Document Detail


Dynamics of cardiac output and systolic time intervals in supine and upright exercise.
MedLine Citation:
PMID:  6662757     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Transient and steady-state responses of stroke volume (SV), heart rate (HR), cardiac output (Q), left ventricular ejection time (LVET), preejection period (PEP), and the ratio of LVET to PEP during bicycle exercises of 50 and 100 W were studied in four healthy male subjects in supine and upright postures. A computer-based system in which impedance cardiography was incorporated served to determine the above parameters on a 10-s interval basis. SV remained almost unchanged in response to exercises in a supine posture, whereas it increased significantly in an upright posture, although the individual differences among subjects were found to be large. The half-response times of variables to a step work load were determined. An approximate accordance was observed among the response times for HR, Q, and LVET/PEP. There was an inverse relationship between LVET and HR, the slope of which was found to be steeper in the supine posture than in the upright posture, reflecting the difference between the SV responses in both postures. LVET fell shortly after the cessation of exercise despite the decreasing HR. Inasmuch as the paradoxical reduction of LVET was also found in the case where SV remained unchanged in response to exercise, no changes in SV can be the cause thereof. Thus, a transient increase in ejection rate, which is due to either the increased myocardial contractility or decreased peripheral vascular resistance, may be responsible for the phenomenon.
Authors:
Y Miyamoto; J Higuchi; Y Abe; T Hiura; Y Nakazono; T Mikami
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Journal of applied physiology: respiratory, environmental and exercise physiology     Volume:  55     ISSN:  0161-7567     ISO Abbreviation:  J Appl Physiol Respir Environ Exerc Physiol     Publication Date:  1983 Dec 
Date Detail:
Created Date:  1984-02-28     Completed Date:  1984-02-28     Revised Date:  2013-09-26    
Medline Journal Info:
Nlm Unique ID:  7801242     Medline TA:  J Appl Physiol Respir Environ Exerc Physiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1674-81     Citation Subset:  IM; S    
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MeSH Terms
Descriptor/Qualifier:
Adult
Cardiac Output*
Heart Rate
Homeostasis
Humans
Male
Myocardial Contraction*
Physical Exertion*
Posture*
Stroke Volume
Systole*

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


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