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Human diaphragmatic endurance during different maximal respiratory efforts
1Unit of Clinical Neurophysiology, Prince Henry Hospital, School of Medicine, University of New South Wales, Sydney, Australia.
The Journal of Physiology
|January 1, 1988
Summary
Human diaphragmatic endurance is lower during maximal expulsive efforts compared to inspiratory efforts. This reduced capacity, observed during high abdominal pressure, may stem from impaired muscle perfusion, not muscle activation failure.
Area of Science:
- Physiology
- Respiratory Mechanics
- Muscle Endurance
Background:
- Diaphragmatic function is crucial for respiration.
- Understanding diaphragmatic endurance under different pressure conditions is important for respiratory health.
Purpose of the Study:
- To compare human diaphragmatic endurance during maximal inspiratory and expulsive efforts.
- To investigate the factors contributing to diaphragm fatigue during expulsive efforts.
Main Methods:
- Assessed diaphragmatic endurance during sustained maximal inspiratory and expulsive efforts.
- Measured trans-diaphragmatic pressure decline and compared diaphragm performance to elbow flexors.
- Used electromyography and phrenic nerve stimulation to assess muscle activation and fatigue.
Main Results:
- Diaphragmatic endurance was significantly lower during expulsive efforts than inspiratory efforts.
- Diaphragm fatigue, not abdominal muscle fatigue, was identified as the cause of reduced performance.
- The diaphragm demonstrated greater endurance than elbow flexor muscles.
Conclusions:
- Reduced diaphragmatic endurance during expulsive efforts is not due to abdominal muscle failure or incomplete diaphragm activation.
- Impaired muscle perfusion during elevated abdominal pressure may explain the decreased diaphragmatic performance.