Document Detail

Metabolic myopathies: functional evaluation by analysis of oxygen uptake kinetics.
MedLine Citation:
PMID:  19915508     Owner:  NLM     Status:  MEDLINE    
PURPOSE: The aim was to identify additional noninvasive tools allowing to detect and to quantify the metabolic impairment in patients with mitochondrial myopathies (MM) or McArdle's disease (McA).
METHODS: Kinetics of adjustment of pulmonary oxygen uptake (VO2 kinetics) during transitions to constant-load moderate-intensity cycle ergometer exercise were determined on 15 MM, 8 McA, 21 patients with signs and/or symptoms of metabolic myopathy but a negative biopsy ("patient controls"; P-CTRL), and 22 healthy untrained controls (CTRL).
RESULTS: VO2 kinetics were slower in MM and in McA versus P-CTRL and CTRL, slower in McA versus MM, and not significantly different between P-CTRL and CTRL. The time constants (tau) of the monoexponential function describing the VO2 kinetics were (X +/- SE) 59.2 +/- 8.5 s in MM, 87.6 +/- 16.4 s in McA, 36.9 +/- 3.1 s in P-CTRL, and 35.4 +/- 1.9 s in CTRL. In a subgroup of the patients (eight MM and seven McA), tau of VO2 kinetics were negatively correlated with two variables determined in a previous study (Grassi B, Marzorati M, Lanfranconi F, et al. Impaired oxygen extraction in metabolic myopathies: detection and quantification by near-infrared spectroscopy. Muscle Nerve. 2007;35:510-20): a) a muscle oxygenation index, obtained by near-infrared spectroscopy, estimating the peak capacity of skeletal muscle fractional O2 extraction; and b) VO2 peak.
CONCLUSIONS: In MM and McA patients, analysis of pulmonary VO2 kinetics during moderate-intensity exercise allows to identify and to quantify, noninvasively, the impairment of skeletal muscle oxidative metabolism. In these patients, the slower VO2 kinetics can be considered a marker of the impaired exercise tolerance. The present data could be useful for clinicians who need an objective, quantitative, and longitudinal evaluation of the impairment to be used in the follow-up of these patients as well as in the assessment of therapeutic interventions.
Bruno Grassi; Simone Porcelli; Mauro Marzorati; Francesca Lanfranconi; Paola Vago; Claudio Marconi; Lucia Morandi
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Medicine and science in sports and exercise     Volume:  41     ISSN:  1530-0315     ISO Abbreviation:  Med Sci Sports Exerc     Publication Date:  2009 Dec 
Date Detail:
Created Date:  2009-11-20     Completed Date:  2010-02-18     Revised Date:  2011-11-24    
Medline Journal Info:
Nlm Unique ID:  8005433     Medline TA:  Med Sci Sports Exerc     Country:  United States    
Other Details:
Languages:  eng     Pagination:  2120-7     Citation Subset:  IM; S    
Department of Science and Biomedical Technologies, University of Udine, Udine, Italy.
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MeSH Terms
Energy Metabolism / physiology
Exercise Test / methods
Glycogen Phosphorylase, Muscle Form / blood,  deficiency
Mitochondrial Myopathies / metabolism*
Muscular Diseases / metabolism*
Oxygen Consumption / physiology*
Pulmonary Gas Exchange / physiology
Spectroscopy, Near-Infrared
Grant Support
Reg. No./Substance:
EC 2.4.1.-/Glycogen Phosphorylase, Muscle Form

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

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