Reliability of maximal lactate-steady-state.

Area of Science:

• Exercise Physiology
• Sports Science
• Biochemistry

Background:

• Maximal lactate steady-state (MLSS) is a key indicator of endurance performance.
• Understanding the reliability of physiological markers at MLSS is crucial for training.
• Previous research has explored various lactate threshold concepts.

Purpose of the Study:

• To analyze the day-to-day reliability and variability of power (PMLSS), blood lactate concentration (BLCMLSS), and heart rate (HRMLSS) at MLSS.
• To determine the consistency of these physiological measures over time in male cyclists.

Main Methods:

• 32 male subjects performed constant-load tests for 30 minutes to determine 4 PMLSS.
• Blood lactate concentration (BLCMLSS) was measured at multiple time points during each test.
• Power (PMLSS), BLCMLSS, and heart rate (HRMLSS) were recorded, and coefficients of variability (CV) and Intra-Class Coefficients (ICC) were calculated.

Main Results:

• Mean PMLSS was 244±45 W (75% VO2max), with a low CV of 3% and high ICC of 0.98.
• Mean HRMLSS was 166±10 bpm, showing a CV of 6.3% and ICC of 0.92.
• Mean BLCMLSS was 5.3±1.5 mmol/l, exhibiting a higher CV of 16.6% and ICC of 0.71.

Conclusions:

• PMLSS and HRMLSS are reliable and consistent measures for assessing MLSS in cyclists.
• BLCMLSS demonstrates greater day-to-day variability compared to PMLSS and HRMLSS.
• These findings support the use of PMLSS and HRMLSS for monitoring training adaptations in endurance athletes.