| Spontaneous baroreflex measures are unable to detect age-related impairments in cardiac baroreflex function during dynamic exercise in humans. | |
| | |
MedLine Citation:
|
PMID: 19139062 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
|
The dynamic relationship between 'spontaneous' fluctuations in arterial blood pressure (BP) and heart rate (HR) is increasingly being used to provide an estimate of resting cardiac baroreflex sensitivity. Given the ease of use and clinical utility, spontaneous methods are now also being used to examine cardiac baroreflex sensitivity in distinct subject groups during various laboratory stressors and tasks encountered during daily life, such as physical activity. However, the utility of such spontaneous measures to estimate cardiac baroreflex function during exercise remains unclear, particularly when comparing groups. Therefore, we tested the ability of spontaneous indices to detect age-related differences in cardiac baroreflex function during dynamic exercise. Beat-to-beat HR and BP were measured in eighteen healthy young subjects (24 +/- 1 years) and sixteen healthy middle-aged subjects (59 +/- 1 years) at rest and during steady-state leg cycling. Estimates of spontaneous cardiac baroreflex sensitivity using the sequence technique (G(SEQ)) and low-frequency transfer function gain (G(TF)) were compared with the operating point (G(OP)) and maximal gain (G(MAX)) of the full carotid-cardiac baroreflex function curve. At rest G(SEQ), G(TF), G(OP) and G(MAX) were all significantly lower in older subjects. During moderate-intensity steady-state exercise no differences were observed in G(SEQ) and G(TF) (older 0.26 +/- 0.03 beats min(-1) mmHg(-1) versus younger 0.32 +/- 0.04 beats min(-1) mmHg(-1); P > 0.05), whereas G(OP) and G(MAX) (older -0.21 +/- 0.02 beats min(-1) mmHg(-1) versus younger -0.39 +/- 0.03 beats min(-1) mmHg(-1); P < 0.05) remained lower in older subjects. These data indicate that spontaneous measures of cardiac baroreflex sensitivity alone provide limited information when comparing age-groups during exercise, which makes genuine differences in baroreflex function difficult to identify. |
| | |
Authors:
|
James P Fisher; Shigehiko Ogoh; Chelif Junor; Azamuddin Khaja; Mindy Northrup; Paul J Fadel |
Publication Detail:
|
Type: Comparative Study; Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't Date: 2009-01-12 |
Journal Detail:
|
Title: Experimental physiology Volume: 94 ISSN: 1469-445X ISO Abbreviation: Exp. Physiol. Publication Date: 2009 Apr |
Date Detail:
|
Created Date: 2009-03-16 Completed Date: 2009-05-28 Revised Date: 2011-05-27 |
Medline Journal Info:
|
Nlm Unique ID: 9002940 Medline TA: Exp Physiol Country: England |
Other Details:
|
Languages: eng Pagination: 447-58 Citation Subset: IM |
Affiliation:
|
Department of Medical Physiology and Pharmacology, University of Missouri, Colombia, MO 65212, USA. |
Export Citation:
|
APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
|
Adult Age Factors Baroreflex* Bicycling Blood Pressure* Exercise* Female Heart Rate* Humans Lower Extremity Male Middle Aged Models, Cardiovascular Muscle Contraction* Muscle, Skeletal / physiology* Young Adult |
| Grant Support | |
ID/Acronym/Agency:
|
HL-093167/HL/NHLBI NIH HHS; R01 HL093167-02/HL/NHLBI NIH HHS |
| Comments/Corrections | |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
Previous Document: The guanine nucleotide binding protein beta polypeptide 3 gene C825T polymorphism is associated with...
Next Document: A meta-analysis of cardiac electrophysiology computational models.