Mediators of increased physical activity and change in subjective well-being: Results from the Activity Counseling Trial (ACT)

The purpose of this study was to examine whether change in satisfaction with physical function (SF), satisfaction with physical appearance (SA), and self-efficacy (SE) mediate the effects that increased physical activity has on change in subjective well-being (SWB). Participants in this investigation consisted of 854 men (n = 471) and women (n = 383) who took part in the Activity Counseling Trial (ACT). ACT was a 24-month multicenter, randomized controlled trial to evaluate the effectiveness of interventions to promote physical activity in the primary care setting. Participants were assigned to one of three treatments: standard care control, staff-assisted intervention, or staff-counseling intervention. Results revealed that, irrespective of treatment arm, change in physical activity was related to change in SEW and to change in all mediators of interest. A statistical test of mediation revealed that the influence of change in physical activity on SWB was due to change in all three mediators with change in SF making the greatest contribution to the model.