Beta-alanine supplementation most improves performance in high-intensity exercise tasks lasting 1 to 4 minutes, particularly those performed until exhaustion.

Study: Incremental effects of 28 days of beta-alanine supplementation on high-intensity cycling performance and blood lactate in masters female cyclists

Taking beta-alanine for a month helped older female cyclists ride longer and do more work before getting too tired, which is exactly what the claim says it should do.

Study: The effect of beta-alanine supplementation on isokinetic force and cycling performance in highly trained cyclists.

Taking beta-alanine didn’t make cyclists faster in a 4-minute race, but it did help their muscles stay stronger and tire less during short, intense bursts—exactly what the claim says it should do.

Study: beta-Alanine supplementation augments muscle carnosine content and attenuates fatigue during repeated isokinetic contraction bouts in trained sprinters.

Taking beta-alanine helped athletes maintain more strength during repeated all-out leg exercises, especially toward the end when they were tired — exactly what the claim says. But it didn’t help them run faster in a 400-meter race or hold a static position longer.

Study: Effects of β-alanine supplementation on exercise performance: a meta-analysis

Beta-alanine helps people exercise harder for 1 to 4 minutes before getting too tired, and this study proves it works best in that time range — not for shorter sprints. It doesn’t help with timed races, but it does help you last longer when you’re pushing until you can’t anymore.