Fibre types in skeletal muscles of chronic obstructive pulmonary disease patients related to respiratory function and exercise tolerance. Skeletal muscle structure and function in response to electrical stimulation in moderately impaired COPD patients. Skeletal muscle effects of electrostimulation after COPD exacerbation: a pilot study Improved skeletal muscle performance after individualized exercise training in patients with chronic obstructive pulmonary disease. Inspiratory muscle training in patients with chronic obstructive pulmonary disease: structural adaptation and physiologic outcomes. Nutritional depletion in relation to respiratory and peripheral skeletal muscle function in out-patients with COPD. Skeletal muscle strength and endurance in patients with mild COPD and the effects of weight training. Skeletal muscle microbiopsy: a validation study of a minimally invasive technique Neuromuscular electrical stimulation prevents muscle function deterioration in exacerbated COPD: a pilot study. Inspiratory muscle dysfunction and chronic hypercapnia in chronic obstructive pulmonary disease. Disease Progression and Changes in Physical Activity in Patients with Chronic Obstructive Pulmonary Disease. Impact of preinduced quadriceps fatigue on exercise response in chronic obstructive pulmonary disease and healthy subjects. Control of breathing in patients with chronic pulmonary obstructive disease: response to bamiphylline. Evaluation of the Effects of Neuromuscular Electrical Stimulation of The Lower Limbs Combined with Pulmonary Rehabilitation on Exercise Tolerance in Patients with Chronic Obstructive Pulmonary Disease Resistance training prevents deterioration in quadriceps muscle function during acute exacerbations of chronic obstructive pulmonary disease. Polyunsaturated fatty acids improve exercise capacity in chronic obstructive pulmonary disease. Limb muscle dysfunction in COPD: effects of muscle wasting and exercise training.
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 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 Muscle dysfunction is a major problem in chronic obstructive pulmonary disease ( COPD ) , particularly after exacerbations . We thus asked whether neuromuscular electrostimulation ( NMES ) might be directly useful following an acute exacerbation and if such a therapy decreases muscular oxidative stress and /or alters muscle fibre distribution . A pilot r and omised controlled study of NMES lasting 6 weeks was carried out in 15 in- patients ( n=9 NMES ; n=6 sham ) following a COPD exacerbation . Stimulation was delivered to the quadriceps and hamstring muscles ( 35 Hz ) . Primary outcomes were quadriceps force and muscle oxidative stress . At the end of the study , quadriceps force improvement was statistically different between groups ( p=0.02 ) , with a significant increase only in the NMES group ( median ( interquartile range ) 10 ( 4.7–11.5 ) kg ; p=0.01 ) . Changes in the 6-min walking distance were statistically different between groups ( p=0.008 ) , with a significant increase in the NMES group ( 165 ( 125–203 ) m ; p=0.003 ) . NMES did not lead to higher muscle oxidative stress , as indicated by the decrease in total protein carbonylation ( p=0.02 ) and myosin heavy chain carbonylation ( p=0.01 ) levels . Finally , we observed a significant increase in type I fibre proportion in the NMES group . Our study shows that following COPD exacerbation , NMES is effective in counteracting muscle dysfunction and decreases muscle oxidative stress BACKGROUND In addition to the respiratory limitation in patients with chronic obstructive pulmonary disease ( COPD ) , skeletal muscle abnormalities may occur and contribute to the exercise intolerance . This study assessed the ability of the skeletal muscle of patients with COPD to adapt to individualized exercise training at the gas exchange threshold ( GET ) METHODS : Fourteen patients ( 8 in a training group and 6 controls ) performed the following exercise tests before and after a 3-week training period : an incremental exercise test , maximal voluntary contraction of the quadriceps , and three endurance tests consisting of dynamic contractions of the quadriceps until exhaustion . These endurance tests , characterized by three different power outputs , were used to