Accepted Manuscript

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Short Communication

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Evaluation of differences in exercise load due to varied lower limb weight during stair3

ascending and descending: a pilot study

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Seiya Shimizu1, Taisei Matsui2, Kurumi Yoshikane3, Sachi Hiramatsu4 and Kohji Iwai5*

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Toyokawa City, Aichi 442-0862, Japan

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2

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City, Aichi 465-0087, Japan

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Division of Rehabilitation, Toyokawa Sakura Hospital, 30-1 Omichishita, Ichida-cho,

Division of Rehabilitation, Kimura Hospital, 2-22-1 Meitohondori, Meitoku, Nagoya

Division of Rehabilitation, Juko-Osu Hospital, 2-17-5 Matsubara, Nakaku, Nagoya City,

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Aichi 460-0017, Japan

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4

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Nagoya City, Aichi 457-0841, Japan

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5

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172, Fukinodai, Tokai City, Aichi 476-8588, Japan

Division of Rehabilitation, Meinan Fureai Hospital, 5-15-18 Toyoda, Minamiku,

Division of Physical Therapy, Faculty of Rehabilitation and Care, Seijoh University, 2-

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Number of tables and figures: 3 tables and 3 figures

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Running title: Stair load variation due to lower limb weight

18*Correspondence: iwai@seijoh-u.ac.jp

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Abstract

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This study aimed to investigate the differences in exercise load due to variations in lower

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limb weight during stair ascent and descent. The study involved 10 healthy adult men and22

women without respiratory or circulatory diseases (five men and five women). Using a

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respiratory gas analysis device, the participants performed stair climbing under three24

conditions: 1) full weight, 2) half (partial) weight-bearing, and 3) non-weight-bearing.

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The maximum oxygen uptake during stair climbing was defined as the peak oxygen

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uptake. Additionally, the time required for ascent and descent was measured using a

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stopwatch, and heart rate and perceived fatigue at the end were assessed using the Borg

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scale. Peak oxygen uptake and Borg scale scores significantly increased during ascent29

and descent under the non-weight-bearing condition compared to those under the full30

weight-bearing and half-weight-bearing conditions. The required time was significantly

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extended under the half-weight-bearing and non-weight-bearing conditions compared to32

that under the full-weight-bearing condition. Therefore, when stair ascent and descent are

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necessary during a period requiring the use of both crutches, it is considered desirable to34

perform them only after at least half-weight-bearing condition or more is permitted, as

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this approach results in a considerable reduction in load.

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Keywords: exercise load, lower limb load, oxygen uptake

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階段昇降時の下肢重量の違いによる運動負荷の差異についての検討; 予備的研

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究

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著者：清水聖也 1), 松井大晟 2), 吉兼未来 3), 平松さち 4), 岩井宏治(PhD) 5) *41

所属：1) 豊川さくら病院リハビリテーション室, 2) 木村病院リハビリテーショ

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ン科, 3) 重工大須病院リハビリテーション部, 4) 名南病院リハビリテーション

43課, 5) 星城大学リハビリテーション学部理学療法学専攻

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責任著者：岩井宏治* (iwai@seijoh-u.ac.jp)

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要旨

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本研究の目的は、階段昇降時の下肢重量の違いによる運動負荷の差異を調べる

48ことである。本研究では、呼吸器および循環器疾患の既往がない健康な成人男女49

10 名（男性 5 名、女性 5 名）を対象とした。呼吸ガス分析装置を用いて、参加

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者は 3 つの条件下で階段昇降を行った： 1）全荷重負荷、2）部分荷重 (1/2 荷重)

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負荷、3）非荷重負荷。階段昇降中の酸素摂取量の最大値を最高酸素摂取量と定52義した。さらに、階段昇降に要した時間をストップウォッチで計測た。また終了

53時の心拍数を測定し、疲労感はボルグスケールで評価した。

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最高酸素摂取量とボルグスケールのスコアは、非荷重負荷において、全荷重負荷

