Comparison of methods to estimate physical activity and energy expenditure in African American children

Low levels of physical activity and high levels of obesity among children in the US is a public health concern. Accurate methods to estimate physical activity are needed to determine the efficacy of intervention programs and to explore relationships between daily physical activity and health status in children. The purpose of this study was to compare the simultaneous use of the Tritrac-R3D accelerometer (Tritrac), Yamax SW-200 Digiwalker step-counter (Digiwalker) and the Self Administered Physical Activity Checklist (SAPAC) to assess physical activity (PA) and energy expenditure (EE) in African-American children aged 7 to 10 years, using the doubly-labeled water (DLW) as the criterion method. Physical activity and energy expenditure were measured over seven consecutive days under free-living conditions. Resting metabolic rate and peak VO(2) were measured before the experimental period. There was no difference in physical activity energy expenditure (PAEE) measured by Tritrac or DLW (p > 0.05). Tritrac activity counts were highly correlated with DLW-PAEE (r = 0.81). High correlations between Digiwalker and DLW were observed when body weight was considered. A low correlation (r = 0.49) was observed between the physical activity energy expenditure by SAPAC and DLW. In conclusion, with some limitations the Tritrac and Digiwalker can provide useful and accurate information about PA and EE in 7- to 10-year-old children.