Effects of β-alanine supplementation on high-intensity intermittent exercise performance and post-exercise blood lactate responses in team-sport athletes: a systematic review and three-level meta-analysis

Abstract

Abstract Background β-Alanine is widely used for high-intensity exercise, but its effects in team-sport athletes are uncertain. This systematic review and three-level meta-analysis evaluated high-intensity intermittent exercise (HIIE) performance and post-exercise blood lactate. Methods Following PRISMA 2020, five databases were searched from inception to May 30, 2026 for randomized controlled trials (RCTs) in team-sport athletes. Hedges’ g and 95% confidence intervals (CIs) were pooled using three-level random-effects models with cluster-robust variance estimation and CR2 adjustment. Subgroup and univariable meta-regression analyses examined task types and supplementation characteristics. Sensitivity analyses and study-level Egger tests assessed robustness and funnel-plot asymmetry. Risk of bias and certainty were assessed using RoB 2.0 and GRADE. Results Fourteen RCTs included 268 athletes. β-Alanine produced a small effect in favor of HIIE performance (22 effect sizes; Hedges’ g = 0.33, 95% CI 0.09 to 0.58, P = 0.011; low-certainty evidence), whereas its effect on post-exercise blood lactate remained uncertain (24 effect sizes; Hedges’ g = − 0.15, 95% CI − 0.51 to 0.21, P = 0.403; very-low-certainty evidence). Effects did not differ significantly by task type (P-diff = 0.766): Hedges’ g was 0.44 (95% CI 0.03 to 0.84) for intermittent endurance, 0.34 (95% CI − 0.01 to 0.68) for repeated-sprint performance and 0.18 (95% CI − 0.46 to 0.82) for simulated match performance. Alternative within-study correlations, one-outcome-per-study selection, leave-one-study-out analyses, restriction to post-HIIE lactate and exclusion of high-risk studies did not alter the conclusions. Meta-regression showed that performance effects were positively associated with supplementation duration (β = 0.155 per week, P = 0.042) and total dose (β = 0.444 per 100 g, P = 0.040), but not with daily dose (β = −0.003 per g/day, P = 0.979). Egger tests were nonsignificant but underpowered. Conclusions β-Alanine may produce a small beneficial effect on HIIE performance in team-sport athletes, but its effect on post-exercise blood lactate remains uncertain. Subgroup and meta-regression findings were exploratory and did not establish task-specific effects or an optimal supplementation regimen. Given the limited evidence, findings should be interpreted cautiously and not be generalized to match performance. Larger standardized trials with more female athletes are needed. Registration PROSPERO CRD420261413463.