What amino acid is known to reduce the risk of upper respiratory infections during endurance training?

Glutamine is recognized for its role in supporting the immune system, especially during periods of strenuous exercise, such as endurance training. During intense physical activity, the body's stores of glutamine can become depleted, which may compromise immune function and increase the risk of upper respiratory infections. Supplementing with glutamine has been shown to help maintain immune system integrity, potentially reducing the incidence of infections related to heavy endurance training. This is particularly important because athletes often experience increased stress on their immune systems, making adequate glutamine levels critical for recovery and health. By promoting immune health, glutamine helps athletes maintain better overall well-being during rigorous training regimens.