Fibre types in skeletal muscles of chronic obstructive pulmonary disease patients related to respiratory function and exercise tolerance. Redox balance following magnetic stimulation training in the quadriceps of patients with severe COPD Skeletal muscle structure and function in response to electrical stimulation in moderately impaired COPD patients. The effects of exercise training on muscle atrophy in haemodialysis patients. High-intensity knee extensor training restores skeletal muscle function in COPD patients Skeletal muscle microbiopsy: a validation study of a minimally invasive technique The occurrence of fibre-type grouping in healthy human muscle: a quantitative study of cross-sections of whole vastus lateralis from men between 15 and 83 years
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 In severe COPD patients , oxidative stress , which is involved in their peripheral muscle dysfunction , increases in response to exercise . In this study , muscle oxidative stress was explored after quadriceps magnetic stimulation training . A r and omized controlled study was conducted on very severe COPD patients , who underwent quadriceps magnetic stimulation training for 8 weeks . A control group was also studied . In both groups , vastus lateralis specimens were obtained before and after the 8-week period . Muscle protein carbonylation and nitration and antioxidant enzymes were determined using immunoblotting and proportions and sizes of type I and II fibres using immunohistochemistry . Compared to controls , magnetic stimulation muscle training did not modify redox balance , whilst inducing a significant increase in type I fibre sizes . In severe COPD patients , it is concluded that quadriceps magnetic stimulation training was a well-tolerated therapeutic intervention , which did not enhance muscle oxidative stress , while increasing the size of slow-twitch fibres STUDY OBJECTIVE To determine the structural and functional consequences of high-frequency neuromuscular electrical stimulation ( hf-NMES ) in a group of moderately impaired out patients with chronic obstructive pulmonary disease ( COPD ) . DESIGN A prospect i ve , cross-over r and omized trial . SETTING An university-based , tertiary center . PATIENTS AND MATERIAL S Seventeen patients ( FEV(1)=49.6+/-13.4 % predicted , Medical Research Council dyspnoea grade s II-III ) underwent 6-weeks hf-NMES ( 50Hz ) and sham stimulation of the quadriceps femoris in a r and omized , cross-over design . Knee strength was measured by isokinetic dynamometry ( peak torque ) and leg muscle mass ( LMM ) by DEXA ; in addition , median cross-sectional area ( CSA ) of type I and II fibres and capillary-fibre ratio were evaluated in the vastus lateralis . The 6-min walking distance ( 6MWD ) was also determined . RESULTS At baseline , patients presented with well-preserved functional capacity , muscle strength and mass : there was a significant relationship between strength and type II CSA ( P<0.05 ) . NMES was not associated with significant changes in peak torque , LMM or 6MWD as compared to sham ( P>0.05 ) . At micro-structural level , however , electrical stimulation increased type II , but decreased type I , CSA ; no change , however , was found in the relative fibre distribution or capillary : fibre ratio ( P<0.05 ) . There was no significant association between individual changes in structure and function with training ( P>0.05 ) . Post-NMES increase in type II CSA was inversely related to baseline mass and strength ( P<0.05 ) . CONCLUSION NMES may promote a modest degree of type II muscle fibre hypertrophy in COPD patients with well-preserved functional status . These micro-structural changes , however , were not translated into increased volitional strength in this sub- population BACKGROUND Patients with end-stage renal disease on haemodialysis ( HD ) have limited work capacity . Many structural and functional alterations in skeletal muscles contribute to this disability . METHODS To evaluate the effects of exercise training on uraemic myopathy , seven HD patients ( mean age 44.1+/-17.2 years ) were studied . Open muscle biopsies were taken from their vastus lateralis muscle before and after a 6-month exercise rehabilitation programme and examined by routine light- and transmission electron-microscopy . Histochemical stainings of frozen sections were performed and morphometric analysis was also applied to estimate the proportion of each fibre type and the muscle fibre area . Spiroergometric and neurophysiological testing and peak extension forces of the lower limbs were measured before and after exercise training . RESULTS All patients showed impaired exercise capacity , which was associated with marked muscular atrophy ( mean area 2548+/-463 microm2 ) and reduction in muscle strength and nerve conduction velocity . All types of fibres were atrophied , but type II were more affected . The ultrastructural study showed severe degenerative changes in skeletal muscle fibres , mitochondria , and capillaries .  