The Mediating Role of Sarcopenia in the Association between Physical Activity and Falls among Chinese Older Adults: A Cross-Sectional Study

Physical inactivity and sarcopenia are potentially modifiable risk factors for falls in older adults, but the strength of the association between physical activity (PA), sarcopenia, and falls in Chinese older adults is unclear. This study sought to investigate the potential mediation mechanism relationship in the connection between PA, sarcopenia, including its elements (muscle strength, physical performance, and skeletal muscle mass), and falls among Chinese older people. The subjects were 3592 community-dwelling Chinese aged 60 or over, selected from the China Health and Retirement Longitudinal Study (CHARLS). PA was evaluated through the International Physical Activity Questionnaire (IPAQ), and sarcopenia was determined through the Asian Working Group on Sarcopenia (AWGS) 2019 guidelines. We employed logistic regression to explore the link between physical activity, sarcopenia, and falls. Additionally, we applied Karlson, Holm and Breen's (KHB) method to estimate two different mediation models. The results demonstrated that PA lowers the risk of falls [odds ratio (OR) 0.54, 95% confidence interval (CI) 0.48-0.61], whereas sarcopenia increases the risk of falls (OR 1.34, 95% CI 1.16-1.55). Sarcopenia mediated the association between PA and falls, explaining a total of 2.69% of the association (indirect effect = -0.02). PA also had a significant mediating effect on the association between sarcopenia and falls, explaining a total of 20.12% of the association (indirect effect = 0.06). The proportion mediated by sarcopenia was 2.69% for PA and falls (indirect effect = -0.02). Our findings suggest that PA and sarcopenia have a direct effect on falls as well as an indirect effect through each other. Enhancing PA levels and preventing sarcopenia may help prevent falls in older adults.