Understanding physical activity in adults with type 2 diabetes after completing an exercise intervention trial: A mediation model of self-efficacy and autonomous motivation

This study was set out to test if autonomous motivation mediated the relationship between self-efficacy and 12-month physical activity (PA) in adults with type 2 diabetes involved in a randomized exercise trial. Participants (n = 234) completed questionnaires measuring barrier self-efficacy at 3 months, autonomous motivation at 6 months, and PA at 12 months. A mediational analysis of longitudinal data revealed that autonomous motivation mediated the relationship between barrier-self-efficacy and PA. High barrier self-efficacy can therefore help predict 12-month PA in adults with type 2 diabetes, although this effect is attenuated by autonomous motivation. Hence, participating in PA for autonomous reasons such as by choice and/or for fun further explains PA at 12 months in this population. Results of this study extend our understanding of the motivational constructs involved in PA in the maintenance phase. This study has important theoretical implications in that it helps to organize and consolidate well-known correlates of PA by proposing a temporal relationship between them that could be tailored in interventions.