Exercise training had an impressive effect on muscular atrophy ; in particular the proportion of type II fibres increased by 51 % and mean muscle fibre area by 29 % . Favourable changes were also seen on the structure and number of capillaries and mitochondria . These results were confirmed by a 48 % increase in VO2 peak and a 29 % in exercise time , as well as an improvement in the peak muscle strength of the lower limbs and in nerve conduction velocity . CONCLUSIONS Skeletal muscle atrophy in HD patients contribute to their poor exercise tolerance . The application of an exercise training rehabilitation programme improved muscle atrophy markedly , and therefore had beneficial effects in overall work performance Improving reduced skeletal muscle function is important for optimising exercise tolerance and quality of life in chronic obstructive pulmonary disease ( COPD ) patients . By applying high-intensity training to a small muscle group , we hypothesised a normalisation of muscle function . Seven patients with COPD performed 6 weeks ( 3 days·week−1 ) of high-intensity interval aerobic knee extensor exercise training .  Five age-matched healthy individuals served as a reference group  . Muscle oxygen uptake and mitochondrial respiration of the vastus lateralis muscle were measured before and after the 6-week training programme . Initial peak work and maximal mitochondrial respiration were reduced in COPD patients and improved significantly after the training programme . Peak power and maximal mitochondrial respiration in vastus lateralis muscle increased to the level of the control subjects and were mainly mediated via improved complex I respiration . Furthermore , when normalised to citrate synthase activity , no difference in maximal respiration was found either after the intervention or compared to controls , suggesting normal functioning mitochondrial complexes . The present study shows that high-intensity training of a restricted muscle group is highly effective in restoring skeletal muscle function in COPD patients The study of the peripheral skeletal muscle function in patients with chronic obstructive pulmonary disease ( COPD ) is of growing interest , but often requires biopsies , usually with the Bergström technique . The current study was design ed to test the validity of a minimally invasive technique : the microbiopsy . In 17 patients with COPD and four normal subjects , two specimens of the vastus lateralis were taken percutaneously under local anaesthesia , one with a 16-gauge needle ( microbiopsy ) and the other with the Bergström needle .  The enzymatic activity of citrate synthase ( CS ) and phosphofructokinase ( PFK ) , and the myosin heavy chain ( MyoHC ) composition were measured for both techniques . The subjects reported no pain or much less with the microbiopsy compared with the Bergström biopsy . The microbiopsy sample weight reached 55±17 mg . The two techniques showed excellent agreement for CS activity and MyoHC composition . The PFK activity did not differ statistically between the techniques , but the agreement was moderate . The agreement between both biopsy techniques was stable over time . The median ( range ) fibre number within the microbiopsy specimens was 144 ( 38–286 ) . In conclusion , the current study shows the feasibility and validity of a minimally invasive muscle biopsy technique that appears more comfortable for subjects , compared with the Bergström technique Summary Methods that objective ly assess the muscle fibre-type arrangement may improve the detection of fibre-type grouping , a diagnostic sign of a denervation and reinnervation process . To distinguish between a diseased and a normal muscle , there is a need for quantitative data on the fibre-type arrangement in healthy human muscles at different ages . In this study , cross-sections were prepared of whole autopsied vastus lateralis muscle  from 24 previously physically healthy men , aged 15 to 83 years . The arrangements of type 1 and type 2 fibres were assessed in terms of the number of enclosed fibres in individual fascicles throughout each muscle . Recent improvements to the enclosed fibre method were used to define measures of r and omness which facilitated the combination of several sample areas and the quantification of the fibre-type arrangements . Segregation was typical for young muscles , r and omness was most common between 30 and 50 years of age , while some fibre-type grouping was considered “ normal ” in old muscles . The arrangements of type 1 and type 2 fibres were quantitatively similar , irrespective of the age of the individual . The results imply that the fibre population changes considerably during a lifetime , and that it undergoes a continuous denervation and reinnervation process with normal ageing . Because of its importance , age should be accommo date d in the analysis of a muscle sample , irrespective of the statistical model and method used
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 .