心身科学 第 7 巻第 1 号（ 9 ┉19）（2015）

Effect of Maximal Intermittent Handgrip Training on Muscle Sympathetic Nerve Activity
Tesshin Hachiya＊2）, Andrew P Blaber＊2）, Mitsuru Saito＊1）

Aim: This study tested the hypothesis that maximal intensity conditioning does not alter increased muscle
sympathetic nerve activity (MSNA) induced by central command at the same workload using 15-s strenuousintermittent handgrip contractions to evaluate training effects. Methods: Eleven males participated in thisstudy. Handgrip contractions with 75% maximal voluntary contraction (MVC) were performed to evaluate thetraining effects on the MSNA responses before and after maximal intermittent handgrip training. The subjects
trained three times a day, 4 days per week, for 4 weeks repeating maximal 10-s handgrip exercises 10 times
during each session. The MSNA was recorded from the left tibial nerve using a microneurography technique.
MSNA, heart rate and blood pressure data during a 15-s contraction were divided into two segments to compare
the responses in each portion. The non-dominant hand was trained and the dominant hand used as a control.
Results: The MSNA responses induced by central command during a 15-s intermittent contraction increased
during the first bout from the baseline through five repetitions, but the enhancement in the MSNA did notchange after the training program. Conditioning did not alter the maximal muscle force and heart rate, but did
alter the blood pressure response. Conclusion: We found no change in the MSNA increment under the same
exercise load with small training effects. The exercise scheme with 75% MVC intermittent strenuous exercise
increased the MSNA response with central command involvement, suggesting that 15-s strenuous intermittent
contractions were appropriate for evaluating MSNA training effects.
Keywords: MSNA; central command; strength training; intermittent handgrips

reﬂex is believed to be sensitized by metabolites that accuⅠ INTRODUCTION

mulate as exercise continues 9, 15). Sinoway et al. 26) reported

Muscle sympathetic nerve activity (MSNA) is augmented

tization was reduced during non-fatiguing rhythmic forearmthat the increase in MSNA caused by mechanoreﬂex sensiduring exercise. Several factors are involved in the increase

exercise after conditioning. Therefore, training attenuates

in MSNA during contraction, including central command andexercise-induced augmentation of MSNA mediated by two

peripheral reﬂexes such as the metaboreﬂex and mechanore-

peripheral reﬂexes.

ﬂex, and MSNA should change with chronic exercise adap-

Central command augments MSNA during a contraction,tation. It is generally accepted that the increase in MSNA

especially at the onset of a strenuous contraction 29), whereas

mediated by the metaboreﬂex can be attenuated during exer-

central command does not affect the MSNA response dur-cise after conditioning 27). The mechanoreﬂex activated bying moderate-intensity exercise 28). It is not known whether

generated muscle tension induces increased MSNA 9). The

conditioning affects the central command involvement in＊ 1 ）Department of Health Science, Faculty of Psychological and Physical Science, Aichi-Gakuin University＊ 2 ）Aerospace Physiology Laboratory, Department of Biomedical Physiology and Kinesiology, Simon Fraser University,（連絡先）齊藤満 〒 470-0195 愛知県日進市岩崎町阿良池 12 愛知学院大学心身科学部健康科学科
Department of Health Science, Faculty of Psychological and Physical Science, Aichi-Gakuin University
12 Araike Iwasaki-cho, Nisshin, Aichi, 470-0195

─ 9 ─

Tesshin Hachiya, Andrew P Blaber, Mitsuru Saito

the MSNA responses. We observed exponential increases
Ⅱ METHODS

during continuous static handgrip contraction until exhaustion, which led us to speculate that central command plays
a substantial role in enhancing MSNA when voluntary

1 Subjects

effort reaches the maximum level 22). Because muscle force,

Eleven males (one left handed) participated in this study

initially at 25% of the maximum voluntary contraction

after providing informed consent. This study was approved(MVC), was maintained until exhaustion, the input from theby the Human Ethics Committee of Toyota Technologicalmechanoreﬂex was thought to remain constant. Although

