Muscle fibre types and enzyme activities after training with local leg ischaemia in man.
Eight healthy men performed supine one-legged training on a bicycle ergometer 45 min per leg four times per week for 4 week. The ergometer and 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 blood 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 training biopsies were taken from the vastus lateralis of both legs and maximal one-legged exercise tests were executed with both legs. Biopsies were 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 had higher activity of citrate synthase (CS), a marker of oxidative capacity, and lower activity of the M-subunit of lactate dehydrogenase isoenzymes. 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 greater number of capillaries per fibre. It is concluded that ischaemic training 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.
Esbjörnsson
M
M
Karolinska Institute, Department of Clinical Physiology, Huddinge Hospital, Stockholm, Sweden.
Jansson
E
E
Sundberg
C J
CJ
Sylvén
C
C
Eiken
O
O
Nygren
A
A
Kaijser
L
L
D000328:Adult; D002196:Capillaries / Q000502:physiology; D002950:Citrate (si)-Synthase / Q000378:metabolism; D005080:Exercise Test; D006003:Glycogen / Q000378:metabolism; D006019:Glycolysis / Q000502:physiology; D006801:Humans; D007511:Ischemia / Q000201:enzymology / Q000473:pathology*; D007527:Isoenzymes; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D007866:Leg / Q000098:blood supply*; D008297:Male; D009132:Muscles / Q000166:cytology* / Q000201:enzymology*; D010084:Oxidation-Reduction; D010732:Phosphofructokinase-1 / Q000378:metabolism; D010806:Physical Education and Training; D005082:Physical Exertion / Q000502:physiology; D012039:Regional Blood Flow / Q000502:physiology
D007527:Isoenzymes; D006003:Glycogen; D007770:L-Lactate Dehydrogenase; D002950:Citrate (si)-Synthase; D010732:Phosphofructokinase-1