Peak oxygen consumption and skeletal muscle bioenergetics in African-American and Caucasian men.
OBJECTIVE
To compare peak oxygen consumption (VO2peak) and skeletal muscle oxidative metabolism between nine African-American and nine Caucasian men.


METHODS
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.


RESULTS
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).


CONCLUSIONS
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.
Suminski
R R
RR
The Ohio State University, School of Physical Activity and Educational Services, Columbus 43210, USA. suminski.l@osu.edu
Robertson
R J
RJ
Goss
F L
FL
Arslanian
S
S
D000328:Adult; D044383:Black People; D004734:Energy Metabolism; D015444:Exercise / Q000502:physiology*; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology*; D010101:Oxygen Consumption; D010725:Phosphocreatine / Q000032:analysis; D010758:Phosphorus / Q000032:analysis; D044465:White People; D001741:Black or African American
D010725:Phosphocreatine; D010758:Phosphorus