Comparison of maximal oxygen consumption between obese black and white adolescents.

The purpose of this investigation was to determine whether maximal oxygen consumption (VO2max) differed between clinically obese black and white children and if a difference existed to determine whether it was related to hematological profiles and/or physical activity/inactivity levels. Twenty-three black and 21 white adolescents were matched for age, BMI, and Tanner stage (II-V). Body composition was determined by DEXA and CT scan. Daily physical activity/inactivity was assessed by questionnaire. VO2max was assessed using the Bruce treadmill protocol. Black participants had significantly lower VO2max and VO2maxFFM values when compared with white adolescents (26.1 +/- 4.2 versus 29.9 +/- 3.1 mL . kg(-1) . min(-1); 48.3 +/- 8.8 versus 55.6 +/- 5.2 mL . kgFFM(-1) . min(-1), respectively). Black adolescents also had significantly lower Hb concentrations ([Hb]) than white children (12.7 +/- 1.3 versus 13.4 +/- 0.7 g/dL). Black adolescents were more physically inactive than their white peers. VO2max correlated with [Hb] for the combined groups. Obese black adolescents had lower VO2max compared with white children and this difference was explained, in part, by the lower [Hb] observed in the black participants. Further investigations should study Hb flow rate (a function of [Hb] . maximal cardiac output) and physical activity/inactivity patterns in obese black and white children as it relates to VO2max.