Association between physical activity levels and intrinsic capacity impairment among Chinese older adults: A...

Promoting and maintaining intrinsic capacity is a key component of achieving healthy ageing, and identifying modifiable determinants is essential for developing effective intervention strategies. Physical activity, as an important modifiable lifestyle factor, has attracted increasing attention regarding its association with intrinsic capacity in older adults. This study aimed to examine the association between physical activity levels and intrinsic capacity impairment and its individual domains among older adults, providing evidence for the prevention and intervention of intrinsic capacity impairment.

This study was based on data from the 2015 China Health and Retirement Longitudinal Study (CHARLS). A total of 2307 participants aged ≥60 years were included. Multivariable logistic regression models were used to examine the association between physical activity levels and intrinsic capacity impairment, including its individual domains. Restricted cubic spline (RCS) models were applied to assess potential non-linear dose-response relationships. Subgroup analyses and interaction tests were conducted to explore heterogeneity across populations.

After adjustment for potential confounders, physical activity levels were significantly associated with the risk of intrinsic capacity impairment. Restricted cubic spline (RCS) analysis further indicated a significant non-linear dose-response relationship, demonstrating a U-shaped association, whereby the risk of intrinsic capacity impairment initially decreased and then increased with higher physical activity levels, with an inflection point at approximately 2633 MET-min/week. Domain-specific analyses revealed marked heterogeneity across intrinsic capacity domains. A protective association for cognitive function was primarily observed in the Q2 and Q3 physical activity groups, whereas no significant association was found in the Q4 group. In the locomotion domain, a lower risk of impairment was observed only in the highest physical activity group (Q4). For vision, a significant protective association was observed only in the Q3 group. No consistent or statistically significant associations were observed between physical activity levels and impairment in the psychological, vitality, and hearing domains.

Physical activity levels were non-linearly associated with the risk of intrinsic capacity impairment, with moderate levels being associated with a lower risk. This study further identified marked heterogeneity in the associations between physical activity and different intrinsic capacity domains, suggesting that the benefits are not uniform across functional domains. These findings highlight the importance of maintaining an appropriate level of physical activity and support the development of individualized intervention strategies to promote healthy ageing.