Document Detail


The intramuscular contribution to the slow oxygen uptake kinetics during exercise in chronic heart failure is related to the severity of the condition.
MedLine Citation:
PMID:  22033530     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The mechanism for slow pulmonary O(2) uptake (Vo(2)) kinetics in patients with chronic heart failure (CHF) is unclear but may be due to limitations in the intramuscular control of O(2) utilization or O(2) delivery. Recent evidence of a transient overshoot in microvascular deoxygenation supports the latter. Prior (or warm-up) exercise can increase O(2) delivery in healthy individuals. We therefore aimed to determine whether prior exercise could increase muscle oxygenation and speed Vo(2) kinetics during exercise in CHF. Fifteen men with CHF (New York Heart Association I-III) due to left ventricular systolic dysfunction performed two 6-min moderate-intensity exercise transitions (bouts 1 and 2, separated by 6 min of rest) from rest to 90% of lactate threshold on a cycle ergometer. Vo(2) was measured using a turbine and a mass spectrometer, and muscle tissue oxygenation index (TOI) was determined by near-infrared spectroscopy. Prior exercise increased resting TOI by 5.3 ± 2.4% (P = 0.001), attenuated the deoxygenation overshoot (-3.9 ± 3.6 vs. -2.0 ± 1.4%, P = 0.011), and speeded the Vo(2) time constant (τVo(2); 49 ± 19 vs. 41 ± 16 s, P = 0.003). Resting TOI was correlated to τVo(2) before (R(2) = 0.51, P = 0.014) and after (R(2) = 0.36, P = 0.051) warm-up exercise. However, the mean response time of TOI was speeded between bouts in half of the patients (26 ± 8 vs. 20 ± 8 s) and slowed in the remainder (32 ± 11 vs. 44 ± 16 s), the latter group having worse New York Heart Association scores (P = 0.042) and slower Vo(2) kinetics (P = 0.001). These data indicate that prior moderate-intensity exercise improves muscle oxygenation and speeds Vo(2) kinetics in CHF. The most severely limited patients, however, appear to have an intramuscular pathology that limits Vo(2) kinetics during moderate exercise.
Authors:
T Scott Bowen; Daniel T Cannon; Scott R Murgatroyd; Karen M Birch; Klaus K Witte; Harry B Rossiter
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2011-10-27
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  112     ISSN:  1522-1601     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  2012 Feb 
Date Detail:
Created Date:  2012-02-03     Completed Date:  2012-08-23     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:  378-87     Citation Subset:  IM    
Affiliation:
Institute of Membrane and Systems Biology, University of Leeds, Leeds, UK.
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MeSH Terms
Descriptor/Qualifier:
Aged
Exercise / physiology*
Heart Failure / metabolism*
Humans
Kinetics
Male
Muscle, Skeletal / metabolism
Oxygen / metabolism*
Oxygen Consumption / physiology*
Pulmonary Gas Exchange / physiology
Spectroscopy, Near-Infrared / methods
Grant Support
ID/Acronym/Agency:
//Medical Research Council
Chemical
Reg. No./Substance:
7782-44-7/Oxygen
Comments/Corrections

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