determine muscle limit times and critical power . RESULTS The results showed that training increased exercise tolerance ( + 11 % for symptom limited peak oxygen consumption ( VO2 sl ] , P < 0.05 ) , maximum voluntary contraction ( + 8 % , P < 0.05 ) , limit times ( from + 45 % to + 161 % , P < 0.05 ) and critical power ( + 39 % , P < 0.05 ) . CONCLUSIONS These findings indicate greater muscle strength and endurance after training in COPD patients and suggest better muscular recruitment and improved oxidative capacity in the exercising muscles . The sharp differences in the magnitude of VO2 sl and limit times suggest that the kinetics of peripheral and central changes in response to training are different . In conclusion , peripheral muscle performance can be increased rapidly in response to an individualized training program at the GET in COPD patients The present study was aim ed at evaluating the effects of a specific inspiratory muscle training protocol on the structure of inspiratory muscles in patients with chronic obstructive pulmonary disease . Fourteen patients ( males , FEV1 , 24 + /- 7 % predicted ) were r and omized to either inspiratory muscle or sham training groups . Supervised breathing using a threshold inspiratory device was performed 30 minutes per day , five times a week , for 5 consecutive weeks . The inspiratory training group was subjected to inspiratory loading equivalent to 40 to 50 % of their maximal inspiratory pressure . Biopsies from external intercostal muscles and vastus lateralis ( control muscle ) were taken before and after the training period . Muscle sample s were processed for morphometric analyses using monoclonal antibodies against myosin heavy chain isoforms I and II . Increases in both the strength and endurance of the inspiratory muscles were observed in the inspiratory training group . This improvement was associated with increases in the proportion of type I fibers ( by approximately 38 % , p < 0.05 ) and in the size of type II fibers ( by approximately 21 % , p < 0.05 ) in the external intercostal muscles . No changes were observed in the control muscle . The study demonstrates that inspiratory training induces a specific functional improvement of the inspiratory muscles and adaptive changes in the structure of external intercostal muscles Although increasing attention has been paid to nutritional aspects in chronic obstructive pulmonary disease ( COPD ) , limited information is available regarding the prevalence and consequences of nutritional depletion in a r and om out-patient COPD population . We studied body composition in relation to respiratory and peripheral skeletal muscle function in 72 COPD patients ( mean ( SD ) forced expiratory volume in one second ( FEV1 ) 53 ( 15 ) % predicted ) , who came to the lung function laboratory for routine lung function measurements . Patients were characterized by the degree of body weight loss and fat-free mass depletion . According to this definition , 14 % of the group suffered from both loss of body weight and depletion of fat-free mass , whereas 7 % had one of these conditions . We found that tissue depletion was concomitant with lower values for respiratory and peripheral skeletal muscle strength ( 46.0 ( 27.2 ) vs 77.1 ( 29.8 ) kg ) , and a significantly lower transfer coefficient for carbon monoxide ( KCO 64.9 ( 16.2 ) vs 81.9 ( 24.5 ) % pred ) . Stratification by KCO ( < 60 % vs > 80 % ) also revealed significantly lower values for fat-free mass and higher values for intrathoracic gas volumes , total lung capacity ( TLC ) and residual volume ( RV ) in the group with a KCO < 60 % pred . Analysis of covariance , taking fat-free mass as covariate , indicated an independent contribution of KCO on maximal inspiratory mouth pressure ( PImax ) but not on peripheral skeletal muscle strength . It is concluded that a substantial number of COPD out- patients suffer from nutritional depletion , preferentially affecting peripheral skeletal muscle function This study poses two questions : 1 ) is there an abnormality in isokinetic skeletal muscle strength and endurance in mild chronic obstructive pulmonary disease ( COPD ) ? and 2 ) what is the effect of a r and omized , controlled , 12 week hospital outpatient weight training programme in terms of skeletal muscle function