Exercise test mode dependency for ventilatory efficiency in women but not men

Area of Science:

• Exercise Physiology
• Cardiopulmonary Function
• Biostatistics

Background:

• Ventilatory efficiency, assessed via indices like the V(E)/V(CO(2)) slope and lowest V(E)/V(CO(2)), is crucial in cardiopulmonary exercise testing (CPET).
• Understanding potential mode dependency of these indices is important for accurate interpretation of CPET results.

Purpose of the Study:

• To evaluate the mode dependency of ventilatory efficiency indices (V(E)/V(CO(2)) slope and lowest V(E)/V(CO(2))) during treadmill versus cycle ergometer CPET in healthy adults.
• To examine the relationship between these two ventilatory efficiency indices.

Main Methods:

• Twenty-eight healthy subjects (14 men) completed both treadmill and cycle ergometer CPET.
• Ventilation and expired gas fractions (O2, CO2) were measured using a metabolic cart.
• Paired t-tests were used to compare ventilatory efficiency indices between exercise modes.

Main Results:

• Women exhibited higher ventilatory efficiency index values on the treadmill compared to the cycle ergometer, indicating mode dependency.
• Men did not show a significant mode dependency for either ventilatory efficiency index.
• The lowest V(E)/V(CO(2)) values were consistently higher than the V(E)/V(CO(2)) slope, aligning with theoretical predictions.

Conclusions:

• Healthy women demonstrate a mode dependency in ventilatory efficiency indices during CPET, while healthy men do not.
• The observed relationship between the lowest V(E)/V(CO(2)) and its slope supports established physiological models of ventilatory efficiency.