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Expiratory muscle recruitment during inspiratory flow-resistive loading and exercise
P H Abbrecht1, K R Rajagopal, R R Kyle
1Department of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland.
The American Review of Respiratory Disease
|July 1, 1991
Summary
Increased use of expiratory muscles during exercise with inspiratory loading was observed. Higher resistive loads led to greater expiratory muscle recruitment and altered breathing mechanics.
Area of Science:
- Exercise Physiology
- Respiratory Mechanics
Background:
- Inspiratory flow-resistive loading and exercise can independently recruit expiratory muscles.
- The combined effects on inspiratory muscle work and expiratory muscle recruitment are not fully understood.
Purpose of the Study:
- To evaluate expiratory muscle recruitment during combined exercise and inspiratory flow-resistive loading.
- To estimate the impact of this combined loading on inspiratory muscle work.
Main Methods:
- Five healthy men (26-39 years) performed 1-hour exercise runs at 30% maximal oxygen consumption.
- Subjects inspired through resistors of varying loads (1.4 to 30.6 cm H2O/s/L).
- Mouth/esophageal pressure, flow rate, and chest/abdominal motion were continuously recorded.
Main Results:
- Abdominal expansion increasingly led rib cage expansion with higher resistive loads.
- End-expiratory volume decreased as resistive load increased.
- Expiratory muscle recruitment intensified with escalating resistive loads.
Conclusions:
- Inspiratory flow-resistive loading during exercise increases expiratory muscle use.
- Abdominal expansion at high loads reflects elastic recoil from expiratory muscle compression.
- Breathing mechanics are significantly altered by combined exercise and inspiratory resistive loads.
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