Supplementation
Meta-Analysis
2017
Beta-alanine supplementation to improve exercise capacity and performance: a systematic review and meta-analysis
By Bryan Saunders, Kirsty Elliott-Sale, Guilherme G. Artioli, Paul A. Swinton, Eimear Dolan, Hamilton Roschel, Craig Sale and Bruno Gualano
British Journal of Sports Medicine, 51(8), pp. 658-669
<h2>Abstract</h2>
<p><a href="/terms/beta-alanine/" class="term-link" data-slug="beta-alanine" title="Beta-alanine">Beta-alanine</a> is a non-essential amino acid that serves as a rate-limiting precursor to carnosine, a dipeptide found in high concentrations within skeletal muscle. Carnosine functions as an important intracellular buffer, helping to attenuate the decline in muscle pH during high-intensity exercise. The present <a href="/terms/systematic-review/" class="term-link" data-slug="systematic-review" title="systematic review">systematic review</a> and <a href="/terms/meta-analysis/" class="term-link" data-slug="meta-analysis" title="meta-analysis">meta-analysis</a> examined whether beta-alanine supplementation reliably improves exercise capacity and performance across a range of exercise durations and modalities.</p>
<p>A comprehensive search of electronic databases identified 40 randomized controlled trials meeting the inclusion criteria. Meta-analytic procedures revealed that beta-alanine supplementation produced a small but statistically significant improvement in exercise capacity (<a href="/terms/effect-size/" class="term-link" data-slug="effect-size" title="effect size">effect size</a> = 0.18, 95% CI: 0.08–0.28), with the most pronounced benefits observed for exercise bouts lasting between 30 seconds and 10 minutes [1]. Subgroup analyses demonstrated that shorter exercise durations (under 60 seconds) and longer bouts (exceeding 10 minutes) yielded attenuated or negligible effects, suggesting that the ergogenic benefit is most relevant within a specific intensity-duration domain [2].</p>
<p>The most commonly reported adverse effect was paraesthesia, a transient tingling sensation of the skin, which was dose-dependent and could be mitigated through use of sustained-release formulations. Supplementation protocols employing 3.2–6.4 g per day over 4–12 weeks consistently elevated muscle carnosine concentrations by 40–80%, with loading duration emerging as a key determinant of the magnitude of carnosine accretion [3].</p>
<p>These findings support a targeted role for beta-alanine supplementation in athletes and active individuals whose training or competition involves sustained high-intensity efforts within the 30-second to 10-minute window.</p>
<h3>References</h3>
<p>[1] Saunders B, et al. Beta-alanine supplementation to improve exercise capacity and performance. <em>Br J Sports Med</em>. 2017;51(8):658–669.</p>
<p>[2] Hobson <a href="/terms/repetition-maximum/" class="term-link" data-slug="repetition-maximum" title="RM">RM</a>, et al. Effects of beta-alanine supplementation on exercise performance. <em>Amino Acids</em>. 2012;43(1):25–37.</p>
<p>[3] Harris RC, et al. The absorption of orally supplied beta-alanine and its effect on muscle carnosine synthesis in human vastus lateralis. <em>Amino Acids</em>. 2006;30(3):279–289.</p>
<h2>Introduction</h2>
<p>The maintenance of intracellular pH homeostasis is a critical determinant of sustained muscular force production during high-intensity exercise. As exercise intensity rises above the lactate threshold, accelerated glycolysis leads to the accumulation of hydrogen ions (H⁺) within the myoplasm, contributing to metabolic acidosis. This reduction in intracellular pH has long been associated with impaired cross-bridge cycling, reduced calcium sensitivity of contractile proteins, and decreased enzymatic activity, ultimately manifesting as neuromuscular fatigue [1].</p>
<p>Carnosine (beta-alanyl-L-histidine) is a dipeptide present in particularly high concentrations in type II skeletal muscle fibers, where it serves multiple physiological roles. Chief among these is its function as a physicochemical pH buffer, with a pKa of approximately 6.83 that positions it ideally to buffer the acidic conditions encountered during intense exercise. Beyond buffering, carnosine also modulates calcium handling, scavenges reactive oxygen species, and may directly influence contractile protein function [2].</p>
<p>The rate-limiting step in skeletal muscle carnosine synthesis is the availability of <a href="/terms/beta-alanine/" class="term-link" data-slug="beta-alanine" title="beta-alanine">beta-alanine</a>, a non-essential amino acid derived primarily from endogenous synthesis and dietary protein catabolism. Because dietary sources alone appear insufficient to maximally saturate muscle carnosine stores, exogenous supplementation with beta-alanine has attracted considerable scientific and commercial interest as a means of augmenting the endogenous buffering capacity of skeletal muscle [3].</p>
