Same Test, Different Stories? A Critical Look at vLamax Modality-Specific Reliability

Background The maximal rate of blood lactate accumulation ( v 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 v La max testing protocols remain unclear. Objective This systematic review critically examines the reliability of v La max across different exercise modalities and evaluates the methodological consistency of applied testing protocols. Methods 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., ICC , CV ) for v 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. Results Eleven studies across cycling, running, rowing, and isokinetic testing were included. Reported ICC s for v 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 ( ICC : –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 ( ICC ) was generally associated with lower absolute error ( CV and SDC), underscoring the importance of considering both aspects when interpreting v La max results. The methodological quality of included studies was moderate (50%–74%). Conclusion Current v 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 v La max may fall within the margin of measurement error, limiting its standalone utility in applied diagnostics. Until validated and standardized procedures are established, v 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.