Document Detail

Differences in autonomic modulation of heart rate during arm and leg exercise.
MedLine Citation:
PMID:  10451789     Owner:  NLM     Status:  MEDLINE    
Heart rate (HR) is higher during dynamic arm exercise than during leg exercise at equal oxygen consumption levels, but the physiological background for this difference is not completely understood. The vagally mediated beat-to-beat R-R interval fluctuation decreases until the level of approximately 50% of maximal oxygen consumption during an incremental bicycle exercise, but the vagal responses to arm exercise are not well known. Changes in autonomic modulation of HR were compared during arm and leg exercise by measuring beat-to-beat R-R interval variability from a Poincaré plot normalized for the average R-R interval (SD1n), a measure of vagal activity, in 14 healthy male subjects (age 20 +/- 4 years) who performed graded bicycle and arm cranking tests until exhaustion. Seven of the subjects also performed the dynamic arm and leg tests after beta-adrenergic blockade (propranolol 0.2 mg kg-1 i.v.). More rapid reduction occurred in SD1n during the low-intensity level of dynamic arm exercise than during dynamic leg exercise without beta-blockade (e.g. 11 +/- 6 vs. 20 +/- 10 at the oxygen consumption level of 1.2 l min-1; P < 0.001) and with beta-blockade (e.g. 13 +/- 4 vs. 25 +/- 10 at the level of 1.0 l min-1; P < 0.05), and the mean HR was significantly higher during submaximal arm work than during leg work in both cases (e.g. during beta-blockade 81 +/- 12 vs. 74 +/- 6 beats min-1 at the level of 1.0 l min-1; P < 0.05). These data show that dynamic arm exercise results in more rapid withdrawal of vagal outflow than dynamic leg exercise.
M P Tulppo; T H Mäkikallio; R T Laukkanen; H V Huikuri
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Clinical physiology (Oxford, England)     Volume:  19     ISSN:  0144-5979     ISO Abbreviation:  Clin Physiol     Publication Date:  1999 Jul 
Date Detail:
Created Date:  1999-10-12     Completed Date:  1999-10-12     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  8309768     Medline TA:  Clin Physiol     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  294-9     Citation Subset:  IM    
Department of Medicine, University of Oulu, Finland.
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MeSH Terms
Adrenergic beta-Antagonists / pharmacology
Arm / physiology*
Autonomic Nervous System / physiology*
Blood Pressure / physiology
Exercise / physiology*
Exercise Test
Heart Rate / drug effects,  physiology*
Leg / physiology*
Oxygen Consumption / physiology
Propranolol / pharmacology
Vagus Nerve / physiology
Reg. No./Substance:
0/Adrenergic beta-Antagonists; 525-66-6/Propranolol

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

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