MUSCLE-FIBER TYPES AND ENZYME-ACTIVITIES AFTER TRAINING WITH LOCAL LEG ISCHEMIA IN MAN

Eight healthy men performed supine one-legged training on a bicycle er gometer 45 min per leg four times per week for 4 week. The ergometer a nd lower body were inside a pressure chamber, the opening of which was sealed at the level of the crotch. One leg trained with impeded leg b lood flow (I-leg), induced by an increased (50 mmHg) chamber pressure, at the highest tolerable intensity. The contralateral leg trained at the same power under normal pressure (N-leg). Before and after trainin g biopsies were taken from the vastus lateralis of both legs and maxim al one-legged exercise tests were executed with both legs. Biopsies we re repeated when the subjects had been back to their habitual physical activity for 3 months. Training increased exercise time to exhaustion , but more in the I-leg than in the N-leg. After training, the I-leg h ad higher activity of citrate synthase (CS), a marker of oxidative cap acity, and lower activity of the M-subunit of lactate dehydrogenase is oenzymes. It also had a higher percentage of type-I fibres and a lower percentage of IIB fibres, larger areas of all fibre types and a great er number of capillaries per fibre. It is concluded that ischaemic tra ining changes the muscle metabolic profile in a direction facilitating aerobic metabolism. An altered fibre-type composition may contribute, but is not enough prerequisite for the change.