Effect of a 6-week endurance training programme and branched-chain amino acid supplementation on histomorphometric characteristics of aged human muscle

The effects of a 6-week endurance training programme and a branched-chain amino acid (BCAA) supplementation were investigated on skeletal muscle histomorphometric characteristics of elderly men. Seventeen elderly men, age (63 +/- 5 years), height (173 +/- 5 cm) and weight (75 +/- 8 kg) were included in the study. One group (n = 9) received an oral BCAA supplementation for 6 weeks (16, 2 and 2 g per day of leucine, isoleucine and valine, respectively), while another group (n = 8) received a placebo. During these 6 weeks, subjects trained on a Monark cycle ergometer at 75 +/- 9 % of their maximal heart rate for 1 h/day, 4 days/week. Muscle biopsy samples taken at rest before and after endurance training were analyzed for capillarization, fibre type distribution and fibre area. As a result of endurance training, maximal oxygen uptake was significantly increased by about 5 % in control and BCAA supplemented groups (P < 0.01). The number of capillaries per fibre and in contact with type I fibres was significanly increased (P < 0.05), this effect being similar in control and BCAA supplemented groups. The percentage distribution and area of type I, type IIa and type IIb fibres did not differ between the two groups and remained unchanged with endurance training. It is concluded that skeletal muscle of elderly men can adapt to a 6-week endurance training programme and that a BCAA supplementation does not further enhance the induced histomorphometric changes.