Reframing SpO₂ tolerance as a physiological switch: implications for hypoxic adaptation and exercise regulation.

Area of Science:

• Physiology
• Clinical Medicine
• Altitude Medicine

Background:

• Blood oxygen saturation (SpO2) is a key clinical index.
• Individual SpO2 tolerance varies significantly due to age, health, and adaptation.
• Asymptomatic hypoxia and high-altitude athletic performance reveal this variability.

Purpose of the Study:

• Introduce the concept of the SpO2 switch.
• Propose a physiological compensatory response to SpO2 criticality.
• Shift focus from static thresholds to dynamic response analysis.

Main Methods:

• Conceptual review of SpO2 dynamics.
• Analysis of physiological compensatory mechanisms.
• Discussion of individual variability in hypoxia response.

Main Results:

• The SpO2 switch is a dynamic physiological concept.
• Compensatory responses (ventilatory, autonomic, cardiovascular, metabolic) are triggered by SpO2 criticality.
• Individuals exhibit different responses to hypoxia at identical SpO2 values, indicating a threshold switch mechanism.

Conclusions:

• SpO2 value indicates hypoxia onset and reflects the body's compensatory capacity.
• Reconceptualizing SpO2 as a dynamic switch offers new perspectives.
• Applications include precision health, mountain medicine, and personalized hypoxia risk assessment.