Purpose: The purpose of this study was to examine the relationships linking motivational variables with BMI percentile (BMI%) via segmented physical activity (PA) and sedentary behavior (SB) in adolescents using path analysis. Method: Secondary data analysis was performed using participants from the Family, Life, Activity, Sun, Health, and Eating (FLASHE) study. A non-probability panel balanced to the US population on sex, Census division, household income and size, and race/ethnicity were screened for eligibility. The final sample consisted of 1,643 adolescents (822 girls, 821 boys). Motivational variables consisted of PA enjoyment, self-efficacy, and peer social support. Mediator variables consisted of segmented weekly PA and SB assessed using the Youth Activity Profile (YAP). BMI% was the outcome. A recursive bootstrapped path analysis was conducted to examine the relationships between motivational variables, segmented PA and SB, and BMI% with indirect effects calculated via bootstrapped mediation analyses. Results: The relationships between motivational variables and segmented PA and SB were stronger than relationships between segmented PA and SB and BMI%. Three mediated paths were observed: self-efficacy and BMI% using sedentary YAP as the mediator (IE = -0.38, 95%CI: -0.65, -0.18), enjoyment and BMI% using weekend YAP as the mediator (IE = -0.62, 95%CI: -1.14, -0.12) and social support and BMI% using weekend YAP as the mediator (IE = -0.53, 95%CI: -1.00, -0.07). Conclusion: The relationship between adolescent motivational variables and segmented PA and SB is relatively strong and specific motivational variables' relationships with BMI% is mediated through segmented PA and SB.
Keywords: Activity; motivation; obesity; youth.