Protein requirements in individuals who participate in endurance-based exercise training have been suggested to be greater than the current recommended dietary allowance (RDA).

The biological value of protein depends on the amino acid composition. As liebig's law of the minimum, the protein synthesis is limited due to the lack of single rate limiting amino acid. In this case, the first rate limiting amino acid determines protein intakes to maximize the protein synthesis. Adding a small amount of rate-limiting amino acid to the diet improves the biological value of its protein diet.

The indicator amino acid oxidation (IAAO) method has clarified the individual amino acid requirement in children, normal healthy adult and clinical populations. however, the IAAO method has never been utilized for determining the first rate limiting amino acid.

Therefore, the purpose of this study is to address of IAAO method to be applied for determining the rate-limiting amino acid in endurance athlete.

Gender: Male

Age limit: Minimum age 18 years - Maximum age 35 years

Accepts Healthy Volunteers : yes

Inclusion Criteria:

• Endurance-trained participants who regularly more than 40 km/week
• Ability to perform the exercise stimulus (20 km run) on metabolic trial.

Exclusion Criteria:

• Inability to meet health and physical activity guidelines according to the physical activity readiness questionnaire (PAR-Q+)
• Inability to adhere to any of the protocol guidelines (i.e. alcohol, caffeine consumption)
• Regular tobacco use
• Illicit drug use