The inconsistency in measurement of fatigue decrement during repeated sprint ability across studies, due to non-standardized calculation methods, contributes to high heterogeneity and reduces confidence in the evidence that beta-alanine has no effect on fatigue resistance.

During short, all-out sprints, muscles use up their stored phosphocreatine to make energy quickly. Between sprints, the muscles need time to rebuild that phosphocreatine using oxygen, and if they don't recover enough, the next sprint is weaker. This recovery depends on how fast the muscles can produce energy with oxygen, not on how well they neutralize acid. Beta-alanine increases a substance that reduces acid, but it does not speed up this oxygen-based recovery, so it does not improve performance across repeated sprints.