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 Effects of strength and endurance training on muscle fibre characteristics in elderly women. Skeletal muscle effects of electrostimulation after COPD exacerbation: a pilot study Safety and efficacy of resistance training in germ cell cancer patients undergoing chemotherapy: a randomized controlled trial Contractile fatigue, muscle morphometry, and blood lactate in chronic obstructive pulmonary disease. Exercise training restores uncoupling protein-3 content in limb muscles of patients with chronic obstructive pulmonary disease. Skeletal muscle adaptations to interval training in patients with advanced COPD. Dynamic muscle strength alterations to detraining and retraining in elderly men. High intensity knee extensor training, in patients with chronic heart failure. Major skeletal muscle improvement. Motor Control of the Vastus Medialis Oblique and Vastus Lateralis Muscles is Disrupted during Eccentric Contractions in Subjects with Patellofemoral Pain Knee extension torque and intramuscular pressure of the vastus lateralis muscle during eccentric and concentric activities Localization and quantification of intramuscular damage using statistical parametric mapping and skeletal muscle parcellation Inspiratory muscle training in patients with chronic obstructive pulmonary disease: structural adaptation and physiologic outcomes. Effects of dynamic resistance training on fascicle lengthand isometric strength Effect of resistance exercise on skeletal muscle myopathy in heart transplant recipients. Influence of complete spinal cord injury on skeletal muscle within 6 mo of injury. In vivo human muscle structure and function: adaptations to resistance training in old age.
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 The effects of 18 weeks ' intensive strength and endurance training on fibre characteristics of the vastus lateralis muscle were studied in 76- to 78-year-old women . Type I and type IIa fibres constituted over 90 % of the cell population and were almost equally represented . No changes were observed in the proportions of the different fibre types . When comparing the baseline and the 18-week measurements within the groups , the strength group showed a mean increase of 34 % ( P = 0.028 ) in mean type I fibre area . The frequency histograms showed an increased proportion of larger type I fibres after strength training and a decreased proportion of smaller type IIa fibres after endurance training . In the control subjects , the proportion of smaller type I and type IIa fibres increased during the experimental period . The results indicate that intensive strength training induces type I fibre hypertrophy , whereas the effects of endurance training are less evident . The considerable variation found in the change in muscle fibre cross-sectional areas is also noteworthy 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 : Bleomycin – etoposid – cisplatin ( BEP ) chemotherapy is curative in most patients with disseminated germ cell cancer ( GCC ) but also associated with toxic actions and dysfunction in non-targeted tissues . We investigated changes in muscle function during BEP and the safety and efficacy of resistance training to modulate these changes . Methods : Thirty GCC patients were r and omly assigned to resistance training ( resistance training group ( INT ) , n=15 ) or usual care ( CON , n=15 ) during 9 weeks of BEP therapy . Resistance training consisted of thrice weekly sessions of four exercises , 3–4 sets/exercise of 10–15 repetitions at 12–15 repetition maximum load . The primary endpoint was muscle fibre size , assessed in muscle biopsies from musculus vastus lateralis . Secondary endpoints were fibre phenotype composition , body composition , strength , blood biochemistry and patient-reported endpoints . Healthy age-matched subjects ( REF , n=19 ) performed the same RT-programme for comparison purpose s. Results : Muscle fibre size decreased by −322 μm2 ( 95 % confidence interval ( CI ) : −899 to 255 ; P=0.473 ) in the CON-group and increased by + 206 μm2 ( 95 % CI : −384 to 796 ; P=0.257 ) in the INT-group ( adjusted mean difference ( AMD ) , + 625 μm2 , 95 % CI : −253 to 1503 , P=0.149 ) . Mean differences in type II fibre size ( AMD , + 823 μm2 , P=0.09 ) and lean mass ( AMD , + 1.49 kg , P=0.07 ) in favour of the INT-group approached significance . The REF-group improved all muscular endpoints and had significantly superior changes compared with the INT-group ( P<0.05 ) . Conclusions : BEP was associated with significant reduction in lean mass and strength and trends toward unfavourable changes in muscle fibre size and phenotype composition  . Resistance training was safe and attenuated dysfunction in