大学生産工学部助教）

顕一（日本女子体育大学ポスドク研究員）「運動時のモーターユニットの動員特性」

加茂美冬（日本女子体育大学准教授）「活動筋代謝の有酸素性依存から無酸素性依存への変移」

笹原千穂子（東海学園大学講師）「筋活動による心拍出量の変化と血流分配」

奥山靜代（慶應義塾大学講師）「筋形状の変化が筋循環に与える影響」
大森芙美子（日本女子体育大学附属基礎体力研究所客員研究員）「随意運動時の呼吸循環応答にみられるセントラルコマンドの働き」
佐藤
14 ： 15 〜 14 ： 45

耕平（日本女子体育大学助教）

質疑応答＆コーヒーブレイク

14 ： 45 〜 15 ： 35
Session 2

プログラム作成の基礎となる科学的エビデンス 2 −発育，老化，疾患およびトレーニングによる循環系の変化−
座長「子どもの循環機能の発達」

加茂佐藤

美冬（日本女子体育大学准教授）
耕平（日本女子体育大学助教）「高齢者の左室重量と骨格筋量の関係」

奥山靜代（慶應義塾大学講師）「有疾患者における運動と虚血に対する末梢血流調節」

長田卓也（東京医科大学講師）

484

「身体トレーニングによる循環機能の向上」

斉藤

満（豊田工業大学教授）

質疑応答
15 ： 35 〜 16 ： 00
Session 3 提案

−安全で効果的な運動プログラム構築に向けて−座長「運動に対する循環応答からみた提案」

定本

斉藤

満（豊田工業大学教授）

朋子（日本女子体育大学教授）

質疑応答

16 ： 10-17 ： 10
特別講演
座長
翻訳概略
「Circulatory regulation during exercise」

加賀谷淳子（日本女子体育大学名誉教授）
長田卓也（東京医科大学講師）

佐藤耕平（日本女子体育大学助教）
Niels H. Secher（Professor, The Copenhagen Muscle Research Center, Department of Anesthesia, Rigshospitalet,
University of Copenhagen, Denmark.）
17 ： 10

閉会

485

■特別講演Circulatory regulation during exercise
Niels H. Secher
Department of Anesthesia, The Copenhagen Muscle Research Center, Rigshospitalet,
University of Copenhagen, Denmark.
During exercise the circulation is challenged by the ability to balance a marked increases in vascular
conductance as muscle blood flow increases with the ability to maintain arterial blood pressure. Central in
the regulation of arterial pressure is the arterial baroreceptors, which regulated blood pressure beat to beatby controlling sympathetic nerve activity via integrating various signal in the nucleus tractus solitarius（NTS）. The signals that NTS integrates include besides the influence from the arterial baroreceptors, neural influence from the working skeletal muscles （the muscle pressor reflex）, influence from other parts ofthe brain （central command） probably dominated by signals from the cortex and the insula area,
besides influence from variation in the central blood volume. In other words, the arterial baroreceptors
may be viewed as the instrument that the NTS uses to control the set blood pressure.
In response to exercise these various neural influences reset the arterial baroreceptors to control an elevated heart rate and blood pressure and two strategies can be defined to defend the elevation in bloodpressure. The ideal strategy is that the circulation is able to secure the increase in blood pressure by elevation of cardiac output. On the other hand, if the increase in cardiac output is not large enough to elevate
blood pressure to the set level, then blood pressure is defended by peripheral vasoconstriction that primarily affects the splachnic blood flow and flow to the kidneys, but also affects skin blood flow, flow the
working skeletal muscles and even to the brain. Such manifestations of restricted peripheral flow areimportant especially during whole body exercise, where the challenge to blood pressure control is thelargest. Thus, during whole body exercise flow to the exercising muscles is lower than what is establishedwhen the investigated limb is working in isolation and the restriction in muscle blood flow is demonstrated
to be by enhanced sympathetic activity. However, a restricted flow to both working skeletal muscles andto the brain manifests especially in diseases associated with a reduced ability to enhance cardiac output,
i.e. with a failing heart.
A significant effect of endurance training is to elevate blood volume primarily by enhancing plasma volume. The likely mechanism involves that the central blood volume is reduced many hours after exercise
because the muscle blood volume remains elevated in the recovery and hormonal variables restrain urine
production, while thirst compensates for the reduced central blood volume. Also total hemoglobin increases may be in response to arterial desaturation during intense whole body exercise and may be also
because of the reduced kidney blood flow. Whatever the mechanism, both the increase in plasma and red
cell volume enhances preload to the heart and makes it possible for the heart to increase it output. Thus
following training the cardiovascular response to upright exercise approaches that seen during supine exercise with attenuated heart rate and blood pressure responses.
While the training induced enlarged central blood volume readily explains heart rate both at rest andduring exercise, several mechanisms may be involved in attenuating the blood pressure response to exercise. Besides attenuation by the enlarged central blood volume, also enhanced muscle blood flow is likely486

to attenuate the muscle pressure reflex and thereby the upward resetting of the arterial baroreceptors.
Furthermore, habituation to the exercise mode makes the need for central command smaller, further
reducing resetting of the arterial baroreceptors
Also the influence of training on cerebral blood flow and oxygenation is complex. Cerebral blood flow is
influenced primarily by the arterial carbon dioxide tension. Thus it is significant for maintained cerebral
blood flow that the exponential increase in ventilation with increasing exercise intensity is delayed as theability to perform more work is enhanced. In other words, only at a higher workload manifests a reductionin cerebral blood flow as the arterial carbon dioxide tension decreases. Yet, at exhaustion the calculated
cerebral capillary and mithochondrial oxygen tension decreases and at least indirect evidence point to thatexhaustion may be coupled to this reduction in cerebral oxygenation.

Niels H. Secher 氏の略歴
Department of Anesthesia, Rigshospitalet 2041, Blegdamsvej 9, DK-2100 Copenhagen Ø, Denmark
e-mail nhsecher@rh.dk

Associate professor of Anesthesiology 1990 〜
Head, Department of Anesthesia, the Abdominal Center, Rigshospitalet 1996 〜 2003
Professor of Anesthesiology 2004 〜
Professional affiliations
Nordic Physiological Society
Danish Society for Anesthesiology
Nordic Society for Anesthesiology
American Physiological Society
The Copenhagen Muscle Research Center （1994 〜
The Danish Cardiovascular Research Academy （2002 〜
The Academy for Muscle Biology, Exercise and Health Research （2005 〜
The MuscleCluster, Faculty of Health Sciences, University of Copenhagen （2005 〜
European Journal of Applied Physiology, editor 2000 Editorial Board, Scandinavian Journal of Medicine and Science in Sports and Exercise, section editor 2007
〜 2009.
Journal of Sports Sciences, editorial board 1984
Experimental Physiology, editor （2001 〜 2005）
Journal of Applied Physiology, editorial board 2005 〜