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および部分荷重負荷と比較して、昇段降段の両方で有意に増加した。所要時間は、

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全荷重負荷に比べ、部分荷重負荷および非荷重負荷では有意に延長した。従って、

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両松葉杖の使用が必要な期間に階段の昇降が必要な場合は、少なくとも部分荷58

重 (1/2 荷重) が許可された以降に昇降することが、負担軽減になり望ましいと59

考えられる。

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Introduction

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When surgery is performed for conditions such as open or complex fractures of the lower

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limb, weight-bearing restrictions are often imposed, necessitating the use of crutches.

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Therefore, for a certain period, using crutches is essential as an independent means of65

mobility and to promote bone healing. Walking with crutches results in an increased load

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compared to normal walking [1]. Adedoyin et al. measured cardiovascular responses

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during stair ascent and descent using axillary and elbow crutches, reporting significant

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increases in parameters, including blood pressure and heart rate (HR), with no difference

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between axillary and elbow crutches [2]. Furthermore, Moran et al. measured oxygen

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consumption during walking on level ground and stair ascent and descent with crutches,

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identifying a significant increase in oxygen consumption during stair ascent and descent72

with no differences between sexes [3]. Under non-weight-bearing (NWB) conditions of

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the lower limbs, previous studies have demonstrated that oxygen consumption

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significantly increases when walking with bilateral crutches without a prosthetic limb

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compared with walking with a prosthetic limb [4]. Additionally, during stair76

ascent/descent in the NWB condition, there is a significant increase in the activity of the77

gluteus medius of the supporting leg [5]. This suggests that bilateral crutch walking under78

NWB conditions imposes higher muscle and cardiopulmonary loads, with further

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increases during stair ascent. However, the differences in exercise load due to variations

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in lower limb weight-bearing during stair ascent remain unknown. Therefore, this study

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aimed to investigate differences in exercise load during stair ascent with three conditions

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altering lower limb weight-bearing (full weight-bearing [FWB], half (partial) weight-

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bearing [1/2 PWB], and NWB) using respiratory gas analysis equipment. The objective

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was to elucidate differences in exercise load due to changes in lower limb weight-bearing85

and provide information for lifestyle guidance using crutches.

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Materials and Methods

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Participants

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This pilot study involved 10 healthy adult individuals (five men, five women) without90

cardiovascular or other medical contraindications. Basic information was obtained, and91lung function, respiratory muscle strength (Autospiro AS-507; MINATO Co., Osaka,

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Japan), grip strength (TKK-5401; Takei Scientific Instruments Co., Tokyo, Japan), and93

quadriceps torque (Isoforce GT-360; OG Wellness Co., Okayama, Japan) were assessed

94(Table 1). Lower limb weight-bearing conditions were set as FWB, 1/2 PWB, and NWB.

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To eliminate any order effects, the 10 participants were divided into three groups

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comprising three, three, and four individuals, and measurements were performed. A

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washout period of at least 3 days was implemented after each measurement session (Fig.

981). Furthermore, to eliminate the thermal effects of food, all participants were required to99

fast for 2 h before the examination (water intake was allowed). The crutches were adjusted

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according to each participant’s physique, and the final height was set to the most101

comfortable level for each participant [6]. Prior to the measurements, an educational102

session of 10–15 min was conducted to practice stair ascent/descent using crutches. In the103

1/2 PWB condition, visual feedback was provided during practice using a body scale.

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These sessions were supervised by two members of the research team. In all three105

conditions, with the dominant leg as the weight-bearing side, ascent was performed

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starting from the dominant leg, and descent was performed starting from the non-107

dominant leg (the NWB condition was for the dominant leg only). Stair ascent and descent108

were performed in a two-action, one-step pattern for all conditions (Fig. 2).