selected endpoints , but BEP blunted several positive adaptations observed in healthy controls . Thus , our study does not support the general application of resistance training in this setting but larger-scaled trials are required to confirm this finding We hypothesized that patients with chronic obstructive pulmonary disease developing contractile fatigue of the quadriceps during cycle exercise may have characteristic metabolic and muscle features that could increase their susceptibility to fatigue , thus differentiating them from those who do not develop fatigue . We examined , in 32 patients , the fiber-type proportion , enzymatic activities , and capillary density in the vastus lateralis and the arterial blood lactate level during constant work-rate cycling exercise . Contractile fatigue was defined as a postexercise fall in quadriceps twitch force greater than 15 % of resting values . Twenty-two patients developed contractile fatigue after exercise . No significant differences were found between fatiguers and non-fatiguers for the endurance time , fiber-type proportion , and oxidative enzyme activities . The lactate dehydrogenase activity was significantly higher ( p < 0.05 ) and muscle capillarization significantly reduced in fatiguers ( p < 0.05 ) . Compared with non-fatiguers , the arterial lactate level during exercise was significantly higher in fatiguers ( p < 0.001 ) . A significant relationship was found between the fall in quadriceps twitch force and lactate dehydrogenase activity , capillary/fiber ratio , and blood lactate level . We conclude that changes in muscle enzymatic profile and capillarization with a greater reliance on glycolytic metabolism during exercise are associated with contractile fatigue in 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 STUDY OBJECTIVES To investigate the response to interval exercise ( IE ) training by looking at changes in morphologic and biochemical characteristics of the vastus lateralis muscle , and to compare these changes to those incurred after constant-load exercise ( CLE ) training . DESIGN R and omized , controlled , parallel , two-group study ( IE vs CLE training ) . SETTING Multidisciplinary , outpatient , hospital-based , pulmonary rehabilitation program . PATIENTS Nineteen patients with stable advanced COPD ( mean + /- SEM FEV1 , 40 + /- 4 % predicted ) . INTERVENTIONS Patients ( n = 10 ) assigned to IE training exercised at a mean intensity of 124 + /- 15 % of baseline peak exercise capacity ( peak work rate [ Wpeak ] ) with 30-s work periods interspersed with 30-s rest periods for 45 min/d . Patients ( n = 9 ) allocated to CLE training exercised at a mean intensity of 75 + /- 5 % Wpeak for 30 min/d . Patients exercised 3 d/wk for 10 weeks . MEASUREMENTS AND RESULTS Needle biopsies of the right vastus lateralis muscle were performed before and after rehabilitation . After IE training , the cross-sectional areas of type I and IIa fibers were significantly increased ( type I before , 3,972 + /- 455 microm2 ; after , 4,934 + /- 467 microm2 [ p = 0.004 ] ; type IIa before , 3,695 + /- 372 microm2 ; after , 4,486 + /- 346 microm2 [ p = 0.008 ] ) , whereas the capillary-to-fiber ratio was significantly enlarged ( from 1.13 + /- 0.08 to 1.24 + /- 0.07 [ p = 0.013 ] ) . Citrate synthase activity increased ( from 14.3 + /- 1.4 to 20.5 + /- 4.2 micromol/min/g ) , albeit not significantly ( p = 0.097 ) . There was also a significant improvement in Wpeak ( by 19 + /- 5 % ; p = 0.04 ) and in lactate threshold ( by 17 + /- 5 % ; p = 0.02 ) . The magnitude of changes in all the above variables was not significantly different compared to that incurred after CLE training . During training sessions , however , ratings of dyspnea and leg discomfort , expressed as fraction of values achieved at baseline Wpeak , were significantly lower ( p < 0.05 ) for IE training ( 73 + /- 9 % and 60 + /- 8 % , respectively ) compared to CLE training ( 83 + /- 10 % and 87 + /- 13 % , respectively ) . CONCLUSIONS High-intensity IE training is equally effective to moderately intense CLE training in inducing peripheral muscle adaptations ; however , IE is associated with fewer training symptoms To investigate the effects of cessation and subsequent resumption of training on muscle strength in elderly men , 11 men ( aged 65 - 77 years ) , just completing a 24-week r and omized controlled trial of recombinant human growth hormone ( rhGH ) and resistance exercise ( rhGH  , n = 6 ; placebo , n = 5 ) , detrained for 12 weeks and subsequently retrained for 8 weeks . During the detraining and retraining phase , subjects did not receive rhGH . The resistance programme included three sets of eight repetitions at 75 % of one-repetition maximum ( 1-RM ) , three times per week , for 10 upper and lower body exercises .  