SportsDanish championship in rowing × 9 （1964 〜 1974）
Nordic championship in rowing × 3 （1967 〜 1972）
International West German championship in rowing × 2 （1969, 1970）
Holland Becker （1967, 1970）
North American Champion in single scull （1967）
World Champion in double sculls （1970）487

本プロジェクトのねらい加賀谷淳子（日本女子体育大学名誉教授）
本研究プロジェクト「運動時における循環調節機構の統合的解明−スポーツによる健康・体力づくりプログラ
ムの構築に向けて−」は，2004 年度の文部科学省学術フロンティア推進事業に選定され，平成 16 年度〜平成 20
年度の 5 年間実施された．この事業は，私立大学の大学院，研究所の中から，研究実績をあげ，将来の研究発展が期待される卓越した研究組織を選定し，内外の研究機関との共同研究に必要な研究施設，研究装置・設備の整備に対し，重点的かつ総合的支援を行うものとされている．したがって，本プロジェクトでは課題とする研究を推進して学術的貢献をすると同時に，運動時の循環調節研究の拠点となるようにハード・ソフト両面の研究環境の整備を推進することをねらいとしている．

1．健康・体力づくりプログラム構築にむけた運動時循環調節の研究の推進運動に対する循環系の適応は極めて巧妙にできていると考えられる．複雑な仕組みになっていることは，ひとつの系が破綻しても他の系が補償し，生命維持に必要な循環システムを破綻させないような安全弁が用意されているということであろう．安静時につくられた循環システムの安定性は，運動という外乱によって一旦はその整合性が破られる．そこで，運動開始と同時に，運動を遂行するに必要な循環調節と生命を維持するための循環調
節という二つの方向の再調整がなされる．効果的な運動と同時に運動の安全性を考えなければならない所以である．しかし，運動に対する循環系調整の機序はまだ全貌が明らかにされていない．本プロジェクトでは，運動時の循環調整に関する科学的エビデンスを，運動特性と関連させて蓄積し，それらを統合して得られたエビデンスを基盤とし，健康・体力づくりのための運動プログラムの構築に向けた提案を行うことを目指している．
課題解明に向けた本プロジェクトでの取り組みは図 1 に示した通りである．5 年間のプロジェクト研究期間の最初の 3 年間（2004 〜 2006 年度）は，運動時の循環調節に関する知見を集積し，それを統合して循環調節の解明に貢献することを目指した．そのために，運動時の生体応答研究の基盤となる運動単位の動員特性を明らかにすると共に，人を対象とした循環研究に必要な非侵襲的計測法（近赤外線分光法，超音波法など）の研究への適切な適用等を進めながら，1）運動時の血流再分配と 2）循環系に対するセントラルコマンドを中心とした神経性調節に焦点を当てた研究が遂行された．中心的課題である「運動時の血流分配に関する研究」と「運動時のセントラルコマンドが循環に与える影響に関する研究」はプロジェクトメンバー全員が参加する共同研究として行われた．さらに，特化したテーマについては，個別に研究を実施し，プロジェクト全体で討議して統合するという研究体制をつくった．これに関する個々の成果は，2006 年 11 月の中間報告会で公表されている．さらに，それらを統合した運動時の循環調節の機序については，2008 年 11 月の国際シンポジウムで報告した．
プロジェクト最後の 2 年間（2007 〜 2008 年度）では，それまでの成果を様々な身体特性を持つ対象者で検証することと，運動の継続が循環調節に与える影響を横断的，縦断的に明らかにすることを中心課題とした．そして，それまでに得られたすべての知見を基に，スポーツによる健康・体力づくりプログラムの構築に対して，循
環調整の観点から提案を行うこととした（2009 年 2 月）．
以上のように，研究面では，本テーマに関して，学術的な貢献をすること，それを基に，運動プログラム構築にむけた提案を行い，社会のニーズに応えることが本プロジェクトのねらいである．

2．運動時循環調整研究の拠点整備
本プロジェクトでは，初年度に脳の酸素動態を非侵襲的・連続的に計測する近赤外線分光法や解像度が高く，画像分析が自動化した超音波測定装置を購入した．2 年目以降は既存の計測装置や運動負荷装置をシステム化して，

488

統合的分析

図1

本プロジェクトの研究デザイン

ハード・ソフト面の整備が一段と進んだ．
多様な因子によって調節されている循環調節について，様々な様式・強度・持続時間の運動を用い，異なる姿
勢や環境の影響等を考慮しながら，性年齢・身体特性の異なる対象者で検証するには多くの研究者による共同研
究が必要である．本プロジェクトでは本研究所と他の研究機関との共同研究や本研究所を拠点として若手研究者が参加する研究プロジェクト実施についてもいくつかの試みを行った．本プロジェクトの実施による拠点整備により，実施母体である日本女子体育大学のさらなる研究活性化と他機関の多くの研究者が参加できる研究拠点となるシステムづくりをすることはプロジェクト実施の大きなねらいであった．

489

Session 1
プログラム作成の基礎となる科学的エビデンス 1−運動時の循環調節−

運動準備や想起に伴う脳活性岩館

雅子（日本大学生産工学部助教）

運動時の循環調節は，運動の始まる前からすでに開始されており，運動準備や想起に伴い生じる心拍上昇や筋血流上昇はその代表的な応答である．運動準備期の循環応答は運動時とは異なり筋収縮が生じていないことから，
運動性循環反射がない状態で中枢指令（セントラルコマンド）が発現したことによる応答であるといえる．セン
トラルコマンドの起源は，近年，大脳や視床下部，脳幹部などに存在することが示唆されている．心臓や筋血管で生じる循環応答の神経調節としては，セントラルコマンドが自律神経系を介して標的部位に作用していることが明らかになりつつあるが，一方，セントラルコマンドの中枢と線維連絡のある脳領域は，どう影響を受けるのかは明らかでなかった．特に，運動出力に関連する大脳皮質運動野は視床下部などと密接な連絡がある．そのため，セントラルコマンドにより心臓や筋に予測制御応答が生じているとき，脳においてもすでに変化が生じている可能性があった．従来，運動準備期の運動野周辺領域の脳活動は，非侵襲的手法である脳波を用い，大脳皮質
運動野の活動が運動準備期や運動想起時に見られることは多数報告されてきた．一方，運動制御に関する神経科学の研究では，研究視点の違いもあり，循環反応との対応は検討がされてこなかった．その理由の一つは，脳波を用いた研究では，加算平均を必要とするため被験者に同一試行を数十回繰り返し行わせるが，この繰り返しによる慣れや疲労が循環反応を変化させ，両変数の対応関係の検討を困難にするためと考えられた．このような状況の中で，近赤外分光法（NIRS）を用いた大脳皮質酸素動態の計測は，時間分解能にも比較的優れ，脳波のような加算を必ずしも必要としないことから，変動しやすい循環反応との対応関係をみるには，現時点では最も適していた．
そこで本研究では，NIRS を用いた大脳皮質運動野酸素動態の変化を脳活動の指標とし，掌握運動の開始約 1 分
前からの大脳皮質運動野酸素動態，心拍数，平均血圧，心拍出量，前腕屈筋酸素動態を同時記録し，これらの対応関係を検討した．
その結果，運動準備や想起に伴い，循環応答としては，心拍上昇および心拍出量増加および筋血流速度上昇という応答がみられた．これに対し，大脳皮質運動野酸素動態においても，oxyHb および totalHb の上昇，
deoxyHb の低下傾向という，神経活動賦活に伴う血流増加を反映する脳酸素動態変化がみられた．このことから，運動開始前において運動準備や想起により，心拍数の上昇，心拍出量増加および活動肢の筋血流速度上昇が生じるとき，大脳運動野周辺の脳活動も同時に亢進することが示された．
以上のことから，ヒトは実際に運動を行う前から，心臓，骨格筋における予測制御とほぼ同時期から運動出力を担う大脳皮質運動野の活性化を連動して生じていることが明らかになった．このことは，運動時に適応するためのプログラム化された一連の予測制御が，脳も含め全身性にフィードフォワード的に生じることを示すと考え
られる．

