| GXT responses in altitude-acclimatized cyclists during sea-level simulation. | |
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MedLine Citation:
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PMID: 17909399 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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PURPOSE: This study examined the effects of gender on graded exercise stress test (GXT) response in moderate-altitude (MA)-acclimatized cyclists during sea-level (SL) simulation. It was hypothesized that alterations in arterial saturation would relate to changes in VO2peak. METHODS: Twenty competitive cyclists (12 males, 8 females) who were residents of MA locations underwent two randomized bicycle GXTs: one under local normoxic hypobaria, and the other under simulated SL conditions. RESULTS: Under the SL condition, the cyclists demonstrated a significant increase (2-3%) in absolute and relative VO2peak, improved (4%) economy at lactate threshold (LT), and time-adjusted peak power (7%); the range of improvement between individuals varied from -6% to +25%. Simulated SL also resulted in a greater arterial saturation (S(a)O2) at rest and VO2peak, and significantly less desaturation (4 vs 8%) from rest to VO2peak. The individual variability in the change (Delta) in VO2peak was not significantly correlated to SL S(a)O2 or any other S(a)O2 variable analyzed, regardless of whether we examined each gender individually or combined. Significant correlations were found between Delta-peak power and Delta-economy as well as Delta-VO2peak and Delta-GXT time. These correlations as well as degree of improvement varied by gender. CONCLUSIONS: These data suggest that chronic residence at MA may attenuate the occurrence of exercise-induced arterial hypoxemia and eliminate the relationship between S(a)O2 and Delta-VO2peak that has been reported among SL residents acutely exposed to altitude. Additionally, the improvements that occur in predictors of aerobic performance when MA residents are exposed acutely to SL conditions have a large degree of individual variability, and the mechanism(s) for improvement may vary by gender. |
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Authors:
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Michael D Brothers; Kristin Hilger; John M Carson; Luisa Sullivan; William C Byrnes |
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Publication Detail:
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Type: Journal Article; Randomized Controlled Trial; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: Medicine and science in sports and exercise Volume: 39 ISSN: 0195-9131 ISO Abbreviation: Med Sci Sports Exerc Publication Date: 2007 Oct |
Date Detail:
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Created Date: 2007-10-02 Completed Date: 2008-01-11 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 8005433 Medline TA: Med Sci Sports Exerc Country: United States |
Other Details:
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Languages: eng Pagination: 1727-35 Citation Subset: IM; S |
Affiliation:
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Department of Integrative Physiology, University of Colorado, Boulder, CO, USA. michael.brothers@colorado.edu |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Acclimatization* Adult Altitude* Anoxia / etiology Bicycling / physiology* Colorado Exercise / physiology* Exercise Test / methods* Exhalation / physiology Female Humans Lactic Acid / analysis Male Maximal Expiratory Flow Rate / physiology Oxygen Consumption / physiology |
| Chemical | |
Reg. No./Substance:
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50-21-5/Lactic Acid |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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