| Substrate oxidation is altered in women during exercise upon acute altitude exposure. | |
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MedLine Citation:
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PMID: 11880806 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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PURPOSE: The purpose of this study was to determine whether substrate oxidation during submaximal exercise in women is affected by an acute exposure to 4300-m altitude and menstrual cycle phase. METHODS: Eight female lowlanders (mean +/- SD; 33 +/- 3 yr, 58 +/- 6 kg, 163 +/- 8 cm) completed a peak oxygen uptake (VO2peak) and submaximal exercise to exhaustion (EXH) test at 70% of their altitude-specific VO2peak at sea level (SL) and during an acute altitude (AA) exposure to 4300 m in a hypobaric chamber (446 mm Hg) in their early-follicular and midluteal menstrual cycle phase. The respiratory exchange ratio (RER) was calculated from oxygen uptake and carbon dioxide output measurements made during the EXH tests, and used to estimate the percent contribution of fat and carbohydrate to energy metabolism. Blood samples were taken at rest and every 15 min during the EXH tests. Blood samples were evaluated for glucose, lactate, glycerol, free fatty acids, insulin, growth hormone, cortisol, glucagon, epinephrine, norepinephrine, estradiol, and progesterone concentrations. RESULTS: Despite increased (P < 0.05) estradiol and progesterone levels in the midluteal phase, substrate oxidation, energy substrates, and metabolic hormones were not affected by cycle phase at SL or AA. However, free fatty acids and cortisol were increased (P < 0.05) whereas RER was decreased (P < 0.05) during exercise upon AA exposure compared with SL in both cycle phases. CONCLUSIONS: These data suggest that substrate oxidation is altered in women during exercise at AA compared with SL but is not affected by cycle phase. Whether increased fat or protein oxidation accounts for the lower RER values during the AA exposure cannot be determined from this study but warrants further investigation. |
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Authors:
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Beth A Beidleman; Paul B Rock; Stephen R Muza; Charles S Fulco; Lindsay L Gibson; Gary H Kamimori; Allen Cymerman |
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Publication Detail:
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Type: Journal Article |
Journal Detail:
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Title: Medicine and science in sports and exercise Volume: 34 ISSN: 0195-9131 ISO Abbreviation: Med Sci Sports Exerc Publication Date: 2002 Mar |
Date Detail:
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Created Date: 2002-03-06 Completed Date: 2002-04-16 Revised Date: 2004-11-17 |
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: 430-7 Citation Subset: IM; S |
Affiliation:
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Thermal and Mountain Medicine Division, United States Army Research Institute of Environmental Medicine, Natick, MA 01760, USA. beth.beidleman@na.amedd.army.mil |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Adult Altitude* Energy Metabolism* Exercise / physiology* Exercise Test Female Hormones / metabolism Humans Luteal Phase / physiology Menstrual Cycle / physiology* Respiration |
| Chemical | |
Reg. No./Substance:
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0/Hormones |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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