490

運動を持続させる大脳皮質の働き澁谷

顕一（日本女子体育大学附属基礎体力研究所ポスドク研究員）

1．はじめに
運動中の脳における活動を計測することは，脳が運動をどのようにコントロールしているかを知るだけでなく，運動による身体における変化をどのように捉え，その情報を処理しているのかを理解するために重要である．そして，それにより，運動指令がどのように脳から末梢へ向けて放出されているのかを知ることができる．運動指令に関する知見は運動制御に関する分野だけでなく，循環調節に関わる分野にとっても重要な知見となる．本プ
ロジェクトでは，近赤外線分光法を用い前頭前野および一次運動野の活動を計測し，皮質レベルにおける活動を計測し，運動を持続させるための大脳皮質の働きの一部を明らかにすることを目的とした．
2．運動中の前頭前野における活動
運動の持続に対しては前頭前野における活動が関与している可能性も示唆されている．本研究では，学際的な視点を取り入れ，主に，心臓血管系と代謝は脳と筋の酸素化および代謝に影響を及ぼす心臓血管系および代謝機構について検証してきた．特に，1）運動中の筋疲労のメカニズムや安静から運動への移行期の酸素化動態のメカ
ニズムの理解を進めた．また，2）前腕筋の出力維持と，巧妙な運動の制御と協働を必要とする正確な動作遂行を可能なものとする上で，前頭前野が重要な役割を果たすという仮説を支持する結果が得られた．
3．運動中の一次運動野における活動
しかし，運動に対して実際に指令を出しているのは一次運動野である．その一次運動野における活動動態を知ることで，上記の仮説はより強固なものとなるであろう．そこで，本研究では左右半球における一次運動野の活動を記録した．左右の半球における一次運動野は相互作用を持つことが知られている．これまで，活動肢と同側半球における一次運動野は，活動肢の運動を直接制御することはないと考えられてきた．つまり対側半球一次運動野の制御により行われていると考えられてきた．しかし，近年の研究では，左右半球間の一次運動野の相互作用が存在する可能性が示されている．本研究の近赤外線分光法を用いた脳酸素化動態の時系列的分析により，運動開始後の左半球の一次運動野と右半球一次運動野の酸素化動態に時間的差異が存在することが明らかとなり，運動開始後の左右半球間の一次運動野の相互作用形成の可能性が示された．このような両側半球間の結合は対側半球の一次運動野だけでは力発揮が十分ではない場合に，それを補完するために同側半球一次運動野の活動が動員されると考えられる．また，トップアスリートと一般成人の一次運動野の活動比較から，疲労困憊に至る運動
時に一次運動野の酸素化動態に明確な相違があることも示された．
4．まとめ
以上のことから，前頭前野のみならず，一次運動野においても活動肢に対して同側部位の活動が運動の調節に大きく関わっていることが明らかとなった．今後，さらにこれらの検討を行うことで，運動を遂行する命令が脳からどのように発信されているのかを知ることができるであろう．

491

運動時のモーターユニットの動員特性
加茂美冬（日本女子体育大学准教授）

運動は，時間的，空間的に様々な組み合わせで起こるモーターユニット（Motor unit; MU）活動を基礎として成り立っている．すなわち，筋力は，筋を構成する MU の発揮張力の総和であり，筋力増大は，活動する MU 数の増大と参加した MU の放電頻度の上昇により実現される．MU の収縮は種々の血管拡張シグナルを発すること，また，十分でない酸素供給は MU 活動を変化させることなど，MU 活動と循環系機能は密接に関わっていることは明らかである．しかしながら，種々の筋力発揮条件における両者の相互関係，さらには各々の動態についても不明な点が多く残されている．本プロジェクトにおいては，以下の 3 つのアプローチにより両者の関係を探ろうとした．
【動的膝関節伸展運動の強度変化に対する筋・循環系の対応（平成 17 年度共同研究）】
MU 活動〔表面筋電位積分値（IEMG）から評価〕と循環系機能の関係を検討した．各種強度で 1 分間動的筋力発揮を反復したとき，IEMG は 30 ％ MVC 以上の強度において時間に伴い直線的に増大した．血圧，筋血流量および筋酸素動態の境界強度も約 30 ％ MVC で確認された．IEMG 増大は主に MU 活動参加を反映することから，
新たな MU の動員が，循環系・代謝系機能変化の引き金になることおよびその発現強度は約 30 ％ MVC であることがわかった．
【静的（等尺性）一定筋力発揮における運動単位放電特性を規定する因子（個別研究課題）】
等尺性一定筋力を持続的に発揮するとき，MU は放電間隔を時間と伴に延長させる．この延長は全ての筋力レベ
ルにおいて観察される特徴的な現象であることから，筋力調節および筋疲労発現に重要な役割を担っていることが示唆されている．したがって，この現象を理解することは，筋力発揮時の循環応答の統合的解明において意義をもつ．本実験では，その合目的性および発現メカニズムを動刺激による末梢感覚情報操作

反復電気刺激に対する誘発張力応答および振から検討した．その結果，放電間隔延長現象は筋反復収縮初期の不完全強縮張

力増強に対して抑制効果をもつことが確かめられた．さらに，低筋力発揮レベルではその効果は充分でないことを新たに見出した．また，人為的な末梢感覚刺激の増減により放電間隔延長は必ずしも消失しなかったことから，
MU 放電間隔延長の発現に対する central drive による制御の重要性が示唆された．
【静的（等尺性）筋力発揮における運動単位活動と循環系機能の関係（個別研究課題）】
Ascending ramp 収縮（〜 10 ％ MVC，30 s）を緊張性振動反射（RC）と随意収縮（VC）で行い，両条件における MU 活動と循環系・代謝系機能を比較した．IEMG は VC より RC において有意に大きいあるいは大きい傾向にあった．VC において心拍数と血圧はこれまでに報告されている随意筋力発揮における central cardiovascularcommand の制御による変化と同様な傾向を示したが，RC では観られなかった．筋酸素化へモグロビンの筋力発
揮開始時低下の大きさは VC に比較し RC で大きかった．これらのことは，随意収縮では，central motor command による効率のよい MU 活動と central cardiovascular command による循環系機能制御が効率のよい酸素利用もたらすことを示唆している．

