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Amino acids with branched chain (ACRT)
Last reviewed: 19.10.2021
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Main functions
- Prevent fatigue.
- Increase aerobic endurance.
Theoretical basis
The fatigue hypothesis of the CNS suggests that an increase in the neurotransmitter of the nervous system of serotonin (5-hydroxytryptamine) during prolonged exercise contributes to fatigue and inhibits the ability to perform physical work. Intensification of the synthesis of serotonin occurs when the brain receives an increased amount of tryptophan - the precursor of serotonin. Elevated levels of 5-hydroxytryptamine are associated with a feeling of fatigue and drowsiness.
Tryptophan (TRP) is usually associated with serum albumin, while unbound, or free, tryptophan (c-TRP) moves through the blood-brain barrier. ACRC competes with c-TRF and restricts its entry into the brain. However, plasma levels of ACRT decrease during exercise of endurance exercises, as in muscles, their oxidation occurs with the release of energy. An increase in the level of free fatty acids during exercise also increases plasma c-TRP by displacing tryptophan from albumin. These high levels of plasma c-TRP in combination with low levels of ACRP (high c-TRF / ACRCC ratio) increase brain serotonin and cause fatigue during a prolonged endurance load.
Theoretically, the addition of ARCT will compete with plasma c-TRP to cross the blood-brain barrier, reduce the c-TRP / ACRT ratio, and ease the fatigue of the central nervous system. Carbohydrate supplements can also reduce plasma c-TRP, suppressing the increase in the increase in free fatty acids that compete with tryptophan.
Research results
Madsen et al. Studied the effect of glucose, glucose plus ACRT or placebo on improving the performance of nine well-trained cyclists, participants in a 100 km race. To complete this run as quickly as possible, they took glucose, glucose plus ACRT or placebo. In all cases, the race time was the same.
Davis et al. The consumption of a 6% carbohydrate-electrolyte beverage, a 12% carbohydrate-electrolyte beverage and a placebo during a long cycling race before fatigue at 70% V02max were evaluated. When subjects consumed placebo, the plasma c-TRP content increased 7-fold. When subjects consumed a 6% or 12% carbohydrate-electrolyte drink, the amount of plasma c-TRP was greatly reduced, and fatigue occurred approximately 1 hour later.
Recommendations
Although in theory the use of ARQs as an ergogenic tool seems reasonable, but the available scientific data are limited and questionable. Moreover, the large amounts of ACRCC required for physiological changes in the c-THF / ACRT ratio in plasma increase plasma ammonia, which can be toxic to the brain and worsen muscle metabolism. Consuming large doses of ACE during exercise can also slow the absorption of water from the intestine and cause gastrointestinal disorders.
Since ADRC supplements are unsafe or ineffective, and it is possible to obtain the required amount of these amino acids from food, currently these supplements are not recommended.
On the other hand, carbohydrate intake is associated with a sharp decrease in the c-TRP / ACRT ratio in plasma. It is impossible to determine whether the primary consumption of carbohydrates is caused by the easing of central fatigue in the brain or peripheral in the working muscles. However, in contrast to the additives of ACRT, carbohydrate nutrition can be recommended, since its harmlessness, impact on indicators and benefits are well studied.
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