The stages of physical activity and exercise behavior: an integrated approach to the theory of planned behavior.

This research aims to verify whether it is possible to explain the health-promoting behaviors based on sociodemographic characteristics by integrating the theory of planned behavior (TPB) proposed by Ajzen in 1988 and the transtheoretical model (TTM) proposed by Prochaska and DiClemente in 1983. In particular, the aim was to verify whether the variables of the TPB can properly distinguish the stages of change in exercise in the proposed integrated model and to figure out how attitude, subjective norm, perceived behavior control, influence, and intention-can explain the stages of change in exercise. Investigators who have taken previous training for the survey visited and interviewed 3658 people older than 30 years in the chosen town by multistage sampling method from July 27 to July 31, 2003. After the exclusion of inappropriate data out of 760 participants, only data from 584 participants were used for this research. chi2 test, t test, and 1-way analysis of variance were used to identify the difference between the distribution of the stages of change in exercise and the variables of the means. A discriminant analysis to verify the accuracy of the stages of change in exercise by means of the variables of the TPB and a path analysis to verify the fit of the integrated model were also used. The variables of the TPB were useful to satisfactorily distinguish and predict the stages of change in exercise. But to clarify the validity of this model, more diversified research should be conducted in the future, and the results must be accumulated.