492

活動筋代謝の有酸素性依存から無酸素性依存への変移
笹原千穂子（東海学園大学講師）
1．はじめに筋収縮の強度は活動筋への血流を規定する重要な要素であり，筋内圧の機械的変化と筋の代謝性変化を伴い，活動筋における動脈血流入量と静脈血流出量を決定する．運動強度が異なると，動員される筋線維タイプが異なり，活動筋への酸素需要の増加による応答として，循環システムは心拍出量の増加や他の組織への血流減少という形で調節を行うが，その詳細については十分には検討されていない．本研究では，運動強度の変化に対する筋
代謝と循環器系の調節との関係を解明することを目的とした．
2．動的運動時の筋酸素動態と運動強度
動的運動時の筋代謝の時間経過に伴う変化が運動強度により異なるか否か，さらに筋代謝に部位特異性があるか否かを明らかにするため，筋の浅部と深部や内側と外側で筋酸素動態の変化を測定し，さらに筋疲労感覚や血圧との関係を検討した．低，中，高強度の動的膝伸展運動を行った結果，①低強度運動では筋脱酸素化は時間経過に伴い小さくなったが，中・高強度運動においては筋脱酸素化は運動継続中維持された．②筋の部位特異性は見られなかった．③さらに筋脱酸素化と筋疲労感覚は血圧の上昇しない低強度運動でのみ相関関係がみられた．
低強度での筋酸素動態は筋疲労感覚に関与しているが，中・高強度では血圧上昇と関連した他の要因が筋疲労感覚に関与しているものと考えられた．
3．静的運動後の筋再酸素化時間と運動強度
運動中の筋酸素動態は，筋内圧の上昇による活動筋への血流制限の影響が大きい．一方，運動後の筋再酸素化
時間（運動後の回復期に酸素動態が元に戻るまでの時間で，この時間が延長すると筋の有酸素性代謝貢献が低いという関係性が示されている）はより筋代謝の影響を反映すると考えられる．運動中の筋内の酸素化動態が遠位と近位では異なることは既に知られているが，筋の浅部と深部間の不均一性については検討がなされていない．
浅部では速筋線維が多く，深部では遅筋線維が多いといわれ，その酸素化動態が筋の深さにより異なることは十分に仮定される。筋再酸素化時間の延長し始める運動強度があるか否か，あるとすればその強度に筋内で部位特異性があるか否かついて検討した．その結果①筋再酸素化時間が顕著に延長する運動強度が存在することが明らかになった．②どの強度においても筋再酸素化時間は浅部と深部で差がみられなかった．静的膝伸展運動時に活動筋における代謝が有酸素性依存から無酸素性依存へと移行するのは，比較的高強度（最大随意筋力の 70 ％）であり，筋の有酸素性代謝貢献度が深さによって相違があるとは言えないことが示唆された．
筋代謝や循環指標等の複数のパラメータの代謝変移点を知ることで，健康・体力づくりにおいて安全且つ効果的な運動強度の設定に役立つと考えられる．

493

筋活動による心拍出量の変化と血流分配
奥山靜代（慶應義塾大学講師）

1．はじめに運動時の循環系の対応は手際よくシステム全体の再調整が行われるため，筋活動による血流再分配を明らかにすることにより，安全で効果的な健康のための運動に貢献できる．
2．筋の活動による心拍出量の変化と骨格筋，脳，腹部内臓への血流分配
骨格筋への血流量が心臓の拍出量とどう対応するかについて，局所運動時に低負荷では心拍出量の増加を伴わずに活動筋への血流再分配が起こり，強度が高くなると心拍出量を増加させて骨格筋へ血流分配を行うことが示された．一方，骨格筋への動脈血流量は，筋収縮期は一旦安静時より低下するが，筋収縮中止直後は顕著に増加する．逆に静脈血流速度は筋収縮期に加速され，筋弛緩期には顕著に低下し，両者は筋内圧の局所的変化により関連していることが示された．また筋活動が繰り返される動的運動時の動静脈血流量は相互に関連していることが明らかになった． 骨格筋の血流がどこまで増加するか，最高血流量に達する運動条件を調べた結果，動的運動
時筋弛緩期の膝窩動脈血流量は，運動強度とテンポが密接な関係を保って変化し，両者の組み合わせによって運
動時血流量が最高値に達することが示された．一方，運動時の非活動肢血流量は，運動開始初期は一過性に強度依存の増加が起こるが，時間経過に伴い減少が起こった．このことは，運動開始後活動筋へ特化して血流量増加が起こるように調節されるまでには時間を要することを示唆している．さらに，運動時の脳への血流再分配は，内頸動脈血流量の変化はみられないのに対して，椎骨動脈経路では血流量が増加することが明らかになった．また運動に直接関与しない腹部内臓への血流量は，運動時の腎動脈血流の減少がみられたが，上腸間膜動脈では顕著な変化はみられず，運動時の腹部内臓器官への血流再分配は一律の変化ではなかった．加えて，重力の影響に対する血流量の応答をみると，掌握運動時の前腕を心臓より垂下した場合や下肢の血液プーリングの影響をみた
結果，静脈血流量が減少し筋血液量が増加を示した．
3．運動強度と循環系応答：血圧変移点
筋収縮がある強度を超えると血圧の上昇が顕著になる（Kagaya et al. 2001）．そこで血圧上昇が高くなる負荷を基準として強度をとらえ血流再分配をみると，運動後血流量に対する運動中血流量の比は，血圧変移点負荷とほぼ類似の負荷強度で急激に低下し，運動中の血流需要を満たす割合が低くなることが確認された．さらに，筋の酸素代謝は運動時の活動肢筋酸素動態が負荷強度に対して低負荷と異なる対応を示すのは，血圧変移点よりやや低い負荷からであった．また運動時の活動筋での変化を中心に身体の様々な変化を統合して感知する主観的筋
疲労感覚は，血圧変移点より低い負荷（38 ％ MVC）から急上昇した．
4．血流再分配からみた運動プログラム作成への提案
運動時の循環系応答や主観的筋疲労感覚の変化がみられる時点が血圧変移点の出現付近の負荷強度に類似したことから，運動プログラム作成では適切な運動強度を選択する基準として血圧変移点の負荷を手がかりにすることが有用であると考えられる．

