Skeletal muscle fibre type and capillary density in college-aged blacks and whites.
The purpose of this study was to compare muscle fibre type proportions and capillary density in untrained, college-aged blacks (n = 14) and whites (n = 14). Both groups were similar in terms of peak oxygen uptake (VO2peak), measured during cycle ergometry (blacks: 42.6 +/- 4, whites: 44.3 +/- 4 ml.kg-1 min-1, mean +/- SD). Muscle samples were obtained from the quadriceps femoris (vastus lateralis) by the needle biopsy technique. Fibre type was determined by myosin ATPase stain (pH = 4.54) and capillaries were identified by amylase-periodic acid Schiff (PAS) stain. The percentage of type I, IIa, and IIb fibres in the blacks was 39.5 +/- 11.5, 40.0 +/- 8.4, and 22.8 +/- 9.8, respectively. In whites the percentage of type I, IIa, and IIb fibres was 44.9 +/- 8.5, 36.6 +/- 6.9, and 18.3 +/- 9.6, respectively. No significant differences were noted between the two racial groups for type I, IIa, or IIb fibres. Capillary density was 277 +/- 39/mm2 in the blacks compared to 289 +/- 32/mm2 in the whites. Capillary density was positively correlated to percentage of type I fibres (r = 0.497) and negatively correlated to percentage of type IIa fibres (r = -0.389), in the overall study population. These data suggest that if racial differences in fibre type do exist, such differences are small compared to the variability in this measure.
Duey
W J
WJ
University of Tennessee, Knoxville, USA.
Bassett
D R
DR
Torok
D J
DJ
Howley
E T
ET
Bond
V
V
Mancuso
P
P
Trudell
R
R
D000293:Adolescent; D000328:Adult; D044383:Black People; D002196:Capillaries / Q000033:anatomy & histology; D006801:Humans; D008297:Male; D018485:Muscle Fibers, Skeletal / Q000166:cytology; D018482:Muscle, Skeletal / Q000033:anatomy & histology* / Q000098:blood supply*; D010101:Oxygen Consumption; D044465:White People