Meghan Baruth and Rebecca A Schlaff
Objective: Although progress has been made in developing effective interventions that change physical activity behaviors, much work remains in understanding how interventions exert their effects. The purpose of this study was to examine psychosocial mediators of change in physical activity resulting from a group-based, behavioral, physical activity intervention (Active Living Every Day) in older adults. Methods: This study was a randomized controlled trial carried out in 2015. Participants (n=47) completed a survey assessing demographic and psychosocial variables, and wore an Actigraph at baseline and 12 weeks (postintervention). A multiple mediator model, testing social support (family and friends separately), self-efficacy, and self-regulation as mediators of change in physical activity was conducted. Results: Results showed that the intervention was not successful in changing the targeted mediators, and changes in mediators were not associated with changes in physical activity. None of the variables examined were significant mediators of change in physical activity. Conclusion: Despite significant changes in physical activity, the mechanisms by which the changes occurred are unknown. Potential explanations and implications of the null findings are discussed. Continued efforts focused on understanding how behavioral interventions exert their effects on physical activity outcomes are needed in an effort to develop the most efficacious and costeffective interventions aimed at improving health.