494

筋形状の変化が筋循環に与える影響
大森

芙美子（日本女子体育大学基礎体力研究所客員研究員）

1．はじめに運動の実践現場では，筋腱を伸張させるストレッチングが良く用いられている．その効果は，筋腱だけでなく，循環系の活性化にも影響を及ぼすと考えられるが，ヒトについてのそのエビデンスは十分ではない．もし，スト
レッチングにより，循環系機能が促進あるいは抑制することが明らかになれば，循環機能を促進する効果的なス
トレッチングの方法を明らかにすることにより，健康・体力づくりのための運動プログラム作成に貢献できる．
2．ストレッチングが筋循環に与える影響
ストレッチングが筋循環に与える影響を明らかにするために，仰臥位での下腿筋受動的ストレッチングを 2 種の角度[解剖学的正位（AP）と快適最大角度（痛みを感じる角度− 3 °： CP）]を用いて行った．そして， 1）筋
束長の変化，2）筋酸素動態の変化，3）ストレッチング部位より上位に位置する当該筋へ血液を供給する膝窩動脈および静脈血流速度の変化，について検討した．
その結果，1）足関節の背屈に従って，腓腹筋内側頭（MG）とヒラメ筋（SOL）は筋束が伸長し，それらの拮抗筋である前脛骨筋（TA）は短縮し，協働筋である MG と SOL の筋束長伸張率が異なることを示した（伸長率：MG73 ％，SOL30 ％，短縮率： TA19 ％）．2）ストレッチング中，SOL では両角度において筋血液量は増加した
が，MG においては，AP ではほとんど変化せず，CP では減少したことから，筋血液量の応答には下腿協働筋間で相違があり，ストレッチングによって減少する（MG）だけではなく増加する（SOL）筋もあることがわかった．
3）ストレッチング中の動脈血流速度および静脈血流速度は有意な変化を示さなかったが，ストレッチング終了に伴う足底屈と共に，動脈血流速度は有意に上昇し，静脈血流速度はそれより数秒遅れて有意に増加した．動脈血流量の増加に遅れて起こる静脈血流量の増加は動脈血流依存であると考えられた．また，ストレッチング中の血流速度を順行成分速度と逆行成分速度に分けて計測すると，CP では安静時より有意に速度が速くなることが示された．筋束長の伸長度が高い CP では，ストレッチによって当該筋内の血管が大きく伸長され，血管径が短縮し，血管抵抗が増加したことにより，逆行成分速度が速くなったと考えられる．
次に，MRI（Flesh Blood Image 法）を用いて，ストレッチング中の末梢血管の撮像を行った．その結果，静脈血 index がストレッチング中に減少することが示された．ストレッチングによる筋線維の形状的変化が各筋の血管形状をどのように変化させるはまだ明らかにされていないので，今後は，この方法を用い，各筋別に検討していく必要がある．
3．循環機能促進に効果的なストレッチングプログラムについて
以上のことから，筋形状を変化させるストレッチングは，その角度や時間等を適切に選定すれば，筋循環へ効
果を及ぼすことが確かめられた．本結果からは，快適最大角度で 1 分間のストレッチングを行うことにより，筋循環への効果が認められた．より効果的なプログラム作成には，まだ更なる検討が必要である．

495

随意運動時の呼吸・循環応答にみられるセントラルコマンドの働き佐藤耕平（日本女子体育大学助教）

1．セントラルコマンドとは？
運動時に起こる呼吸・循環活動の制御機構の一つとしてセントラルコマンド説がある．このセントラルコマン
ドは，大脳皮質から生じる運動指令と同期して高位中枢から起こり，呼吸・循環機能を修飾する，フィードフォ
ワード型の調節であると定義されてきた．一方，運動時に筋弛緩薬を投与し，運動努力（effort）を増加させた侵襲的な実験モデルでは，運動努力に比例した循環応答の増加がみられることが報告されている．また，運動をイメージしただけでも，呼吸・循環応答が引き起こされることが知られている．これらは，セントラルコマンドによる循環調節が，必ずしも運動指令を伴わないものであること，さらには努力感や疲労度を反映したセントラル
コマンドが循環応答に作用するという，フィードバック型の調節機構であることも示唆する．
2．セントラルコマンドと運動時の循環調節
本プロジェクトでは，運動時の循環調節に対するセントラルコマンドの役割を検討した．検討した課題は主に，
1）運動時の脳・内臓血流に対するセントラルコマンドの役割と，2）身体トレーニングに伴う筋交感神経活動の変化に対する，セントラルコマンドの影響である．課題 1）では，セントラルコマンドが運動時における脳血流調節に関与するか否かを，2 つの実験モデルを用いて検討した．一つ目は「随意-受動運動モデル」，二つ目は「バイブレーションモデル」である．「無負荷随意-受動運動モデル」を用いた実験では，動的運動開始初期に起こる脳血流の増加は，セントラルコマンドが関与する可能性が示唆された．また，セントラルコマンドの脳血流に対する影響は，部位差（地域差）がある可能性が示された．さらに，「バイブレーションモデル」を用いて静的運動時の努力感・疲労感を低下させた場合，努力感に応じた脳血流の応答が見られることが明らかになった．しかしながら，このモデルでは，腎血流応答に対するセントラルコマンドの影響は認められなかった．これらの知見は，セントラルコマンドは，交感神経系を介して応答を調節しているとされているが，交感神経全体に均一して作用す
るのではなく，地域差があることを示唆するものである．課題 2）では，最大努力での局所的なレジスタンストレーニングを介入することにより，上位中枢機能（セントラルコマンド）に刺激を与え，運動時の筋交感神経活動がトレーニング前後において変化するか否かを検討した．その結果，トレーニング後に静的運動時の筋交感神経
活動は増加することが明らかとなり，その亢進は筋からの末梢神経反射よりも，セントラルコマンドの増加が関与する可能性が示唆された．
3．高強度運動時の循環調節
セントラルコマンドの活動が極めて亢進するような，高強度運動時の循環調節の解明は，安全で有効な運動プ
ログラムを構築するうえで重要な課題である．稀にではあるが，ウエイトリフティングやレジスタンス運動時には，脳出血や失神・眩暈を起こすことが報告されている．これは，過度の血圧および脳血流の増減が影響しており，これらの応答には運動中の呼吸法が密接に関連すると考えられている．本研究では運動時の息こらえと，運動前の過換気が脳血流調節に及ぼす影響を検討した．その結果，高強度運動時に息こらえをした場合，運動中の脳血流の低下と，運動後の急激な増加を誘発することが明らかになった．また，運動前の自発的な過換気による脳血流の低下は，運動後まで持続することが明らかになった．これらの結果は，息こらえによるバルサルバ呼吸と，過換気による低炭酸ガス血症が，運動時の脳血流応答に作用したと考えられる．また，運動前の過換気および運動中の息こられを防いだ場合，脳血流の増減は抑制された．本研究は，アスリートや一般人がウエイトトレ
ーニングを行う際の，安全な呼吸法を提言するものでると考えられた．

