Maximal lactate steady state concentration (MLSS): experimental and modelling approaches

Area of Science:

• Exercise Physiology
• Sports Science
• Biophysics

Background:

• Maximal lactate steady state (MLSS) is defined as the highest exercise intensity without blood lactate accumulation.
• Blood lactate concentrations (BLC) at MLSS differ across various exercise modes and populations.
• This variability suggests MLSS is influenced by exercise-specific factors like muscle recruitment.

Purpose of the Study:

• To investigate the factors influencing task-specific maximal lactate steady state (MLSS).
• To model the relationship between exercise, blood lactate concentration (BLC), and oxygen transport.
• To determine if load per unit of engaged muscle mass explains MLSS variations across exercise types.

Main Methods:

• Development of a computer model integrating theories of exercise BLC and oxygen transport.
• Simulations to test the hypothesis that load per engaged muscle mass affects MLSS.
• Comparison of MLSS and lactate lactate steady state (LLSS) differences between rowing and cycling.

Main Results:

• Model simulations supported the hypothesis that load per engaged muscle mass influences task-specific MLSS.
• Simulated MLSS differences were observed, suggesting MLSS may not always reflect the true lactate steady state (LLSS).
• Rowing showed a greater difference between MLSS and LLSS compared to cycling, indicating higher BLC sensitivity to intensity changes.

Conclusions:

• Load per unit of engaged muscle mass is a key factor in determining task-specific MLSS.
• MLSS may not consistently represent the maximal equilibrium between lactate production and clearance (LLSS).
• Task-specific training strategies may need to consider the differential BLC responses observed in activities like rowing versus cycling.