Document Detail

Effect of acute hypoxia on heart rate variability at rest and during exercise.
MedLine Citation:
PMID:  15162245     Owner:  NLM     Status:  MEDLINE    
The purpose of this study was to investigate sympathovagal balance as inferred from heart rate variability (HRV) responses to acute hypoxia at rest and during exercise. HRV was evaluated in 12 healthy subjects during a standardized hypoxic tolerance test which consists of four periods alternating rest and moderate exercise (50 % V.O (2)max) in normoxic and hypoxic conditions. Ventilatory responses were determined and HRV indexes were calculated for the last 5 min of each period. In well-tolerant subjects, hypoxia at rest induced a decrease of root-mean-square of successive normal R-R interval differences (RMSSD) (p < 0.05) and of absolute high frequency (HF) power (p < 0.001). All absolute HRV indexes were strongly reduced during exercise (p < 0.001) with no further changes under the additional stimulus of hypoxia. A significant increase (p < 0.05) in the HF/(LF+HF) ratio (where LF is low frequency power) was found during exercise in hypoxia compared to exercise in normoxia, associated with similar mean changes in ventilation and tidal volume. These results indicate a vagal control withdrawal under hypoxia at rest. During exercise at 50 % V.O (2)max, HRV indexes cannot adequately represent cardiac autonomic adaptation to acute hypoxia, or possibly to other additional stimuli, due to the dominant effect of exercise and the eventual influence of confounding factors.
M Buchheit; R Richard; S Doutreleau; E Lonsdorfer-Wolf; G Brandenberger; C Simon
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Publication Detail:
Type:  Clinical Trial; Comparative Study; Journal Article    
Journal Detail:
Title:  International journal of sports medicine     Volume:  25     ISSN:  0172-4622     ISO Abbreviation:  Int J Sports Med     Publication Date:  2004 May 
Date Detail:
Created Date:  2004-05-26     Completed Date:  2004-09-28     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  8008349     Medline TA:  Int J Sports Med     Country:  Germany    
Other Details:
Languages:  eng     Pagination:  264-9     Citation Subset:  IM    
Laboratoire des Régulations Physiologiques et des Rythmes Biologiques chez l'Homme, Strasbourg, France.
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MeSH Terms
Adaptation, Physiological / physiology
Anoxia / physiopathology*
Exercise / physiology*
Heart Rate / physiology*
Pulmonary Ventilation / physiology
Rest / physiology*

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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