Document Detail

Analysis of initial autonomic adjustments to moderate exercise in humans.
MedLine Citation:
PMID:  8903628     Owner:  NLM     Status:  MEDLINE    
OBJECTIVE: To determine whether signs of cardiac sympathetic activation (together with vagal withdrawal) can be observed in the autonomic balance modulating the sino-atrial node as early as the initial levels of a graded light dynamic exercise. PATIENTS AND METHODS: We studied 15 healthy ambulant subjects (mean +/- SD age 32 +/- 9 years; systolic/diastolic blood pressure 120 +/- 19/77 +/- 7 mmHg; heart rate 65 +/- 9 beats/min), who underwent a control recording of 10 min, followed by a three-step progressive (10, 20 and 30% of nominal maximum for age and sex) supine bicycle exercise. Spectral and cross-spectral analysis of RR and systolic arterial pressure variabilities were used to obtain non-invasive markers of the autonomic adjustments to exercise. RESULTS: The low-frequency component of RR interval variability (which, in normalized units, is a marker of sympathetic modulation of the sino-atrial (SA) node) was progressively increased during all three stages of bicycle exercise. No significant changes were observed in the low-frequency component of systolic arterial pressure variability (i.e. a marker of sympathetic drive to the vasculature) in the early stages of exercise, while a significant increase was observed at 30% of maximum. The index alpha (which provides a measure of the gain of the arterial pressure-heart period baroreflex) was progressively reduced during all three stages of exercise. CONCLUSIONS: While the sympathovagal balance modulating the SA node is immediately shifted towards sympathetic predominance (and vagal withdrawal), markers of peripheral vascular sympathetic activation appear increased only when 30% of maximum exercise is attained.
D Lucini; V Trabucchi; A Malliani; M Pagani
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Journal of hypertension     Volume:  13     ISSN:  0263-6352     ISO Abbreviation:  J. Hypertens.     Publication Date:  1995 Dec 
Date Detail:
Created Date:  1997-03-19     Completed Date:  1997-03-19     Revised Date:  2004-11-17    
Medline Journal Info:
Nlm Unique ID:  8306882     Medline TA:  J Hypertens     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  1660-3     Citation Subset:  IM    
Centre for Cardiovascular Research (CNR), University of Milan, Italy.
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MeSH Terms
Blood Pressure
Exercise / physiology*
Sinoatrial Node / innervation*,  physiology
Vagus Nerve / physiology*

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