Document Detail


Differences in exercising limb blood flow variability between cardiac and muscle contraction cycle related analysis during dynamic knee extensor.
MedLine Citation:
PMID:  17119525     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
AIM: Blood flow in peripheral conduit arteries during steady-state, dynamic exercise, can be estimated noninvasively with Doppler ultrasound, by measuring the conduit arterial diameter and the mean blood velocity averaged over consecutive cardiac beat-by-beat cycles (BB(cycle)) or muscle contraction-relaxation cycles (CR(cycle)). The precise impact fluctuations in the 1-BB(cycle)- or 1-CR(cycle)-rate may impose on the average blood flow measurements has previously not been clearly defined. The hypothesis investigated in the present study was that the blood flow measurements obtained, and its variability, during exercise, may differ between the 1-BB(cycle) and 1-CR(cycle) at incremental exercise intensities; as the BB(cycle)-measurements may be influenced by transient alterations in heart rate; whereas the CR(cycle)-measurements are dependent on the muscle contraction-relaxation frequencies independent of the exercise intensities per se. The main purpose was therefore to determine if fluctuations in blood flow for 1-BB(cycle) and 1-CR(cycle)varies at incremental exercise intensities (work rates) using the one-legged dynamic knee-extensor exercise (DKE) model. METHODS: Limb femoral artery blood flow (LBF) was determined, for 1-BB(cycle) and 1-CR(cycle), in 8 healthy male subjects during 4-min of steady-state DKE at 60 contractions per minute at 10, 20, 30 and 40 W. The variability of LBF was determined from the coefficients of variation (CVLBF). RESULTS: The CV(LBF) for the CR(cycle)-measurements at each work rate were similar (P=NS). The CV(LBF) for the BB(cycle)-measurements were higher (P<0.05) at 40 W compared to at 10 W. Furthermore, the CV(LBF) for the 1-BB(cycle) was higher (P<0.05) than for the 1-CR(cycle) at 30 and 40 W, despite almost identical mean LBF values for the BB(cycle)- and the CR(cycle)-measurements at each exercise intensity. CONCLUSIONS: The present data suggests that estimates of LBF at slightly higher exercise intensities such as above 30 W, for a few number of consecutive BB(cycle), renders a higher variability than for CR(cycle)-measurements. This may consequently result in slight over- and under-estimations of LBF compared to the CR(cycle)-measurement.
Authors:
T Osada; G Rådegran
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The Journal of sports medicine and physical fitness     Volume:  46     ISSN:  0022-4707     ISO Abbreviation:  J Sports Med Phys Fitness     Publication Date:  2006 Dec 
Date Detail:
Created Date:  2006-11-22     Completed Date:  2007-03-22     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  0376337     Medline TA:  J Sports Med Phys Fitness     Country:  Italy    
Other Details:
Languages:  eng     Pagination:  590-7     Citation Subset:  IM    
Affiliation:
Department of Preventive Medicine and Public Health, Tokyo Medical University, Tokyo, Japan. DENTACMAC@aol.com
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MeSH Terms
Descriptor/Qualifier:
Adult
Blood Flow Velocity / physiology
Exercise / physiology*
Femoral Artery / physiology*,  ultrasonography
Humans
Knee
Leg / blood supply
Male
Muscle Contraction / physiology*
Myocardial Contraction / physiology*
Physical Exertion / physiology
Regional Blood Flow
Ultrasonography, Doppler

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


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