Ischaemia-induced skeletal muscle angiogenesis is impaired in aged compared with young mice. In humans, vascular endothelial growth factor (VEGF) mRNA and protein following an acute exercise bout are lower in aged compared with young untrained men. We hypothesized that exercise-induced skeletal muscle angiogenesis would be attenuated in aged compared with young men. In eight aged (mean age: 64 years) and six young (mean age: 25 years) sedentary men, muscle biopsies were obtained from the vastus lateralis prior to (Pre), after 1 week and after 8 weeks of an aerobic exercise training program for the measurement of capillarization and VEGF mRNA. Dialysate VEGF protein collected from the muscle interstitial space was measured at rest and during submaximal exercise at Pre, 1 week and 8 weeks. Exercise training increased capillary contacts (CC) and capillary-to-fibre perimeter exchange index (CFPE) of type I and IIA fibres similarly in young and aged. The CC of type IIA and IIB fibres was lower in aged compared with young independent of training status. Exercise-induced interstitial VEGF protein was lower in aged compared with young independent of training status. In untrained, greater exercise-induced interstitial VEGF protein during exercise was associated with greater type I, IIA and IIB CC. Exercise training increased VEGF mRNA similarly in young and aged. These results demonstrate that the angiogenic response to aerobic exercise training is not altered during the ageing process in humans. In addition, muscular activity-associated increases in interstitial VEGF protein may play an important role in the maintenance of skeletal muscle capillarization across the life span.

Editor's Comment. Previous data have suggested that the angiogenic response to ischemia in skeletal muscle is quantitatively less in aged mice. There are no equivalent data available in humans, but it has been hypothesized that aging will impair this capillarization response. This study examines the effect of a physiological stimulus, exercise, in young and aged sedentary men and finds that, contrary to expectation, the angiogenic response is unaffected by the 40-year age difference between the 2 groups. Also the increase in exercise capacity following 8 weeks of exercise training was similar, suggesting such improvement is also age independent in otherwise healthy subjects. There is the issue of wider applicability of this study in that the members of the "aged" group were atypical; they were in excellent physical health, and those with significant disease, especially cardiovascular, were excluded, making them somewhat unrepresentative of their age group. However, the overall results do suggest that skeletal muscle shows exercise-induced changes that are not blunted by age. -SK