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˙o 2 max) oxygen consumption (V˙o 2) in African-American ( n = 44) and Caucasian ( n = 31) prepubertal children aged 5–10 yr. RestingV˙o 2 was measured via indirect calorimetry in the fasted state. SubmaximalV˙o 2 andV˙o 2 max 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˙o 2 max but not resting or submaximalV˙o 2, with African-American children having absoluteV˙o 2 max ∼15% lower than Caucasian children (1.21 ± 0.032 vs. 1.43 ± 0.031 l/min, respectively). The lowerV˙o 2 max 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 lowerV˙o 2 max 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˙o 2 at rest and during submaximal exercise, butV˙o 2 max is ∼15% lower in African-American children, independent of soft LTM, FM, leg LTM, TEE, and AEE.