Effects of Physical Activity on Daily Physical Function in Chinese Middle-Aged and Older Adults: A Longitudinal Study from CHARLS

Objective: Impaired daily physical function has become a common health problem among Chinese middle-aged and elderly people. The aim of this study was to investigate the effects of physical activity on daily physical function in Chinese middle-aged and older adults. Methods: Data from 9056 participants in the China Health and Retirement Longitudinal Study (CHARLS) from 2011 to 2018 were included in this study. Physical activity levels were expressed as metabolic equivalents, and the impairment of daily physical function was determined in a self-reported format by the Activities of Daily Living Scale and the Instrumental Activities of Daily Living Scale. The association between different levels of physical activity and impaired daily physical function was analyzed using Cox proportional hazards regression models. Results: During a mean follow-up period of 6.73 years, 1379 middle-aged and older adults had impaired physical function. After adjusting for all covariates, participants with a physical activity volume (PAV) >= 600 MET-minutes/week had a 61% lower risk of impaired daily physical function than those who were physically inactive (HR = 0.39, 95% CI 0.35-0.44). Participants with a PAV of 1800-2999 MET-minutes/week had the lowest risk of impaired daily physical function (HR = 0.33, 95% CI 0.26-0.42). Subgroup analysis showed that participants with a PAV >= 600 MET-minutes/week had a greater reduction in the risk of impaired daily physical function among participants who were male, older than or equal to 65 years, and without respiratory disease compared to participants who were physically inactive. Conclusions: This study showed that a PAV >= 600 MET-minutes/week could reduce the risk of impaired daily physical function in Chinese middle-aged and elderly people. However, a higher PAV is not better; a PAV in the range of 1800-2999 MET-minutes/week can be more effective in preventing daily physical function impairment in Chinese middle-aged and elderly people.