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.
KeywordsExercise, Fitness, Peer mentors, Social influence, Social cognitive theory, Self-determination theory BACKGROUND Previous research has shown that regular physical activity (PA) contributes to the prevention of overweight/obesity [1-3], decreases risk for obesity-related illnesses [4,5], and is associated with decreased risk for coronary heart disease [6], hypertension, type 2 diabetes mellitus [1,2], and cancer at several sites [7]. These benefits have also been reported in subpopulations such as older adults [8] and persons with disabilities [9]. Unfortunately, most adults do not perform PA at the recommended level to experience such health benefits [10,11]. Indeed, 39 % of adults are completely sedentary [11], and the rate of inactivity increases with age [8,12] and physical impairment (e.g., [13]).Although health care professionals often hold a role of trusted counselor or health mentor for their