496

Session 2プログラム作成の基礎となる科学的エビデンス 2−発育，老化，疾患およびトレーニングによる循環系の変化−

子どもの循環機能の発達佐藤耕平（日本女子体育大学助教）

身体を構成する各部位の形態や諸機能の発達は一様ではなく，部位および機能により相互に異なる発達過程を持つと言われている．他の組織に比べ，脳神経系の発達は早期に完了すると言われているが，脳の神経細胞がその機能を十分に発揮するには，エネルギー供給を担う脳循環の発達が不可欠と言える．先行研究における，脳血流の発育に関する研究は極めて少ない．また，これら研究においては脳血流量の絶対値を算出し，その経年的な変化にのみ注目し，脳循環機能の発達を捉えている．しかしながら，発育期においては，脳循環の発達と同時に，心拍出量などの心臓を中心とした中心循環機能も発達する．故に，脳循環と中心循環の相対的・相互的な発達過程を把握することも重要であると考えられる．このような観点から本研究プロジェクトでは，発育期の子どもの，心拍出量（Cardiac Output: CO）に対する総頸動脈血流量（Common Carotid Artery Blood Flow: QCCA）の比（％）を脳血流配分比率として算出し，脳循環と心循環の相対的・相互的な発達過程を検討した．
本研究の被験者は，小学校高学年男女 66 名（男 35 ：女 31），中学生男女 96 名（男 38 ：女 58），高校生女子
83 名であった．測定項目は，椅子座位での安静時の循環機能の指標として，動脈血圧，心拍数（Heart Rate: HR），
一回拍出量（Stroke Volume: SV），CO をフィノメータ連続指血圧測定装置（Finapres Medical Systems）により測定した．また QCCA を超音波画像診断装置（Logiq5, GE）により算出した．脳血流配分比率は，QCCA ／ CO の計
算式から算出した．
脳血流配分比（％）の経年的変化を男女毎に下図に示した．男女ともに小 5 が最も高く，中 2 から中 3 にかけて漸減することが示された．女子では小 5 −小 6 間および中 1 −中 2 間で有意な減少が見られ，中 3 以降でほぼ成人の値になることが示された．小学および中学期には男女差は認められなかった．本研究における女子における小学 5
年生から中学３年生にかけての脳血流配分比率の低下は 1）小 6 以降の CO（SV 依存）の増加と，2）QCCA の低下によりもたらされた．この小学期に見られる高い脳血流配分比率は，おそらく発育期における脳神経機能の発達を反映したものである可能性が高い．また，中学後期において脳血流配分比率が，ほぼ成人の値に達する現象は，発育に伴って効率的な脳機能が形成され，余剰な血流が不要になったことを示唆する可能性がある．しかしながら，
この発達過程の生理学的な意味については今後の検討が必要である．本研究は，発育期における運動指導や体力作りを行う上での基礎的な資料となるものであり，循環系に対するトレーニングの至適年齢を考慮す
る上でも興味深いものである．

図1

497

発育期における脳血流配分比の経年的変化

有疾患者における運動および筋虚血に対する血流調節プロファイル
長田卓也（東京医科大学講師）

背景：閉塞性動脈硬化症保有者は，下肢動脈血管の動脈硬化に伴う血流障害のために歩行距離の低下が認められ，運動による疾病下肢筋血行動態への影響が示唆される．
目的：一過性運動時における血流動態を検討する事を目的とし，末梢循環障害（Fontaine 分類第 II 度）をきた
す下肢閉塞性動脈硬化症保有者を対象に，運動時における血行動態について検討を行うこととした．
方法：末梢循環障害（血管造影にて確認されている）をきたす 5 名の男性閉塞性動脈硬化症保有者（平均年齢71 ± 2 歳）を対象に，座位姿勢での多段階負荷等尺性片側膝伸展運動を行った．運動開始前の安静時に足関節上腕血圧比（ABI）を測定し，運動は一足ごとに両側について行った．両下肢で ABI が低い下肢を患測とし，反対側の下肢を健側とした．運動強度は，最大随意収縮力の 5 ％，10 ％，30 ％そして 50 ％とそれぞれの強度で 3 分間とし，多段階的漸増負荷とした．下肢運動の頻度は，5 秒間の等尺性膝伸展運動（筋収縮）にひき続き，5 秒間の休止期（筋弛緩）を 1 サイクルとした．下肢血流の評価は，超音波ドプラー法にて大腿動脈部位において行い，血管径と血流速度により算出した．血流速度は，5 秒間の等尺性膝伸展運動及び５秒間の休止期のそれぞれに得られた 3 〜 4 拍動の波形を計測し，血流量評価に使用した．運動中の血流反応は，筋弛緩期である休止期血流量から筋収縮期のそれを差し引いた血流増加量を指標とした．
結果：安静時において患測下肢の ABI 値は，健側に比べ低い値を示した．安静時下肢血流量は，患測が健測より低い傾向を示したが，運動中の下肢血流増加量は，患測において大きい傾向を示した．
考察：動脈硬化が強い下肢動脈血管（ABI 値が低い下肢側）における筋収縮血流増加反応が高い事が示唆された．この事はより運動強度の上昇に伴う骨格筋酸素消費量を代償するための血流増加調節，筋虚血に伴う血管拡
張代謝産物なの影響が強い事が示唆される．本研究では，運動に伴う患側下肢血流反応は，健側と比べて異なることが明かとなり，今後は末梢循環障害が安静時のみならず運動中の骨格筋循環に与える影響を検討する必要があると思われる．

498

高齢者の左室重量と骨格筋量の関係
奥山靜代（慶應義塾大学講師）

1．はじめに心臓は活動筋の酸素需要に応えるために，心拍出量を増加あるいは血流配分を増減させ運動に必要な酸素の需要を満たそうとする．一方，骨格筋では筋収縮時に筋ポンプ作用が働き，静脈還流量を高め，心臓の前負荷を増加させるので，加齢による骨格筋量の低下は，心筋や血管動態に対する刺激を低下させると考えられる．したがって，骨格筋量の低下がみられる高齢者において，心筋と骨格筋のバランスを取りながら，両機能を高めることが重要であると考えられる．
2．左室重量と骨格筋量の関係
心筋と骨格筋の関係をみるために，高齢者（15 名，76 ± 5.4 歳）安静時の心形態（心室中隔厚，左室後壁厚，
左室拡張・収縮末期内径），および大腿部筋厚（大腿直筋，中間広筋）を超音波 B モード法で測定した．その結果，心筋の厚さ（左室後壁厚 + 心室中隔厚）と大腿部筋厚（大腿直筋 + 中間広筋）との関係をみると，両者には有意な相関関係（r ＝ 0.647，p ＜ 0.01）がみられた．さらに大腿部筋厚から推定した大腿部筋体積と，心形態より算出した左室重量との間において，正の相関関係（r ＝ 0.561，p ＜ 0.05）がみられ（図 1），左室重量は大腿部筋体積との間に密接な関係があることが示唆された．
3．提 案
以上のことから，高齢者の心臓の形態（左室重量）は大腿部筋体積と密接に相関することが示された．このことから，高齢者においても骨格筋量の保持が心臓の容量保持に有効であるといえ，高齢者も身体運動による筋量の維持が必要といえる．

図1

左室重量と大腿部筋体積との関係

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身体トレーニングによる循環機能の向上
斉藤満（豊田工業大学教授）

