Predicting, explaining and understanding adolescent exercise behavior using longitudinal and cross-sectional approaches

Sedentary lifestyles have been identified as a serious problem and major public health concern for young people. In addition, the psychological and physiological benefits of exercise are well documented. However, exercise prevalence declines with increasing age and this decrease is most pronounced in adolescence. Despite the developmental decline, and the recognized benefits of exercise, relatively little is known about the mechanisms or motivators underlying exercise during adolescence. Therefore, the overall purpose of this project was to increase the understanding of adolescent exercise behavior. For this purpose 819 Canadian adolescents (mean age = 14.99, SD = 1.22; 51.28% male) were approached for a three-year longitudinal follow-up data collection. The subsample (n = 400; mean age = 14.89, SD = 1.15) that returned follow-up questionnaires did not differ from individuals who did not complete the follow-up on age or other study variables, but was comprised of more females (54.75% vs. 43.68% female, respectively, χ2 = 12.81(1), p \u3c .003). The mean age of the follow-up sample was 17.62 years (SD = 1.18). Variables included at both time points were the stages of exercise, 10 processes of exercise, self-efficacy, pros and cons of the Transtheoretical Model and Godin\u27s Leisure-time Exercise Questionnaire. The follow-up assessment also included a revised stage measure, the Sport Participation Motivation Inventory and sport behavior. Prediction analyses and longitudinal panel designs were used to understand adolescent exercise behavior change. Cross-sectional analyses of the follow-up data compared the different stage conceptualizations and if sport motivations add to the Transtheoretical Model in explaining exercise behavior. The main conclusions from this project are: (1) Self-efficacy and the behavioral processes of change contributed to the prediction of adolescent exercise adoption and maintenance. (2) The processes of change did not lead to exercise behavior or vice versa, whereas exercise behavior lead to self-efficacy, pros and cons. (3) Comparing the stage conceptualizations indicated that immediate intention is preferable over using irregular exercise when defining the preparation stage. Finally, (4) sport participation motivations did not add to the Transtheoretical Model variables addressing exercise behavior. Future investigations should continue to maximize the explanatory power of the Transtheoretical Model to optimize exercise (and other behavior) change interventions