The transtheoretical model of behavior change: A meta-analysis of applications to physical activity and exercise

The purpose of this study was to summarize findings from empirical applicat ions of the transtheoretical model (TTM) (Prochaska & DiClemente, 1983) in the physical activity domain by using the quantitative method of meta-analy sis. Ninety-one independent samples from 71 published reports were located that present empirical data on at least one core construct of the TTM appli ed to exercise and physical activity. In general, results support the appli cation because core constructs differ across stages and most changes are in the direction predicted by the theory. Three general conclusions are offer ed First, existing data are unable to confirm whether physical activity beh avior change occurs in a series of stages that are qualitatively different or along adjacent segments of an underlying continuum. Second, the growing number of studies that incorporate TTM concepts means that there is an incr easing need to standardize and improve the reliability of measurement. Fina lly, the role of processes of change needs reexamining because the higher o rder constructs are not apparent in the physical activity domain and stage- by-process interactions are not evident. There now are sufficient data to c onfirm that stage membership is associated with different levels of physica l activity, self-efficacy pros and cons, and Processes of change. Further s tudies that simply stage participants or examine cross-sectional difference s between core constructs of the TTM are of limited use. Future research sh ould examine the moderators and mediators of stage transition.