A Two-test Protocol for the Precise Determination of the Maximal Lactate Steady State

Area of Science:

• Exercise Physiology
• Sports Science
• Biochemistry

Background:

• Accurate determination of Maximal Lactate Steady State (MLSS) is crucial for optimizing endurance training in athletes.
• Existing methods for identifying MLSS often rely on single incremental tests, which may not provide precise results.
• The lactate deflection point is a key indicator used in various methods to estimate MLSS.

Purpose of the Study:

• To evaluate the efficacy of a two-test protocol for precisely identifying the MLSS in competitive cyclists.
• To compare the accuracy of different lactate threshold determination methods within a single maximal oxygen consumption (V̇O_2max) test and a subsequent submaximal incremental test (SIT).

Main Methods:

• Eight male cyclists completed a V̇O_2max test to determine initial lactate threshold estimates using visual deflection (T_Vis), Log-Log (T_Log), D_max (T_Dmax), RER = 1.00 (T_RER), ventilatory threshold (T_Vent), and T₊₁ methods.
• A second incremental test (SIT) was performed, with stages centered around the predetermined deflection point.
• The T_Vis from the SIT was identified as MLSS and further validated through three 45-minute steady-state exercise bouts at varying intensities (95%, 100%, 105% of estimated MLSS).

Main Results:

• The SIT yielded significantly narrower threshold ranges (27.5 ± 11.01W) compared to the V̇O_2max test (70 ± 42.51W).
• Different threshold estimates were observed across methods in the V̇O_2max test, except for T_Log and T_RER.
• The T_Vis from the SIT accurately identified MLSS, with subsequent steady-state tests confirming significant differences in blood lactate and V̇O₂ at varying intensities.

Conclusions:

• The two-test method, particularly using the visual deflection (T_Vis) during a submaximal incremental test (SIT), accurately identifies MLSS in cyclists.
• A single maximal oxygen consumption (V̇O_2max) test tends to overestimate MLSS intensity.
• A second, targeted submaximal test is essential for precise MLSS determination, enhancing training prescription accuracy.