Institute. All subjects were healthy and had an average age

the inﬂuence of the metaboreﬂex on the increase in MSNA

of 22.7 ± 2.7 years, height of 173.9 ± 4.6 cm, and weight of

was enhanced, an additional factor is needed to produce the63.9 ± 7.2 kg. The subjects were introduced to the routine

exponential increase in MSNA during strenuous exercise. It

1 day before the experiment to familiarize then with the test

was postulated that central command plays an important role

protocol and devices.

in mediating increased MSNA when a near-maximal effort
2 Handgrip exercise and training

is performed.
We reported previously that maximal intermittent hand-

The subjects were asked to perform ﬁve 15-s handgrip

grip training augmented the increase in MSNA during con-contractions at 75% maximal voluntary effort using the non-tinuous, fatiguing static handgrip contraction, and muscle

dominant hand to examine the contribution of central com-strength and exhaustion time increased 19). However, there

mand to MSNA enhancement. Each subject performed thewas no MSNA response during maximal rhythmic contrac-

static handgrip exercise in the supine position after a 15-mintion following the same training protocol 19). Consequent-rest in the supine position. The subjects started and stopped

ly, as rhythmic contraction at the onset, even at maximal

each contraction in response to an order from an experiment-

strength, was thought to be too brief to consistently result

er issued in time with a metronome.

in pronounced MSNA, we postulated that continuous near-

The maximal static handgrip was determined as the high-maximal voluntary effort is necessary to augment the MSNA

est value of three 3-s attempts over a 3-min period in theincrease.

standing position. The handgrip test was performed to evalu-

Previously, we observed that MSNA increased constantly

ate the effects of training on the cardiovascular response atduring continuous short (15-s duration) maximal handgrip

pre- and post-training sessions. The work performance of thecontractions, indicating that central command contributes tohandgrip was calculated by integrating the force curve.

the increase in MSNA not only at the onset of exercise but

The maximal handgrip training consisted of 10 contrac-

also during short continuous exercise . Augmented MSNA

tions of 10-s each separated by 10-s rests. The subjects per-increases were seen during each exercise bout, althoughformed three sets per day, 4 days per week for 4 weeks. After8)

no effects of the metaboreﬂex and mechanoreﬂex weretraining, ﬁve repetitions of a 15-s contraction were per-expected because the duration was too short for metabolites

formed to evaluate training effects. The training paradigm

to accumulate and the muscle force was reduced, despite

required maximal effort with the non-dominant hand. The

sustained maximal effort. We postulated that, unlike thenon-dominant hand was used to avoid unexpected negative

MSNA responses to the metaboreﬂex, which decrease at theeffects, such as augmented blood pressure (BP) increments

same work intensity , those induced by central command

during exercise and to maximize training effects because

may remain unchanged unless training enhances muscle

the initial performance level was generally lower than in thestrength 18).

dominant hand.

27)

Therefore, this study examined the hypothesis that nochange in the MSNA increment would occur for exercise at

3 Measurements

the same intensity using 15-s strenuous intermittent handgrip contractions to evaluate training effects after maximal1) Muscle sympathetic ner ve recording
MSNA was determined for the left tibial nerve. A tungsten

intermittent handgrip training over a 4-week period using

microelectrode with a shaft diameter of 0.1 mm was inserted

short, repeated handgrip exercises.

at the popliteal fossa 20). The nerve spikes, ampliﬁed by a fac-

─ 10 ─

Handgrip Training and Sympathetic Nerve Activity

tor of 100,000 were ﬁltered at 500–3000 Hz, rectiﬁed, andTokyo) by looking at the force generated.

integrated with a 0.1-s time constant to obtain the mean volt-

All signals were digitized at 200 Hz using an analog–

age. Muscle nerve activity was identiﬁed using the MSNA

digital converter (MP 100, BIOPAC Systems, Goleta, CA)

burst rhythm corresponding to the heart-beat cycle. The

and stored for later analysis on a personal computer with an

subjects performed the Valsalva maneuver to evaluate theonline data-acquisition program, which also calculated the

