Document Detail


Flow limitation and regulation of functional residual capacity during exercise in a physically active aging population.
MedLine Citation:
PMID:  2024851     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
In 29 older (69 +/- 1 yr), physically active subjects (VO2max = 44 +/- 2 ml.kg-1.min-1), we determined the effect of an age-related decline in elastic lung recoil (i.e., Vmax50 = 65% of 30-yr-old adults) on the ventilatory response to progressive exercise. More specifically, we assessed if expiratory airflow limits were achieved and how this may modulate the regulation of end-expiratory lung volume (EELV). We found that with only mild to moderate (50 to 75% VO2max) exercise, the mean EELV was reduced 0.38 +/- 0.07 L, and that expiratory flow limitation was present over 25 +/- 4% of the VT. In 11 subjects during this intensity of exercise, EELV was within their closing capacity. As exercise intensity progressed, VT plateaued at 58 +/- 2% of the vital capacity, and increased expiratory air flow rates were achieved by significantly increasing the EELV back to near resting levels, thereby moving a portion of the expiratory tidal flow-volume envelope away from the constraints of the effort independent portion of the maximal flow-volume curve. During heavy exercise, end-inspiratory lung volume (EILV) approached 90% of TLC. To achieve greater expiratory flow with maximal exercise, EELV remained similar to the previous intensity, and a significantly greater portion of the tidal expiratory flow-volume envelope (greater than 40% of the VT) became flow-limited. Despite this significant expiratory limitation, a rise in EELV, and an EILV approaching TLC, TI/Ttot remained constant throughout exercise, and the ventilatory response for the metabolic demand (VA/VCO2) was appropriate.(ABSTRACT TRUNCATED AT 250 WORDS)
Authors:
B D Johnson; W G Reddan; D F Pegelow; K C Seow; J A Dempsey
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  The American review of respiratory disease     Volume:  143     ISSN:  0003-0805     ISO Abbreviation:  Am. Rev. Respir. Dis.     Publication Date:  1991 May 
Date Detail:
Created Date:  1991-06-05     Completed Date:  1991-06-05     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0370523     Medline TA:  Am Rev Respir Dis     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  960-7     Citation Subset:  AIM; IM    
Affiliation:
John Rankin Laboratory of Pulmonary Medicine, Department of Preventive Medicine, University of Wisconsin School of Medicine, Madison.
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MeSH Terms
Descriptor/Qualifier:
Aged
Aging / physiology*
Exercise / physiology*
Female
Functional Residual Capacity / physiology*
Humans
Lung Volume Measurements
Male
Pulmonary Ventilation / physiology*
Running
Walking

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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