Background <p>The maximal rate of blood lactate accumulation (<i>v</i>La_max) is increasingly used as a marker of anaerobic glycolytic performance in various sports. Despite its conceptual relevance, the methodological robustness and reliability of current <i>v</i>La_max testing protocols remain unclear.</p> Objective <p>This systematic review critically examines the reliability of <i>v</i>La_max across different exercise modalities and evaluates the methodological consistency of applied testing protocols.</p> Methods <p>Following PRISMA guidelines, a comprehensive database search (PubMed, SportDiscus, Web of Science) was conducted in April 2025 and updated in June 2025. Studies were included if they reported test–retest reliability metrics (e.g., <i>ICC</i>, <i>CV</i>) for <i>v</i>La_max. Study quality was assessed using a modified COSMIN checklist adapted for sport science. Reliability data were synthesized using random-effects meta-analysis, including subgroup analyses and exploratory correlation analyses between reliability metrics.</p> Results <p>Eleven studies across cycling, running, rowing, and isokinetic testing were included. Reported <i>ICC</i>s for <i>v</i>La_max ranged from 0.47 to 0.96, with CVs from 4.6% to 26.4%. Estimation of the alactic time interval (t_alac) showed the highest variability (<i>ICC</i>: –0.12 to 0.88). The pooled ICC across all modalities was 0.84 [95% CI: 0.80–0.88], with running protocols showing higher consistency than cycling. Exploratory analyses revealed that higher relative reliability (<i>ICC</i>) was generally associated with lower absolute error (<i>CV</i> and SDC), underscoring the importance of considering both aspects when interpreting <i>v</i>La_max results. The methodological quality of included studies was moderate (50%–74%).</p> Conclusion <p>Current <i>v</i>La_max protocols exhibit substantial variability in test–retest reliability, largely driven by inconsistencies in t_alac estimation and protocol design. The observed relationship between relative and absolute reliability emphasizes that small changes in <i>v</i>La_max may fall within the margin of measurement error, limiting its standalone utility in applied diagnostics. Until validated and standardized procedures are established, <i>v</i>La_max should not be used in isolation for performance diagnostics. Future research should prioritize experimental validation of core protocol variables to enable consistent and practically meaningful application in sport-specific contexts.</p>