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Study protocol

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The oxygen consumption was measured using a respiratory gas analysis device

112(COSMED K5 wearable metabolic system; COSMED, Rome, Italy). The participants

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wore the COSMED K5 wearable metabolic system with a harness and performed stair

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ascent/descent from the first to the third floor (49 steps, each 17 cm) under three115

conditions: FWB, 1/2 PWB, and NWB. The maximum oxygen consumption value

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obtained from the data using the breath-by-breath method was defined as the peak oxygen

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uptake (peak VO2) and converted to the metabolic equivalent of task (METs). Similarly,

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minute ventilation (VE) was also measured. Furthermore, previous studies have

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demonstrated the reproducibility and validity of the COSMED wearable metabolic

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system [7,8]. Before the start of the ascent, all participants were seated for at least 5 min

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of rest, and the HR was generally maintained at approximately 80 beats/min. It was

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confirmed that the oxygen intake during rest times was approximately 200 ml/min,123

corresponding to approximately 1 MET. The speed of stair ascent and descent were

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optional for the participants. After completing the stair ascent, the HR of the participants

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was measured, and their breathlessness and fatigue were assessed using the Borg scale.

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Following stair ascent, participants rested adequately until their pre-ascent state was127

confirmed (HR approximately 80 beats/min, oxygen intake approximately 200 ml/min),128

and stair descent was then measured similarly. Additionally, the time required for ascent129

and descent (task completion time) was measured using a stopwatch (TD-392; TANITA

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Co., Tokyo, Japan).

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Ethical consideration

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Ethical considerations were observed, and this study was approved by the Ethics

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Committee of Seijo University (Approval Number: 2023P0002). Additionally, the135

research objectives were explained to all participants, and written consent for research

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participation was obtained.

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Statistical analysis

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Statistical analysis was performed using EZR software (Saitama Medical Center, Jichi

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Medical University, Saitama, Japan), which is a graphical user interface for R (The R

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Foundation for Statistical Computing, Vienna, Austria) [9]. Results were considered142

statistically significant if the two-tailed p-value was < 0.05. Data are expressed as mean

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± standard deviation, except for non-normally distributed variables, which are presented

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as medians. Statistical analysis involved testing for normality (Shapiro–Wilk test),

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followed by repeated measures one-way analysis of variance for the normally distributed

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variables and Friedman test for the non-normally distributed variables for three147

conditions: FWB, 1/2 PWB, and NWB. Post-hoc tests were conducted using the148

Bonferroni method.

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Results

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The average resting oxygen intake before ascent under the three conditions was 197.6 ±

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38.2 ml/min, equivalent to 1.0 ± 0.2 METs. Similarly, the average resting oxygen intake

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before descent under the three conditions was 218.4 ± 69.1 ml/min, equivalent to 1.0 ±154

0.2 METs. The peak VO2, VE, task completion time, Borg scale scores, and HR during

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stair ascent are presented in Table 2. In terms of peak VO2, a significantly higher value

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was observed under the NWB condition (average of 1844 ml/min [9.5 METs]) than that157

under the FWB and 1/2 PWB conditions (p = 0.010, p = 0.005). The rate of increase in158

workload was approximately 31.6–35.7% higher under the NWB condition than under159

the FWB and 1/2 PWB conditions (Fig. 3-A). VE significantly increased under the NWB

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condition compared to that under the FWB and 1/2 PWB conditions (both p < 0.001).

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Regarding task completion time, a significant extension was observed under the 1/2 PWB

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and NWB conditions compared to that under the FWB condition (p = 0.001, p < 0.001).

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Moreover, the NWB conditions were significantly extended compared to the 1/2 PWB

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condition (p < 0.05). The Borg scale results mirrored those of peak VO2, showing a165

significant increase in breathlessness and fatigue under the NWB condition compared to166

that under the FWB and 1/2 PWB conditions (both p < 0.001). HR significantly increased

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under the NWB condition compared to that under the FWB condition (p < 0.05).