Dynamic muscle strength was assessed by the 1-RM method every 2 weeks for 44 weeks . Needle biopsies of vastus lateralis muscle were obtained from seven men . Muscle strength increased during initial training by 40.4 + /- 5.5 % ( mean + /- SEM ) , ranging from 26.0 + /- 5.0 to 83.9 + /- 15.6 % , depending on muscle group . Increased strength was accompanied by hypertrophy ( P < 0.05 ) of type I ( 17.4 + /- 4.1 % ) and II ( 25.8 + /- 12.4 % ) muscle fibres . Of initial strength gains , only 29.9 + /- 5.2 % was lost with detraining . However , type I and II fibre cross-sectional area reverted to pretraining values . After 8 weeks of retraining , muscle strength returned to trained values , but without a significant change in fibre morphology . The results indicate that elderly men lose some muscle strength following short-term detraining , but that only a brief period of retraining suffices to regain maximal strength . Reversal of fibre cross-sectional area with detraining , and only modest improvement with retraining , suggests that much of the retention in strength with detraining and reacquisition of lost strength with retraining reflects neural adaptation Skeletal muscle adaptations to high intensity knee extensor strength and /or endurance training in patients with chronic heart failure were investigated . Eleven patients with chronic heart failure were r and omized into two groups and exercised the m. quadriceps femoris 3 days/week for 8 weeks . After training , the maximal exercise intensity tolerated on the ergometer cycle was raised from 99 ( 32 ) to 114 ( 40 ) watts ( W , P < 0.05 ) for all 11 patients . Peak dynamic knee extensor work rate showed the greatest increase after endurance training ( 40 % , P < 0.01 ) . Maximal dynamic and isometric strength were elevated by 40 - 45 % ( P < 0.05 ) after strength training . The cross-sectional area of m. quadriceps femoris was increased in the strength-trained legs ( 9 % , P < 0.05 ) , and the capillary per fibre ratio of m. vastus lateralis was raised by 47 and 58 % in the endurance-trained legs ( P < 0.05 ) . The oxidative enzyme activity in m. vastus lateralis was significantly raised above 50 % after endurance training , whereas glycolytic enzyme activity was unaltered . The peripheral skeletal musculature in patients with chronic heart failure adapts fairly quickly to high intensity knee extensor training . This results in a marked rise in local , and a small rise in total work capacity , indicating maintained plasticity of skeletal muscle in chronic heart failure patients Background Inappropriate control of the vastus medialis oblique and vastus lateralis muscles by the central nervous system can contribute to maltracking of the patella . Hypothesis The activation timing and amplitude of the vastus medialis oblique and vastus lateralis muscles will be different between normal subjects and patients with patellofemoral pain . Study Design Controlled laboratory study . Methods Subjects with patellofemoral pain and asymptomatic control subjects performed maximum voluntary knee extension contractions initiated from a flexed and an extended position . The activation timing and amplitude of the vastus lateralis and vastus medialis oblique muscles were quantified from the recorded electromyographic signals . Results There were no between-group differences in activation timing . The activation amplitude of the vastus medialis oblique and vastus lateralis muscles of the patellofemoral pain subjects was altered to the greatest extent during eccentric contractions and differed significantly from that of control subjects . Conclusions The activation amplitudes of the vastus medialis oblique and vastus lateralis muscles of subjects with patellofemoral pain are consistent with a laterally tracking patella during eccentric contractions . Clinical Relevance The findings suggest the clinical importance of determining whether altered activation patterns are sensitive to rehabilitation , and , if so , if subjective reports of knee joint pain and function parallel changes in the activation patterns as a result of rehabilitation The objectives of this study were to determine whether the occurrence of  delayed onset muscle soreness ( DOMS )  for the vastus lateralis muscle was associated with elevated intramuscular pressure ( IMP ) ; and to assess , whether high eccentric forces occurred at an increased muscle length ( as determined by joint angle ) . Therefore , peak knee extension torque , peak IMP of the vastus lateralis muscle , and the joint angle at which  peak torque ( JAPT ) occurred were determined in eight male subjects during repetitive eccentric and concentric activities until