Fostering affect-related competencies and positive affective exercise experiences for promoting a physically active lifestyle in inactive young adults: study protocol for the FEEL cluster randomized controlled trial.

Background Growing evidence highlights the role of affective responses in shaping exercise behavior. Various factors, such as social setting, intensity, or activity type, influence affective exercise experiences. However, previous interventions have typically targeted only one factor at a time. The idea of the FEEL exercise program is to address these various factors in a holistic manner. Additionally, it focuses on fostering Physical Activity-Related Affect Regulation (PAAR) competence in participants, which is crucial for maintaining regular exercise behavior and well-being. Methods The FEEL study is a multicenter, cluster-randomized controlled trial. It evaluates the FEEL exercise program's efficacy compared to an active control group participating in a standardized Functional Training program. A total of 160 young adults (aged 18-35) who are not regularly exercising will be recruited across the two cities, Tübingen (Germany) and Bern (Switzerland). Both exercise programs consist of eight weekly 90-min group-based sessions. Primary outcome will assess PAAR using a validated scale, while secondary outcomes will include affective exercise experiences (AFFEXX), motivational competence, physical activity levels, and affective well-being. Measurements will be collected at baseline (t1), post-intervention (t2), and at an 8-week follow-up (t3). Data will be analyzed using multilevel modeling to examine group-by-time interactions, following a modified intention-to-treat approach. Conclusions This study explores the impact of a holistic intervention in a primary and secondary prevention context. It may provide valuable insights for practical considerations of affective processes and related competencies in exercise programs. TRIAL REGISTRATION (RETROSPECTIVELY ON THE 31.10.2024): German Clinical Trials Register; ID: DRKS00035302.