Related Experiment Videos
Effects of respiratory muscle work on exercise performance
C A Harms1, T J Wetter, C M St Croix
1John Rankin Laboratory of Pulmonary Medicine, Department Preventive Medicine, University of Wisconsin, Madison, Wisconsin 53705, USA. caharms@ksu.edu
Journal of Applied Physiology (Bethesda, Md. : 1985)
|July 25, 2000
Summary
High respiratory muscle work significantly impacts exercise performance by reducing leg blood flow and increasing fatigue. Reducing breathing effort improves endurance, while increasing it decreases performance time.
Area of Science:
- Exercise Physiology
- Respiratory Physiology
Background:
- Respiratory muscle work during maximal exercise diverts cardiac output, potentially limiting limb blood flow.
- The impact of respiratory muscle loading and unloading on exercise performance is not fully understood.
Purpose of the Study:
- To investigate the effect of altered respiratory muscle work on exercise performance in trained cyclists.
- To determine if manipulating breathing effort influences time to exhaustion and physiological responses.
Main Methods:
- Seven male cyclists performed randomized trials on a cycle ergometer at 90% maximal oxygen consumption (VO(2)).
- Respiratory muscle work was manipulated through inspiratory loading or unloading conditions.
- Time to exhaustion, oxygen consumption (VO(2)), and perceived exertion were measured.
Main Results:
- Unloading respiratory muscles increased time to exhaustion by 14%, while loading decreased it by 15% compared to control.
- Respiratory muscle unloading reduced VO(2) and hyperventilation, and slowed the perception of discomfort.
- These changes were statistically significant (P < 0.05).
Conclusions:
- The work of breathing significantly influences sustained, heavy-intensity exercise performance.
- Reduced leg blood flow due to respiratory muscle work may contribute to fatigue onset and perceived exertion.
- Manipulating respiratory muscle load offers a potential strategy to modulate exercise performance.