Indirect Assessment of Lactate Minimum and Maximal Blood Lactate Steady-State Intensity for Physically Active Individuals

Abstract

An indirect assessment of the running velocity corresponding to lactate minimum (LMind) and its validity to estimate the maximal blood lactate steady state (MLSS) were analyzed in 22 physically active men (24.6 +/- 4.1 years, 72.6 +/- 8.0 kg, 1.75 +/- 0.1 m, 11.9 +/- 3.7% body fat). The participants were allocated into 2 different groups (G1 and G2). The running velocities (m x min) corresponding to the 1600-m time trial (1600 mV) and lactate minimum (LM) were determined for G1 (n = 12), whereas the G2 participants (n = 10) had their MLSS identified in addition to the 1600 mV and LM tests. The LM test consisted of a 150-m sprint to elevate blood lactate ([lac]) followed by 10 minutes of recovery and then 6 x 800-m at 78, 81, 84, 87, 90, and 93% of 1600 mV, with the velocity corresponding to the lowest [lac] (YSI 2700S) identified in the LM test. The relationship between 1600 mV and LM values for G1 yielded the following equation for indirect assessment of LM velocity: LMind (m x min) = (0.7507 x 1600 mV) + 21.575. The validity of the LMind was tested in the G2 participants by comparing its results with those of the MLSS. The MLSS was identified among 3-4 constant-intensity sessions by considering the highest running velocity for which a [lac] variation was not higher than 0.05 mM x min. No differences were observed for the LM (200.7 +/- 16.8 m x min), LMind (200.8 +/- 15.1 m x min), and MLSS (201.0 +/- 15.6 m x min) for G2, and there was high correlation and agreement among parameters. The LMind was considered valid for estimating LM and MLSS values if applied to physically active individuals with characteristics similar to those of the present study; thus, it is a practical and economical alternative for trainers who cannot directly determine MLSS.