Japan's long-term care insurance (LTCI) system provides rehabilitation services. This study examined whether adding seated aerobic exercises to daycare rehabilitation improves endurance and frailty.

We performed a secondary analysis of a cluster nonrandomized trial conducted at 10 Japanese daycare facilities. Certified older adults requiring care were enrolled in September 2023. Facilities were allocated to the aerobic program or the usual rehabilitation. The aerobic program included seated stepping and arm movements at 120 bpm for two 2-minute sets during rehabilitation for 6 months. Outcomes included the 2-minute step test, Borg scale, grip strength, Timed Up and Go (TUG) test, Barthel Index, and frailty classification using Japanese Cardiovascular Health Study criteria (J-CHS). Analyses used baseline-adjusted analysis of covariance (ANCOVA) with group, frailty category, and interaction as fixed effects. Mixed-effects models with facility as a random intercept were used for sensitivity analyses.

Of 575 screened individuals, 308 were enrolled, and 252 completed the assessment (aerobic, n = 119; usual, n = 133). The aerobic group showed greater 2-minute step test performance (adjusted mean 103.883 vs. 84.494; mean difference 19.388, 95 % CI 7.350–31.426; p = 0.002). Borg scores were lower in the aerobic group (difference −1.093; 95 % CI −2.202 to 0.015; p = 0.053). Other measures showed no significant between-group differences. Frailty distribution differed at 6 months ( p = 0.036), with reduced frailty in the aerobic group.

Brief seated aerobic exercise within LTCI daycare rehabilitation improved endurance and modestly improved frailty classification. These findings support aerobic exercise in LTCI rehabilitation; however, nonrandom allocation and lack of blinding limit interpretation.