Objectively Measured Physical Activity and Cardiovascular Disease Risk Factors in African American Girls

Objective—This study examines the associations between objectively measured physical activity and cardiovascular disease (CVD) risk factors in preadolescent African American girls. Methods—We conducted a cross-sectional analysis of data from Stanford Girls Health Enrichment Multisite Studies (GEMS) trial. Physical activity was assessed for four days by using an ActiGraph accelerometer and was correlated with anthropometric measures, blood pressure, blood lipids, glucose, and insulin. Associations between physical activity and CVD risk factors were computed using by Spearman correlations. Bonferroni adjustment α=.003 was used to correct for multiple testing. Results—A total of 261 girls participated, of which 208 had complete CVD risk measures (mean age 9.4 years, mean body mass index 20.7 kg/m2). Average daily physical activity and time spent in moderate-to-vigorous physical activity (MVPA) were significantly correlated with body mass index (r=−.23, P=.0008 and r=−.29, P\u3c.0001, respectively) and insulin (r=−.27, P=.0001 and r=−. 30, P\u3c.0001, respectively) but not to other CVD factors. After adjusting for age-adjusted pubertal stage of development, the association between MVPA and insulin remained significant. Conclusions—Objective measures of both average daily physical activity and MVPA were inversely associated with body mass index and insulin levels in African American girls