MSNA outﬂow, and arousal stimuli were used to ensure sig-mean arterial pressure. Data at rest were averaged over 3

nals from MSNA. The burst amplitude of the original mean

min before the experiment as the baseline. The subjects werevoltage neurogram signal was normalized (100 arbitrary

placed in the supine position and rested while they were con-units) using the highest MSNA burst throughout the experi-

nected to all of the devices before experiments started.

ment setting . One experimenter monitored the MSNA burst
8)frequency of all data. The burst numbers were expressed as

4 Statistics

the MSNA burst frequency (BF), and the area under each

Each cardiovascular value was evaluated using two-way

burst was referred to as total MSNA (TSNA). The subjects

analysis of variance (ANOVA) for training effects as thewere allowed to breathe normally and instructed not to holdmain effect and the interaction with the contraction ordertheir breath or contract extra muscles, especially the legs.

(Prism 5, Graph Pad Software, San Diego, CA). Values are
expressed as the means ± standard error (SE), and P < 0.05

2) Heart rate, blood pressure, and handgrip

was determined a signiﬁcant difference.

force
Heart rate (HR) was determined using the electrocardio-

Ⅲ RESULTS

gram R–R interval with bipolar electrodes positioned on
the chest (AB 118, Nihon Kohden, Tokyo). Blood pressure

Figure 1 shows an example of MSNA, handgrip perfor-(BP) was recorded with a Finapres blood pressure monitor

mance, and respiration for one subject. MSNA, BF, and(Ohmeda, Englewood, CO ). A ﬁnger cuff was attached to

TSNA in both the training and control hands over a 15-s

the middle ﬁnger of the non-exercising hand. The handgrip

contraction increased from baseline (all P < 0.0001, Fig. 2).

force was displayed on a monitor placed above the bed.

In each contraction, BF and TSNA were greater during the

The subjects were able to perform 75% MVC with a strain

last 7-s portion than during the ﬁrst 7-s for both hands (all P

gauge attached to a hand dynamometer (TKK 5710b, Takei,< 0.0001) (Fig. 3).

Fig. 1 The original records for one subject. Traces from top to bottom: muscle sympathetic
nerve activity during the 15-s intermittent contraction, handgrip force, respiratory flowchanges (upward inhalation, downward exhalation).

─ 11 ─

Tesshin Hachiya, Andrew P Blaber, Mitsuru Saito

Training
Training
Hand
Hand

Control
Control
Hand
Hand

Fig. 2 The MSNA responses during a 15-s intermittent static handgrip exercise. The upper and lower graphs
show the burst frequency and total activity, respectively. The left and right graphs indicate the training and control hands, respectively. * P < 0.05, ** P < 0.001, and *** P < 0.0001: signiﬁcant differences compared withbaseline.

FigFig2 2Training Hand

Early

Control Hand

Later

Fig 3

サイズ：2
サイズ：2
カラム
カラム

サイズ：2 カラム
Fig. 3 The MSNA responses divided into the early and late portions of the 15-s contraction. The upper and lower
graphs show the burst frequency and total activity, respectively. The left and right graphs indicate the training andcontrol hands, respectively. * P < 0.05: signiﬁcant difference between early and late portions of the contraction.

─ 12 ─

Fig 3.

Handgrip Training and Sympathetic Nerve Activity

After conditioning, the handgrip force in the training hand
did not change from before (45.3 ± 6.5 kg) to after (46.1 ±8.3 kg) training (P = 0.55) and did not change in the control
hand (48.5 ± 8.0 kg before and 47.4 ± 7.8 kg after training)(P = 0.44). The MSNA increases during the 15-s contraction(BF: P = 0.76 and TSNA: P = 0.11, Fig. 4) in the training
hand did not differ after conditioning. Additionally, no train-

