Effects of diets supplemented with branched-chain amino acids on the performance and fatigue mechanisms of rats submitted to prolonged physical exercise

Nutrients. 2012 Nov 16;4(11):1767-80. doi: 10.3390/nu4111767.


This study aimed to determine the effects of diets chronically supplemented with branched-chain amino acids (BCAA) on the fatigue mechanisms of trained rats. Thirty-six adult Wistar rats were trained for six weeks. The training protocol consisted of bouts of swimming exercise (one hour a day, five times a week, for six weeks). The animals received a control diet (C) (n = 12), a diet supplemented with 3.57% BCAA (S1) (n = 12), or a diet supplemented with 4.76% BCAA (S2) (n = 12). On the last day of the training protocol, half the animals in each group were sacrificed after one hour of swimming (1H), and the other half after a swimming exhaustion test (EX). Swimming time until exhaustion was increased by 37% in group S1 and reduced by 43% in group S2 compared to group C. Results indicate that the S1 diet had a beneficial effect on performance by sparing glycogen in the soleus muscle (p < 0.05) and by inducing a lower concentration of plasma ammonia, whereas the S2 diet had a negative effect on performance due to hyperammonemia (p < 0.05). The hypothalamic concentration of serotonin was not significantly different between the 1H and EX conditions. In conclusion, chronic BCAA supplementation led to increased performance in rats subjected to a swimming test to exhaustion. However, this is a dose-dependent effect, since chronic ingestion of elevated quantities of BCAA led to a reduction in performance.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acids, Branched-Chain / administration & dosage*
  • Ammonia / blood
  • Animals
  • Diet*
  • Dose-Response Relationship, Drug
  • Fatigue
  • Glycogen / analysis
  • Male
  • Muscle, Skeletal / chemistry
  • Physical Conditioning, Animal / physiology
  • Physical Exertion / drug effects*
  • Rats
  • Rats, Wistar
  • Swimming


  • Amino Acids, Branched-Chain
  • Ammonia
  • Glycogen