Variation in plasma amino acid concentrations during a cycling competition

Area of Science:

• Sports Science
• Biochemistry
• Human Physiology

Background:

• Professional cyclists undergo intense physical exertion during multi-stage competitions.
• Understanding metabolic changes, specifically amino acid (AA) profiles, is crucial for optimizing athletic performance and recovery.

Purpose of the Study:

• To investigate the dynamic changes in plasma amino acid concentrations in male professional cyclists during the initial stages of a demanding cycling competition.
• To analyze how plasma volume modifications influence amino acid measurements during endurance events.

Main Methods:

• Blood samples were collected from 7 male cyclists before and after two competitive stages (EI and EII).
• Plasma concentrations of 24 amino acids were measured, accounting for plasma volume changes.
• Statistical analysis identified significant variations in specific amino acids post-stage.

Main Results:

• Stage EI showed a significant decrease in alpha-aminobutyric acid and increases in cystine, phenylalanine, taurine, and tyrosine.
• Stage EII revealed significant reductions in multiple amino acids including alpha-aminobutyric acid, arginine, cystine, leucine, lysine, methionine, threonine, and valine.
• The recovery period indicated a reversal of the observed amino acid changes.

Conclusions:

• Plasma amino acid utilization by endurance cyclists may vary between the early and later stages of competition, potentially due to escalating stress levels.
• The findings underscore the need for careful consideration of protein input quality in the nutritional strategies for cyclists participating in high-level stage races.