Skeletal muscle fibre type and capillary density in college-aged blacks and whites

• Published in: Annals of human biology Vol. 24; no. 4; pp. 323 - 331
• Main Authors: Duey, W.J., Bassett, D.R., Torok, D.J., Howley, E.T., Bond, V., Mancuso, P., Trudell, R.
• Format: Journal Article
• Language: English
• Published: England Informa UK Ltd 01-07-1997; Taylor & Francis
• Subjects: Adolescent; Adult; African Continental Ancestry Group; Capillaries - anatomy & histology; European Continental Ancestry Group; Human biology; Humans; Male; Muscle Fibers, Skeletal - cytology; Muscle, Skeletal - anatomy & histology; Muscle, Skeletal - blood supply; Oxygen Consumption; Students
• ISSN: 0301-4460; 1464-5033
• DOI: 10.1080/03014469700005072

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 (VO 2peak ), 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/mm 2 in the blacks compared to 289 32/mm 2 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.