Carbohydrates, Branched-Chain Amino Acids, and Endurances: The Central Fatigue Hypothesis

in International Journal of Sport Nutrition and Exercise Metabolism

Click name to view affiliation

J. Mark Davis
Search for other papers by J. Mark Davis in
Current site
Google Scholar
Restricted access

The mechanisms of central fatigue are largely unexplored, but the central fatigue hypothesis suggests that increased brain serotonin (5-HT) can cause a deterioration in sport and exercise performance. There is now convincing evidence that exercise-induced increases in the plasma free tryptophan (f-TRP)/branched-chain amino acids (BCCA) ratio are associated with increased brain 5-HT and the onset of fatigue during prolonged exercise. Furthermore, when drugs are administered to alter brain 5-HT, they have the predicted effects on exercise performance. The influence of nutritional manipulations of f-TRP/BCCA on performance is less well established. The effects of BCCA supplementation on exercise performance are mixed, and the published studies often suffer from methodological flaws. Alternatively, dramatic reductions in f-TRP/BCCA and enhanced performance accompany carbohydrate feedings during prolonged exercise. However, it is difficult to distinguish between the effects of carbohydrate feedings on mechanisms that reside in the brain versus the muscles themselves.

Mark Davis is with the Department of Exercise Science, The University of South Carolina, Columbia. SC 29208.

  • Collapse
  • Expand
All Time Past Year Past 30 Days
Abstract Views 4418 1066 70
Full Text Views 142 28 11
PDF Downloads 129 30 12