Predicting Stage of Exercise Among Patients with Type 2 Diabetes: A Test of the Extended Theory of Planned Behavior.

Purpose: This study aimed to predict stage of exercise among Chinese patients with type 2 diabetes by using an extended theory of planned behavior model (TPB) incorporating descriptive norm and self-identity. Patients and Methods: Participants (N=791) were included in a cross-sectional study. Structural equation modeling was used to explain how the extended TPB could predict the stage of exercise. Results: The model accounted for 41% of the variance in stage of exercise and 81.1% of the variance in intention. Intention (beta=0.359, P<0.01) and self-identity (beta=0.236, P<0.001) had a direct effect on stage of exercise. Self-identity (beta=0.261, P<0.001), descriptive norm (beta=0.035, P<0.05) and PBC (beta=0.683, P<0.001) were strong predicators of intention. The effects of self-identity and PBC on behavior were significantly mediated via intention. Age, BMI and stage of diet behavior were found to be significantly related to intention and behavior. Conclusion: This study has tested the usefulness of the extended TPB for explaining exercise in Chinese diabetic patients. To promote patients to start or continue exercising, interventions should target self-identity and controllability for physical activity.