How does beta-alanine supplementation affect previously trained athletes?

Beta-alanine supplementation has been shown to be particularly beneficial for previously trained athletes by augmenting performance and stimulating lean mass accrual. The primary mechanism of beta-alanine is its role in increasing carnosine levels in the muscles, which helps buffer acid during high-intensity exercise. This buffering capacity reduces fatigue and allows athletes to maintain a higher level of performance during short bursts of intense activity.

In addition to enhancing performance, the boost in muscle endurance and reduced fatigue can lead to more effective training sessions, ultimately contributing to greater muscle growth and lean mass gains over time. As athletes are able to push harder and longer in their workouts, they can stimulate muscle protein synthesis more effectively, resulting in improved lean mass.

While other options may touch on related areas, such as fatigue reduction or endurance during long events, the comprehensive benefit of beta-alanine in enhancing overall performance coupled with its impact on muscle growth makes "augments performance and stimulates lean mass accrual" the most accurate choice in this context.