Multilevel predictors of adolescent physical activity: a longitudinal analysis
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RESEARCH
Open Access
Multilevel predictors of adolescent physical activity: a longitudinal analysis Mary O Hearst1*, Carrie D Patnode2, John R Sirard3, Kian Farbakhsh1 and Leslie A Lytle1
Abstract Background: To examine how factors from a social ecologic model predict physical activity (PA) among adolescents using a longitudinal analysis. Methods: Participants in this longitudinal study were adolescents (ages 10-16 at baseline) and one parent enrolled in the Transdisciplinary Research on Energetics and Cancer-Identifying Determinants of Eating and Activity (TRECIDEA) and the Etiology of Childhood Obesity (ECHO). Both studies were designed to assess a socio-ecologic model of adolescent obesity risk. PA was collected using ActiGraph activity monitors at two time points 24 months apart. Other measures included objective height and weight, adolescent and parent questionnaires on multilevel psychological, behavioral and social determinants of PA, and a home PA equipment inventory. Analysis was conducted using SAS, including descriptive characteristics, bivariate and stepped multivariate mixed models, using baseline adjustment. Models were stratified by gender. Results: There were 578 adolescents with complete data. Results suggest few statistically significant longitudinal associations with physical activity measured as minutes of MVPA or total counts from accelerometers. For boys, greater self-efficacy (B = 0.75, p = 0.01) and baseline MVPA (B = 0.55, p < 0.01) remained significantly associated with MVPA at follow-up. A similar pattern was observed for total counts. For girls, baseline MVPA (B = 0.58, p = 0.01) and barriers (B = -0.32, p = 0.05) significantly predicted MVPA at follow-up in the full model. The full multilevel model explained 30% of the variance in PA among boys and 24% among girls. Conclusions: PA change in adolescents is a complex issue that is not easily understood. Our findings suggest early PA habits are the most important predictor of PA levels in adolescence. Intervention may be necessary prior to middle school to maintain PA through adolescence. Keywords: Adolescent, Multilevel, Predictors of physical activity, Longitudinal
Background The U.S. Department and of Health and Human Services recommends that children and adolescents engage in 60 min or more of physical activity (PA) every day, with most of that time in moderate- to vigorous-intensity [1]. Engagement in moderate-to-vigorous physical activity (MVPA) typically decreases as adolescents move through their teen years. Examining data from a large adolescent cohort, Laska et al. showed that MVPA among girls declined from 5.9 h/week during the transition from early adolescence to mid-adolescence with a * Correspondence: [email protected] 1 Division of Epidemiology and Community Health, University of Minnesota, 1300 South Second Street, Suite 300, Minneapolis, MN 55454, USA Full list of author information is available at the end of the article
further decline to 3.5 h/week by late adolescence [2]. A similar, but less pronounced decline was als
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