- Library Home /
- Search Collections /
- Open Collections /
- Browse Collections /
- UBC Theses and Dissertations /
- Effects of heliox on respiratory mechanics and sensory...
Open Collections
UBC Theses and Dissertations
UBC Theses and Dissertations
Effects of heliox on respiratory mechanics and sensory responses during exercise in endurance-trained men and women Wilkie, Sabrina Shirley
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.
Item Metadata
Title |
Effects of heliox on respiratory mechanics and sensory responses during exercise in endurance-trained men and women
|
Creator | |
Publisher |
University of British Columbia
|
Date Issued |
2012
|
Description |
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.
|
Genre | |
Type | |
Language |
eng
|
Date Available |
2012-10-09
|
Provider |
Vancouver : University of British Columbia Library
|
Rights |
Attribution-NoDerivs 3.0 Unported
|
DOI |
10.14288/1.0073245
|
URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
|
Graduation Date |
2012-11
|
Campus | |
Scholarly Level |
Graduate
|
Rights URI | |
Aggregated Source Repository |
DSpace
|
Item Media
Item Citations and Data
Rights
Attribution-NoDerivs 3.0 Unported