Reliability and validity of the lactate-minimum test. A revisit

The Lactate-Minimum Test (LMT) is a high-resolution, physiologically elegant test for estimating the anaerobic threshold (AnT), or the Maximal Lactate Steady-State (MLSS). Nevertheless, it has not gained the acceptance level of typical progressive lactate-response tests (PLRT). Aim of this study was to compare LMT's validity and reviewer reliability vs. a PLRT-type test and re-evaluate the justification for LMT's dismissal.

Sixteen male distance trained runners (37.1±11.6 yrs) were included in the study. MLSS, LMT, and PLRT tests were performed in separate sessions. Two reviewers, blind to the subjects' identity, independently determined LMT and PLRT's threshold velocities (VLMT, VPLRT) twice. Additionally, VLMT was determined objectively, using best-fit polynomial regressions (VLMTP).

VPLRT, VLMT and VLMTP correlated well with VMLSS (r=0.92, 0.90, 0.93, resp.). VPLRT was identical to VMLSS (13.54 km·h-1), but VLMT and VLMTP were 0.33 and 0.46 km·h-1 lower, respectively. Inter-reviewer reliability was higher for VLMT than VPLRT (ICC=0.96 vs. 0.57, resp.). Intra-reviewer reliability showed a similar pattern.

LMT's underestimation of MLSS appears corrigible. The validity of corrected LMT appears comparable to that of PLRT, while its reliability, objectivity and resolution are superior. Although neither test is a perfect MLSS-substitute, the corrected LMT is not inferior to PLRT-type testing and cannot be dismissed.