Density-dependent airflow and the regulation of ventilation at heavy exercise in older subjects /
This study was conducted to investigate the effects of
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
1997.
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| Subjects: | |
| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=739888061&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | This study was conducted to investigate the effects of resistive unloading of the airways on ventilation (VE) and the mechanism by which VE is augmented during heavy exercise. Eight older subjects (65-74 yr) performed incremental cycle ergometry while breathing room air (RA) or a less dense helium-oxygen mixture (Heliox). Major variables included VE ,calculated ventilatory maximum (Vemax Cal), and expiratory pulmonary resistance (RLe). Additionally, mouth occlusion pressure (P0.1) and airflow limitation (AFL) were determined. Variables were analyzed during both breathing conditions at rest, ventilatory threshold (VTh), and during heavy exercise by a paired t-test. Correlations among variables were also determined during heavy exercise. While breathing the Heliox mixture, VE was nonsignificantly increased (10 ︢13%) compared with breathing RA during heavy exercise. Breathing the Heliox mixture resulted in an increase in VEmaxCal during heavy exercise (21 ︢27%), though this increase did not reach statistical significance. Values for Rle and P0.1 were significantly lower (p < 0.05; p = 0.05, respectively) while breathing Heliox compared with RA during heavy exercise. Correlations between the change in V, and the change in RLe or VEmaxCal during heavy exercise (delta = Heliox value - RA value) were nonsignificant. Significant correlations were detected between the change in RLe and the change in P0.1 (r = 0.88; p < 0.05) and between the change in RLe and the change in AFL during heavy exercise (r = 0.82-7 p = 0.05). These data, though not conclusive, suggest the regulation of VE during heavy exercise is related more to changes in the mechanics of expiratory airways than the change in ventilatory capacity. |
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| Item Description: | Vita. "Major Subject: Veterinary Physiology". |
| Physical Description: | viii, 87 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilms Inc. |
| Bibliography: | Includes bibliographical references: pages 52-57. |