RESULTS The forced expiratory volume in 1 s ( FEV(1 ) ) , the ratio of FEV(1 ) to forced vital capacity ( FVC ) and body mass index were positively associated with the proportion of type I fibres in COPD .
This review sheds new light on the relationship between skeletal muscle abnormalities and important hallmarks of the disease in severe COPD , and identifies absence of data in GOLD stages 1 - 2 .
This review also provides reference values on fibre type composition for diagnostic purpose s in COPD
BACKGROUND Skeletal muscle dysfunction is a common feature in chronic obstructive pulmonary disease ( COPD ) which is associated with intrinsic muscular abnormalities .
One of the most consistently reported alterations is a shift from fibre type I to II in the vastus lateralis of these patients .
Surprisingly , the relationship between this shift and the severity and phenotype of COPD remains unclear .
A study was conducted to determine whether vastus lateralis muscle fibre type proportions are associated with COPD disease severity and to provide reference values for the proportions of fibre types in the vastus lateralis in COPD .
Fibre types in skeletal muscles of chronic obstructive pulmonary disease patients related to respiratory function and exercise tolerance.
This study aim ed to investigate the relationship between skeletal muscle , fibre type composition , functional respiratory impairment and exercise tolerance in patients with moderate to severe chronic obstructive pulmonary disease ( COPD ) . A group of 22 COPD patients and 10 healthy control subjects were studied . In COPD patients , vital capacity ( VC ) and forced expiratory volume in one second ( FEV1 ) were reduced to 79 % and 51 % , respectively . Diffusion indices ( transfer factor of the lung for carbon monoxide ( TL , CO ) and carbon monoxide transfer coefficient ( KCO ) ) were also reduced . Arterial oxygen tension ( Pa , O2 ) was normal or slightly altered . A maximal exercise test was performed and anaerobic threshold was calculated . Muscle sample s from vastus lateralis were obtained by needle biopsy . Myosin heavy chain ( MHC ) and light chain ( MLC ) isoforms were separated by gel electrophoresis and quantified by densitometry . MHC isoforms were considered as molecular markers of fibre types . The proportion of the fast MHC-2B isoform was increased in COPD patients . TL , CO , KCO , VC and FEV1 were positively correlated with slow MHC isoform content . TL , CO and KCO were also negatively correlated with the content of the fast MHC-2B isoform . No correlation was found between exercise parameters and MHC isoform composition . The co-ordinated expression between MHC and MLC isoforms was altered in COPD patients . We conclude that reduced oxygen availability , probably in combination with muscle disuse , may determine muscle alterations in chronic obstructive pulmonary disease patients . The altered correlations between myosin heavy chain and light chain isoforms suggest that co-ordinated protein expression is lost in chronic obstructive pulmonary disease muscles
RESULTS The forced expiratory volume in 1 s ( FEV(1 ) ) , the ratio of FEV(1 ) to forced vital capacity ( FVC ) and body mass index were positively associated with the proportion of type I fibres in COPD .
This review sheds new light on the relationship between skeletal muscle abnormalities and important hallmarks of the disease in severe COPD , and identifies absence of data in GOLD stages 1 - 2 .
This review also provides reference values on fibre type composition for diagnostic purpose s in COPD
BACKGROUND Skeletal muscle dysfunction is a common feature in chronic obstructive pulmonary disease ( COPD ) which is associated with intrinsic muscular abnormalities .
One of the most consistently reported alterations is a shift from fibre type I to II in the vastus lateralis of these patients .
Surprisingly , the relationship between this shift and the severity and phenotype of COPD remains unclear .
A study was conducted to determine whether vastus lateralis muscle fibre type proportions are associated with COPD disease severity and to provide reference values for the proportions of fibre types in the vastus lateralis in COPD .