Effects of change in physical activity on physical function limitations in older women: Mediating roles of physical function performance and self-efficacy

OBJECTIVES: To examine the hypothesis that changes in self-efficacy and functional performance mediate, in part, the beneficial effect of physical activity on functional limitations over time. DESIGN: Prospective, observational study. SETTING: Community-based. PARTICIPANTS: Two hundred forty-nine community-dwelling older women. MEASUREMENTS: Participants completed measures of self-reported physical activity, functional limitations, and self-efficacy. Four measures of physical function performance were also assessed. Measures were completed at baseline and 24 months. Data were analyzed using a panel model within a covariance modeling framework. RESULTS: Results indicated that increases in physical activity over time were associated with greater improvements in self-efficacy, which was associated in turn with improved physical function performance, both of which mediated the association between physical activity and functional limitations. Fewer functional limitations at baseline were also associated with higher levels of self-efficacy at 24 months. Age, race, and health status covariates did not significantly change these relationships. CONCLUSION: The findings support the mediating roles of self-efficacy and physical function performance in the relationship between longitudinal changes in physical activity and functional limitations in older women.