Document Detail


Maximal oxygen uptake is not limited by a central nervous system governor.
MedLine Citation:
PMID:  17068219     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
We tested the hypothesis that the work of the heart was not a limiting factor in the attainment of maximal oxygen uptake (VO2 max). We measured cardiac output (Q) and blood pressures (BP) during exercise at two different rates of maximal work to estimate the work of the heart through calculation of the rate-pressure product, as a part of the ongoing discussion regarding factors limiting VO2 max. Eight well-trained men (age 24.4 +/- 2.8 yr, weight 81.3 +/- 7.8 kg, and VO2 max 59.1 +/- 2.0 ml x min(-1) x kg(-1)) performed two maximal combined arm and leg exercises, differing 10% in watts, with average duration of time to exhaustion of 4 min 50 s and 3 min 40 s, respectively. There were no differences between work rates in measured VO2 max, maximal Q, and peak heart rate between work rates (0.02 l/min, 0.3 l/min, and 0.8 beats/min, respectively), but the systolic, diastolic, and calculated mean BP were significantly higher (19, 5, and 10 mmHg, respectively) in the higher than in the lower maximal work rate. The products of heart rate times systolic or mean BP and Q times systolic or mean BP were significantly higher (3,715, 1,780, 569, and 1,780, respectively) during the higher than the lower work rate. Differences in these four products indicate a higher mechanical work of the heart on higher than lower maximal work rate. Therefore, this study does not support the theory, which states that the work of the heart, and consequently VO2 max, during maximal exercise is hindered by a command from the central nervous system aiming at protecting the heart from being ischemic.
Authors:
T Brink-Elfegoun; L Kaijser; T Gustafsson; B Ekblom
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2006-10-26
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  102     ISSN:  8750-7587     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  2007 Feb 
Date Detail:
Created Date:  2007-02-07     Completed Date:  2007-03-22     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:  781-6     Citation Subset:  IM    
Affiliation:
Department of Physiology and Pharmacology, Karolinska Institute, Stockholm, Sweden.
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MeSH Terms
Descriptor/Qualifier:
Adult
Blood Pressure / physiology
Cardiac Output / physiology
Central Nervous System / physiology*
Exercise / physiology
Heart / physiology*
Heart Rate / physiology
Humans
Male
Oxygen Consumption / physiology*
Physical Exertion / physiology*
Pulmonary Gas Exchange

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


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