Document Detail

Expiratory muscle recruitment during inspiratory flow-resistive loading and exercise.
MedLine Citation:
PMID:  2064116     Owner:  NLM     Status:  MEDLINE    
Both exercise and inspiratory flow-resistive loading may cause recruitment of expiratory muscles. To evaluate the extent of recruitment in combined exercise and flow-resistive loading, and to estimate the effect on inspiratory muscle work, we studied five men, 26 to 39 yr of age, during mild exercise with different degrees of inspiratory flow-resistive loading. Each subject performed four 1-h exercise runs at 30% of their maximal oxygen consumption on different days while inspiring through an external resistor of either 1.4, 14.5, 19.9, or 30.6 cm H2O/s/L. Mouth and esophageal pressure, inspiratory flow rate, and abdominal and rib cage motion were recorded continuously. Abdominal expansion tended to lead and rib cage expansion tended to lag the start of inspiration as judged from the beginning of negative pressure development at the mouth. These time differences increased as resistive load increased. Plots of abdominal versus rib cage motion also showed increase in phase shift, with the abdomen leading the rib cage on inspiration. For all subjects, the esophageal pressure at the end of expiration became less negative as the resistive load increased, indicating that the end-expiratory volume decreased with increasing resistive load. We conclude that there was increasing use of expiratory muscles as the resistive load increased, and that the initial expansion of the abdomen at high resistive loads represented elastic recoil of structures that had been compressed below the volume at FRC by the expiratory muscles.(ABSTRACT TRUNCATED AT 250 WORDS)
P H Abbrecht; K R Rajagopal; R R Kyle
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  The American review of respiratory disease     Volume:  144     ISSN:  0003-0805     ISO Abbreviation:  Am. Rev. Respir. Dis.     Publication Date:  1991 Jul 
Date Detail:
Created Date:  1991-08-08     Completed Date:  1991-08-08     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  0370523     Medline TA:  Am Rev Respir Dis     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  113-20     Citation Subset:  AIM; IM; S    
Department of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland.
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MeSH Terms
Abdomen / physiology
Esophagus / physiology
Physical Exertion / physiology*
Pulmonary Ventilation
Respiration / physiology*
Respiratory Muscles / physiology*
Thorax / physiology
Work of Breathing

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