Effect of an after-school intervention on increases in children's physical activity

Steven L. Gortmaker, Rebekka M. Lee, Rebecca S. Mozaffarian, Arthur M. Sobol, Toben F. Nelson, Barbara A. Roth, Jean L. Wiecha

Research output: Contribution to journalArticlepeer-review

69 Scopus citations


PURPOSE: Evaluate the effect of an after-school intervention on physical activity program changes and individual behaviors among children. METHODS: A quasi-experimental evaluation of a YMCA-driven environmental change intervention with 16 intervention and 16 control sites in four metropolitan areas in the United States. Intervention sites participated in learning collaboratives designed to promote physical activity and nutrition through environmental change, educational activities, and parent engagement. Behavioral foci included increasing overall physical activity levels as well as combined moderate and vigorous physical activity and vigorous physical activity. Outcomes were assessed longitudinally using preintervention and follow-up surveys of program implementation and accelerometer measures of physical activity. ActiGraph accelerometer data were collected from a sample of 212 children, ages 5-11 yr, attending the programs. On average, 3 d of data were gathered per child. Reliability of the accelerometer counts averaged 0.78. Multivariate regression models were used to control for potential confounding variables and to account for clustering of observations. RESULTS: Data indicate greater physical activity increases in children in intervention versus control sites after modest intervention implementation. Controlling for baseline covariates, children in intervention sites showed greater increases in average physical activity level than in control sites (76 counts per minute, P = 0.037, 95% confidence interval (CI) = 8.1-144) and more minutes of moderate and vigorous physical activity (10.5 min•d -1, P = 0.017, 95% CI = 1.5-18.6), minutes of moderate physical activity (5.6 min•d -1, P = 0.020, 95% CI = 0.99-10.2), and minutes of vigorous physical activity (5.1 min•d -1, P = 0.051, 95% CI = 0.21-9.93). CONCLUSIONS: Results indicate significant increases in daily physical activity among children in intervention versus control sites. This study documents the effectiveness of an environmental change approach in an applied setting.

Original languageEnglish (US)
Pages (from-to)450-457
Number of pages8
JournalMedicine and science in sports and exercise
Issue number3
StatePublished - Mar 2012




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