Physiological Responses during Cycle Ergometry at a Constant Perception of Effort

Area of Science:

• Exercise Physiology
• Sports Science
• Human Performance

Background:

• Understanding physiological responses during prolonged exercise at a constant perceived exertion is crucial for training and performance.
• Previous models have attempted to explain physiological and perceptual changes during sustained exercise, but their accuracy during moderate-intensity cycling requires further investigation.

Purpose of the Study:

• To examine oxygen consumption, heart rate, ventilation, respiratory frequency, and power output during a 1-hour cycling bout at a constant Rating of Perceived Exertion (RPE) corresponding to the Physical Working Capacity at the OMNI threshold (PWC(OMNI)).
• To assess the ability of current models to explain physiological and perceptual responses during this sustained moderate-intensity exercise.

Main Methods:

• 13 subjects completed an incremental test to exhaustion, submaximal rides, and a 1-hour ride at a specific RPE (PWC(OMNI)).
• Physiological parameters including oxygen consumption (V̇O2), heart rate (HR), minute ventilation (+V̇(E)), and respiratory frequency (FR) were monitored.
• Power output and RPE were recorded throughout the 1-hour ride.

Main Results:

• The PWC(OMNI) represented a sustainable moderate-intensity exercise level (56±5% V̇O2Peak).
• Oxygen consumption, minute ventilation, and power output significantly decreased over the 1-hour ride.
• Respiratory frequency showed no significant change over time, indicating RPE tracked FR responses most closely.

Conclusions:

• During prolonged moderate-intensity cycling at a constant RPE, physiological parameters like V̇O2 and power output decline, while respiratory frequency remains stable.
• The findings suggest that afferent feedback from respiratory muscles may play a significant role in mediating the perception of effort during sustained cycling at a constant RPE.