1．はじめに生活習慣や加齢変化に伴う健康・体力の低下は最終的に高血圧，心疾患などの循環機能の低下や障害としてみられる．この予防には身体活動が有効なことは広く認められているが，その方法論についてはまだ開発の余地が残されている．
2．循環機能向上を目指す身体トレーニングとしてのハンドグリップ運動
健康の維持・増進を QOL からみると，循環機能に定量的な変化が認められなくても主観的効果として評価されることが少なくない．この背景には定量的には表現できない循環調節システムの機能の向上の存在が考えられる．
心拍出量などの定量的な循環機能向上にハンドグリップ運動はほとんど期待できないことから，トレーニング
運動としての有用性についてはあまり注目されない．しかし，身体運動の一つとして循環調節システムに影響を及ぼす可能性は十分考えられ，何と言っても手軽に行えることから，「トレーニング運動」としての応用可能性は高い．本研究では，ハンドグリップ運動の循環機能向上への効果について，律動的，静的運動，運動時間や強度などを目的合わせて選定し，心拍・血圧反応，循環調節システムの代表としての交感神経活動及び主観的運動感覚の面から検討した．
検討内容は，1）ハンドグリップ運動時の運動意欲・頑張り，疲労感覚や循環反応と交感神経活動の関係，2）
高強度ハンドグリップ運動が循環調節に及ぼす影響，3）長期トレーニングモデルとしての利き腕と非利き腕運動
時の交感神経活動と循環反応の比較，4）神経性循環調節機能に与えるレジスタンストレーニングの効果とその後の脱トレーニングの影響，である．
結果の概要は，1）小筋群の運動でも全身の循環調節に携わる交感神経活動に十分刺激が与えられる，2）使用頻度の高い利き腕運動の循環調節は非利き腕運動とは異なる，3）短期間の強いハンドグリップレジスタンストレーニングは運動時の交感神経活動反応をより高めるが，この効果はトレーニング停止により速やかに消失する（図 1），にまとめられる．
以上の結果から，ハンドグリップを用いた運動トレーニングは，その運動強度や時間等を適切に選定すれば，心拍や血圧などの定量的な改善が認められなくても，循環調節システムとしての交感神経系に十分効果を及ぼすことが確かめられた．

図１ 4 週間のハンドグリップトレーニング及び脱トレーニングに伴う運動及び運動後阻血時の交感神経活動，心拍反応の比較．運動時の交感神経活動反応はトレーニング後高まるが，心拍反応の変化はみられない．

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Session 3
提 案−安全で効果的な運動プログラム構築に向けて−運動に対する循環応答からみた提案
定本

朋子（日本女子体育大学教授）

本プロジェクトで得た運動時の循環応答に関する知見をもとに，安全で効果的な運動プログラムの構築に向けて次のような提案をする．

1．運動様式について
1）動的運動・静的運動
動的運動は心拍数や心拍出量を増加させ，血液循環を促進する運動様式といえる．また筋の収縮と弛緩がリズ
ミカルに繰り返され（収縮期には静脈血が筋から流出し，筋弛緩期には動脈血の流入量が増加する反応をもたらす），活動筋の十分な血管拡張により，運動時の血圧上昇が低く，生体への負担度が少ないという特徴をもつ．また軽強度による脚の動的運動時には，筋交感神経活動が安静時よりも低下することから，安静にするよりもゆっくり歩く方がリラクゼーション効果をもつと示唆される．一方，筋収縮が持続する静的運動は，心拍数や心拍出量の著しい上昇はみられないが，活動筋での血液の流入・流出が制限されるため，動脈血圧を上昇させやすい運動様式となる．特に強度が高くなると，心臓や血管系への負担も大きくなりやすい．このような動的運動と静的運動の特徴を理解した運動プログラムの作成が必要である．

2）大筋群運動（全身的運動）・小筋群運動（局所的運動）
大筋群を用いた全身運動による持久性運動は呼吸循環機能の維持向上のために有効であり，既に運動処方で広く活用されている．本プロジェクトでは，掌握運動のような小筋群の局所的運動であっても，活動筋のみならず
非活動筋への血流量を増加させ，循環機能を活性化させることが示されている．運動強度が高くなると，脳血流増加の頭打ち，腎血流の減少，筋交感神経活動の亢進をもたらすことになる．また高強度負荷の掌握運動レジス
タンストレーニングが運動時の頑張り・努力感に関わる中枢指令（セントラルコマンド）を増強させる効果をもつことも示されている．したがって，対象者の特性を考慮した適切な運動様式や運動強度を選択することにより，
小筋群の局所的運動も循環機能の活性に有効な手段となる．

3）上肢の運動・下肢の運動
上肢の運動と下肢の運動では，一定の酸素摂取量に対する動脈血圧，心拍数，毎分換気量などが異なり，いずれも上肢で高くなることが既に知られている．循環機能からみると，上肢の運動は，心臓との位置関係（重力作用）によって循環応答が変動することを考慮する必要がある．一方，心臓よりも低い位置で運動することが一般的である下肢の運動は，重力作用による血液貯留を避けるよう留意する必要がある．

4）一側性の運動循環促進に有効なサイクリングやウォーキングのような両側性運動が運動プログラムの主体となっている．しかし，腕や脚の運動を片側だけで行った場合でも，運動を行なわない対側や他の体肢（脚運動をしている時の腕501など）の骨格筋血流量を一時的に変化させることから，一側性の運動も運動プログラムとして活用できると考えられる．

5）その他の運動や運動想起
ストレッチングのように筋の長さを変える運動も，筋内循環を促進させることから，ウォーミングアップやクーリングダウンに用いるだけでなく，要介護者や病床にある患者の筋循環の促進を目的とした運動プログラムとしても活用できる．
運動の準備・想起（イメージ）は，運動野皮質関連領域の脳活性，心拍数，活動筋の酸素化動態，脳血流量（椎骨動脈経路）を上昇させたことから，随意的に運動を準備し運動遂行のイメージを持つことは，運動開始後の循環調節および動作をスムーズにさせる手段となる．

2．運動強度の選定について
運動プログラムの作成において，適切な運動強度を選択することは重要課題である．全身的運動における強度
設定指標は確立されているが，局所的運動については未だ確立されてはいない．本プロジェクトの結果から，次の二つの強度選定指標を提案する．

1）負荷増加に対して血圧上昇が顕著になる「血圧変移点」を指標とする．
「血圧変移点」を調べると（下図），随意最大筋力（MVC）の 30 〜 50 ％の運動強度に分布する．この血圧変移
点の出現付近の負荷強度から，血液供給が不足し，筋交感神経活動の亢進も起こる．そして，腎動脈および内頸動脈血流量の減少や頭打ちがみられる．なお，血圧変移点を超えて 50 〜 70 ％ MVC まで上がると，活動筋代謝は有酸素系から無酸素系へとシフトし，活動筋中には代謝産物・局所性ホルモンが蓄積されることになる．

2）主観的筋疲労感覚を指標として活用する．
筋疲労感覚は筋交感神経活動を反映する指標であり，血圧変移点負荷に相当する筋疲労感覚は「4」であり，これは「疲れた」と「かなり疲れた」の中間の感覚である．この指標は誰もが容易に活用できることから，単独で，あるいは他の強度指標と併用して用いることを提案する．また，運動実施時には常にモニターすることを推奨する．

