Understanding for whom, under what conditions, and how group-based physical activity interventions are successful: A realist review

Background: Participation in group-based physical activity (GBPA) interventions has been found to result in higher levels of exercise adherence and program compliance. However, previous reviews of GBPA programs have provided limited insight regarding 'for whom', 'under what conditions', and 'how' these interventions increase physical activity behavior. Methods: A realist review was conducted by following the seven recommended iterative and overlapping steps (J Health Serv Res Policy 10S1:21-34, 2005). The review was limited to group dynamics-based interventions for adults (>17 years of age). The search was conducted in PubMed, PsychInfo, and Web of Science search engines associated with the Science Citation Index Expanded, Social Sciences Citation Index, Arts & Humanities Citation Index, and MEDLINE. Results: Using a realist review approach, data from 52 studies were synthesized. Of those, 92 % (n∈=∈48) reported significant increases in participant physical activity. The synthesis resulted in three main observations and recommendations. Discussion: GBPA interventions have worked for a variety of populations, including those who are hard to reach; however, more research is needed on moderating factors to determine for whom different GBPA programs may be effective. Second, previous interventions have varied in the duration, frequency, and number of group-based strategies used, and comparative effectiveness research may be necessary to isolate the mechanisms of effect. Third, these interventions have been conducted in a diverse range of settings, using a variety of research designs and analytical approaches. Less information is known about the costs or sustainability of these programs in their intended settings. Conclusion: The results of this realist review have important implications for practice, refining trial designs, and replication across diverse populations and settings.