Document Detail


Parasympathetic effects on heart rate recovery after exercise.
MedLine Citation:
PMID:  15612453     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
BACKGROUND: Exercise and its recovery period are associated with increased risk of death relative to sedentary periods. They are also accompanied by dynamic changes in autonomic tone. Little information is available regarding parasympathetic effects during high-intensity exercise and recovery. METHODS: Ten normal subjects (five women; age 33 +/- 2 years) underwent exercise testing on a bicycle ergometer. On day 1, subjects exercised to maximum tolerated workload using a graded protocol with 5 minutes at maximal workload (peak heart rate achieved 174.7 +/- 5.4 bpm). On day 2, subjects performed the identical exercise protocol as on day 1; 1 minute into the maximum exercise stage, atropine (0.04 mg/kg) was administered. Heart rate was recorded every minute during exercise, and an electrocardiogram was recorded every minute in recovery for 10 minutes. The parasympathetic effect on heart rate was defined by the difference in heart rate with and without atropine. RESULTS: The parasympathetic effect during maximal exercise was 3.4 to 6 bpm (p < .05). During recovery, a large parasympathetic effect on heart rate was noted by 1 minute (22.8 bpm; p < .0002), increased until 4 minutes, and then remained stable until 10 minutes. Despite faster heart rates with parasympathetic blockade, the P-R interval was shorter (p < .002), consistent with a significant parasympathetic effect on the atrioventricular node in recovery. Evaluation of the Q-T-R-R relationship on the 2 days demonstrated significant changes in both the slope (p < .0001) and the intercept (p < .0001), consistent with a modification of ventricular repolarization by parasympathetic tone in recovery. CONCLUSION: These data indicate that in normal subjects, parasympathetic effects persist during high-intensity exercise and are prominent in the early phases of recovery. These parasympathetic effects may play an important role in prevention of sudden cardiac death during these periods of increased risk.
Authors:
Prince J Kannankeril; Francis K Le; Alan H Kadish; Jeffrey J Goldberger
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Journal of investigative medicine : the official publication of the American Federation for Clinical Research     Volume:  52     ISSN:  1081-5589     ISO Abbreviation:  J. Investig. Med.     Publication Date:  2004 Sep 
Date Detail:
Created Date:  2004-12-22     Completed Date:  2005-01-13     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  9501229     Medline TA:  J Investig Med     Country:  Canada    
Other Details:
Languages:  eng     Pagination:  394-401     Citation Subset:  IM    
Affiliation:
Division of Cardiology, Department of Medicine, Northwestern University, Chicago, IL, USA.
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MeSH Terms
Descriptor/Qualifier:
Adult
Atropine / diagnostic use
Electrocardiography / drug effects
Exercise / physiology*
Exercise Test
Female
Heart Rate / drug effects,  physiology*
Humans
Male
Parasympathetic Nervous System / drug effects,  physiology*
Recovery of Function / physiology*
Grant Support
ID/Acronym/Agency:
1 R01 HL 70179-01A2/HL/NHLBI NIH HHS; RR-00048/RR/NCRR NIH HHS
Chemical
Reg. No./Substance:
51-55-8/Atropine

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


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