Bicarbonate infusion and pH clamp moderately reduce hyperventilation during ramp exercise in humans

Area of Science:

• Exercise Physiology
• Human Physiology
• Biochemistry

Background:

• During strenuous exercise, humans often exhibit hyperventilation (increased breathing rate).
• The physiological triggers for exercise hyperventilation, particularly at high workloads, are not fully understood.
• A decrease in plasma pH (acidosis) is hypothesized to contribute to this response.

Purpose of the Study:

• To investigate the role of plasma pH decrease in exercise-induced hyperventilation.
• To determine if maintaining arterialized plasma pH at resting levels affects ventilation during high-intensity exercise.

Main Methods:

• Five healthy males underwent ramp exercise tests.
• A control condition was compared with a 'pH clamp' condition using intravenous sodium bicarbonate infusion.
• Plasma pH, partial pressure of carbon dioxide (PaCO2), and ventilation (Ve) were monitored.

Main Results:

• Sodium bicarbonate infusion did not alter oxygen consumption (VO2).
• Infusion significantly increased PaCO2 and plasma bicarbonate concentration.
• Pulmonary ventilation (Ve) and Ve/VO2 were reduced at high workloads during the pH clamp, indicating reduced hyperventilation.

Conclusions:

• The decrease in plasma pH contributes to the hyperventilation observed in humans during high-intensity exercise.
• Modulating plasma pH can alter the ventilatory response to exercise.