Lactate threshold determination: a Monte Carlo comparison of two interpolation methods

Area of Science:

• Exercise Physiology
• Sports Science
• Biomedical Engineering

Background:

• The relationship between blood lactate and oxygen uptake (VO2) during exercise is crucial for understanding exercise intensity.
• Accurate determination of the lactate threshold (LT) is vital for optimizing training and performance.
• Current methods for LT determination, like linear interpolation, may not fully capture the complex relationship between lactate and VO2.

Purpose of the Study:

• To compare the accuracy of a novel inverse parabolic interpolation method (PT) against the traditional linear interpolation method (LT) for determining the lactate threshold.
• To evaluate the bias and precision of both methods in relation to a reference 4-mmol lactate threshold.

Main Methods:

• Development of a heuristic model for the blood lactate (L) and VO2 relationship during exercise.
• Computation of both linear interpolation thresholds (LT) and parabolic thresholds (PT).
• Evaluation of the error of both LT and PT against a "true" 4-mmol lactate threshold using parametric and Monte Carlo simulations.

Main Results:

• Parabolic thresholds (PT) demonstrated generally superior performance compared to linear thresholds (LT).
• The PT method was found to be less biased than the LT method.
• The PT method exhibited greater precision in threshold determination than the LT method.

Conclusions:

• The inverse parabolic interpolation method offers a more accurate and reliable approach to determining the lactate threshold during exercise.
• This finding suggests that the curvilinear nature of the blood lactate and VO2 relationship should be considered for precise threshold assessment.
• The PT method holds potential for improving exercise prescription and physiological monitoring in sports and clinical settings.