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Intermittent hypoxic exposure does not improve endurance performance at altitude.
MedLine Citation:
PMID:  19461532     Owner:  NLM     Status:  In-Process    
Abstract/OtherAbstract:
PURPOSE: This study examined the effect of 1 wk of normobaric intermittent hypoxic exposure (IHE) combined with exercise training on endurance performance at a 4300-m altitude (HA). METHODS: Seventeen male lowlanders were divided into an IHE (n = 11) or SHAM (n = 6) group. Each completed cycle endurance testing consisting of two 20-min steady state (SS) exercise bouts (at 40% and 60% V O2peak) followed by a 10-min break and then a 720-kJ cycle time trial at HA before IHE or SHAM treatment (Pre-T). IHE treatment consisted of a 2-h rest at a PO2 of 90 mm Hg followed by two 25-min bouts of exercise at approximately 80% of peak HR at a PO2 of 110 mm Hg for 1 wk in a hypoxia room. SHAM treatment was identical except that the PO2 was 148 mm Hg for both rest and exercise. After IHE or SHAM treatment (Post-T), all completed a second cycle endurance test at HA. HR, arterial oxygen saturation (SaO2), and RPE were obtained from the 10th to the 15th minute during the two SS exercise bouts and every 5 min during the time trial. RESULTS: Seven volunteers in the IHE group could not finish the 720-kJ time trial either at Pre-T or at Post-T. Time trial analysis was limited, therefore, to the time to reach 360 kJ (halfway point) for all volunteers. From Pre-T to Post-T, there was no improvement in time trial performance (min +/- SE) in the IHE (62.0 +/- 4.8 to 63.7 +/- 5.2) or SHAM (60.9 +/- 6.3 to 54.2 +/- 6.8) group. There was no change from Pre-T to Post-T in HR, SaO2, and RPE during the two SS exercise bouts or time trial in either group. CONCLUSIONS: One week of IHE combined with exercise training does not improve endurance performance at a 4300-m altitude in male lowlanders.
Authors:
Beth A Beidleman; Stephen R Muza; Charles S Fulco; Juli E Jones; Eric Lammi; Janet E Staab; Allen Cymerman
Publication Detail:
Type:  Clinical Trial; Journal Article; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  Medicine and science in sports and exercise     Volume:  41     ISSN:  1530-0315     ISO Abbreviation:  Med Sci Sports Exerc     Publication Date:  2009 Jun 
Date Detail:
Created Date:  2009-05-25     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8005433     Medline TA:  Med Sci Sports Exerc     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1317-25     Citation Subset:  IM; S    
Affiliation:
Thermal and Mountain Medicine Division, US Army Research Institute of Environmental Medicine, Natick, MA 01760, USA. beth.beidleman@us.army.mil
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