Influence of Ingesting a Solution of Branched-Chain Amino Acids on Plasma and Muscle Concentrations of Amino Acids During Prolonged Submaximal Exercise

Nutrition. Jul-Aug 1996;12(7-8):485-90. doi: 10.1016/s0899-9007(96)91723-2.


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.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Amino Acids / blood
  • Amino Acids / metabolism*
  • Amino Acids, Branched-Chain / administration & dosage*
  • Bicycling
  • Biopsy
  • Double-Blind Method
  • Exercise / physiology*
  • Glycogen / metabolism
  • Heart Rate
  • Humans
  • Male
  • Muscle, Skeletal / metabolism*
  • Oxygen Consumption
  • Physical Endurance / physiology
  • Pulmonary Gas Exchange
  • Solutions


  • Amino Acids
  • Amino Acids, Branched-Chain
  • Solutions
  • Glycogen