The transtheoretical model in the context of physical activity in a school-based sample of German adolescents

Physical activity in adolescents is an important public health issue. Regular participation in physical activity is associated with various health benefits. However, problems with motivational adherence to physical activity have been documented. The transtheoretical model is a model of behaviour change. This model, which consists of stages of change, self-efficacy, decisional balance, and processes of change, has not been extensively investigated in youth. In addition, the health-enhancing physical activity concept has rarely been applied in this context. A cross-sectional design was used. A random sample of seven junior high schools from Bremen (Germany) resulted in a sample of 588 adolescents (50.5% males, mean age=15.0 years, s=0.67). Respondents completed a self-administered questionnaire assessing stages of change, self-efficacy, decisional balance, and processes of change. Univariate analyses of variance were used to identify which constructs differed significantly across the stages of change. Discriminant analysis was used to determine which variables best discriminate the stages. Distribution of the sample across the stages was: precontemplation, n=175 (29.8%); contemplation, n=135 (22.0%); preparation, n=63 (10.7%); action, n=20 (3.4%); and maintenance, n=195 (33.2%). Significant effects of stages of change were found for self-efficacy, pros, and seven of the ten processes of change. In general, scores of these constructs increased across the stages. Cons did not differ significantly across the stages. The results provide support for some of the assumptions of the transtheoretical model in a German sample of adolescents. Some of our findings raise questions about the usefulness of five discrete stages. From a public health viewpoint, tailored interventions based on motivational readiness to change would be fruitful, but further research is warranted.