Davis J M
Department of Exercise Science, University of South Carolina, Columbia 29208, USA.
Int J Sport Nutr. 1995 Jun;5 Suppl:S29-38. doi: 10.1123/ijsn.5.s1.s29.
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.
中枢疲劳的机制在很大程度上尚未得到充分研究，但中枢疲劳假说表明，大脑中血清素（5-羟色胺，5-HT）水平升高会导致运动和锻炼表现下降。目前有确凿证据表明，运动引起的血浆游离色氨酸（f-TRP）/支链氨基酸（BCCA）比值升高与大脑5-HT水平升高以及长时间运动期间疲劳的发作有关。此外，当使用药物改变大脑5-HT水平时，它们会对运动表现产生预期的影响。f-TRP/BCCA的营养调控对运动表现的影响尚未得到充分证实。补充BCCA对运动表现的影响喜忧参半，已发表的研究往往存在方法学缺陷。另外，在长时间运动期间，碳水化合物摄入会使f-TRP/BCCA显著降低并提高运动表现。然而，很难区分碳水化合物摄入对大脑机制与肌肉本身机制的影响。