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The peak VO2, VE, task completion time, Borg scale scores, and HR during stair descent169

are presented in Table 3. Similar to stair ascent, peak VO2 under the NWB condition was

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significantly higher than that under the FWB and 1/2 PWB conditions (p = 0.001 and p =1710.017, respectively). Although the workload was not as high as that during ascent, an

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average of 1341 ml/min (7.2 METs) indicated a substantial load during descent. The rate

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of increase in workload was 37.5–44.4% higher under the NWB condition than under the174

FWB and 1/2 PWB conditions (Fig. 3-B). VE significantly increased under the NWB

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condition compared to that under the FWB and 1/2 PWB conditions (p < 0.001 and p =176

0.010, respectively). Regarding task completion time, a significant extension was177

observed under the 1/2 PWB and NWB conditions compared to that under the FWB

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condition (both p < 0.001). Moreover, the NWB conditions were significantly extended

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compared to the 1/2 PWB conditions (p < 0.05). At the end of the Borg scale, results

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reflected those of peak VO2. The findings showed a significant increase in breathlessness

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and fatigue under the NWB condition compared to that under the FWB and 1/2 PWB

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conditions (p < 0.001 and p = 0.001, respectively). HR significantly increased under the183

NWB condition compared to that under the FWB condition (p < 0.05).

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Discussion

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Walking with bilateral crutches in the NWB condition is speculated to impose higher

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muscular and cardiorespiratory loads [4,5], with further increases during stair

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ascent/descent. However, there have been no studies on workload at different load levels

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on the lower extremities. Generally, 1/2 PWB and NWB conditions require the use of190

both crutches, since the use of both crutches is necessary. Therefore, in our study, we

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examined differences in exercise load during stair ascent/descent using bilateral crutches

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under FWB, 1/2 PWB, and NWB conditions.

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The results revealed a significant increase in workload during ascent and descent under194

the NWB condition compared with that under the FWB and 1/2 PWB conditions.

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Similarly, a significant increase in VE was also observed. Furthermore, HR was

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significantly elevated under the NWB condition compared to that under the FWB

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condition. Key findings of our study are the significant increases in workload, by 32–36%

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during NWB ascent and 38–44% during NWB descent, compared with those under the199

FWB and 1/2 PWB conditions.

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Even on level ground, walking with crutches under NWB conditions increases

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cardiopulmonary load; however, during stair ascent under NWB conditions, the202

supporting leg bears high loads and must also lift and lower body weight. Additionally,203

as the load on the lower limbs decreases, the load on the upper limbs increases

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accordingly [10,11], suggesting that under NWB conditions, both upper limbs are

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subjected to high loads. The significant increase in VE and HR under NWB conditions

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provides evidence of high load. These factors likely contribute to the high workload

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observed under the NWB condition.

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On the Borg scale, significant increases in breathlessness and fatigue were observed under209

the NWB condition compared to those under the FWB and 1/2 PWB conditions. These

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results, consistent with those of peak VO2, suggest that as the exercise load increases,

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breathlessness and fatigue also increase.

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Regarding task completion time, a significant extension was observed under 1/2 PWB

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and NWB conditions compared with that under the FWB condition. The prolonged task

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completion time in the NWB and 1/2 PWB conditions suggests that an increase in215

workload and the addition of tasks involving crutch use influenced the extension of time.

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This study has some limitations. First, while a decrease in lower limb load would likely

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result in an increased load on the upper limbs [10,11], we did not investigate its impact

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on the upper limb load. Additionally, we did not account for sex differences in muscle

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strength. Secondly, fractures are also common in older adults [12], necessitating the use

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of crutches; however, our study focused only on young adults, leading to a potential

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selection bias. Additionally, not specifying the speed during stair ascent and descent and222

leaving it to individual discretion should be considered as it may have influenced the223

results.

