{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,24]],"date-time":"2026-08-24T21:24:17Z","timestamp":1787606657477,"version":"build-2736575974"},"reference-count":23,"publisher":"JMIR Publications Inc.","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["JMIR Rehabil Assist Technol"],"abstract":"Abstract<\/jats:title>\n \n Background<\/jats:title>\n Improving exercise self-efficacy (ESE) is a key strategy for promoting sustained physical activity among older adults with frailty. The lumbar-type Hybrid Assistive Limb (HAL), a wearable device that supports voluntary movement through bioelectric signals, may facilitate mastery experiences in individuals with low baseline self-efficacy via adjustable assistance. However, its effects on ESE remain unclear.<\/jats:p>\n <\/jats:sec>\n \n Objective<\/jats:title>\n This study evaluated the effects of lumbar-type HAL exercise on ESE in older adults with frailty and examined whether responsiveness differed according to baseline readiness for exercise.<\/jats:p>\n <\/jats:sec>\n \n Methods<\/jats:title>\n \n A retrospective pooled analysis was conducted using data from 2 prospective studies of a lumbar-type HAL\u2013based frailty prevention program: a feasibility study (n=20) and a randomized controlled trial (RCT; n=76; lumbar-type HAL group: n=38; waitlist control: n=38). Participants aged 50 to 84 years performed sit-to-stand and squat exercises using the lumbar-type HAL twice weekly. ESE was assessed using a validated 4-item questionnaire (range 4\u201020). The prespecified primary analysis examined within-person changes in ESE in the lumbar-type HAL group (2-tailed paired\n t<\/jats:italic>\n test; n=96). A secondary analysis compared changes in ESE between the lumbar-type HAL and waitlist control groups in the RCT using the Welch\n t<\/jats:italic>\n test and baseline-adjusted analysis of covariance. A prespecified subgroup analysis compared participants in stages 1 to 4 of the transtheoretical model of behavior change (exercise habit not established) with those in stage 5 (maintenance). All statistical tests were 2 sided, with significance at\n P<\/jats:italic>\n <.05.\n <\/jats:p>\n <\/jats:sec>\n \n Results<\/jats:title>\n \n The primary pooled paired analysis demonstrated a significant increase in ESE of 1.05 points (95% CI 0.41-1.69;\n P<\/jats:italic>\n =.002). The subgroup analysis was also significant: those in stages 1 to 4 (n=56) improved by 1.73 points vs 0.05 points for those in stage 5 (n=38), a difference of 1.68 points (95% CI 0.41-2.95;\n P<\/jats:italic>\n =.01). The largest within-group improvement was observed in stage 1 (precontemplation: +3.50 points, 95% CI 0.27-6.73;\n P<\/jats:italic>\n =.04; Cohen\n d<\/jats:italic>\n =1.14); 4 of 6 participants improved and none deteriorated. In the secondary RCT between-group comparison, the lumbar-type HAL group showed a directionally favorable improvement (between-group difference=1.21 points, 95% CI \u22120.33 to 2.75;\n P<\/jats:italic>\n =.12; Cohen\n d<\/jats:italic>\n =0.36). The subgroup differences were 2.10 points in stages 1 to 4 (\n P<\/jats:italic>\n =.07; Cohen\n d<\/jats:italic>\n =0.58) and 0.02 points in stage 5 (\n P<\/jats:italic>\n =.99). Sensitivity analyses confirmed robustness to source-related heterogeneity (heterogeneity test:\n P<\/jats:italic>\n =.74; source-adjusted regression:\n P<\/jats:italic>\n =.76).\n <\/jats:p>\n <\/jats:sec>\n \n Conclusions<\/jats:title>\n The pooled analysis demonstrated significant within-person improvement in ESE among older adults with frailty following lumbar-type HAL training, with the greatest improvement in individuals without established exercise habits. The RCT indicated a favorable but inconclusive between-group effect, and adequately powered confirmatory RCTs remain necessary. The exploratory response among precontemplators\u2014typically difficult to engage in interventions\u2014suggests that HAL-supported mastery experiences may support disengaged older adults at high risk of frailty in starting physical exercise.<\/jats:p>\n <\/jats:sec>","DOI":"10.2196\/79358","type":"journal-article","created":{"date-parts":[[2026,7,22]],"date-time":"2026-07-22T10:50:08Z","timestamp":1784717408000},"page":"e79358-e79358","source":"Crossref","is-referenced-by-count":0,"title":["Effects of Using a Lumbar-Type Hybrid Assistive Limb by Older Adults With Frailty on Exercise Self-Efficacy: Retrospective Analysis Based on the Kanagawa Prospective ME-BYO Cohort 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