Document Detail

Respiratory sinus arrhythmia and the heart rate response to carotid baroreceptor activation after hard dynamic exercise in humans.
MedLine Citation:
PMID:  12422964     Owner:  NLM     Status:  MEDLINE    
The aim of this study was to examine the influence of 20 min of hard exercise (HR>160 beats min(-1)) on the efficacy of the cardiac parasympathetic nervous control of heart rate in humans (20-31 years; of either sex). This intensity of exercise was chosen to produce strong activation of the cardiac sympathetic nerves. Using well-controlled stimulus parameters, the efficacy of cardiac parasympathetic control of heart rate was assessed by recording the heart rate response to carotid baroreceptor activation (CBR) and the amplitude of respiratory sinus arrhythmia (RSA). Measurements were made while the subject performed light exercise (100-135 beats min (-1)) before (Control 1) and after very brief (Control 2) and prolonged (20 min; post) periods of hard exercise. There was no difference in the CBR in the three different measurement periods; 0.33 +/- 0.17, 0.38 +/- 0.18 and 0.39 +/- 0.18 beats min(-1) mm Hg(-1) (mean +/- S.D., N=6) for Control 1, Control 2 and post, respectively. At a heart rate of 120 beats min (-1), amplitude of the RSA was 6.1 +/- 2.4, 5.6 +/- 2.4 and 3.3 +/- 2.1 beats min(-1) for Control 1, Control 2 and post, respectively (P<0.001 post vs. Control 1 and Control 2, N=8). The decrease in RSA amplitude following hard exercise may be attributable to an exercise-induced reduction in airway resistance and work of breathing. Overall, these results do not support the hypothesis that sustained hard exercise that produces strong activation of cardiac sympathetic nerves reduces cardiac parasympathetic efficacy.
Rowan W L Herbert; Chris P Bolter
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Publication Detail:
Type:  Clinical Trial; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Autonomic neuroscience : basic & clinical     Volume:  100     ISSN:  1566-0702     ISO Abbreviation:  Auton Neurosci     Publication Date:  2002 Sep 
Date Detail:
Created Date:  2002-11-08     Completed Date:  2002-12-31     Revised Date:  2009-08-12    
Medline Journal Info:
Nlm Unique ID:  100909359     Medline TA:  Auton Neurosci     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  84-9     Citation Subset:  IM    
Department of Physiology, School of Medical Sciences, University of Otago, Dunedin, New Zealand.
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MeSH Terms
Analysis of Variance
Arrhythmia, Sinus / physiopathology*
Baroreflex / physiology*
Carotid Sinus / physiology*
Heart Rate / physiology*
Physical Exertion / physiology*
Time Factors

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