Tryptophan, 5-hydroxytryptamine and a possible explanation for central fatigue

Area of Science:

• Exercise Physiology
• Neuroscience
• Nutritional Biochemistry

Background:

• Prolonged exercise can alter plasma amino acid profiles, potentially impacting neurotransmitter synthesis.
• Decreased plasma branched-chain amino acids (BCAA) and increased fatty acids are observed during endurance activities.
• These changes may influence brain levels of tryptophan and serotonin (5-HT), affecting central fatigue.

Purpose of the Study:

• To investigate the relationship between plasma BCAA levels, tryptophan availability, and central fatigue during exercise.
• To explore the potential of BCAA supplementation to mitigate exercise-induced fatigue and enhance athletic performance.

Main Methods:

• Analysis of plasma concentrations of BCAA, free tryptophan, and fatty acids during prolonged exercise.
• Measurement of brain neurotransmitter levels (e.g., 5-HT) and their correlation with performance metrics.
• Evaluation of the effects of BCAA supplementation on perceived exertion and physical performance in athletes.

Main Results:

• Plasma BCAA levels decrease, while fatty acid levels increase during prolonged exercise.
• This shift enhances the ratio of free tryptophan to BCAA, potentially increasing brain 5-HT synthesis.
• Elevated brain 5-HT is linked to increased fatigue and reduced athletic performance.
• BCAA supplementation may counteract these effects, improving performance and decreasing perceived exertion.

Conclusions:

• Altered plasma amino acid balance during exercise can lead to central fatigue via increased brain serotonin.
• BCAA supplementation shows promise for restoring exercise capacity and reducing fatigue in athletes.
• Further research supports the ergogenic potential of BCAA intake for endurance performance.