Peer-delivered physical activity interventions: an overlooked opportunity for physical activity promotion.

The purpose of this systematic review was to catalogue and synthesize published studies that have examined the effects of peer-delivered physical activity interventions on physical activity behavior. Ten published studies were identified that met the inclusion criteria. The following information was extracted from each study: study design and duration; characteristics of the sample, peers, and interventions; and physical activity outcomes. In all articles reporting within-groups analyses, peer-delivered interventions led to increases in physical activity behavior. When compared to alternatives, peer-delivered interventions were just as effective as professionally delivered interventions and more effective than control conditions for increasing physical activity. Only three studies included measures of social cognitive variables, yielding some evidence that peers may enhance self-efficacy and self-determined forms of motivation. Based on these findings, interventionists are encouraged to include peer mentors in their intervention delivery models. Investigators are encouraged to pursue a more comprehensive understanding of factors that can explain and maximize the impact of peer-delivered activity interventions.