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Changes in respiration in the transition from heavy exercise to rest
R Jeyaranjan1, R Goode, J Duffin
1Department of Physiology and School of Physical and Health Education, University of Toronto, Ontario, Canada.
Summary
Ventilation does not instantly drop when heavy exercise stops. Instead, minute ventilation gradually declines, suggesting sustained respiratory drive mechanisms in the transition from heavy exercise to rest.
Area of Science:
- Exercise Physiology
- Respiratory Control
Background:
- Exercise transitions involve rapid changes in ventilation.
- These changes are well-documented in mild-moderate exercise but not heavy exercise.
- Extrapolation of mild-moderate exercise findings to heavy exercise is not supported.
Purpose of the Study:
- To investigate ventilation changes during the transition from heavy exercise to rest.
- To determine if ventilation drops instantaneously after heavy exercise cessation.
- To explore underlying mechanisms for observed ventilation patterns.
Main Methods:
- Five healthy volunteers performed treadmill running at 80% VO2max, above anaerobic threshold.
- Minute ventilation and end-tidal PCO2 were measured breath-by-breath.
- Abrupt start and stop protocols were used to simulate exercise transitions.
Main Results:
- An instantaneous drop in minute ventilation was absent during the transition from heavy exercise to rest.
- Minute ventilation showed a gradual decline post-exercise.
- End-tidal PCO2 changes were also observed during the off-transition.
Conclusions:
- The typical instantaneous ventilation decrease seen in mild exercise does not occur after heavy exercise.
- A gradual decline in ventilation suggests sustained respiratory drive mechanisms.
- Potential contributing factors include central neural, blood-borne, and peripheral neurogenic stimuli.