Ventilation parallels plasma potassium during incremental and continuous variable intensity exercise

Area of Science:

• Exercise Physiology
• Cardiorespiratory Regulation
• Human Performance

Background:

• Ventilatory control during exercise is complex.
• Plasma potassium (K+) is implicated in exercise-induced hyperpnea.
• The precise relationship between plasma K+ and ventilation (VE) across varying exercise intensities requires further elucidation.

Purpose of the Study:

• To investigate the relationship between plasma potassium (K+) and ventilation (VE) during both incremental and prolonged continuous exercise.
• To determine if plasma K+ is the sole determinant of ventilatory responses during exercise.
• To analyze how exercise intensity affects the VE/K+ ratio.

Main Methods:

• Seven well-trained male cyclists performed graded incremental exercise to 90% VO2max.
• Subjects also completed prolonged continuous exercise with varying low (45% VO2max) and moderate (75% VO2max) intensity intervals.
• Plasma K+ concentration and ventilation (VE) were measured throughout exercise protocols.

Main Results:

• During prolonged exercise, VE and plasma K+ showed coordinated changes, with greater responses at moderate intensity.
• A strong positive relationship was observed between VE and plasma K+ during incremental exercise.
• The VE/K+ ratio increased with exercise intensity, indicating VE rose more steeply than plasma K+.

Conclusions:

• Plasma potassium concentration contributes to ventilatory regulation during exercise.
• Plasma K+ may not be the sole factor driving ventilation, especially at higher intensities.
• The ventilatory response becomes disproportionately greater than the plasma K+ increase as exercise intensity rises.