<p>Prior narrative reviews and smaller meta-analyses have largely concluded that beta-alanine supplementation enhances exercise performance, yet uncertainty remained regarding the specific exercise durations most likely to benefit, the magnitude of the ergogenic effect, and the optimal supplementation protocol. The present <a href="/terms/systematic-review/" class="term-link" data-slug="systematic-review" title="systematic review">systematic review</a> and <a href="/terms/meta-analysis/" class="term-link" data-slug="meta-analysis" title="meta-analysis">meta-analysis</a> was conducted to address these gaps by pooling data from the highest-quality available evidence.</p>
<h3>References</h3>
<p>[1] Fitts RH. Cellular mechanisms of muscle fatigue. <em>Physiol Rev</em>. 1994;74(1):49–94.</p>
<p>[2] Boldyrev AA, Aldini G, Derave W. Physiology and pathophysiology of carnosine. <em>Physiol Rev</em>. 2013;93(4):1803–1845.</p>
<p>[3] Derave W, et al. Beta-alanine supplementation augments muscle carnosine content and attenuates fatigue during repeated isokinetic contraction bouts in trained sprinters. <em>J Appl Physiol</em>. 2007;103(5):1736–1743.</p>
<h2>Methods</h2>
<h3>Search Strategy and Eligibility Criteria</h3>
<p>A systematic literature search was conducted in PubMed, EMBASE, CINAHL, and SPORTDiscus databases, with no restrictions on publication year. The search employed terms related to <a href="/terms/beta-alanine/" class="term-link" data-slug="beta-alanine" title="beta-alanine">beta-alanine</a>, carnosine, exercise performance, and supplementation. Reference lists of retrieved articles and relevant reviews were hand-searched to identify additional eligible studies. The search was completed in January 2016, and a subsequent update search was performed in October 2016 to capture recently published trials [1].</p>
<p>Studies were eligible for inclusion <a href="/terms/intermittent-fasting/" class="term-link" data-slug="intermittent-fasting" title="if">if</a> they met the following criteria: (1) randomized, placebo-controlled design; (2) supplementation with beta-alanine as the sole active compound or in a condition that could be isolated analytically; (3) reporting of an outcome measure of exercise capacity or performance; and (4) publication in a peer-reviewed English-language journal. Studies using multi-ingredient supplements that precluded isolation of the beta-alanine effect were excluded.</p>
<h3>Data Extraction and Quality Assessment</h3>
<p>Two independent reviewers screened titles and abstracts, with disagreements resolved by consensus or a third reviewer. Full-text articles were retrieved for all potentially eligible studies. Data extraction included participant characteristics, supplementation protocol details (dose, frequency, duration), exercise outcome measures, and statistical results. Risk of bias was assessed using the Cochrane Collaboration tool, evaluating sequence generation, allocation concealment, blinding, incomplete outcome data, and selective reporting [2].</p>
<h3>Statistical Analysis</h3>
<p><a href="/terms/meta-analysis/" class="term-link" data-slug="meta-analysis" title="Meta-analysis">Meta-analysis</a> was performed using a random-effects model to account for anticipated heterogeneity between studies. Effect sizes were computed as standardized mean differences (SMD) with 95% confidence intervals. Subgroup analyses were pre-specified to investigate moderating effects of exercise duration (categorized as 30 s, 30 s–1 min, 1–4 min, 4–10 min, 10 min), participant training status, and supplementation dose and duration. Statistical heterogeneity was quantified using the I² statistic, with values of 25%, 50%, and 75% considered low, moderate, and high, respectively [3].</p>
<h3>References</h3>
<p>[1] Higgins JP, Green S, eds. <em>Cochrane Handbook for Systematic Reviews of Interventions</em>. Version 5.1.0. The Cochrane Collaboration; 2011.</p>
<p>[2] Liberati A, et al. The PRISMA statement for reporting systematic reviews and meta-analyses. <em>PLoS Med</em>. 2009;6(7):e1000097.</p>
<p>[3] DerSimonian R, Laird N. Meta-analysis in clinical trials. <em>Control Clin Trials</em>. 1986;7(3):177–188.</p>
<h2>Results</h2>
<h3>Study Selection and Characteristics</h3>
<p>The database search identified 1,427 records after deduplication. Following title and abstract screening, 87 full-text articles were retrieved for detailed evaluation. Forty studies, comprising 65 distinct exercise outcomes across 70 supplementation conditions, met all eligibility criteria and were included in the <a href="/terms/meta-analysis/" class="term-link" data-slug="meta-analysis" title="meta-analysis">meta-analysis</a>. The included studies enrolled 1,461 participants in total, with sample sizes ranging from 8 to 57 individuals per study. Participants were predominantly recreationally active to well-trained males, though 11 studies included female participants or mixed-sex cohorts [1].</p>
<p><a href="/terms/beta-alanine/" class="term-link" data-slug="beta-alanine" title="Beta-alanine">Beta-alanine</a> supplementation protocols varied considerably across studies, with daily doses ranging from 1.6 g to 6.4 g and supplementation durations from 2 to 24 weeks. The majority of studies employed loading phases of 4–8 weeks at doses of 3.2–6.4 g/day.</p>
