Document Detail


Stroke volume decline during prolonged exercise is influenced by the increase in heart rate.
MedLine Citation:
PMID:  10066688     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
This study determined whether the decline in stroke volume (SV) during prolonged exercise is related to an increase in heart rate (HR) and/or an increase in cutaneous blood flow (CBF). Seven active men cycled for 60 min at approximately 57% peak O2 uptake in a neutral environment (i.e., 27 degrees C, <40% relative humidity). They received a placebo control (CON) or a small oral dose (i.e., approximately 7 mg) of the beta1-adrenoceptor blocker atenolol (BB) at the onset of exercise. At 15 min, HR and SV were similar during CON and BB. From 15 to 55 min during CON, a 13% decline in SV was associated with an 11% increase in HR and not with an increase in CBF. CBF increased mainly from 5 to 15 min and remained stable from 20 to 60 min of exercise in both treatments. However, from 15 to 55 min during BB, when the increase in HR was prevented by atenolol, the decline in SV was also prevented, despite a normal CBF response (i.e., similar to CON). Cardiac output was similar in both treatments and stable throughout the exercise bouts. We conclude that during prolonged exercise in a neutral environment the decline in SV is related to the increase in HR and is not affected by CBF.
Authors:
R G Fritzsche; T W Switzer; B J Hodgkinson; E F Coyle
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  86     ISSN:  8750-7587     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  1999 Mar 
Date Detail:
Created Date:  1999-05-07     Completed Date:  1999-05-07     Revised Date:  2013-09-26    
Medline Journal Info:
Nlm Unique ID:  8502536     Medline TA:  J Appl Physiol (1985)     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  799-805     Citation Subset:  IM; S    
Affiliation:
Human Performance Laboratory, The University of Texas at Austin, Austin, Texas 78712, USA.
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MeSH Terms
Descriptor/Qualifier:
Adrenergic beta-Antagonists / pharmacology
Adult
Atenolol / pharmacology
Blood Volume / drug effects,  physiology
Body Temperature / drug effects,  physiology
Exercise / physiology*
Heart Rate / physiology*
Hemodynamics / drug effects,  physiology
Humans
Male
Oxygen Consumption / drug effects,  physiology
Regional Blood Flow / drug effects,  physiology
Respiratory Mechanics / drug effects,  physiology
Skin / blood supply
Stroke Volume / physiology*
Sweating / drug effects,  physiology
Chemical
Reg. No./Substance:
0/Adrenergic beta-Antagonists; 29122-68-7/Atenolol

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


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