Background/Purpose: Data have been accumulated to determine the prevalence of physical activity (PA) and sedentary behaviors (SB) among US children, but they were mostly limited to cross-sectional studies. The purpose of this study is to examine the trajectories of PA and SB using a nationally representative longitudinal sample of US children.
Method: The five years (2002-2006) of longitudinal data of Youth Media Campaign Longitudinal Survey (YMCLS) were analyzed. A total of 1,623 children, baseline aged 9-13 (853 boys), were included in the analysis. The growth trends of frequency of participating in free time PA (FTPA) and organized PA (ORPA) during last 7 day as well as time spent in media uses (min)- (TSM) were estimated using unconditional models of Latent Growth Modeling. Further, time-invariant covariates including gender, household income, baseline age, parent's marital status and parental education level were used in a conditional multivariate model to examine the effects on the trajectories.
Analysis/Results: The quadratic growth trends model fit for the unconditional models. The mean of initial status intercept, B0i (u00), were 1.78, .61, and 98.65 for FRPA, ORPA, and TSM, respectively (p<.05 for all). The mean of initial growth rate, B1i (u01), were -.01, .03, and 10.93 with a same order (p<.05 for only TSM). The mean acceleration parameter, B2i (u02), were -.02, -.01, and -1.64 (p<.05 for all). The time-invariant covariates were significant predictors of each parameter in a conditional multivariate model.
Conclusions: There were different growth trends of PA and SB with variations by time-invariant covariates.
See more of: Research Consortium