Abstract

ARMADA-DA-SILVA, Paulo  and  ALVES, Francisco. The role of branched chain amino acids supplementation on central fatigue. Rev. Port. Cien. Desp. [online]. 2005, vol.5, n.1, pp.102-113. ISSN 1645-0523.

Evidence of changes in the concentration of certain neurotransmitters in the brain during and after long distance high-intensity exercise, especially serotonin (5-hydroxytryptamine, 5-HT), raised the question of the relationship between the well known depressor effect of these compounds and the metabolic and neuro-hormonal regulation present in the acute response to this type of physical exertion. Functional disturbance of the brain monoaminergic systems induced may be the reason for the inability to maintain central activation of muscle in near the limit situations as happens so often to long distance athletes in competition. Since it is well known that the rate of synthesis of 5-HT is sensitive to the plasma content in free triptophan (TRP), branched-chain amino acids (BCAA) and free fatty acids, it has been postulated that an increase in free fatty acids during and after endurance exercise mediates an increment of free TRP which, in combination with a decline of circulating BCAA, facilitates the entry of TRP into the brain, there by increasing cerebral serotonergic tone. This way, supplementation with BCAAs and/or carbohydrates during exercise becomes an interesting procedure to explore, since it may reduce the rate of penetration of 5-HT precursors through the blood-brain barrier. The aim of this review is to discuss the efficacy of nutritional strategies on the mechanisms underlying central fatigue from present knowledge on the complex metabolic and neurohumoral regulation mechanisms.

Keywords : fadiga central; aminoácidos de cadeia ramificada; serotonina; central fatigue; branched-chain amino acids; serotonin.

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