Document Detail


Autonomic control of heart rate during physical exercise and fractal dimension of heart rate variability.
MedLine Citation:
PMID:  8458809     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The objectives of the present study were to investigate autonomic nervous system influence on heart rate during physical exercise and to examine the relationship between the fractal component in heart rate variability (HRV) and the system's response. Ten subjects performed incremental exercise on a cycle ergometer, consisting of a 5-min warm-up period followed by a ramp protocol, with work rate increasing at a rate of 2.0 W/min until exhaustion. During exercise, alveolar gas exchange, plasma norepinephrine (NE) and epinephrine (E) responses, and beat-to-beat HRV were monitored. HRV data were analyzed by "coarse-graining spectral analysis" (Y. Yamamoto and R. L. Hughson. J. Appl. Physiol. 71: 1143-1150, 1991) to break down their total power (Pt) into harmonic and nonharmonic (fractal) components. The harmonic component was further divided into low-frequency (0.0-0.15 Hz) and high-frequency (0.15-0.8 Hz) components, from which low-frequency and high-frequency power (Pl and Ph, respectively) were calculated. Parasympathetic (PNS) and sympathetic (SNS) nervous system activity indicators were evaluated by Ph/Pt and Pl/Ph, respectively. From the fractal component, the fractal dimension (DF) and the spectral exponent (beta) were calculated. The PNS indicator decreased significantly (P < 0.05) when exercise intensity exceeded 50% of peak oxygen uptake (VO2 peak). Conversely, the SNS indicator initially increased at 50-60% VO2peak (P < 0.05) and further increased significantly (P < 0.05) at > 60% VO2peak when there were also more pronounced increases in NE and E.(ABSTRACT TRUNCATED AT 250 WORDS)
Authors:
Y Nakamura; Y Yamamoto; I Muraoka
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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:  74     ISSN:  8750-7587     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  1993 Feb 
Date Detail:
Created Date:  1993-04-27     Completed Date:  1993-04-27     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  8502536     Medline TA:  J Appl Physiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  875-81     Citation Subset:  IM    
Affiliation:
Department of Sports Sciences, Waseda University, Saitama, Japan.
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MeSH Terms
Descriptor/Qualifier:
Adult
Autonomic Nervous System / physiology*
Catecholamines / blood,  metabolism
Electrocardiography
Exercise / physiology*
Exercise Test
Female
Heart Rate / physiology*
Humans
Lactates / blood
Lactic Acid
Male
Oxygen Consumption
Parasympathetic Nervous System / physiology
Sympathetic Nervous System / physiology
Chemical
Reg. No./Substance:
0/Catecholamines; 0/Lactates; 50-21-5/Lactic Acid

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