Influence of ingesting a solution of branched-chain amino acids on plasma and muscle concentrations of amino acids during prolonged submaximal exercise.
On two occasions, seven male endurance-trained cyclists performed sustained exhaustive exercise with reduced muscle glycogen stores. During exercise, the subjects were supplied in random order with an aqueous solution of branched-chain amino acids (BCAA) or flavored water (placebo). Ingestion of BCAA caused the concentration of these amino acids to increase by 135% in the plasma and by 57% in muscle tissue during exercise, whereas in the placebo trial there was no change or a slight decrease in the concentration in plasma and a decrease of 18% in the muscle. The plasma concentration of alanine increased by 48% during exercise when BCAA were ingested, and the increase in the muscle concentration of alanine during exercise was larger (70% versus 31% in the placebo trial), suggesting an increased rate of alanine production. Also, the plasma concentration of arginine increased by 14% during exercise when BCAA were ingested, whereas there was no change during exercise in the placebo trial. There was a smaller decrease in the muscle glutamate concentration during exercise in the BCAA trial (32% versus 47% in the placebo trial; p < 0.05), but, for the remaining amino acids, there was no difference between the BCAA and placebo trials. There was a significant decrease in the muscle glycogen concentration during exercise in the placebo trial, whereas only a small decrease was found in the BCAA trial (28 and 9 mmol/kg wet wt [p < 0.05] in the placebo and BCAA trial, respectively). This might indicate that an increased supply of BCAA has a sparing effect on muscle glycogen degradation during exercise.
Blomstrand
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E
Pripps Bryggerier, Research Laboratories, Bromma, Sweden.
Ek
S
S
Newsholme
E A
EA
D000328:Adult; D000596:Amino Acids / Q000097:blood / Q000378:metabolism*; D000597:Amino Acids, Branched-Chain / Q000008:administration & dosage*; D001642:Bicycling; D001706:Biopsy; D004311:Double-Blind Method; D015444:Exercise / Q000502:physiology*; D006003:Glycogen / Q000378:metabolism; D006339:Heart Rate; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism*; D010101:Oxygen Consumption; D010807:Physical Endurance / Q000502:physiology; D011659:Pulmonary Gas Exchange; D012996:Solutions
D000596:Amino Acids; D000597:Amino Acids, Branched-Chain; D012996:Solutions; D006003:Glycogen