Exercise identity and physical activity behavior during late adolescence: A four wave cross-lagged panel model

Research has shown that physical activity behavior tends to decline across adolescence before stabilizing in adulthood. Identifying salient factors underlying these behavioral changes is therefore imperative for informing intervention development. This study explored the temporal nature of the relationship between exercise identity and physical activity behavior during the transition out of high school. An analysis of data from the Application of integrated Approaches to understanding Physical activity during the Transition to emerging adulthood (ADAPT) prospective cohort study was conducted, involving 1451 Canadian adolescents (M_age = 15.93 ± 0.53 years; 52.4% female). Participants completed the International Physical Activity Questionnaire-Short Form to report weekly moderate-to-vigorous physical activity and an abbreviated version of the Exercise Identity Scale yearly for four years beginning in Grade 11. A four-wave cross-lagged panel model was used to test bi-directional associations between exercise identity and physical activity behavior. Significant auto-regressive effects for exercise identity and physical activity were observed across all four time points. Significant positive cross-lagged paths were observed for exercise identity predicting future physical activity at all time points; however, none of the cross-lagged paths with physical activity predicting future exercise identity were significant. Collectively, these findings support existing theory that emphasizes the role that identity plays in physical activity behavior. Interventions seeking to attenuate the physical activity declines typically observed during the transition to emerging adulthood should therefore consider adopting behavior change techniques that target identity, as it appears to be an important psychological determinant underlying future physical activity engagement.