Mental imagery increases self-determined motivation to exercise with university enrolled women: A randomized controlled trial using a peer-based intervention

Objectives: The purpose of this study was to examine the effects of a peer-based mental imagery intervention on the self-determined motivation and cardio-respiratory fitness of university enrolled women. Design: Randomized controlled trial. Method: 43 University enrolled women were randomized to peer-mentored or peer-mentored plus mental imagery conditions while 32 completed three meetings with peer-mentors and post-testing (M^age=19.91; SD=1.70). Results: Significant improvements in cardio-respiratory endurance, ratings of perceived endurance, and self-determined motivation to exercise were observed across both study conditions. Participants assigned to the peer mentored plus mental imagery condition reported significantly greater increases in self-determined motivation to exercise at post-test compared to those in the peer-mentored condition. Conclusions: Peer-based interventions are a viable way to improve fitness and health outcomes while mental imagery appears to be associated with increases in autonomous forms of exercise motivation.