Document Detail

Chemoreflex and metaboreflex responses to static hypoxic exercise in aging humans.
MedLine Citation:
PMID:  16531899     Owner:  NLM     Status:  MEDLINE    
PURPOSE: We tested the hypothesis that aging decreases the contribution of metaboreceptors to sympathetic responses during exercise in hypoxia. METHODS: We recorded sympathetic nerve traffic to muscle circulation (MSNA), heart rate (HR), blood pressure (BP), minute ventilation (VE), and blood lactate (BL) in 12 older (55 +/- 10 yr) and 12 younger (22 +/- 2 yr) normal subjects during three randomized interventions: isocapnic hypoxia (chemoreflex activation), isometric handgrip exercise (HG) in normoxia (metaboreflex activation), and HG during isocapnic hypoxia (concomitant metaboreflex and chemoreflex activation). All interventions were followed by a forearm circulatory arrest period to allow metaboreflex activation in the absence of exercise and chemoreflex activation. RESULTS: Older subjects had higher resting MSNA (38 +/- 12 vs 23 +/- 9 bursts per minute; P < 0.01) and BP (P < 0.001). Heart rate, minute ventilation, and blood lactate did not differ (all P > 0.5). MSNA responses to HG in normoxia (P < 0.05) and in hypoxia (P < 0.05) were smaller in the older subjects, but were similar during hypoxia alone. The increase in HR was smaller in the older subjects for all interventions (all P < 0.05). In contrast, the increase in systolic and diastolic BP, VE, and BL were similar in both groups (P > 0.05). During the local circulatory arrest, MSNA and BP remained elevated in both groups after HG in normoxia (P < 0.01) and in hypoxia (P < 0.01), but MSNA changes were smaller in the older subjects (P < 0.05). CONCLUSION: Aging reduces sympathetic reactivity to isometric handgrip, but does not prevent the metaboreceptors to remain the main determinant of sympathetic activation during exercise in hypoxia.
Anne Houssiere; Boutaina Najem; Atul Pathak; Olivier Xhaët; Robert Naeije; Philippe Van De Borne
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Medicine and science in sports and exercise     Volume:  38     ISSN:  0195-9131     ISO Abbreviation:  Med Sci Sports Exerc     Publication Date:  2006 Feb 
Date Detail:
Created Date:  2006-03-13     Completed Date:  2006-06-23     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  8005433     Medline TA:  Med Sci Sports Exerc     Country:  United States    
Other Details:
Languages:  eng     Pagination:  305-12     Citation Subset:  IM; S    
Department of Physiology, Erasme Hospital, Brussels, Belgium.
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MeSH Terms
Aging / physiology*
Analysis of Variance
Anoxia / physiopathology*
Blood Pressure / physiology
Chemoreceptor Cells / physiology
Exercise / physiology*
Hand Strength / physiology
Heart Rate / physiology
Lactates / blood
Middle Aged
Muscle, Skeletal / blood supply
Sympathetic Nervous System / physiology*
Reg. No./Substance:

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