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Maximal aerobic capacity in African-American and Caucasian prepubertal children
C A Trowbridge1, B A Gower, T R Nagy
1Department of Nutrition Sciences, University of Alabama at Birmingham, 35294-3360, USA.
Insights
African-American children exhibit approximately 15% lower maximal oxygen consumption (VO2max) compared to Caucasian children. This difference in VO2max persists regardless of body composition or energy expenditure factors.
Area of Science:
- Pediatric Exercise Physiology
- Ethnic Differences in Physiology
- Cardiorespiratory Fitness
Background:
- Understanding ethnic variations in physiological responses during childhood is crucial for tailored health and fitness recommendations.
- Prepubertal children's cardiorespiratory fitness, particularly maximal oxygen consumption (VO2max), may differ across ethnic groups.
- Previous research has not fully elucidated ethnic differences in VO2max adjusted for body composition and energy expenditure in young children.
Purpose of the Study:
- To investigate ethnic disparities in resting, submaximal, and maximal oxygen consumption (VO2max) between African-American and Caucasian prepubertal children.
- To determine if differences in VO2max are influenced by body composition (fat mass, lean tissue mass) and energy expenditure (TEE, AEE).
Main Methods:
- Indirect calorimetry for resting VO2 measurement.
- Progressive treadmill tests to determine submaximal and maximal VO2 (VO2max).
- Dual-energy X-ray absorptiometry for body composition analysis (FM, LTM, leg LTM).
- Doubly labeled water technique to assess total energy expenditure (TEE) and activity energy expenditure (AEE).
Main Results:
- A significant ethnic effect was observed for VO2max (P < 0.01), with African-American children showing approximately 15% lower absolute VO2max than Caucasian children.
- These ethnic differences in VO2max remained significant after adjusting for soft lean tissue mass, leg soft lean tissue mass, and fat mass.
- The lower VO2max in African-American children persisted even after adjustments for total energy expenditure and activity energy expenditure.
Conclusions:
- African-American and Caucasian children demonstrate similar resting and submaximal oxygen consumption rates.
- Maximal oxygen consumption (VO2max) is significantly lower in African-American children compared to Caucasian children.
- This ethnic disparity in VO2max is independent of variations in body composition and energy expenditure.
Abstract:
The purpose of this study was to examine differences in resting, submaximal, and maximal (VO2max) oxygen consumption (VO2) in African-American (n = 44) and Caucasian (n = 31) prepubertal children aged 5-10 yr. Resting VO2 was measured via indirect calorimetry in the fasted state. Submaximal VO2 and VO2max 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 VO2max but not resting or submaximal VO2, with African-American children having absolute VO2max approximately 15% lower than Caucasian children (1.21 +/- 0.032 vs. 1.43 +/- 0.031 l/min, respectively). The lower VO2max 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 VO2max 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 VO2 at rest and during submaximal exercise, but VO2max is approximately 15% lower in African-American children, independent of soft LTM, FM, leg LTM, TEE, and AEE.