Testing and integrating self-determination theory and self-efficacy theory in a physical activity context.

Stemming from the need for theoretical integration, this study aimed at individually testing and integrating self-determination theory (SDT) and self-efficacy theory (SET) to predict physical activity. University students (n 225) completed questionnaires measuring constructs from SDT and SET as well as the Godin Leisure Time Exercise Questionnaire. Using path analysis, individual SDT and SET models and 2 hypothesised integrated models were tested. The preferred integrated model was selected on the basis of model fit indices. The selected integrated model was then compared with the individual theoretical models by examining the number of theoretical links that remained constant and the explained variance in the variables. Results revealed that the individual and integrated models were supported. The second integration model, which had self-determined motivation and confidence in equal agenic roles, had better model fit, 2(7) 28.87, p .001, comparative fit index .95, root-mean-square error of approximation .12, standardized root mean residual .05, Akaike Information Criterion 84.87, and was preferred over the individual theoretical models. Overall, integrating 2 motivational theories in physical activity research is feasible, and more studies are needed to enhance our understanding of physical activity participation.