Testing the Weiss-Harter-Model in a prospective study design: the importance of perceived social support for youth physical activity

To counteract low physical activity levels in children and adolescents, it is crucial to understand the relevant psychological processes that can promote physical activity in this age group. The Weiss-Harter model focuses on self-esteem as a central construct for physical activity promotion in youth, which mediates the effects of perceived competence and perceived social support on enjoyment and physical activity. However, in two cross-sectional studies, an adapted model was found to have a better model fit in which perceived social support has additional direct effects on physical activity and enjoyment. The purpose of the present study was to compare the original Weiss-Harter model and the adapted model in a prospective study design. Data were based on two assessment waves of the German Motorik-Modul-Study involving 1107 participants (603 female) with a mean age of 13.98 years (SD = 2.03). Participants filled out questionnaires on perceived competence, perceived social support, self-esteem, enjoyment, and moderate-vigorous physical activity (MVPA) during the first assessment. MVPA was again assessed about five years later allowing to test whether the models could predict (1) future MVPA and (2) the difference of MVPA from the first to the second assessment. For both research questions, the original Weiss-Harter model (Model 1a: χ(2) = 812.44; df = 95; p < 0.01; CFI = 0.905; RMSEA = 0.083; Model 2a: χ2 = 755.29; df = 95; p < 0.01; CFI = 0.910; RMSEA = 0.079) had a worse fit than the adapted model (Model 1b: χ(2) = 512.19; df = 93; p < 0.01; CFI = 0.943; RMSEA = 0.065; Model 2b: χ(2) = 513.25; df = 93; p < 0.01; CFI = 0.943; RMSEA = 0.064). The results of this study highlight the role of perceived social support for youth MVPA.