Effects of beta-alanine supplementation on performance and muscle fatigue in athletes and non-athletes of different sports: a systematic review.

INTRODUCTION

Beta-alanine (BA) is a non-essential amino acid that can be synthesized in the liver and obtained from diet, particularly from white and red meat. Increased availability of BA via dietary supplement, may improve performance of athletes. The aim of this study was to conduct a review of the use of BA supplementation as an ergogenic aid to improve performance and fatigue resistance in athletes and non-athletes.

EVIDENCE ACQUISITION

In this systematic review, a search in PubMed and Bireme databases was performed for the terms "beta-alanine," "beta-alanine and exercise," "carnosine" or "carnosine and exercise" in the titles or abstracts. We included randomized, clinical trials published between 2005 and 2015.

EVIDENCE SYNTHESIS

Twenty-three studies were selected. Most of them included physically active individuals. The mean intervention period was 5.2±1.8 weeks, and mean BA dose was 4.8±1.3 g/day. The main outcome measures were blood lactate, pH, perceived exertion, power and physical working capacity at fatigue threshold. After BA supplementation, no statistically significant difference was observed in total work, exercise performance time, oxygen consumption and time to exhaustion.

CONCLUSIONS

BA supplementation seems to improve perceived exertion and biochemical parameters related to muscle fatigue and less evidence was found for improvement in performance.