Purpose: A mathematical model to describe the interplay of distinct metabolic rates during exercise was developed decades ago. Despite its use in endurance performance diagnostics, attempts to validate the model’s assumptions and predictions on experimental data are rare. We here provide a comprehensive study for the steady state.
Methods: We rewrote the mathematical equations in the steady state and tested them on a data set of N = 101 individuals derived from four studies in cycling and running.
Results: The rewritten equations reveal a unique relationship between the ratio of the maximum oxygen uptake and the lactate accumulation rate, and the fractional utilization of oxygen uptake at the maximum lactate steady-state. Experimental data for running do not provide evidence that this relation holds. For cycling, the experimental evidence is less devastating but can also not be considered as convincing.
Conclusion: The simulation in its current form is not suitable for a practical use in performance diagnostics. Additional model layers and/or more precise methods of measurement may improve the model’s performance, but require experimental validation.