Protein requirements for endurance athletes

Area of Science:

• Exercise Physiology
• Nutritional Biochemistry
• Sports Nutrition

Background:

• Endurance exercise stimulates amino acid oxidation, primarily leucine, via the branched-chain oxo-acid dehydrogenase (BCOAD) enzyme.
• BCOAD activity increases significantly during exercise but is downregulated with endurance training.
• Energy and carbohydrate availability influence amino acid oxidation rates and protein requirements.

Purpose of the Study:

• To investigate the impact of endurance exercise on amino acid oxidation.
• To examine the role of BCOAD in exercise-induced amino acid metabolism.
• To determine protein requirements for athletes under varying energy intakes.

Main Methods:

• Analysis of amino acid oxidation during acute endurance exercise.
• Measurement of BCOAD enzyme activity and expression.
• Assessment of protein requirements based on exercise intensity and energy availability.

Main Results:

• Acute exercise increases amino acid oxidation (1-6% of energy cost), with leucine oxidation being significant.
• Endurance training attenuates BCOAD activation and amino acid oxidation, despite increased BCOAD enzyme levels.
• Low energy/carbohydrate intake elevates amino acid oxidation and protein needs.

Conclusions:

• Protein requirements for endurance athletes are generally met with 1.0 g/kg/d, except for elite athletes (up to 1.6 g/kg/d).
• Nutritional guidance is crucial for athletes with low energy or carbohydrate intake to ensure adequate protein consumption.
• Optimizing dietary protein intake is essential for performance and recovery in endurance athletes.