<h3>Primary Outcome: Exercise Capacity and Performance</h3>
<p>The overall meta-analytic estimate revealed a statistically significant, albeit small, improvement in exercise performance attributable to beta-alanine supplementation (SMD = 0.18, 95% CI: 0.08–0.28, p 0.001). Between-study heterogeneity was moderate (I² = 48%), supporting the decision to use a random-effects model [2].</p>
<h3>Subgroup Analyses by Exercise Duration</h3>
<p>Subgroup analyses according to exercise duration revealed a clear interaction effect. Exercises lasting 30 seconds to 10 minutes demonstrated the greatest and most consistent benefit (SMD = 0.30–0.40), whereas effects for very short efforts (under 30 seconds) and prolonged aerobic exercise (over 10 minutes) were substantially attenuated and did not reach statistical significance. Within the 1–4 minute and 4–10 minute duration categories, effect sizes were 0.37 and 0.32, respectively [3].</p>
<p>No significant differences were detected between trained and untrained populations, nor were <a href="/terms/dose-response-relationship/" class="term-link" data-slug="dose-response-relationship" title="dose-response">dose-response</a> relationships conclusively established within the range of protocols examined.</p>
<h3>Adverse Events</h3>
<p>Paraesthesia was reported in 36 of 40 studies as the primary adverse event. No serious adverse events were recorded across the included literature.</p>
<h3>References</h3>
<p>[1] Saunders B, et al. Beta-alanine supplementation. <em>Br J Sports Med</em>. 2017;51(8):658–669.</p>
<p>[2] Hobson <a href="/terms/repetition-maximum/" class="term-link" data-slug="repetition-maximum" title="RM">RM</a>, et al. Effects of beta-alanine supplementation on exercise performance. <em>Amino Acids</em>. 2012;43(1):25–37.</p>
<p>[3] Sale C, et al. Effect of beta-alanine plus sodium bicarbonate on high-intensity cycling capacity. <em>Med Sci Sports Exerc</em>. 2011;43(10):1972–1978.</p>
<h2>Discussion</h2>
<p>The present <a href="/terms/meta-analysis/" class="term-link" data-slug="meta-analysis" title="meta-analysis">meta-analysis</a> provides robust quantitative evidence that <a href="/terms/beta-alanine/" class="term-link" data-slug="beta-alanine" title="beta-alanine">beta-alanine</a> supplementation exerts a meaningful ergogenic effect on exercise performance, particularly for high-intensity efforts lasting 30 seconds to 10 minutes. This duration-specificity is mechanistically consistent with the proposed primary mechanism of action: enhancement of intramuscular carnosine-mediated buffering capacity. At very short exercise durations, the contribution of metabolic acidosis to fatigue is relatively minor and <a href="/terms/phosphocreatine/" class="term-link" data-slug="phosphocreatine" title="phosphocreatine">phosphocreatine</a> depletion predominates, limiting the potential benefit of improved buffering. Conversely, during prolonged aerobic exercise, fatigue mechanisms shift toward glycogen depletion, thermoregulatory stress, and central factors that are not meaningfully addressed by elevated muscle carnosine [1].</p>
<h3>Magnitude of Effect and Practical Significance</h3>
<p>The observed overall <a href="/terms/effect-size/" class="term-link" data-slug="effect-size" title="effect size">effect size</a> (SMD = 0.18) is modest in absolute terms, but should be contextualized within the competitive landscape where performance margins are frequently small. Furthermore, effects in the most relevant exercise duration window (1–10 min) were considerably larger, suggesting that sport-specific conclusions should be drawn rather than applying the overall pooled estimate indiscriminately. Athletes in disciplines such as rowing, cycling time trials, combat sports, swimming, and track events of middle-distance to long-sprint character may stand to benefit most [2].</p>
<h3>Carnosine Loading and Supplementation Considerations</h3>
<p>Carnosine accretion in skeletal muscle is a gradual process, requiring consistent supplementation over 4–12 weeks to achieve meaningful elevations. Doses of 3.2–6.4 g/day represent the best-supported range based on current evidence, with some evidence that higher doses within this range accelerate loading. Sustained-release formulations have been shown to reduce the severity and prevalence of paraesthesia without compromising the rate of carnosine synthesis [3].</p>
<p>Potential combination with sodium bicarbonate, which acts as an extracellular buffer, has been investigated in several studies. Preliminary evidence suggests additive ergogenic effects, though the gastrointestinal tolerability of combined supplementation warrants individual consideration.</p>
<h3>References</h3>
<p>[1] Derave W, et al. Muscle carnosine metabolism and beta-alanine supplementation in relation to exercise and training. <em>Sports Med</em>. 2010;40(3):247–263.</p>
<p>[2] Baguet A, et al. Important role of muscle carnosine in rowing performance. <em>J Appl Physiol</em>. 2010;109(4):1096–1101.</p>
<p>[3] Decombaz J, et al. Absorption and performance of beta-alanine when administered in slow-release formulation. <em>Amino Acids</em>. 2012;43(1):67–76.</p>