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Based on the above results, ascending and descending approximately 50 stairs with225

bilateral crutches under NWB conditions impose a high load (7.1–9.5 METs or more),226

even in healthy adults. This results in approximately a 30–45% increase in cardiac load

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compared to that under FWB and 1/2 PWB conditions. Therefore, stair ascent and descent228

under NWB conditions are not recommended for older individuals with low exercise

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tolerance or those with heart or respiratory conditions. Conversely, when half of the body230

weight is supported, the load is significantly reduced. Therefore, when stair ascent and231

descent are necessary during a period requiring the use of both crutches, they should

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ideally be performed only after at least 1/2 PWB or more is permitted.

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Acknowledgments

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We would like to thank Editage (www.editage.jp) for English language editing.

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Conflicts of Interest

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The authors declare that there are no conflicts of interest.

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240

Contributions

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SS, TM and KI conceptualized the study design and protocol. SS, TM, SH, KY and KI

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collected and assembled the data. SS and TM carried out the analysis and interpretation

243of data. SS, TM and KI drafted the manuscript. All authors have critically reviewed,244

revised and approved the final.

245
246

References247

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expenditure of ambulation using the Sure-Gait crutch and the standard axillary crutch.

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Phys Ther 70: 18-23. doi: 10.1093/ptj/70.1.18.

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2. Adedoyin RA, Opayinka AJ and Oladokun ZO. 2002. Energy expenditure of stair251

climbing with elbow and axillary crutches. Physiotherapy 88: 47-51. doi:252

10.1016/S0031-9406(05)60528-7.

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J. 2015. The energy expenditure of non-weight bearing crutch walking on the level255

and ascending stairs. Gait Posture 42: 23-26. doi: 10.1016/j.gaitpost.2014.

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4. Mohanty RK, Lenka P, Equebal A and Kumar R. 2012. Comparison of energy cost in

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transtibial amputees using ‘‘prosthesis’’ and ‘‘crutches without prosthesis’’ for258

walking259

10.1016/j.rehab.2012.02.006.

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V, McKay I and Carpes FP. 2022. Effects of Elbow Crutch Locomotion on Gluteus

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Medius Activation During Stair Ascending. Front Bioeng Biotechnol 10: 890004. doi:263

10.3389/fbioe.2022.890004.

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6. Mullis R and Dent RM. 2000. Crutch length: Effect on energy cost and activity

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10.1016/s0003-9993(00)90036-4.

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Cosmed Quark b2 and K4b2 gas analysis systems during submaximal exercise. J

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9. Kodama Y. 2013. Investigation of the freely available easy-to-use software 'EZR' for274

medical statistics. Bone Marrow Transplant 48: 452-458. doi: 10.1038/bmt.2012.244.

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10. Fischer J, Nüesch C, Göpfert B, Mündermann A, Valderrabano V and Hügle T. 2014.

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Forearm pressure distribution during ambulation with elbow crutches: a cross-277

sectional study. J Neuroeng Rehabil 11: 61. doi: 10.1186/1743-0003-11-61.

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11. Bellenfant KB, Robbins GL, Rogers RR, Kopec TJ and Ballmann CG. 2021. Effects

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of Dominant and Nondominant Limb Immobilization on Muscle Activation and280

Physical Demand during Ambulation with Axillary Crutches. J Funct Morphol

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Kinesiol 6: 16. doi: 10.3390/jfmk6010016.

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12. Je M, Kang K, Yoo JI and Kim Y. 2023. The Influences of Macronutrients on Bone

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Mineral Density, Bone Turnover Markers, and Fracture Risk in Elderly People: A

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Legends

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Table 1. Baseline characteristics of the participants.

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Table 2. Results of stair ascent under three conditions.

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Table 3. Results of stair descent under three conditions.

290

Fig. 1. Order of measurement.

291

Fig. 2. Stair ascent in three conditions. Stair ascent was performed starting from the292

dominant leg, and stair descent was performed starting from the non-dominant leg.

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Fig. 3. Rate of load increase stair ascension/descent in three conditions. (A) Stair ascent,294(B) stair descent.

