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 .
Exercise training restores uncoupling protein-3 content in limb muscles of patients with chronic obstructive pulmonary disease.
Oxidative capacity and uncoupling protein-3 ( UCP3 ) content are reduced in limb muscles of patients with chronic obstructive pulmonary disease ( COPD ) . It has been hypothesized that the physiological role of UCP3 is to protect mitochondria against lipotoxicity in cases where fatty acid influx exceeds the capacity to oxidize them . Exercise training improves oxidative capacity and reduces UCP3 protein content in healthy subjects , but the response of UCP3 to training in COPD is unknown . We studied the effect of exercise training on UCP3 content in limb muscles of COPD patients . For this , seven healthy age-matched subjects and thirteen patients with COPD were studied . All patients were admitted to an 8-wk exercise training intervention .  Exercise capacity was assessed by means of an incremental cycle ergometry test . Biopsies were taken from the vastus lateralis in which UCP3 and lipid peroxidation levels were determined by Western blotting . Citrate synthase and 3-hydroxyacyl-CoA dehydrogenase ( HAD ; an enzyme involved in fatty acid oxidation ) were measured as indexes of muscle oxidative capacity . UCP3 in COPD was approximately 50 % lower compared with healthy age-matched controls . In COPD , training induced upregulation of UCP3 [ from 67.7 ( SD 41.8 ) to 113.8 ( SD 104.2 ) arbitrary units ( AU ) , P = 0.062 ] , especially in the patients who showed no increase in HAD activity [ from 80.9 ( SD 52.6 ) to 167.9 ( SD 109.1 ) AU , P = 0.028 ] , whereas lipid peroxidation levels remained unaltered . We conclude that exercise-training can restore muscle UCP3 protein level in COPD , and the nature of this response complies with the hypothesis that UCP3 may protect against lipotoxicity
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 .