Longitudinal Effects of Snow-season Activity Decline on Physical Function in Older Adults in Rural Snowy Regions

Physical activity levels vary seasonally, but the short-term impact of intensity-specific activity changes on older adults' physical function remains unclear. This study aimed to examine seasonal changes in physical activity and their effects on physical function among older adults in a rural, snowy region.

Thirty-nine older adults from Tobetsu-cho, Hokkaido, Japan, were included. Body composition and physical function were assessed during the non-snowfall season (June-September 2023) and 1 year later (June-September 2024). Accelerometers measured step counts and activity levels during both the non-snowfall and snowfall seasons (January-February 2024). Participants were grouped by the extent of change in activity levels (greater-change vs. smaller-change). Two-way analysis of variance (ANOVA) assessed differences in 1-year changes in physical function.

Repeated-measures 2-way ANOVA showed a significant main effect of season on body fat percentage, appendicular skeletal muscle mass index, grip strength, and walking speed in the light-intensity physical activity (LPA) category. A significant interaction was observed for the Five Times Sit-to-Stand Test (FTSST). Bonferroni's test revealed a significant worsening of FTSST scores (p <0.01) after 1 year, but only in the group with a greater LPA decline.

A greater decrease in LPA during the snowfall was associated with short-term declines in lower-limb function, as measured by FTSST. Given its link to fall risk and loss of independence, maintaining LPA during snowy seasons may be essential for maintaining lower-limb function in older adults.