and exercise tolerance ? Upper and lower limb isokinetic maximum and sustained muscle function were compared in 43 COPD patients ( age 49+/-11 yrs ) , mean forced expiratory volume in one second ( FEV1 ) 77+/-23 % pred and 52 healthy , sedentary subjects ( age 51 ( 10 ) yrs ) , mean FEV1 109+/-16 % pred . The 43 COPD patients were r and omly allocated into training ( n=26 ) and control ( n=17 ) groups . Isokinetic and isotonic muscle function , whole body endurance , maximal exercise capacity and lung function were measured . The COPD patients had reduced isokinetic muscle function ( with the exception of sustained upper limb strength ) as compared with healthy sedentary subjects . Muscle function improved after weight training in the COPD patients . Whole body endurance during treadmill walking also improved with no change in maximal oxygen consumption . A deficit in skeletal muscle function can be identified in patients with mild chronic obstructive pulmonary disease which can not be explained by factors such as hypoxaemia and malnutrition . Intervention with weight training is effective in countering this deficit which the authors conclude is probably due to muscle deconditioning 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 PURPOSE COPD is a condition with systemic effects of which peripheral muscle dysfunction is a prominent contributor to exercise limitation , health related quality of life ( HRQoL ) impairment , and is an independent predictor of morbidity and mortality . Pulmonary rehabilitation ( PR ) is a successful strategy to improve exercise tolerance and HRQoL through the improvement of muscle function in patients with stable COPD or early after severe exacerbations of COPD ( SE COPD ) . However , muscle function further deteriorates during SE COPD before early PR programmes commence . We aim ed to investigate the feasibility and efficacy of quadriceps neuromuscular electrical stimulation ( NMES ) applied during a SE COPD to prevent muscle function deterioration . METHODS We have conducted a pilot study in eleven COPD patients ( FEV(1 ) 41.3 ± 5.6 % pred ) admitted to hospital with a SE COPD . We r and omly allocated one leg to receive NMES ( once a day for 14 days ) with the other leg as a control ( non-stimulated leg ) . We measured the change in quadriceps maximal voluntary contraction ( ΔQMVC ) as the main outcome . RESULTS Mean quadriceps muscle strength decreased in control legs ( ΔQMVC -2.9 ± 5.3 N , p = ns ) but increased in the stimulated legs ( ΔQMVC 19.2 ± 6.1 N , p < 0.01 ) . The difference in ΔQMVC between groups was statistically significant ( p < 0.05 ) . The effect of NMES was directly related to the stimulation intensity ( ∑mA ) applied throughout the 14 sessions ( r = 0.76 , p < 0.01 ) . All patients tolerated NMES without any side effects . CONCLUSIONS NMES is a feasible and effective treatment to prevent quadriceps muscle strength derangement during severe exacerbations of COPD and may be used to compliment early post-exacerbation pulmonary rehabilitation A prospect i ve evaluation of the prevalence of CO2 retention and its relationship to lung mechanics and inspiratory muscle strength was carried out in 311 clinical ly stable patients with chronic obstructive pulmonary disease ( COPD ) . Of these patients 32.8 % had hypercapnia ( PaCO2 greater than or equal to 43 mm Hg ) . PaCO2 was directly related to lung resistance ( RL ; r = 0.53 ) and inversely related to FEV1 ( r = 0.53 ) and to an expression of the dead space/tidal volume ratio ( 1 - VD/VT ) ( r = 0.48 ) . RL was found to be a major determinant of the mean intrathoracic pressure swing developed during inspiration ( PI ) at rest ( r = 0.85 ) . Maximal inspiratory pressure ( PImax ) was found to improve the predictive value for PaCO2 of several mechanical loads , with RL/PImax the best predictor ( r = 0.57 ) . The prevalence of hypercapnia increased from virtually 0 to 100 % with increases in the RL/PImax value and was higher in the obese subjects at intermediate RL/PImax values , probably because of the burden placed on the respiratory muscles by chest wall mass loading . Our results show that chronic alveolar hypoventilation is likely to develop in COPD patients who have a combination of high inspiratory loads and inspiratory muscle weakness . hypercapnia may be one strategy available to avoid overloading of the inspiratory muscles leading to fatigue and possible irreversible failure RATIONALE Little is known about the role of physical activity in the course of chronic obstructive pulmonary disease ( COPD ) . OBJECTIVES To assess changes in physical activity in COPD in relation to severity stages and changes in other disease components , and to evaluate the longitudinal association between sustained physical inactivity and disease progression . METHODS In this prospect i ve cohort study , we measured  physical activity ( multisensory armb and ) , airflow obstruction ( FEV1 ) , health status ( St. George 's Respiratory Question naire ) , exercise capacity ( 6-min-walk distance [ 6MWD ] ) , muscle mass ( fat-free mass [ FFM ] ) , and systemic inflammation ( fibrinogen and high-sensitivity C-reactive protein ) over a 3-year period in 137 patients with COPD and 26 with chronic bronchitis ( normal spirometry ) . MEASUREMENTS AND MAIN RESULTS Independent of baseline disease severity , steps per day , total daily energy expenditure , and ( daily ) physical activity level ( PAL ) decreased by 393 , 76 kcal , and 0.04 per year , respectively . The decline in PAL was significantly associated with a decline in FEV1 and an increase in St. George 's Respiratory Question naire total score . Changes in 6MWD , FFM , and inflammatory markers were not associated with changes in PAL . Independent of FEV1 , sustained physical inactivity ( i.e. , PAL(T0 and T1 ) < 1.40 ) was related to a greater decline in 6MWD and FFM compared with that in patients with some level of activity ( i.e. , PAL(T0 and /orT1 ) ≥ 1.40 ; difference , 17 m/yr and 0.87 kg/yr , respectively ) . CONCLUSIONS Over time , physical activity  substantially decreases across all severity stages of COPD , and this decline is paralleled by a worsening of lung function and health status . Sustained physical inactivity is associated with a progression of exercise intolerance and muscle depletion Exercise intolerance in chronic obstructive pulmonary disease ( COPD ) results from a complex interaction between central ( ventilatory ) and peripheral ( limb muscles ) components of exercise limitation . The purpose of this study was to evaluate the influence of quadriceps muscle fatigue on exercise tolerance and ventilatory response during constant-workrate cycling exercise testing ( CWT ) in patients with COPD and healthy subjects . Fifteen patients with COPD and nine age-matched healthy subjects performed , 7 days apart , two CWTs up to exhaustion at 80 % of their predetermined maximal work capacity . In a r and omized order , one test was performed with preinduced quadriceps fatigue and the other in a fresh state . Quadriceps fatigue was produced by electrostimulation-induced contractions and quantified by maximal voluntary contraction and potentiated twitch force ( TwQ(pot ) ) . Endurance time and ventilatory response during CWT were compared between fatigued and fresh state . Endurance time significantly decreased in the fatigued state compared with the fresh condition in COPD ( 356 + /- 69 s vs. 294 + /- 45 s , P < 0.05 ) and controls ( 450 + /- 74 s vs. 340 + /- 45 s , P < 0.05 ) . Controls showed significantly higher ventilation and end-exercise dyspnea scores in the fatigued condition , whereas , in COPD , fatigue did not influence ventilation or dyspnea during exercise . The degree of ventilatory limitation , as expressed by the Ve/maximum voluntary ventilation ratio , was similar in both conditions in patients with COPD . We conclude that it is possible to induce quadriceps fatigue by local electrostimulation-induced contractions . Our findings demonstrate that peripheral muscle fatigue is an additional important factor , besides intense dyspnea , that limits exercise tolerance in COPD In two groups ( A and B ) of patients with severe chronic obstructive pulmonary disease ( COPD ) , matched for age and routine pulmonary function testing , we evaluated inspiratory muscle strength ( MIP ) , breathing pattern , mouth occlusion pressure ( P0.1 ) , inspiratory neural drive , assessed in terms of electromyographic activity of both diaphragm ( EMGd ) and intercostal ( EMGint ) muscles , and P0.1/EMGd ratio , an index of inspiratory neuromuscular coupling . Group A ( 8 patients ) was studied before and after a 7-day period of a new oral xanthine derivative ( bamiphylline , 1.2 g daily ) , and group B ( 7 patients ) was given a placebo . Under control conditions , compared with an age-matched normal control group , groups A and B both exhibited a decrease in MIP , more rapid ( increase in respiratory frequency RF ) and shallower ( decrease in tidal volume ; VT ) breathing ( RSB ) , a marked increase in both EMGd and EMGint and a lower P0.1/EMGd ratio . With bamiphylline  FEV1 and PaO2 significantly increased , while a substantial increase in MIP was found in 5 out of the 8 patients . VT and inspiratory time ( Ti ) also significantly increased , and RF decreased . Both EMGd and EMGint significantly decreased , whereas P0.1/EMGd exhibited a substantial increase in 5 out of the 8 patients . Conversely , no significant changes were observed in group B during the study period . From these data we conclude that in patients with COPD , clinical manifestations , probably associated with inspiratory muscle overloading ( decrease in muscle strength , RSB , increase in respiratory neural drive , and derangement in neuromuscular coupling ) may benefit from a short-term treatment with bamiphylline Abstract Chronic obstructive pulmonary disease ( COPD ) is a systemic disease with multiple extrapulmonary manifestations including impeded skeletal muscle function , leading to decreased muscular strength and endurance in patients with COPD . Pulmonary rehabilitation eases the symptoms of the condition and produces increased muscular endurance . Neuromuscular electrical stimulation ( NMES ) may serve as a treatment alternative to traditional pulmonary rehabilitation . The aim of the study was to assess the effects of NMES combined with pulmonary rehabilitation on exercise tolerance in patients in comparison with pulmonary rehabilitation alone . The subjects included 30 patients with COPD r and omly assigned to one of the two groups . The first group consisted of 15 patients who were treated with neuromuscular electrical stimulation at frequency of 35Hz and pulmonary rehabilitation ( NMES+RP ) . The second group comprised 15 patients treated with pulmonary rehabilitation only ( RP ) . Pre- and post study assessment s were performed . The retrospective evaluation including an exercise tolerance test ( i.e. six minute walk test ( 6MWT ) ) , spirometry and blood gasometry was carried out after 3 weeks . Twenty-eight patients in total completed the study . In the NMES+RP group , an increase in exercise tolerance manifested by a longer distance walked in the 6MWT was observed in comparison to the pulmonary rehabilitation group . No effects of NMES combined with pulmonary rehabilitation on selected spirometric and gasometric parameters in patients with COPD were observed in comparison with traditional pulmonary rehabilitation . The acquired results suggest that NMES of the lower limbs may be applied as an additional form of pulmonary rehabilitation in patients with COPD RATIONALE Exacerbations of chronic obstructive pulmonary disease ( COPD ) acutely reduce skeletal muscle strength and result in long-term loss of functional capacity . OBJECTIVES To investigate whether resistance training is feasible and safe and can prevent deteriorating muscle function during exacerbations of COPD . METHODS Forty patients ( FEV(1 ) 49 + /- 17 % predicted ) hospitalized with a severe COPD exacerbation were r and omized to receive usual care or an additional resistance training program during the hospital admission . Patients were followed up for 1 month after discharge . Primary outcomes were quadriceps force and systemic inflammation . A muscle biopsy was taken in a subgroup of patients to assess anabolic and catabolic pathways . MEASUREMENTS AND MAIN RESULTS Resistance training did not yield higher systemic inflammation as indicated by C-reactive protein levels and could be completed uneventfully . Enhanced quadriceps force was seen at discharge ( + 9.7 + /- 16 % in the training group ; -1 + /- 13 % in control subjects ; P = 0.05 ) and at 1 month follow-up in the patients who trained . The 6-minute walking distance improved after discharge only in the group who received resistance training ( median 34 ; interquartile range , 14 - 61 m ; P = 0.002 ) . In a subgroup of patients a muscle biopsy showed a more anabolic status of skeletal muscle in patients who followed training . Myostatin was lower ( P = 0.03 ) and the myogenin/MyoD ratio tended to be higher ( P = 0.08 ) in the training group compared with control subjects . CONCLUSIONS Resistance training is safe , successfully counteracts skeletal muscle dysfunction during acute exacerbations of COPD , and may up-regulate the anabolic milieu in the skeletal muscle . Clinical trial registered with www . clinical trials.gov ( NCT00877084 ) BACKGROUND Muscle wasting and decreased muscle oxidative capacity commonly occur in patients with chronic obstructive pulmonary disease ( COPD ) .  Polyunsaturated fatty acids ( PUFA ) have been shown to mediate several inflammatory and metabolic pathways which may be involved in the pathogenesis of muscle impairment in COPD . The aim of this study was to investigate the effect of PUFA modulation on systemic inflammation , reversal of muscle wasting , and functional status in COPD . METHODS Eighty patients with COPD ( 57 men ) with forced expiratory volume in 1 second ( FEV1 ) 37.3 (13.8)% predicted received 9 g PUFA or placebo daily in a double blind r and omised fashion during an 8 week rehabilitation programme . Body composition ( bioelectrical impedance ) , functional capacity ( lung function , incremental cycle ergometry test , submaximal cycle test , isokinetic quadriceps strength ) and inflammatory markers ( C-reactive protein ( CRP ) , interleukin (IL)-6 and tumour necrosis factor (TNF)-alpha ) were assessed at baseline and after 8 weeks . RESULTS Both groups had similar increases in weight , fat-free mass ( FFM ) , and muscle strength . The peak load of the incremental exercise test increased more in the PUFA group than in the placebo group ( difference in increase 9.7 W ( 95 % CI 2.5 to 17.0 ) , p = 0.009 ) even after adjustment for FFM . The duration of the constant work rate test also increased more in patients receiving PUFA ( difference in increase 4.3 min ( 95 % CI 0.6 to 7.9 ) , p = 0.023 ) . The positive effects of PUFA could not be attributed to a decrease in systemic levels of CRP , IL-6 and TNF-alpha . CONCLUSIONS This is the first study to show beneficial effects of PUFA on exercise capacity in patients with COPD PURPOSE Lower-limb muscle weakness has often been reported in COPD , and contributes to exercise intolerance . Controversial information is available regarding upper-limb muscle adaptations and the influence of muscle wasting on muscle weakness . We investigated leg and arm muscle function in 59 stable COPD patients ( GOLD stage III ) with preserved fat-free mass ( FFM ) and in 28 patients with reduced FFM relative to age- and sex-matched healthy control subjects and studied the effects of 8 wk of whole-body exercise training . METHODS FFM was measured with bioelectrical impedance analysis .  Isokinetic quadriceps ( F-leg ) and biceps strength ( F-arm ) , as well as quadriceps ( E-leg ) and biceps endurance ( E-arm ) were determined with a Biodex dynamometer . Exercise training consisted of cycle ergometry , treadmill walking , weight training , and gymnastics during 5 d.wk . RESULTS F-leg ( 76.2 + /- 3.6 vs 118.2 + /- 6.3 N.m , P < 0.001 ) and F-arm ( 25.6 + /- 1.3 vs 38.1 + /- 2.1 N.m , P < 0.001 ) were significantly and similarly reduced in the COPD patient group compared with controls . Also , E-leg ( -2.13 + /- 0.12 vs -1.61 + /- 0.11 , P < 0.01 ) , but not E-arm ( -2.72 + /- 0.11 and -2.47 + /- 0.13 NS ) , was decreased in patients . F-leg ( 62.4 + /- 4.3 vs 82.8 + /- 4.7 N.m , P < 0.01 ) , but not F-arm or muscle endurance , was reduced in FFM-depleted compared with non-FFM-depleted patients . Whereas after training F-leg and E-leg significantly increased by 20 % in the whole COPD group , biceps muscle function remained unchanged . CONCLUSION Lower- and upper-limb muscle dysfunction was observed in COPD patients , irrespective of the presence of FFM depletion . Generalized muscle weakness suggests systemic muscular involvement , although the preserved arm endurance and the poor response of arm performance to exercise training is indicative for intrinsic differences in muscular adaptations between leg and arm 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 .