Go to  Advanced Search

Effects of heliox on respiratory mechanics and sensory responses during exercise in endurance-trained men and women

Show simple item record

dc.contributor.author Wilkie, Sabrina Shirley
dc.date.accessioned 2012-10-09T18:04:54Z
dc.date.available 2012-10-09T18:04:54Z
dc.date.copyright 2012 en
dc.date.issued 2012-10-09
dc.identifier.uri http://hdl.handle.net/2429/43351
dc.description.abstract Mechanical ventilatory constraints have been shown to develop in healthy endurance-trained (ET) men, and both ET and untrained women due to structural and functional sex-based differences with respect to the pulmonary system. The purpose of this study was to compare the effects of unloading the respiratory system using a heliox (He-O₂) inspirate on expiratory flow limitation (EFL), the work of breathing (WOB), operational lung volumes and sensory responses (leg and breathing discomfort) between men and women. It was hypothesized that He-O₂ would reduce EFL, operational lung volumes, the WOB and sensory responses while increasing airflow rates, minute ventilation (V’E) and exercise performance. The aforementioned changes would occur to a greater extent in women and those developing EFL breathing room air (RA). Endurance trained men (n = 11) and women (n = 11) competitive cyclists completed two 5 km time trials (TT), breathing either RA or He-O₂. The maximum expiratory flow-volume (MEFV) curve method was used to determine EFL. An esophageal balloon catheter was used to measure the WOB as determined by transpulmonary pressure (the difference between esophageal and mouth pressures). Sensory responses were recorded throughout the TTs. Both sexes had a small (albeit non-significant) 2.3% improvement in power output breathing He-O₂. During the RA TT, 60% of women and 36% of men developed EFL. Heliox significantly increased the MEFV curve for both sexes however 40% of women and 45% of men still developed EFL. The magnitude of EFL was variable throughout both TT’s for all subjects due to alterations in end expired lung volume and expiratory flow rates, as subjects utilized the He-O₂ induced enhanced ventilatory reserve. Despite significantly lower V’E, women had similar WOB and operational lung volumes as men. Sensory responses were not affected by sex, inspirate, or presence of EFL. Collectively these findings suggest that EFL occurs to various extents throughout endurance exercise in both sexes and may limit endurance performance. Sex-based differences in pulmonary structure and function predispose women to mechanical ventilatory constraints breathing RA and increase women’s relative cost of breathing compared to men. en
dc.language.iso eng en
dc.publisher University of British Columbia en
dc.relation.ispartof Electronic Theses and Dissertations (ETDs) 2008+ en
dc.rights Attribution-NonCommercial 2.5 Canada
dc.rights.uri http://creativecommons.org/licenses/by-nd/3.0/
dc.title Effects of heliox on respiratory mechanics and sensory responses during exercise in endurance-trained men and women en
dc.type Text en
dc.degree.name Master of Science - MSc en
dc.degree.discipline Kinesiology en
dc.degree.grantor University of British Columbia en
dc.date.graduation 2012-11 en
dc.type.text Thesis/Dissertation en
dc.description.affiliation Education, Faculty of en
dc.degree.campus UBCV en
dc.description.scholarlevel Graduate en

Files in this item

Files Size Format Description   View
ubc_2012_fall_wilkie_sabrina.pdf 4.528Mb Adobe Portable Document Format   View/Open

This item appears in the following Collection(s)

Show simple item record

Attribution-NonCommercial 2.5 Canada Except where otherwise noted, this item's license is described as Attribution-NonCommercial 2.5 Canada

UBC Library
1961 East Mall
Vancouver, B.C.
Canada V6T 1Z1
Tel: 604-822-6375
Fax: 604-822-3893