title: Skeletal muscle fibre type and capillary density in college-aged blacks and whites.
abstract: 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.
authors.affiliation: University of Tennessee, Knoxville, USA.
authors.forename: W J
authors.initials: WJ
authors.lastname: Duey
authors.forename: D R
authors.initials: DR
authors.lastname: Bassett
authors.forename: D J
authors.initials: DJ
authors.lastname: Torok
authors.forename: E T
authors.initials: ET
authors.lastname: Howley
authors.forename: V
authors.initials: V
authors.lastname: Bond
authors.forename: P
authors.initials: P
authors.lastname: Mancuso
authors.forename: R
authors.initials: R
authors.lastname: Trudell
mesh_terms: 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