Peak oxygen consumption and skeletal muscle bioenergetics in African-American and Caucasian men
To compare peak oxygen consumption (VO2peak) and skeletal muscle oxidative metabolism between nine African-American and nine Caucasian men. Subjects performed arm ergometry to exhaustion. On a separate occasion 31phosphorous-nuclear magnetic resonance spectroscopy (31P-NMRS) was used to determine th...
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Veröffentlicht in: | Medicine and science in sports and exercise 2000-12, Vol.32 (12), p.2059-2066 |
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Sprache: | eng |
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Zusammenfassung: | To compare peak oxygen consumption (VO2peak) and skeletal muscle oxidative metabolism between nine African-American and nine Caucasian men.
Subjects performed arm ergometry to exhaustion. On a separate occasion 31phosphorous-nuclear magnetic resonance spectroscopy (31P-NMRS) was used to determine the concentrations of phosphorous (Pi), phosphocreatine (PCr), and the intracellular pH of the flexor carpi radialis before and during 4 min of steady-state, wrist flexion exercise performed at 28% (15 W) of each subject's peak voluntary contraction.
The Pi/PCr ratio was used as an indirect measure of skeletal muscle oxidative metabolism. VO2peak was lower in the African-Americans compared with the Caucasians (means +/- SD, 19.4 +/- 3.4 vs 23.3 +/- 4.0 mL x kg(-1) x min(-1)) (P < 0.05). No significant between group difference was noted in the Pi/PCr ratio at rest (0.10 +/- 0.02 both groups). However, resting pH was lower in the African-Americans (6.99 +/- 0.04 vs 7.03 +/- 0.05) (P < 0.05). Exercise caused an increase in the Pi/PCr ratio in the African-Americans (1.06 +/- 0.11), which was higher than the increase observed in the Caucasians (0.50 +/- 0.14) (P < 0.05). pH levels decreased to a lower level during exercise in the African-Americans (6.89 +/- 0.04) than in the Caucasians (6.98 +/- 0.05) (P < 0.05).
This select group of African-American men achieved a lower VO2peak than the Caucasian men. Variations in skeletal muscle oxidative metabolic components may explain this difference. |
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ISSN: | 0195-9131 1530-0315 |
DOI: | 10.1097/00005768-200012000-00015 |