Maximal aerobic capacity in African-American and Caucasian prepubertal children

The purpose of this study was to examine differences in resting, submaximal, and maximal ((V) over dot o(2max)) oxygen consumption ((V) over dot o(2)) in African-American (n = 44) and Caucasian (n = 31) prepubertal children aged 5-10 yr. Resting (V) over dot o(2) was measured via indirect calorimetry in the fasted state. Submaximal (V) over dot o(2) and (V) over dot o(2max) were determined during an all out, progressive treadmill exercise test appropriate for children. Dual-energy X-ray absorptiometry was used to determine total fat mass (FM), soft lean tissue mass (LTM), and leg soft LTM. Doubly labeled water was used to determine total energy expenditure (TEE) and activity energy expenditure (AEE). A significant effect of ethnicity (P < 0.01) was found for (V) over dot o(2max) but not resting or submaximal (V) over dot o(2), with African-American children having absolute (V) over dot o(2max) similar to 15% lower than Caucasian children (1.21 +/- 0.032 vs. 1.43 +/- 0.031 l/min, respectively). The lower (V) over dot o(2max) persisted in African-American children after adjustment for soft LTM (1.23 +/- 0.025 vs. 1.39 +/- 0.031 l/min; P < 0.01), leg soft LTM (1.20 +/- 0.031 vs. 1.43 +/- 0.042 l/min; P < 0.01), and soft LTM and FM (1.23 +/- 0.025 vs. 1.39 +/- 0.031 l/min; P < 0.01). The lower (V) over dot o(2max) persisted also after adjustment for TEE (1.20 +/- 0.02 vs. 1.38 +/- 0.0028 l/min P < 0.001) and AEE (1.20 +/- 0.024 vs. 1.38 +/- 0.028 l/min; P < 0.001). In conclusion, our data indicate that African-American and Caucasian children have similar rates of (V) over dot o(2) at rest and during submaximal exercise, but (V) over dot o(2max) is similar to 15% lower in African-American children, independent of soft LTM, FM, leg LTM, TEE, and AEE.