Amino acids and central fatigue

Area of Science:

• Exercise Physiology
• Neuroscience
• Biochemistry

Background:

• Central fatigue mechanisms are increasingly studied, focusing on brain monoamine metabolism and amino acid influences.
• Physical exercise elevates brain 5-hydroxytryptamine (5-HT) synthesis and metabolism, potentially contributing to fatigue.
• Brain 5-HT levels, influenced by tryptophan and branched-chain amino acids (BCAA), are linked to performance impairment or improvement.

Purpose of the Study:

• To investigate the role of amino acids, specifically BCAA, in modulating central fatigue.
• To explore how BCAA supplementation affects perceived exertion, mental fatigue, and cognitive performance during exercise.
• To examine the potential of BCAA to enhance physical performance under specific exercise conditions.

Main Methods:

• Review of existing studies on exercise, 5-HT metabolism, and amino acid transport into the brain.
• Analysis of human studies involving BCAA supplementation during sustained heavy exercise.
• Examination of research on the effects of altered 5-HT levels on performance in animal models and humans.

Main Results:

• Elevated brain 5-HT levels impair performance, while decreased levels improve it.
• The plasma ratio of free tryptophan to BCAA increases post-exercise, favoring tryptophan transport and 5-HT synthesis.
• BCAA ingestion during exercise reduced perceived exertion and mental fatigue, and improved post-exercise cognitive performance.

Conclusions:

• BCAA supplementation shows promise in mitigating central fatigue during strenuous exercise.
• BCAA may enhance cognitive function and potentially physical performance, especially in heat or competitive scenarios.
• Further research is needed to fully elucidate the effects of BCAA and tryptophan on physical and mental fatigue.