Second-order simultaneous components model for the overshoot and "slow component" in V̇O₂ kinetics.

Area of Science:

• Exercise Physiology
• Human Physiology
• Sports Science

Background:

• Human oxygen uptake during exercise exhibits varied responses like overshoot and slow component.
• The conventional First-Order Multi-Exponential (FOME) model uses add-on terms, increasing complexity and limiting unified explanations.

Purpose of the Study:

• To test if a Two Second-Order Simultaneous Components (SOSC) model offers superior fitting performance compared to the FOME model for oxygen uptake transients.
• To evaluate the SOSC model's ability to explain diverse oxygen uptake responses across different exercise intensities.

Main Methods:

• Fourteen trained male cyclists underwent step-transition cycling tests at moderate, heavy, and severe intensities.
• Oxygen uptake responses were mathematically modeled using both the FOME and the proposed SOSC models.
• Model performance was compared using root mean squared errors.

Main Results:

• The SOSC model demonstrated significantly smaller root mean squared errors across all tested intensities (moderate, supra-moderate, and combined).
• The SOSC model provided a more comprehensive fit without requiring delayed add-on components, unlike the FOME model.

Conclusions:

• The SOSC model is a more effective and unified approach for modeling human oxygen uptake during exercise step-transitions.
• This finding suggests the SOSC model as a valuable alternative to the FOME model in exercise physiology research.