Physical activity associations with physical function and body composition among community-dwelling older adults in Japan: The Kyotango Longevity Cohort Study.

Abstract

Physical activity benefits health, whereas physical inactivity increases the risk of age-related conditions and adverse health outcomes. Kyotango City in Japan is known for its residents' longevity, and many centenarians live there. This study investigated the physical activity associations with physical function and body composition in older adults living in this area. Community-dwelling older adults (n = 727; mean age 74.1 years; 59.4% women) participated in this study. Multiple linear regression analyses were carried out to examine objectively-measured physical activity associations with physical function (handgrip strength, knee extension strength and maximum gait speed) and body composition (skeletal muscle mass index and whole-body phase angle), adjusting for potential confounders. Additionally, isotemporal substitution models were applied to estimate changes resulting from replacing sedentary behavior with light-intensity physical activity (LPA) and moderate-to-vigorous-intensity physical activity (MVPA). All physical function and body composition indicators were significantly associated with SB and MVPA (all P < 0.050). However, LPA was associated with only handgrip strength and body composition indicators. Replacing 30 min of SB per day with LPA was associated with a 0.176 kg increase in handgrip strength, 0.018 kg/m 2 increase in skeletal muscle mass index and 0.016° increase in whole-body phase angle. Alternatively, replacing sedentary behavior with MVPA improved all physical function and body composition indicators. Older adults in a region of Japan known for longevity might maintain physical function and favorable body composition through engaging in abundant physical activity. Public health strategies should prioritize MVPA promotion while recognizing LPA's complementary role for physically inactive older adults. Geriatr Gerontol Int 2025; 25: 1511-1517.