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

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.