The transtheoretical model in the context of physical activity in adolescents

Background: Physical activity (PA) in adolescence is an important public health issue. But problems of motiva-tional adherence to PA have been documented. In addition a steep decline of activity levels occurs in adolescence. The transtheoretical model (TTM) is an established theory of behaviour change. In youth, studies on TTM in the context of PA have been scarcely conducted. Purpose: The TTM assumes that a specific pattern of processes of change, decisional balance and self-efficacy differentiates the five stages of change. Main focus of the recent examination was to explore these assumptions in a sample of adolescents. The addressed hypotheses are analysed with respect to a wide interpretation of PA.Methods: A random sample of seven junior high schools from Bremen (Germany) resulted in a sample of 598 adolescents (50.5% males, meanage = 15.0). In addition to some descriptive statistics the quality of the questionnaire was examined by confirmatory and factor analysis. With respects to the main hypotheses univariate analysis of variance followed-up with Schef-fà ©s multiple comparison test was used. To verify the entire TTM discriminant analysis was used.Results: Distribution of the sample across the stages was: precontemplation, n=175 (29.3%); contemplation, n=135 (22.6%); preparation, n=63 (10.5%); action, n=20 (3.3%); maintenance, n=195 (32.6%). The applicability of the questionnaire was acceptable. The construct validity of the staging algorythm was limited. Significant effects for stages of change were found for self-efficacy, pros and seven of the ten processes of change. In general, the scores of these constructs increase across the stages of change and Scheffà ©s post-hoc analyses revealed at least differences between precontemplation and one other stage. Cons did not differ significantly across stages. An interaction between gender and stages was not found. Discriminant analysis predicted group membership which was similar to the assumptions of the TTM.Conclusions: From a public health vantage tailored interventions based on TTM seem to be fruitful. The results give support for some of the assumptions of the TTM in a German sample of adolescents. Some findings of this study raise questions about the usefulness of five discrete stages. The concept of different motivational stages of change provides important hints for the development of a tailored intervention