Accepted for/Published in: JMIR Rehabilitation and Assistive Technologies
Date Submitted: Jun 30, 2025
Date Accepted: Jul 22, 2026
Warning: This is an author submission that is not peer-reviewed or edited. Preprints - unless they show as "accepted" - should not be relied on to guide clinical practice or health-related behavior and should not be reported in news media as established information.
Effects of using a lumbar-type hybrid assistive limb by frail older adults on exercise Self-efficacy : a retrospective analysis based on the Kanagawa Prospective ME-BYO Cohort Study
ABSTRACT
Background:
Improving exercise self-efficacy (ESE) may be a key strategy in promoting sustainable physical activity among frail older adults. The lumbar-type Hybrid Assistive Limb (HAL) is a wearable cyborg that supports voluntary movements through bioelectric signals detected from the skin surface. While previous studies have shown that HAL improves physical function, the impact of lumbar-type HAL on psychological outcomes such as ESE remains unclear.
Objective:
This study aimed to evaluate the effects of an exercise program using the lumbar-type HAL on ESE among frail older adults.
Methods:
We conducted a pooled analysis using data from two studies of a HAL-based care prevention program: a feasibility study and a randomized controlled trial. Participants aged 65–85 years performed core and leg exercises, such as sit-to-stand and squats, using the lumbar-type HAL twice weekly. ESE was assessed using a validated four-item questionnaire that evaluates confidence in exercising under various conditions (e.g., fatigue, low motivation, lack of time, poor weather). The primary outcome was the total ESE score before and after the intervention.
Results:
A total of 96 participants were included in the analysis. ESE scores significantly improved from a mean of 12.0 (SD = 3.06) to 13.0 (SD = 3.21) following HAL training (p < 0.01). Subgroup analysis based on the Transtheoretical Model of behavior change revealed that participants in the pre-contemplation, contemplation, preparation, and action stages showed greater improvements (mean increases: 3.5, 1.1, 1.5, and 2.8 points, respectively), whereas those in the maintenance stage showed minimal change (0.1 point).
Conclusions:
An exercise program using the lumbar-type HAL significantly improved ESE in frail older adults, particularly among those with lower baseline motivation for exercise. These findings suggest that HAL-based interventions may enhance both physical and psychological readiness for exercise in aging populations. By improving ESE such programs could facilitate long-term engagement in physical activity and support the adoption of active lifestyles among older adults. Tailoring interventions based on behavioral change stages may further optimize outcomes.
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