Early

ing effect was observed in the two portions of the exercise

Later

for BF and TSNA in each contraction (BF: P = 0.94 early
portion and P = 0.95 late portion, Fig. 5; TSNA: P = 0.47
early portion and P = 0.09 late portion, Fig. 6).
The baseline HR and BP did not differ change during
training (HR: P = 0.87 and BP P = 0.19). The BP responses
in the training hand increased throughout the contraction,
whereas that in the control hand decreased (P < 0.05 and P< 0.05, respectively, Table 1). However, the HR during the
15-s contraction showed no training effect in either the nondominant training hand or dominant control hand (P = 0.51
and P = 0.19, respectively, Table 1), and the HR responses ineach portion of the exercise did not change after condition-

Fig. 5 MSNA BF responses in the early and late portionsof a 15-s contraction in the training hand before and afterFig 5

conditioning. The upper and lower graphs show the burst frequency.
Early Portion

サイズ：１カラム

Later Portion

Fig 4

Fig. 4 The MSNA responses during a 15-s intermittent static

Fig. 6 TSNA response in the early and late portions of a 15-s

handgrip exercise before and after maximal handgrip training. Fig 6

contraction in the training hand before and after conditioning.

The upper and lower graphs show the burst frequency and

The upper and lower graphs show the total activity.

total activity, respectively.
サイズ：１カラム

サイズ：１カラム─ 13 ─

Tesshin Hachiya, Andrew P Blaber, Mitsuru Saito

ing in either hand (P = 0.77 early and P = 0.99 late portion,(P = 0.25, Table 2), but it was greater in the late portion after

Table 2). BP in the early portion did not change after training

training (P < 0.01, Table 2).

Table 1. Heart rate and mean blood pressure before and after training during 15-s contraction.
N

Heart Rate(beats・min －1 )

Mean
Blood
Pressure(mmHg)

Base

One

Two

Three

Four

Five

Training
Hand

10

B-T

62.3

81.7

81.5

81.5

82.5

84.0

10

A-T

62.0

82.1

82.4

81.8

84.6

84.3

Control
Hand

10

B-T

62.3

84.9

82.2

85.1

84.3

85.9

10

A-T

62.0

82.5

82.5

82.1

83.1

84.1

Training
Hand

9

B-T

80.5

81.7

88.7

87.3

85.7

83.3

9

A-T

76.0

86.7

90.7

92.7

95.5

94.8

Control
Hand

9

B-T

80.5

89.5

97.2

98.9

102.3

100.1

9

A-T

76.0

85.7

92.0

94.4

95.1

96.4

p-value
p=0.51

p=0.19(increased)
p<0.05(decreased)
p<0.05

B-T and A-T indicate before training and after training, respectively. N: number of subjects.

Table 2. Heart rate and mean blood pressure in the Early and Late portions in training hand and before and after training.
N

Heart Rate(beats・min －1 )

Mean
Blood
Pressure(mmHg)

Base

One

Two

Three

Four

Five

B-T

10

Early

62.3

78.1

78.7

78.1

80.1

81.1

A-T

10

Early

62.0

77.4

80.1

78.4

80.9

81.3

B-T

10

Late

62.3

86.8

84.8

84.9

85.2

88.5

A-T

10

Late

62.0

86.4

84.5

84.6

87.7

87.1

B-T

9

Early

80.5

79.5

88.0

87.4

84.3

81.8

A-T

9

Early

76.0

82.9

85.9

89.2

91.2

90.9

B-T

9

Late

80.5

84.3

89.2

87.0

87.0

84.6

A-T

9

Late

76.0

90.8

95.4

95.7

99.5

98.5

p-value
p=0.77p=0.99p=0.25p<0.01

B-T and A-T indicate before training and after training, respectively. N: number of subjects. In the late portion after training mean bloodpressure was greater than the early portion (p < 0.0001).

hand during the intermittent 15-s handgrip after the 4-week
Ⅳ DISCUSSION

period of repeated maximal contractions, but BP increased at
the same work load with no change in muscle strength. We

During 15-s handgrip at 75% MVC, MSNA, BF, andconsidered two hypotheses to account for the results. First, it

