Related Experiment Videos
Breathing pattern and exercise endurance time after exhausting cycling or breathing.
C M Spengler1, C Knöpfli-Lenzin, K Birchler
1Swiss Federal Institute of Technology Zurich and University of Zurich, Switzerland. spengler@physiol.unizh.ch
European Journal of Applied Physiology
|April 6, 2000
Summary
Changes in breathing patterns during exhaustive exercise are caused by leg muscle work, not respiratory muscle effort. This study found that isolated breathing exercises did not alter endurance, indicating leg fatigue drives breathing changes.
Area of Science:
- Exercise Physiology
- Respiratory Physiology
Background:
- Breathing pattern changes, such as increased breathing frequency, often occur during intense exercise.
- It remains unclear whether these respiratory adjustments result from the work of breathing itself or from signals originating in the locomotor muscles.
Purpose of the Study:
- To determine if the work of respiratory muscles, independent of locomotor muscle activity, influences breathing patterns at the end of exhaustive exercise.
- To differentiate the contributions of respiratory and leg muscle work to exercise-induced breathing pattern modifications.
Main Methods:
- Eight healthy subjects underwent three randomized conditions: sequential endurance cycling tests, isolated isocapnic hyperpnea followed by cycling, and higher-level isocapnic hyperpnea followed by cycling.
- Minute ventilation (VE) and breathing frequency (fb) were monitored during all conditions.
- Endurance time and breathing patterns were compared across conditions.
Main Results:
- Isolated isocapnic hyperpnea did not affect subsequent cycling endurance or breathing patterns.
- Sequential cycling tests showed a significant decrease in endurance only in the second test (A2), which was associated with altered breathing patterns (increased VE and fb).
- Cycling tests following hyperpnea (B2, C2) did not show significant changes in endurance or breathing patterns compared to the initial cycling test (A1).
Conclusions:
- The findings suggest that changes in breathing patterns observed at the end of exhaustive exercise are primarily driven by factors related to locomotor (leg) muscle work.
- Respiratory muscle work alone does not appear to induce the significant alterations in breathing frequency and tidal volume seen during fatiguing exercise.
- Leg muscle fatigue, rather than respiratory muscle fatigue, is likely the main determinant of altered breathing patterns during maximal exertion.