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

چکیده اصلی

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.

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