Direct and indirect effects of social support on youth physical activity behavior.

Social support (SS) from parents and peers are key reinforcing factors in the Youth Physical Activity Promotion (YPAP) model. This study aims to identify the relative contribution of parental and peer SS on youth participation in moderate to vigorous physical activity (MVPA). Participants included 203 high school students (n = 125 girls; mean age 14.99 ± 1.55 years). MVPA was assessed by accelerometry. SS influences were evaluated using a well-established scale. Structural equation modeling measured (AMOS, Version 19) the relative fit of the YPAP models using both parental and peer SS. Parental SS had significant associations with both predisposing factors, enjoyment (β = .62, p < .01), and self-efficacy (β= .32, p < .01), as well a direct effect on MVPA (β = .30, p < .01). Peer SS had direct effect on MVPA (β = .33, p < .05), also significantly influenced levels of enjoyment (β = .47, p < .01) and self-efficacy (β = .67, p < .01). In both models self-efficacy mediated the influence on MVPA. The direct effects for parents and peers were similar. This demonstrates that both parental and peer social support exert a strong influence on adolescent MVPA.