Critical Power and Maximal Lactate Steady State in Cycling: "Watts" the Difference?

Area of Science:

• Exercise Physiology
• Sports Science

Background:

• The maximal metabolic steady state is crucial for athletic performance evaluation and training program design.
• Critical power (CP) and maximal lactate steady state (MLSS) are commonly used to estimate this threshold.
• Previous research shows significant discrepancies between CP and MLSS power outputs, leading to debates on their interchangeability.

Purpose of the Study:

• To review the methodological factors influencing CP and MLSS determination.
• To investigate the reasons for discrepancies between CP and MLSS.
• To establish criteria for valid estimation of the maximal metabolic steady state.

Main Methods:

• Critical review of existing literature on CP and MLSS determination.
• Analysis of laboratory data using strict and appropriate determination criteria.
• Integration of findings to reconcile differences between CP and MLSS.

Main Results:

• Methodological inconsistencies and inappropriate determination methods contribute to reported differences between CP and MLSS.
• When strict and appropriate criteria are applied, the difference between CP and MLSS is minimal (within a few Watts).
• Both CP and MLSS can be used interchangeably to estimate the maximal metabolic steady state.

Conclusions:

• Discrepancies between CP and MLSS are largely due to methodological variations.
• With standardized and rigorous methods, CP and MLSS are interchangeable indices for the maximal metabolic steady state.
• Guidelines for best practices in CP and MLSS determination are provided for researchers and coaches.