Capillary density and capillary-to-fibre ratio in vastus lateralis muscle of untrained and trained men

Abstract

Muscle fibre profile area (Af), volume density (V_v), capillary-to-fibre ratio (CF) and number of capillaries per fibre square millimetre (CD) were determined from needle biopsies of vastus lateralis of twenty-four male volunteers (mean &#177; SD: age 25.4&#177;5.8 years, height 178.6&#177;5.5 cm, body mass 72.1&#177;7.7 kg) of different training background. Seven subjects were untrained students (group A), nine were national and sub-national level endurance athletes (group B) with the background of 7.8&#177;2.9 years of specialised training, and eight subjects were sprint-power athletes (group C) with 12.8&#177;8.7 years of specialised training. Muscle biopsies of <i>vastus lateralis</i> were analysed histochemically for mATPase. Capillaries were visualized and counted using CD31 antibodies against endothelial cells. There were significant differences in the V_v of type I and type II muscle fibres in both trained groups, B (51.8%; 25.6%) and C (50.5%; 26.4%). However, in untrained group A that was treated as a reference group, the difference between V_v of type I and type II fibres was less prominent, nevertheless statistically significant (42.1%; 35.1%). There was also a significant difference in CF: 1.9 in group A and 2.1 in groups B and C. The number of capillaries per mm² (CD) was 245 (group A), 308 (group B) and 325 (group C). Significant differences (P<0.05) in CF and CD, were found only between group A (1.9; 245) and both groups of trained men, B and C (2.1; 308 and 325). However, endurance athletes (group B), such as long-distance runners, cyclists and cross country skiers, did not differ from the athletes representing short term, high power output sports (group C) such as ice hockey, karate, ski-jumping, volleyball, soccer and modern dance.

Keywords

• Training
• Muscle
• Capillaries
• Exercise
• Sport