A group-based prevention program fostering mental health and physical activity: Session-level mechanisms and pre-to post-program outcomes

Physical activity (PA) and psychoeducational sessions (PsycEd) represent popular components of well-being-oriented prevention programs. Yet, the mechanisms through which these components contribute to global program outcomes are largely unclear. Potential mechanisms are the translation of immediate, session-level effects, amount of attended sessions, and social support. Ecological momentary assessment might reveal these mechanisms at the session-level and determine their link with program-level outcomes.We investigated an 8-week, naturalistic, health-insurance-provided group-based secondary prevention program comprising weekly outdoor PA with weekly PsycEd in individuals experiencing mild mood disturbances. To assess session-level mechanisms, 80 participants reported their current mood and stress (time pressure and burden) before (3 pm) and after (9 pm) session times and further rated each session on helpfulness, group atmosphere, and social support. In addition, session attendance was recorded. Concerning pre-post program effects, affective well-being (WHO-5) was assessed. Regarding potential links, we examined moderation of pre-post program effects by the assessed mechanisms. Regarding session-level mechanisms, results revealed that sessions improved both mood and stress burden compared to non-session days, while only PA sessions improved time pressure. PA sessions were also rated higher on helpfulness, group atmosphere, and social support. Concerning program-level outcomes, WHO-5 scores improved from pre- to post-program with small effect size. Regarding links, participants attending more sessions had higher WHO-5 improvements, but no other mechanism variable moderated the improvement. These findings illustrate immediate improvements on the session level in mood and stress. Yet, these effects did not translate into more global outcomes such as affective well-being across the program, but attendance did. Potential program effectiveness might be boosted by targeting continued attendance. Outdoor PA might be slightly superior to PsycEd in activating group benefits and could potentially be expanded.