Document Detail

Inflection points of cardiovascular responses and oxygenation are correlated in the distal but not the proximal portions of muscle during incremental exercise.
MedLine Citation:
PMID:  15107412     Owner:  NLM     Status:  MEDLINE    
To test whether there is a regional difference in the exercise pressor reflex within a given muscle, we investigated the relationship between the inflection points of cardiovascular responses and muscle oxygenation during exercise. Seven subjects performed incremental exercise, which consisted of incremental 30-s static knee extensions, each separated by 30 s of recovery. The workload started at 5% maximal voluntary contraction (MVC) and increased by 5% MVC for each increment until exhaustion. Changes (Delta) in the concentrations (denoted by brackets) of oxygenated Hb (O2Hb) and deoxygenated Hb (HHb) were monitored in proximal and distal portions of the vastus lateralis by near-infrared spectroscopy. The inflection points of mean arterial pressure (MAP), calf vascular resistance (CVR), and muscle deoxygenation index (Delta[O2Hb-HHb]) were calculated as the intersection point of two regression equations obtained at lower and higher workloads. The inflection point of Delta[O2Hb-HHb] differed significantly between proximal and distal portions (28.5 +/- 3.0 vs. 39.5 +/- 3.0%MVC, P < 0.05). Linear regression analysis showed significant correlations between the inflection point of Delta[O2Hb-HHb] in the distal portion and MAP (r = 0.89; P < 0.01) and CVR (r = 0.89; P < 0.05), but no significant relationship between the inflection point in the proximal portion and MAP or CVR. These data show that the inflection point of muscle deoxygenation differs between proximal and distal portions within the vastus lateralis during incremental exercise and suggest that the distal portion of the vastus lateralis contributes more to the pressor response than does the proximal portion.
Masaki Mizuno; Ken Tokizawa; Takashi Iwakawa; Isao Muraoka
Publication Detail:
Type:  Clinical Trial; Journal Article     Date:  2004-04-23
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  97     ISSN:  8750-7587     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  2004 Sep 
Date Detail:
Created Date:  2004-08-30     Completed Date:  2005-02-10     Revised Date:  2013-09-26    
Medline Journal Info:
Nlm Unique ID:  8502536     Medline TA:  J Appl Physiol (1985)     Country:  United States    
Other Details:
Languages:  eng     Pagination:  867-73     Citation Subset:  IM    
Graduate School of Human Sciences, Waseda University, Tokorozawa, Saitama, 359-1192 Japan.
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MeSH Terms
Adaptation, Physiological / physiology
Blood Pressure / physiology*
Cardiovascular Physiological Phenomena
Exercise Test
Heart Rate / physiology*
Knee Joint / physiology
Muscle, Skeletal / blood supply*,  physiology*
Oxygen / metabolism*
Physical Endurance / physiology*
Physical Exertion / physiology*
Statistics as Topic
Reg. No./Substance:

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

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