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Human respiratory muscle actions and control during exercise
A Aliverti1, S J Cala, R Duranti
1Politecnico di Milano, Dipartimento di Bioingegneria, Centro di Bioingegneria, Milan, Italy.
Journal of Applied Physiology (Bethesda, Md. : 1985)
|October 24, 1997
Summary
Respiratory muscle recruitment shifts during exercise, with the diaphragm acting as a flow generator and chest wall muscles maintaining pressure. This coordinated action minimizes rib cage distortion during breathing.
Area of Science:
- Physiology
- Respiratory Mechanics
- Exercise Physiology
Background:
- Understanding respiratory muscle function during exercise is crucial for assessing respiratory limitations.
- The interplay between diaphragm, rib cage, and abdominal muscles during varying workloads is not fully elucidated.
Purpose of the Study:
- To investigate the pressures, power, and volume changes of respiratory muscles during exercise.
- To analyze the coordination and control of respiratory muscles across different exercise intensities.
Main Methods:
- Five healthy men performed graded exercise up to 70% maximum workload (Wmax).
- Three-dimensional marker tracking quantified chest wall compartment volumes (rib cage and abdomen).
- Pressures and power of diaphragm, rib cage, and abdominal muscles were measured.
Main Results:
- End-inspiratory lung volume increased, while end-expiratory lung volume decreased with workload.
- Diaphragmatic pressure, velocity, and workload increased significantly with exercise intensity.
- Abdominal and rib cage muscle pressures were out of phase and coordinated to equalize pressures, minimizing distortion.
Conclusions:
- A switch in respiratory muscle control occurs with exercise onset, involving immediate recruitment of accessory muscles.
- The diaphragm functions as a flow generator, while rib cage and abdominal muscles generate pressure.
- This respiratory muscle strategy minimizes rib cage distortion and optimizes breathing mechanics during exercise.