Physical activity and stages of change: a longitudinal test in types 1 and 2 diabetes samples

The transtheoretical model's (TTM's) ability to predict physical activity stage transitions that incorporates all social-cognitive constructs from the original model has not been conducted among adults with diabetes. The purpose of this study was to test the capacity of the TTM for predicting physical activity stage transitions among adults (≥18 years of age) with type 1 (N = 517) or type 2 (N = 1,157) diabetes over 6 months. Participants were identified by a random-digit dialing telephone protocol through the Alberta Diabetes Registry. Assessments of TTM's stage of physical activity behavior change, self-efficacy, pros and cons, cognitive Processes of Change, and behavioral Processes of Change at baseline (time 1) and 6 months (time 2) were assessed by questionnaire. Over this time period, participants were categorized as having regressed (moved back at least one stage), remained (no stage change), or progressed (moved forward at least one stage). Baseline TTM constructs were analyzed for their ability to predict transition over 6 months. Moderate support for the TTM constructs in predicting physical activity stage transitions was found. Self-efficacy, pros, and behavioral Processes of Change hold relatively strong predictive power for stage progression over 6 months, with very few differences found between the types 1 and 2 diabetes groups. The capacity of the model in predicting stage transition is partially supported. When promoting physical activity among adults with diabetes, targeting self-efficacy, pros, and cognitive Processes of Change may favorably support stage transition in the pre-action stages, while strategies to enhance the behavioral Processes of Change may be appropriate for the Action and Maintenance stages.