Document Detail

Smaller lungs in women affect exercise hyperpnea.
MedLine Citation:
PMID:  9609779     Owner:  NLM     Status:  MEDLINE    
We subjected 29 healthy young women (age: 27 +/- 1 yr) with a wide range of fitness levels [maximal oxygen uptake (VO2 max): 57 +/- 6 ml . kg-1 . min-1; 35-70 ml . kg-1 . min-1] to a progressive treadmill running test. Our subjects had significantly smaller lung volumes and lower maximal expiratory flow rates, irrespective of fitness level, compared with predicted values for age- and height-matched men. The higher maximal workload in highly fit (VO2 max > 57 ml . kg-1 . min-1, n = 14) vs. less-fit (VO2 max < 56 ml . kg-1 . min-1, n = 15) women caused a higher maximal ventilation (VE) with increased tidal volume (VT) and breathing frequency (fb) at comparable maximal VT/vital capacity (VC). More expiratory flow limitation (EFL; 22 +/- 4% of VT) was also observed during heavy exercise in highly fit vs. less-fit women, causing higher end-expiratory and end-inspiratory lung volumes and greater usage of their maximum available ventilatory reserves. HeO2 (79% He-21% O2) vs. room air exercise trials were compared (with screens added to equalize external apparatus resistance). HeO2 increased maximal expiratory flow rates (20-38%) throughout the range of VC, which significantly reduced EFL during heavy exercise. When EFL was reduced with HeO2, VT, fb, and VE (+16 +/- 2 l/min) were significantly increased during maximal exercise. However, in the absence of EFL (during room air exercise), HeO2 had no effect on VE. We conclude that smaller lung volumes and maximal flow rates for women in general, and especially highly fit women, caused increased prevalence of EFL during heavy exercise, a relative hyperinflation, an increased reliance on fb, and a greater encroachment on the ventilatory "reserve." Consequently, VT and VE are mechanically constrained during maximal exercise in many fit women because the demand for high expiratory flow rates encroaches on the airways' maximum flow-volume envelope.
S R McClaran; C A Harms; D F Pegelow; J A Dempsey
Related Documents :
3137329 - Effects of pedal rate on respiratory responses to incremental bicycle work.
6421079 - Distribution of expiratory gas and rebreathing in t-piece modifications used in weaning.
4708899 - Studies of the pulmonary vagal control of central respiratory rhythm in the absence of ...
3406549 - Diffusion-dependent contribution to the slope of the alveolar plateau.
9620519 - Esophageal stethoscope placement depth: its effect on heart and lung sound monitoring d...
2347779 - Effect of naloxone on spectral shifts of the diaphragm emg during inspiratory loading.
22027399 - Non-stationarities significantly distort short-term spectral, symbolic and entropy hear...
6836649 - Pathophysiology of ischemic cell death: iii. role of extracellular factors.
14570529 - A connectionist implementation of the theory of planned behavior: association of belief...
Publication Detail:
Type:  Clinical Trial; Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  84     ISSN:  8750-7587     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  1998 Jun 
Date Detail:
Created Date:  1998-07-07     Completed Date:  1998-07-07     Revised Date:  2013-09-26    
Medline Journal Info:
Nlm Unique ID:  8502536     Medline TA:  J Appl Physiol (1985)     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1872-81     Citation Subset:  IM; S    
John Rankin Laboratory of Pulmonary Medicine, Department of Preventive Medicine, University of Wisconsin-Madison, Madison, Wisconsin 53705, USA.
Export Citation:
APA/MLA Format     Download EndNote     Download BibTex
MeSH Terms
Aerobiosis / physiology
Blood Gas Analysis
Blood Volume / physiology*
Body Height / physiology
Exercise / physiology*
Hydrogen-Ion Concentration
Lactic Acid / blood
Lung / anatomy & histology*,  physiology*
Lung Volume Measurements
Peak Expiratory Flow Rate
Potassium / blood
Respiratory Function Tests
Vital Capacity / physiology
Grant Support
Reg. No./Substance:
50-21-5/Lactic Acid; 7440-09-7/Potassium

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

Previous Document:  Recovery of muscle transfers replacing the total plantar flexor muscle group in rats.
Next Document:  Bioenergetics of contracting skeletal muscle after partial reduction of blood flow.