Soft Hip Exoskeleton Reduces Physiological Cost and Perceived Exertion In Older Adults During Uphill Walking

Summary

This protocol evaluates the efficacy of a lightweight soft hip exoskeleton in reducing physiological stress during uphill walking in older adults. Using a randomized crossover design, the method demonstrates that the device significantly reduces physiological cost and subjective fatigue in the elderly.

Abstract

Mountain hiking and mountaineering are common activities for active older adults to maintain cardiovascular fitness; however, the high physiological demands of these activities often accelerate the onset of neuromuscular fatigue. This fatigue is a critical risk factor for sports-related injuries, such as falls and musculoskeletal strains. This study aims to investigate whether a lightweight soft hip exoskeleton can mitigate these risks and support safe physical activity for older adults during simulated mountaineering tasks. Twenty healthy older adults (63.45 ± 3.70 years) participated in a randomized crossover trial on a treadmill set to a 15% incline at 3.5 km/h. Participants walked for 15 min under three conditions: No Exoskeleton (NO_EXO), Exoskeleton Active (EXO_ON), and Exoskeleton Passive (EXO_OFF). Outcomes included Physiological Cost Index (PCI), Peak Heart Rate (HR_Peak), and Rating of Perceived Exertion (Borg RPE). Active assistance (EXO_ON) significantly reduced the Physiological Cost Index to 13.80 ± 1.51, compared to NO_EXO (14.68 ± 2.11) and EXO_OFF (15.35 ± 1.83; p = 0.033). Similarly, RPE was significantly lower with active assistance (12.95 ± 1.15) than with unassisted (13.50 ± 1.19) or passive (14.00 ± 1.17) conditions (p = 0.023). Although Peak Heart Rate was lowest in EXO_ON (133.65 ± 7.74 bpm), differences across conditions were not statistically significant (p = 0.267). The device effectively offsets the physiological burden of its own mass, resulting in a net reduction in cardiovascular effort, as evidenced by lower PCI and RPE. These findings suggest that soft hip exoskeletons may improve walking efficiency and reduce perceived exertion during uphill walking in older adults.

Introduction

As the global population ages, maintaining functional mobility in older adults has become a significant public health challenge¹. Regular aerobic exercise plays a clear protective role in preventing cardiovascular disease, musculoskeletal degeneration, and cognitive decline². Among various physical activities, outdoor hiking and mountaineering are widely adopted leisure activities for older adults due to their combination of social engagement and aerobic conditioning benefits². However, compared to level walking, uphill walking imposes a substantial biomechanical load, requiring lower limb joints ....

Protocol

The study protocol was approved by the Clinical Research Ethics Committee of the First Affiliated Hospital, Zhejiang University School of Medicine (Approval No. 2024-Research-022). All experimental procedures were performed in accordance with the principles of the Declaration of Helsinki.

Subject recruitment and screening
For this study, 20 healthy older adults (aged 60–75) were recruited from The First Affiliated Hospital, Zhejiang University School of Medicine¹⁵. Subjects were screened according to the following inclusion criteria: age 60–75 years; capability for independent walki....

Results

Subject characteristics

A total of 20 healthy older adults (10 male, 10 female) completed the study. The subjects had a mean age of 63.45 ± 3.70 years, a height of 1.65 ± 0.07 m, a weight of 60.51 ± 6.59 kg, and a Body Mass Index (BMI) of 22.13 ± 1.58 kg/m² (Table 1). All subjects successfully completed the three walking conditions (NO_EXO, EXO_ON, EXO_OFF) with no reported adverse events.

Physiological cost index.......

Discussion

This study evaluated the impact of a lightweight, soft hip exoskeleton on physiological and psychological metrics in older adults during simulated uphill walking, using a randomized, crossover design. The results show that, compared with the baseline condition (NO_EXO) and the passive wear condition (EXO_OFF), the active assistance mode (EXO_ON) significantly reduced PCI and subjective fatigue rating (RPE). This finding supports our hypothesis that targeted hip joint assistance can effectively reduce physiological stress.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Borg RPE Scale	N/A	6-20 Scale	Standardized scale for assessing Rating of Perceived Exertion.
GraphPad Prism	GraphPad Software	Version 9.0	Used for data visualization and generating boxplots.
Medical Weight/Height Scale	Meilen	M-C-MSG100	Used for baseline physical characteristic measurements (BMI).
Soft Hip Exoskeleton (GOGO-H)	Hangzhou RoboCT Technology Development Co., Ltd	100189510835	Lightweight soft robotic suit (2.3 kg) providing hip flexion assistance.
SPSS Statistics Software	IBM	Version 26.0	Used for statistical analysis.
Standard Motorized Treadmill	YPOO	M5max	Used for simulated uphill walking at a 15% incline and 3.5 km/h.
Visual Analog Scale (VAS)	N/A	10 cm line	Used for subjective assessment of lower limb pain and discomfort.
Wearable smart band	Xiaomi Communications Co., Ltd.	6932554419790	Wearable smart band used for real-time heart rate and blood oxygen monitoring.