TSNA increased from baseline in the ﬁrst through ﬁfth

is possible that 75% MVC intermittent contractions were notbouts. Central command is thought to contribute to MSNA

adequate for evaluating MSNA changes, and second, it may

augmentation during short contractions, whereas increased

be that maximal intensity exercise was insufﬁcient to affectstrenuous voluntary effort is required to sustain constantchanges in MSNA responses.

muscle force. No change was observed in the MSNA
response induced by central command in the non-dominant─ 14 ─

Handgrip Training and Sympathetic Nerve Activity

1 Training effects on MSNA

command to the values. The MSNA increases during thePreviously, we observed exponential increases in MSNA

early portion should result mainly from central command 29)

22)

in the fatigued stage during static handgrip at 20% MVC ,(Fig. 3), although mechanoreﬂex involvement was not ruled

leading us to postulate that greater enhancements in MSNA

out because it begins within 4~6 s 9). We found that the latewere elicited by both peripheral reﬂexes and central com-part of the MSNA response increased more than the early

mand contributions. We applied this ﬁnding to investigate

portion despite the steady muscle force (Fig. 1), indicating

the training effects of central command involvement inthat central command continued to increase with the aug-

MSNA responses and found that MSNA increases weremented voluntary effort.

enhanced without metaboreﬂex inﬂuences during moderate

The MSNA enhancement during contraction was notstatic contraction to exhaustion, although the time to fatigue

necessarily stimulated by the mechanoreﬂex because thewas extended, and the maximal handgrip force increased

mechanoreﬂex involvement is associated with muscle force

after maximal intermittent handgrip training . We postulat-

production 4, 6, 10). Therefore, the exercise paradigm was19)

ed that voluntary fatiguing efforts would produce maximal

considered to be adequate for evaluating the effects of cen-force generation at the ﬁnal stage, when central commandtral command on the MSNA responses during training. We

might be involved in the augmented MSNA responses.

believe that the MSNA increases were enhanced by training

The same previous study tested the MSNA response toeffects, resulting in an increase in muscle strength as long as

maximal rhythmic contraction as an evaluation exercise,continuous maximal voluntary effort was performed during

and no change in the MSNA response was seen 19). Because

the 15-s handgrip, similar to the ﬁnal stage of a fatiguing

maximal intermittent contraction did not consistently induce

contraction. However, the results indicated that no training

MSNA increments 29), no training effect of MSNA enhance-

inﬂuence on augmentation of the MSNA increases initiatedment on central command involvement appeared during

by central command was obtained, suggesting that the vol-each contraction. Therefore, we assumed that to evaluate theuntary effort was insufﬁcient to stimulate further MSNA

role of central command in MSNA augmentation, strenuous

increments, as 15 s may be an insufﬁcient duration to sustain

effort must be continued so as to enhance the MSNA incre-a maximal voluntary effort.
Although no training effect on an augmented MSNA

ment during the evaluation exercises.
We demonstrated that central command played an impor-response was observed, we believe that the training protocoltant role in enhancing the MSNA response during 15-s hand-

was adequate, as subjects in a previous study, who trained

grip intermittent contraction with maximal voluntary effort,

using the same training paradigm, increased their maximal

whereas the muscle force declined over 10 repeated exercise

force 19). One of the reasons for the difference in results,

bouts 8). The intermittent contraction removed the inﬂuence

including the lack of change in muscle strength, may be aof the MSNA increments caused by fatigue as a mental

difference in the study subjects. Although we followed thestress, inducing a rise in MSNA . This approach avoided

previous training protocol, in which the subjects trained at

the inﬂuence of the metaboreﬂex induced by accumulated

their own pace, the subjects in this study trained with lessmetabolites.

focus than the former subjects did.

