Objectively assessed associations between physical activity and body composition in middle-school girls: the Trial of Activity for Adolescent Girls

Am J Epidemiol. 2007 Dec 1;166(11):1298-305. doi: 10.1093/aje/kwm202. Epub 2007 Sep 12.

Abstract

Declining levels of physical activity probably contribute to the increasing prevalence of overweight in US youth. In this study, the authors examined cross-sectional and longitudinal associations between physical activity and body composition in sixth- and eighth-grade girls. In 2003, girls were recruited from six US states as part of the Trial of Activity for Adolescent Girls. Physical activity was measured using 6 days of accelerometry, and percentage of body fat was calculated using an age- and ethnicity-specific prediction equation. Sixth-grade girls with an average of 12.8 minutes of moderate-to-vigorous physical activity (MVPA) per day (15th percentile) were 2.3 times (95% confidence interval: 1.52, 3.44) more likely to be overweight than girls with 34.7 minutes of MVPA per day (85th percentile), and their percent body fat was 2.64 percentage points greater (95% confidence interval: 1.79, 3.50). Longitudinal analyses showed that percent body fat increased 0.28 percentage points less in girls with a 6.2-minute increase in MVPA than in girls with a 4.5-minute decrease (85th and 15th percentiles of change). Associations between MVPA in sixth grade and incidence of overweight in eighth grade were not detected. More population-based research using objective physical activity and body composition measurements is needed to make evidence-based physical activity recommendations for US youth.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Adolescent
  • Anthropometry
  • Body Composition*
  • Cross-Sectional Studies
  • Female
  • Humans
  • Longitudinal Studies
  • Motor Activity*
  • Overweight
  • Regression Analysis
  • United States