A self-determination process model of physical activity adoption in the context of a randomized controlled trial

Objective: The PA Counseling (PAC) trial tested a primary care intervention using Self-Determination Theory (SDT) as the guiding framework. This paper presents specific results related to SDT constructs in a physical activity (PA) context. Specifically, whether patients who received both brief autonomy supportive PA counseling from their health-care provider and intensive (3 month) autonomy supportive counseling from a PA counselor would report greater levels of autonomy support, autonomous motivation, perceived competence and PA adoption, than patients receiving only brief counseling. In addition, we tested Williams’ SDT process model in the context of PA adoption.Method: Measures of autonomous motivation and perceived competence for PA were measured at baseline and 6 weeks. PA was assessed at baseline and 13 weeks. An autonomy support index was calculated by multiplying minutes of counseling by perceptions of autonomy support. Group differences in autonomy support, autonomous motivation, perceived competence and PA were examined. The SDT process model of PA adoption was tested via path analysis.Results: The results showed higher autonomy support and autonomous motivation at 6 weeks and higher PA levels at 13 weeks for the experimental group. The SDT process model for PA adoption showed that autonomous motivation and perceived competence at 6 weeks significantly predicted 13-week PA for the experimental group.Conclusions: This study provides a rigorous field test of SDT theory in a PA context. It demonstrates the versatility and applicability of the SDT model for health behavior change. SDT-trained PA counselors appear to provide valuable contribution to facilitating patient behavior change, by increasing patient autonomous motivation for PA.