12)

Although a previous study indicated that central com-

In terms of a training effect on the MSNA changes, there

mand enhanced the MSNA increases during 15-s intermit-

is agreement that MSNA augmentation by the metaboreﬂex

tent maximal contractions, contractions performed at 75%

might be attenuated after moderate-intensity conditioning

intensity were needed to show enhanced MSNA increases

due to changes in the resistance to metabolites, as endurance

caused by central command. Therefore, compared with thetraining improved the resistance to hydrogen ions, one ofprevious exercise paradigm in which the generating force

the by-products of exercising muscle 1, 26, 27). These studies

might decline 8), the subjectsʼ efforts increased in this study

indicated that conditioning improved the MSNA response toso as to sustain the 75% voluntary force, thereby maintain-

the metaboreﬂex at the same workload.

ing constant input from the mechanoreﬂex. When analyzing

However, we believe that moderate workloads were notthe cardiovascular data, we divided each 15-s bout into two

suitable when the change in the MSNA increment induced

portions to examine the enhanced contribution of central

by central command with strenuous effort was assessed,

─ 15 ─

Tesshin Hachiya, Andrew P Blaber, Mitsuru Saito

and thus maximal intensity training might not inﬂuence

These results countered the results of Ray and Carrasco 17),the metaboreﬂex. Although no MSNA increment under the

who found that resting BP and HR, but not MSNA, decreased

inﬂuence of central command was found with training in thisfollowing handgrip conditioning. Our inconsistent results

study, the changes in BP showed that the training affectedsuggest that the training load we used was insufﬁcient tothe subjects, although it did not change muscle strength. We

exhibit a training effect on HR.

think that the MSNA responses at the same workload were

BP increased in the training hand, unlike the control hand,

not affected after training because central command involve-

during the 15-s contraction after conditioning due to a great-ment in the cardiovascular response was enhanced, with aner increase in the late portion of the contraction (Table 2).

increase in muscle strength 18). Previously, we found that the

Glannattsaio et al. 7) demonstrated that BP in weightlifters

increase in MSNA declined after 4 weeks of detraining 19).

was greater than that in sedentary subjects, and the peripheral

Therefore, in this study, the training was sustained at the ini-

vessel walls in weightlifters were thicker than those in theirtial level without a reduction in the physical properties ofcounterparts. Our results suggest that this training regimen

the subjects, indicating that the increase in MSNA induced

had similar effects on the peripheral blood vessels (Table 2).

by central command did not change at the same workload.

However, we postulate that the central contribution to the

However, it was also possible that the training load was

BP change occurred after strenuous handgrip training, as BP

insufﬁcient, as the MSNA responses in the control subjects

changed in both the training and control hands (Table 1).
The non-dominant hand was used as the training limb

during training and detraining did not differ 19).
Metabolites sensitize the mechanoreﬂex 9, 15), although we

because we expected that the training effects might be

do not know how the mechanoreﬂex itself affects the MSNA

greater than in the dominant hand 27). Greater training effects

response after conditioning. Mechanically sensitized MSNA

should be obtained when the initial ﬁtness level is relatively

responses were reportedly attenuated during non-fatiguing

moderate. However, there was no difference in the MSNA

rhythmic contractions after conditioning 26), but it was not

response during the 15-s contraction between the training

clear how intermittent maximal intensity training affects

and control hands either before or after conditioning, prob-

such sensitization. The possibility of enhanced sensitivity

ably because the training hand demonstrated no training

was unlikely after 10-s intermittent handgrip training wheneffect.

the evaluation exercise was performed with unchanged

Although an electromyogram (EMG) was not used tomechanoreﬂex input 8). We attempted to minimize the inﬂu-

visualize the increase in muscle activity with continuous

ence of the metaboreﬂex and the effect of change in thevoluntary effort, we previously reported increased EMG dur-mechanoreﬂex on MSNA increases by applying a short

ing static handgrip at 30% MVC while subjects watched anstrenuous contraction in both the training and evaluation

oscilloscope displaying their steady muscle force 21). It was

schemes. Consequently, appropriate training paradigms andthought that muscle activity reﬂected by the EMG increased

exercise schemes must be chosen to evaluate the training

gradually to continue generating a constant force 23, 24). Sinceinﬂuence on the MSNA response due to central command.

our subjects were asked to perform at 75% MVC, they tried

One major concern in our studies is the inﬂuence of

to maintain the force at a level as much as possible. Althoughrespiration. However, Debeck et al. 5) found no difference

additional effort might have approached the maximum level,

between the effects of spontaneous breathing and of con-

we believe that they maintained 75% MVC, as shown in Fig

trolled breathing at a constant tempo on the MSNA increase.

