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

Area of Science:

• Exercise Physiology
• Sports Science
• Biotechnology

Background:

• The Lactate-Minimum Test (LMT) is a precise method for estimating the anaerobic threshold (AnT) or Maximal Lactate Steady-State (MLSS).
• Despite its physiological elegance, LMT has not achieved widespread adoption compared to traditional progressive lactate-response tests (PLRT).
• This discrepancy necessitates a re-evaluation of LMT's utility and justification for its limited acceptance.

Purpose of the Study:

• To compare the validity and inter-reviewer reliability of the LMT against a PLRT-type test.
• To objectively reassess the rationale behind the dismissal of the LMT in exercise performance testing.
• To determine the threshold velocities (VLMT, VPLRT) and compare them with the Maximal Lactate Steady-State (MLSS).

Main Methods:

• Sixteen trained male distance runners participated in separate MLSS, LMT, and PLRT test sessions.
• Two independent reviewers determined threshold velocities (VLMT, VPLRT) twice, blinded to subject identity.
• Objective determination of VLMT was performed using best-fit polynomial regressions (VLMTP).

Main Results:

• All tested velocities (VPLRT, VLMT, VLMTP) showed strong correlations with VMLSS (r=0.92, 0.90, 0.93).
• VPLRT matched VMLSS, while VLMT and VLMTP were slightly lower (0.33 and 0.46 km·h-1, respectively).
• Inter-reviewer reliability was significantly higher for VLMT (ICC=0.96) than for VPLRT (ICC=0.57), with similar intra-reviewer reliability.

Conclusions:

• The underestimation of MLSS by LMT is likely correctable, suggesting improved accuracy.
• The corrected LMT demonstrates validity comparable to PLRT, with superior reliability, objectivity, and resolution.
• While not a perfect substitute, the corrected LMT is a viable alternative to PLRT for MLSS estimation.