Estimating the risk reduction in disability incidence by adhering to recommendation-based physical activity in older adults: a cohort study

BACKGROUND: The WHO recommends ≥150 min/week of moderate-to-vigorous physical activity (MVPA) for older adults, while the Japanese Ministry of Health, Labour and Welfare suggests ≥6000 steps/day. However, the potential of meeting these recommendations to reduce the incidence of disability remains unclear. METHODS: This study included 4079 community-dwelling older people from the National Center for Geriatrics and Gerontology-Study of Geriatric Syndromes. Physical activity was measured using triaxial accelerometers over 1 month, with 12-month data used in sensitivity analyses. Disability incidence was defined as new certification by the Japanese Long-Term Care Insurance system for 58 months. To compare the cumulative incidence of disability between adherent and non-adherent groups, we applied the parametric g-formula accounting for sociodemographic, physical and medical covariates. RESULTS: For MVPA adherence, disability incidence was reduced by -2.17% (95% CI -4.50% to 0.16%). Continuous MVPA adherence over 12 months significantly reduced disability incidence by -3.15% (95% CI -6.08% to -0.22%). A significant reduction in severe disability incidence was observed with MVPA adherence (-1.18%, 95% CI -3.59% to -0.17%). Subgroup analyses indicated greater reductions in disability incidence among individuals aged <75 years (-2.56%, 95% CI -4.81% to -0.31%). For daily step adherence, the largest risk reduction was observed in the subgroup of older adults aged ≥75 years (-4.40%, 95% CI -10.12% to 1.33%), although the CI was wide. CONCLUSIONS: Adherence to recommendation-based physical activity may effectively prevent disability in community-dwelling Japanese older adults.