1. However, one subject did not maintain constant force, andWe asked our subjects to avoid the Valsalva maneuver andhis data were removed from the analysis.

not to hyperventilate because both actions affect the MSNA
response during contraction 11).

In conclusion, we found that the MSNA response during
a 15-s handgrip contraction did not change after handgrip
training involving three sets of 10 10-s maximal contrac-

2 HR and BP response

tions a day 4 days a week for 4 weeks. The MSNA response

We did not ﬁnd effects of training on HR and BP at rest

induced by central command did not change under the sameor during contraction, except that BP in the training handtraining load, although the training load, frequency, andincreased during contraction after conditioning (Table 1).

duration may have been insufﬁcient to induce a change in─ 16 ─

Handgrip Training and Sympathetic Nerve Activity

the study subjects. We postulate that the appropriate train-14) Matsukawa K (2011) Central command: control of cardiac sympathetic and vagal efferent nerve activity and the rterial barore-ing scheme and training evaluation exercise are important

ﬂex during spontaneous motor behaviour in animals. Exp Physiol

to observe the effects of training on the MSNA response,and 15-s strenuous intermittent contraction was consideredadequate for evaluating the MSNA responses induced by

97:20-28
15) Middlekauff HR, Chiu J (2004) Cyclooxygenase products sensitize muscle mechanoreceptors in healthy humans. Am J Physiol

central command．

Heart Circ Physiol 287:H1144-H1149
16) OʼLeary DS (1993) Autonomic mechanisms of muscle metaboreﬂex control of heart rate. J Appl Physiol 74:1748-1754

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Journal of the Institute for Psychological and Physical Science, Vol. 7 , No. 1 , 9 ┉19, 2015

筋交感神経活動に及ぼす間欠的最大握力トレーニングの効果
蜂矢

鉄心＊2），Andrew P Blaber＊2），齊藤

満＊1）

Abstract【目的】 本研究の目的はセントラルコマンドによる運動時の筋交感神経活動亢進はトレーニングの影
響を受けないという仮説の検証である．
【方法】 11 名の健康な成人男性を対象とし，10 秒間の最大努力ハンドグリップを 10 回繰り返すセッ
ト運動を一日 3 回，週 4 日，4 週間実施した．トレーニング側は非利き手とし，利き手は対照とした．
筋交感神経活動に対する最大努力ハンドグリップ運動の効果は 15 秒間のハンドグリップ運動とし，最大握力（MVC）の 75％張力発揮を 5 回繰り返す運動テストと，その際の筋交感神経活動反応を観察した．筋交感神経活動は膝窩部脛骨神経より微小神経電図法により導出した．交感神経活動および心循環反応は 15 秒間の運動の前半と後半に分割し解析した．
【結果】 間欠運動の 1 回目から運動開始と同時にセントラルコマンド性の筋交感神経活動の増加が認められ，5 回を通して同程度の反応が認められた．間欠運動時の筋交感神経活動反応はトレーニン
グ前後において差は認められなかった．
運動時の血圧反応はトレーニング後に高まる傾向を示したが，心拍反応の差は認められなかった．トレーニング後の最大握力の増加量には有意差は認められなかった．
【結論】 筋収縮時のセントラルコマンド性筋交感神経活動亢進が最大努力ハンドグリップトレーニ
ングの影響を受けないことを間欠的な高い筋収縮運動で確認した．この結果は，運動時の筋交感神経活動亢進に対するセントラルコマンドの影響に関するトレーニング効果の評価法として間欠的な75%MVC 筋収縮運動が有用であることを示唆する．
キーワード：筋交感神経活動；セントラルコマンド；筋力トレーニング；間欠ハンドグリップ運動

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