Document Detail

Assessing autonomic function by analysis of heart rate recovery from exercise in healthy subjects.
MedLine Citation:
PMID:  15219511     Owner:  NLM     Status:  MEDLINE    
Although delayed recovery of heart rate (HR) after exercise indicates poor prognosis, the relative role of parasympathetic reactivation versus sympathetic withdrawal in controlling exercise HR recovery remains controversial. Quantifying HR recovery is difficult because the rate of recovery varies with exercise level. This study develops a model of HR recovery applicable to multiple exercise levels simultaneously. Using the Levenberg-Marquardt method for nonlinear models, HR curves for 11 healthy volunteers recovering from 4 different levels of exercise were fit to equations incorporating 1 first-order time constant for parasympathetic reactivation and 1 for sympathetic withdrawal. Results provided time constants for parasympathetic reactivation of 44 +/- 37 seconds and for sympathetic withdrawal of 65 +/- 56 seconds. The model fit the HR recovery curves very closely, explaining 99.7 +/- 0.1% of the variance in the data. In conclusion, this study presents a unique method for quantitatively testing theories on the relative roles of sympathetic withdrawal and parasympathetic reactivation during recovery from exercise. It provides indexes of dynamic sympathetic and parasympathetic functions, with the parasympathetic system having a faster response time. It supports theories of coordinated interaction of parasympathetic reactivation and sympathetic withdrawal during exercise recovery and does not support using simple measures of exercise HR recovery as indexes of vagal function alone.
Gordon L Pierpont; Eric J Voth
Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  The American journal of cardiology     Volume:  94     ISSN:  0002-9149     ISO Abbreviation:  Am. J. Cardiol.     Publication Date:  2004 Jul 
Date Detail:
Created Date:  2004-06-28     Completed Date:  2004-07-21     Revised Date:  2004-11-17    
Medline Journal Info:
Nlm Unique ID:  0207277     Medline TA:  Am J Cardiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  64-8     Citation Subset:  AIM; IM    
Department of Cardiology, Minneapolis VA Medical Center, and Department of Medicine, University of Minnesota, 55417, USA.
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MeSH Terms
Autonomic Nervous System / physiology*
Exercise / physiology*
Heart Rate / physiology*
Middle Aged
Models, Cardiovascular*
Reference Values
Rest / physiology

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

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