FWB; full weight-bearing, 1/2 PWB; half (partial)
weight-bearing, NWB; non-weight-bearing
Figure 1. Order of measurement.

Order ① → ②
FWB; full weight-bearing, 1/2 PWB; half(partial) weight-bearing, NWB; non-weightbearing
Figure 2. Stair ascent in three conditions.
Stair ascent was performed staring from thedominant leg, and descent was performed
staring from the non-dominant leg.

FWB; full weight-bearing, 1/2 PWB; half (partial) weight-bearing, NWB; nonweight-bearing
Figure 3. Rate of load increase during stair ascent / descent in three conditions. (A)Stair ascent, (B) stair descent.

Table 1. Baseline characteristics of the participants
All participants (n=10)
Age (years)

21 (21-22)

Gender (Men, %)5 (50)Height (cm)162.6 ± 8.6

Weight (kg)58.6 ± 13.3

Grip strength (kg)37.4 ± 10.2

Quadriceps torque (Nm)

131.3 ± 38.3

VC (L)

4.1 ± 0.8

%VC (%)

96.8 ± 5.5

FEV1 (L)

3.5 ± 0.6

FEV1 /FVC (%)

87.3 ± 4.6

Inspiratory muscle strength (cmH2O)

74.2 ± 15.5

Expiratory muscle strength (cmH2O)

83.6 ± 28.0

VC; vital capacity, FEV1; forced expiratory volume in one second,
FVC; forced vital capacity

Table 2. Results of stair ascent under three conditions
effect size

FWB

1/2 PWBNWB

Peak VO2 (ml/min)

1305.0 ± 311.2

1246.6 ± 479.7

1843.7 ± 361.7♭♭(METs)(6.5 ± 1.3)

(6.1 ± 1.9)(9.5 ± 2.5)

Minute ventilation (L/min)29.2 ± 5.6

31.6 ± 7.2

43.2 ± 9.0 ♭♭

0.29

**
♭

0.46

**
♭♭

0.41

Task completion time (s)63.6 ± 5.1

(η2)
**

**

**

89.0 ± 11.5

98.1 ± 13.3

Borg scale

1.0 (1.0-1.8)

2.0 (1.0-2.0)

5.0 (3.3-5.0)

Heart rate (beat/min)

103.4 ± 16.3

117.7 ± 19.6

127.0 ± 14.6

*

0.16

0.07

p<0.01vs FWB, ＊p<0.05 vs FWB, ♭♭p<0.01 vs 1/2 PWB, ♭p<0.05 vs 1/2 PWB＊＊

FWB; full weight-bearing, 1/2 PWB; half (partial) weight-bearing, NWB; non-weight-bearing,
Peak VO2; peak oxygen uptake, min; minute, s; second

Table 3 Results of stair descent under three conditions
effect size

FWB

1/2 PWBNWB

Peak VO2 (ml/min)

822.6 ± 235.0

887.4 ± 321.1

1341.2 ± 250.4(METs)(4.0 ± 0.7)

(4.5 ± 1.5)

(7.2 ± 1.8)

Minute ventilation (L/min)

Task completion time (s)23.7 ± 4.2

53.9 ± 2.5

(η2)
**
♭

**
♭

27.2 ± 6.9

34.4 ± 6.9**

85.7 ± 13.8

0.27

0.25
**
♭

102.5 ± 23.4**♭♭

Borg scale

1.0 (0.3-1.0)

1.0 (1.0-1.8)

3.0 (3.0-3.8)

Heart rate (beat/min)

94.7 ± 12.7

102.8 ± 14.1

111.3 ± 8.6

*

0.42

0.35

0.07

p<0.01vs FWB, ＊p<0.05 vs FWB, ♭♭p<0.01 vs 1/2 PWB, ♭p<0.05 vs 1/2 PWB＊＊

FWB; full weight-bearing, 1/2 PWB; half (partial) weight-bearing, NWB; non-weight-bearing,
Peak VO2; peak oxygen uptake, min; minute, s; second