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 wit h physical function (SF), satisfaction with physical appearance (SA), and s elf-efficacy (SE) mediate the effects that increased physical activity has on change in subjective well-being (SWB). Participants in this investigatio n consisted of 854 men (n = 471) and women (n = 383) who took part in the A ctivity 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 t o one of three treatments: standard care control, staff-assisted interventi on, or staff-counseling intervention. Results revealed that, irrespective o f treatment arm, change in physical activity was related to change in SEW a nd 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 t o change in all three mediators with change in SF making the greatest contr ibution to the model.