Effects of combined versus single supplementation of creatine and beta-alanine on aerobic and anerobic performance: a systematic review and network meta-analysis

Background Creatine (Cr) and β-alanine (BA) are among the most studied ergogenic supplements, acting on distinct physiological pathways—Cr facilitates phosphocreatine resynthesis and rapid ATP turnover, while BA elevates intramuscular carnosine to enhance acid–base buffering. Although both compounds improve high-intensity performance independently, the ergogenic potential of their combined use remains uncertain.Objective To systematically evaluate and compare the isolated and combined effects of Cr and BA supplementation on aerobic and anaerobic performance indices using a network meta-analytic approach.Methods Following PRISMA guidelines, a comprehensive search of PubMed, Scopus, and Web of Science (to August 2025) identified randomized controlled trials (RCTs) examining Cr, BA, or Cr + BA supplementation (≥2 weeks) in healthy adult athletes. Fifty-two RCTs (PEDro ≥ 6) met the inclusion criteria. Standardized mean differences (SMD) and 95% confidence intervals (CI) were computed within random effects models. Performance outcomes included sprint, jump, agility, upper- and lower-body muscular endurance (UME, LME), and repeated-sprint ability (RSA).Results Cr supplementation significantly improved sprint performance (SMD = −0.64; p = 0.04), jump performance (SMD = 0.33; p = 0.002), RSA (SMD = −0.78; p = 0.01), and UME (SMD = 0.43; p = 0.01) versus placebo, with P scores ≥ 0.90 across these domains. In contrast, BA supplementation produced non-significant or context-specific effects, and combined Cr + BA showed no synergistic benefits. Agility and LME outcomes remained unaffected (p > 0.05). Heterogeneity ranged from low to moderate (I2 = 0–73%), with no global inconsistency or substantive publication bias.Conclusion Evidence indicates Cr supplementation alone yields the most consistent improvements in high-intensity and anaerobic performance by enhancing phosphocreatine recovery and neuromuscular output. BA’s buffering advantage appears task-specific and insufficient to augment Cr’s ergogenic efficacy. Co-supplementation of Cr and BA offers no additional advantage beyond Cr monotherapy. Standardized, long-term, multi-arm RCTs are warranted to further clarify potential interactive mechanisms and sex or sport-specific responses.