Document Detail

Relationships between the extent of apnea-induced bradycardia and the vascular response in the arm and leg during dynamic two-legged knee extension exercise.
MedLine Citation:
PMID:  22159992     Owner:  NLM     Status:  MEDLINE    
Our aim was to test the hypothesis that apnea-induced hemodynamic responses during dynamic exercise in humans differ between those who show strong bradycardia and those who show only mild bradycardia. After apnea-induced changes in heart rate (HR) were evaluated during dynamic exercise, 23 healthy subjects were selected and divided into a large response group (L group; n = 11) and a small response group (S group; n = 12). While subjects performed a two-legged dynamic knee extension exercise at a work load that increased HR by 30 beats/min, apnea-induced changes in HR, cardiac output (CO), mean arterial pressure (MAP), arterial O(2) saturation (Sa(O(2))), forearm blood flow (FBF), and leg blood flow (LBF) were measured. During apnea, HR in the L group (54 ± 2 beats/min) was lower than in the S group (92 ± 3 beats/min, P < 0.05). CO, Sa(O(2)), FBF, LBF, forearm vascular conductance (FVC), leg vascular conductance (LVC), and total vascular conductance (TVC) were all reduced, and MAP was increased in both groups, although the changes in CO, TVC, LBF, LVC, and MAP were larger in the L group than in the S group (P < 0.05). Moreover, there were significant positive linear relationships between the reduction in HR and the reductions in TVC, LVC, and FVC. We conclude that individuals who show greater apnea-induced bradycardia during exercise also show greater vasoconstriction in both active and inactive muscle regions.
Takeshi Nishiyasu; Rina Tsukamoto; Katsuhito Kawai; Keiji Hayashi; Shunsaku Koga; Masashi Ichinose
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2011-12-09
Journal Detail:
Title:  American journal of physiology. Heart and circulatory physiology     Volume:  302     ISSN:  1522-1539     ISO Abbreviation:  Am. J. Physiol. Heart Circ. Physiol.     Publication Date:  2012 Feb 
Date Detail:
Created Date:  2012-02-01     Completed Date:  2012-03-20     Revised Date:  2012-05-23    
Medline Journal Info:
Nlm Unique ID:  100901228     Medline TA:  Am J Physiol Heart Circ Physiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  H864-71     Citation Subset:  IM    
Institute of Health and Sports Science, University of Tsukuba, Tsukuba, Japan.
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MeSH Terms
Apnea / complications,  physiopathology*
Arm / blood supply,  physiology
Bicycling / physiology
Bradycardia / etiology,  physiopathology*
Exercise / physiology*
Heart Rate / genetics,  physiology
Leg / blood supply,  physiology
Models, Cardiovascular
Muscle, Skeletal / blood supply,  physiology
Physical Exertion / physiology*
Regional Blood Flow / physiology
Vasoconstriction / physiology
Young Adult

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

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