502

3．運動実施にあたっての留意点
本プロジェクトの成果に関連する運動実施上の留意点をまとめた．
1）運動時間の観点から①運動開始前：運動への準備やイメージを持つことは運動開始後の循環調節および動作をスムーズにさせる有効な手段となる．
②運動開始時：運動に適した循環システムを再調整するには，運動開始後約 30 秒間は必要である．この調整がう
まく運ばないと，血圧が低下することもある．したがって，運動開始時の急激な負荷上昇を避け，ゆっくりと徐々に運動強度を上げるようにする．
③運動終了前（疲労時）：運動持続時間とともに活動筋の疲労が始まる．筋疲労に抗して「頑張り・努力感」を働かせると，交感神経活動を介した力の維持が可能となる．しかし，運動経験の少ない人や低体力者の人は，無理のない時点で運動を終了させるようにする．その判断基準には主観的運動強度や筋疲労感覚を用いる（図参照）．
④運動終了直後：運動終了とともに，身体の各部位の調節機能は運動前のレベルに戻ろうとする．しかし，活動筋では運動時に生じた血管拡張物質が洗い出されるまで，血流増加が続くことになる．この運動後の著しい血流増加が静脈還流量を低下させ，ひいては運動終了後低血圧を招く場合もある．そのため，軽い運動（クーリングダウン）を運動終了後にも行い，筋ポンプ作用により静脈還流の急激な低下を予防する必要がある．

2）対象者の身体特性の観点から①発育期の子どもにおける循環機能の発達：心機能および脳循環が著しく発達する時期は，心機能（推定心拍出量）が 10 〜 12 歳頃であり，脳循環（頸動脈血管内径）が 12 〜 15 歳である（男女差がある）．したがってこのような心臓および血管機能が発達する時期を考慮した運動のプログラムが発育期には必要である．
②高齢者における筋量の保持：高齢者の心臓の形態（左室重量）は大腿部筋体積と密接に相関することが示された．このことから，高齢者においても骨格筋量の保持が心機能の保持に有効であるといえ，高齢者も筋量の維持に結びつく運動プログラムが必要である．
③末梢循環系有疾患者の運動：閉塞性動脈硬化症保有者は筋虚血を代償するために著しい血流量増加が生じる．
しかし，運動時の心拍出量の増大には限界があることを考えると，健常人よりも運動時の血流および血圧調節が難しい．このことを踏まえたプログラム作成が必要である．

3）呼吸法との関連について
短時間の高強度レジスタンス運動時の脳血流応答から，息こらえは脳血流減少を，過呼吸は運動終了後の著し
い血流増加（オーバーシュート）をもたらせることから，運動時の呼吸をコントロールすることに留意する必要がある．

4）運動時の姿勢（重力作用）について
活動筋と心臓との位置関係によって生じる重力作用が循環応答を大きく変動させることに留意する必要がある．
活動筋が心臓よりも高い位置にある場合は，筋への動脈血流量が低下し筋から流出する静脈血流量が増加し，運動遂行には不利なことが多い（上肢の運動・下肢の運動参照）．

503

学術フロンティアセミナー（1） 学術フロンティア国際セミナー
実施日： 2004年10 月26 日（火）テーマ： Brain and muscle oxygenation/hemodynamics during exercise monitored by different
approaches of near infrared spectroscopy.
Valentina Quaresima（University of L'Aquila, Italy）（2） 第１回 学術フロンティアセミナー
実施日： 2004年12 月18 日（土）テーマ：筋疲労とタスク−アメリカ研究生活で学んだこと，学んでいること−篠原稔 先生（Department of Integrative Physiology, University of Colorado, Boulder, Colorado, USA）

（3） 第 2回 学術フロンティアセミナー
実施日： 2005年5月 11 日（水）テーマ： Exercise induced hypoxemia and excessive respiratory muscle work
Craig A. Harms（Department of Kinesiology, Kansas State University, USA）

（4） 第 3回 学術フロンティアセミナー
実施日： 2005年5月 30 日（月）テーマ：動脈硬化に対する運動の効果
田中弘文 先生（Department of Kinesiology, University of Wisconsin, Madison, USA）

（5） 第 4回 学術フロンティアセミナー
実施日： 2005年10 月18 日（火）テーマ： Human Calf Metabolism by 31P-NMR and NIRS
Valentina Cettolo（University of L'Aquila, Italy）（6） 第 5回 学術フロンティアセミナー
実施日： 2006年2月 15 日（水）テーマ： Why is maximal cardiac output reduced in chronic hypoxia？
Jose Antonio Lopez Calbet（Professor of Exercise Physiology in the Department of Physical
Education, University of Las Palmas de Gran Canaria, Canary Islands, Spain）（7） 第 6回 学術フロンティアセミナー「若手研究者・大学院生のためのセミナー I」
実施日： 2006年3月 4日（土）
第一部
テーマ：日本女子体育大学学術フロンティア若手研究者の課題への取り組み
佐藤耕平（日本女子体育大学・助手）

504

岩館雅子（学術フロンティア研究支援スタッフ・ポスドク研究員）
大森芙美子（日本女子体育大学・技術職員）
第二部
テーマ：よりよい科学論文を書く「神経生理学の立場から」
Charles L. Rice（The University of Western Ontario, Canada）「循環研究の立場から」
西保

岳 先生（筑波大学体育科学系）「環境生理学の立場から」
近藤徳彦 先生（神戸大学発達科学部）（8） 第 7回 学術フロンティアセミナー「若手研究者・大学院生のためのセミナー II」
実施日： 2006年6月 10 日（土）第一部
テーマ：初心者のための運動と循環研究斉藤
第二部

満 先生（豊田工業大学教授）

レクチャー・デモンストレーション『超音波ドップラー法による循環調節の研究法』「骨格筋への血流分配」
長田卓也 先生（東京医科大学助手）「脳への血流分配」
定本朋子 先生（日本女子体育大学教授）（9） 第 8回 学術フロンティアセミナー
実施日： 2006年6月 22 日（木）テーマ：乳酸シャトルへのアプローチ
橋本健志 先生（University of California, Berkeley, USA)

（10） 第 9回 学術フロンティアセミナー
実施日： 2007年7月 23 日（月）テーマ：力調節の神経筋メカニズムと交感神経活動篠原稔 先生（School of Applied Physiology Georgia Institute of Technology, Atlanta, USA)（11） 第 10回 学術フロンティアセミナー
実施日： 2007年12 月13 日（木）テーマ：筋機械受容器反射と循環調節
松川寛二 先生（広島大学大学院保健学研究科）

505

平成 21 年5月 発行
文部科学省私立大学学術研究高度化推進事業「学術フロンティア推進事業」研究成果報告書（平成 16年度−平成 20年度）
日本女子体育大学附属基礎体力研究所

運動時における循環調節機構の統合的解明−スポーツによる健康・体力づくりプログラムの構築にむけて−
研究代表者

定本

朋子