Association of objectively measured physical activity with incidence disability in older adults with/without social isolation

PURPOSE: This study aimed to investigate association between objectively measured physical activities with incidence disability in older adults with and without social isolation. METHODS: This 5-year longitudinal observational study used a population-based study from a sub-cohort of the National Center for Geriatrics and Gerontology Study of Geriatric Syndrome. In Japan, Incident disability is defined as a new case of public insurance certification for long-term care. As participants, we enrolled 5,257 community-dwelling older adults aged ≥ 70 years. The Participants on whom incomplete baseline physical activity assessments were performed; who required long-term care; had a history of dementia, Parkinson's disease, stroke, or depression; who lacked independence in basic ADL; who had Mini-Mental State Examination scores; or who had missing measurements; were excluded. Thus, 2,071 participants were included. RESULTS: Of the participants, 1,183 non-socially isolated participants had 151 (4.3%) cases of disability, while socially isolated participants had 150 (13%) cases. Cox proportional-hazards regression analysis presented the adjusted hazard ratio (HR) and 95% confidence interval (95%CI) of daily steps and low-intensity and moderate-to-vigorous physical activities-0.62(0.43-0.89), 0.84(0.60-1.18), 0.62(0.43-0.89) in participants with social isolation, and 0.58(0.40-0.85), 0.86(0.60-1.24), 0.70(0.49-1.01) in those with social isolation. CONCLUSIONS: Daily steps were significantly associated with a decreased risk of incidence disability, regardless of social isolation. These results suggest the greater importance of daily physical activity than its specific intensity in socially isolated older adults.