β-alanine supplementation to improve exercise capacity and performance: a systematic review and meta-analysis.
Level 1 - systematic review of randomized trials
Systematic review and meta-analysis of double-blind, placebo-controlled trials.
PubMed 27797728 · doi:10.1136/bjsports-2016-096396
What was done
A systematic review and meta-analysis conducted under PRISMA guidelines evaluated the effects of chronic β-alanine supplementation on exercise measures. Searches across PubMed, Google Scholar, and Web of Science identified double-blind, placebo-controlled studies in healthy participants. Crossover designs were excluded due to long skeletal muscle carnosine washout times. A 3-level mixed-effects model was used to calculate effect sizes across 40 studies, 65 exercise protocols, and 70 exercise measures in 1,461 participants.
What was found
β-alanine supplementation showed a significant overall effect size of 0.18 (95% CI 0.08 to 0.28). Exercise duration was a significant moderator of effect size (p = 0.004). For exercise lasting 0.5 to 10 minutes, exercise type was also a significant moderator (p = 0.013), yielding a larger effect size for exercise capacity (0.4998, 95% CI 0.246 to 0.753) compared to exercise performance (0.1078, 95% CI -0.201 to 0.416). Training status (p = 0.559), intermittent versus continuous exercise (p = 0.436), and total amount of β-alanine ingested (p = 0.438) did not moderate effects. Co-supplementation with sodium bicarbonate produced an effect size of 0.43 (95% CI 0.22 to 0.64) compared with placebo.
Why it matters
This paper clarifies that beta-alanine is primarily ergogenic for open-ended capacity tests lasting between 30 seconds and 10 minutes, while showing little measurable benefit for direct performance trials or outside this time window.
Limits
The overall effect size is small (0.18), and the 95% confidence interval for exercise performance (as opposed to capacity) crossed zero in the 0.5–10 minute range. Excluding crossover trials eliminated a subset of available literature. The abstract does not report risk of bias, adverse effects, or baseline dietary carnosine status.
Cited by
- supports Beta-alanine does not provide significant benefits for maximal strength, speed, power, or long-duration endurance.
- supports Beta-alanine requires 3 to 5 weeks of chronic daily dosing to accumulate sufficiently in muscle tissue before providing performance benefits.