BCAA intake affects protein metabolism in muscle after but not during exercise in humans.
Branched-chain amino acids (BCAA) or a placebo was given to seven subjects during 1 h of ergometer cycle exercise and a 2-h recovery period. Intake of BCAA did not influence the rate of exchange of the aromatic amino acids, tyrosine and phenylalanine, in the legs during exercise or the increase in their concentration in muscle. The increase was approximately 30% in both conditions. On the other hand, in the recovery period after exercise, a faster decrease in the muscle concentration of aromatic amino acids was found in the BCAA experiment (46% compared with 25% in the placebo condition). There was also a tendency to a smaller release (an average of 32%) of these amino acids from the legs during the 2-h recovery. The results suggest that BCAA have a protein-sparing effect during the recovery after exercise, either that protein synthesis has been stimulated and/or protein degradation has decreased, but the data during exercise are too variable to make any conclusions about the effects during exercise. The effect in the recovery period does not seem to be mediated by insulin.
Blomstrand
E
E
Copenhagen Muscle Research Centre, Rigshospitalet, DK-2200 Copenhagen N, Denmark. eva.blomstrand@ihs.se
Saltin
B
B
D000284:Administration, Oral; D000328:Adult; D001158:Arteries; D001706:Biopsy; D001783:Blood Flow Velocity / Q000187:drug effects; D005080:Exercise Test; D005973:Glutamine / Q000097:blood; D006003:Glycogen / Q000378:metabolism; D013006:Growth Hormone / Q000097:blood; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007328:Insulin / Q000097:blood; D007532:Isoleucine / Q000008:administration & dosage / Q000378:metabolism*; D019344:Lactic Acid / Q000378:metabolism; D007930:Leucine / Q000008:administration & dosage / Q000378:metabolism*; D008297:Male; D018482:Muscle, Skeletal / Q000098:blood supply / Q000187:drug effects / Q000378:metabolism*; D009638:Norepinephrine / Q000097:blood; D010101:Oxygen Consumption / Q000187:drug effects; D010649:Phenylalanine / Q000097:blood; D005082:Physical Exertion / Q000502:physiology*; D011506:Proteins / Q000378:metabolism*; D011659:Pulmonary Gas Exchange / Q000187:drug effects; D014443:Tyrosine / Q000097:blood; D014633:Valine / Q000008:administration & dosage / Q000378:metabolism*
D007328:Insulin; D011506:Proteins; D007532:Isoleucine; D005973:Glutamine; D019344:Lactic Acid; D014443:Tyrosine; D010649:Phenylalanine; D013006:Growth Hormone; D006003:Glycogen; D007930:Leucine; D014633:Valine; D009638:Norepinephrine