Advices for Life


September 20, 2016 23:06

Branched chain amino acids ( BCAA )

main functions

  • Warn fatigue.
  • Increase aerobic endurance.

Theoretical Foundations

CNS fatigue hypothesis suggests that the increase in the neurotransmitter serotonin nervous system (5-HT) during prolonged load promotes fatigue and inhibits the ability to perform physical work.Intensification of serotonin synthesis occurs when the brain receives an increased amount of tryptophan - the precursor of serotonin.Elevated levels of 5-HT associated with a sense of fatigue and sleepiness.

Tryptophan (TRF) is typically associated with serum albumin, while the unbound or free tryptophan (c-TRF) moves through the blood-brain barrier.BCAA compete with a TRF-limit and its delivery to the brain.However, the levels of plasma BCAA reduced during exercise endurance as occurs in the muscles of their oxidation with release of energy.Increased levels of free fatty acids during exercise also increases with plasma-TRF by displacing tryptophan albumin.These high levels of plasma C-TRF in conjunction with low levels

of BCAA (with high-TRF / BCAA ratio) increase brain serotonin and cause fatigue during prolonged load endurance.

Theoretically, BCAA supplement will compete with Plasma-TRF to cross the blood-brain barrier, reducing the ratio of C-TRF / BCAA fatigue and weaken the central nervous system.The carbohydrate additive may also reduce plasma with TRF-suppressing growth increase the level of free fatty acids that compete with tryptophan.

research results

Madsen et al.studied the effect of glucose, glucose plus BCAA or placebo at improving performance in nine well-trained cyclists, participants in the race for 100 km.To finish this run as quickly as possible, they took glucose, glucose plus BCAA or placebo.In all cases was the same race time.

Davis et al.We evaluated the consumption of 6% solution of carbohydrate-electrolyte drink, 12% solution of a carbohydrate-electrolyte drink placebo during prolonged cycling to exhaustion at 70% V02max.When subjects consumed a placebo, with the content of the plasma-TRF increased 7 times.When subjects consumed b th% or a 12% carbohydrate-electrolyte drink, the amount of plasma to-TRF much reduced, and fatigue occurred approximately 1 hour later.


Although in theory the use of BCAA as ergogenic agent seems reasonable, however, the available scientific data are limited and uncertain.Moreover, large quantities of BCAA required for physiological changes in proportion to the TRF-/ plasma BCAA, increased plasma ammonia, which can be toxic to brain and impair muscle metabolism.Consumption of large doses of BCAA during exercise can also slow down the absorption of water from the intestines and cause gastro-intestinal disturbances.Since

BCAA additives are unsafe or ineffective, and obtain the necessary amount of these amino acids can be food, currently use these additives is not recommended.

On the other hand, the carbohydrate intake is associated with a sharp decrease in the ratio of C-TRF / BCAA plasma.Determine whether caused by the preferential consumption of carbohydrates weakening central fatigue in the brain or peripheral to the working muscles, impossible.However, unlike the BCAA supplements, carbohydrate food can be recommended, as its safety, impact on the performance and advantages of a well-studied.