fatigue occurred . Peak torque was significantly higher for eccentric compared to concentric activity ( P < 0.01 ) and declined significantly for both activities ( P < 0.01 ) throughout the protocol s. When comparing the start ( prior to fatigue ) to the end ( fatigue state ) , mean torque for eccentric activity declined from 191 to 147 ( N · m ) and for concentric activity declined from 166 to 104 ( N · m ) . In contrast , peak IMP was not significantly different between the types of activity and did not change significantly with time . At the start and the end , the mean IMP remained constant for eccentric activity at 54 mmHg ( 7.2 kPa ) but for concentric activity was 78 mmHg ( 10.4 kPa ) and 96 mmHg ( 12.8 kPa ) , respectively . All the subjects , however , experienced DOMS of the vastus lateralis muscle exclusively for the eccentric activity leg . The JAPT was not different between activity types and did not change significantly with time ; however , a significant interaction between activity type and time was observed ( P = 0.01 ) . For eccentric activity JAPT ( 0 ° = fully extended leg ) was 81 ° ( 1.38 rad ) and 79 ° ( 1.34 rad ) and for concentric activity was 76 ° ( 1.29 rad ) and 83 ° ( 1.41 rad ) at the start and the end , respectively . From our studies we concluded that during eccentric activity the magnitude of IMP for the vastus lateralis muscle did not reflect the high muscles forces ; therefore it would appear that IMP was not an etiologic indicator of DOMS , and that JAPT measurements did not offer an explanation for the high forces which were associated with eccentric activity In the present study , we proposed an original and robust methodology which combines the spatial normalization of skeletal muscle images , the statistical parametric mapping ( SPM ) analysis and the use of a specific parcellation in order to accurately localize and quantify the extent of skeletal muscle damage within the four heads of the quadriceps femoris . T2 maps of thigh muscles were characterized before , two ( D2 ) and four ( D4 ) days after 40 maximal isometric electrically-evoked contractions in 25 healthy young males . On the basis of SPM analysis of coregistrated T2 maps , the alterations were similarly detected at D2 and D4 in the superficial and distal regions of the vastus medialis ( VM ) whereas the proportion of altered muscle was higher in deep muscle regions of the vastus lateralis at D4 ( deep : 35 ± 25 % , superficial : 23 ± 15 % ) as compared to D2 ( deep : 18 ± 13 % , superficial : 17 ± 13 % ) . The present methodology used for the first time on skeletal muscle would be of utmost interest to detect subtle intramuscular alterations not only for the diagnosis of muscular diseases but also for assessing the efficacy of potential therapeutic interventions and clinical treatment strategies 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 Abstract The aims of this study were to assess changes in muscle architecture , isometric and dynamic strength of the leg extensor muscles , result ing from dynamic resistance training , and the relationships between strength and muscle architecture variables . The participants ( n = 30 ) were r and omly assigned to one of two groups . The training group ( n = 16 ; age 21.8 ± 2.3 years , body mass 74.8 ± 9.2 kg , height 1.75 ± 0.08 m ) performed dynamic resistance training for 13 weeks . The control group ( n = 14 ; age 19.9 ± 1.5 years , body mass 74.0 ± 8.5 kg , height 1.76 ± 0.05 m )  did not perform any resistance training .  Maximal dynamic and isometric strength were tested in both groups , before and after the training period . The members of the training group used the free-weight squat lift ( 90 ° ) as their training exercise . The concentric phase of the squat was performed explosively . Skeletal muscle architecture of the vastus lateralis was visualized using ultrasonography . At the end of the study , significant increases in vastus lateralis muscle thickness ( + 6.9 % , P < 0.001 ) , fascicle length ( + 10.3 % , P < 0.05 ) , one-repetition maximum ( + 8.2 % , P < 0.05 ) , rate of force development ( + 23.8 % , P < 0.05 ) and average force produced in the first 500 ms ( + 11.7 % , P < 0.05 ) were seen only in the training group . Adaptations to the muscle architecture in the training group limited the loss of fibre force , and improved the capacity for developing higher velocities of contraction . The architectural changes in the training group were similar to those seen in studies where high-speed training was performed . In conclusion , dynamic resistance training with light loads leads to increases in muscle thickness and fascicle length , which might be related to a more efficient transmission of fibre force to the tendon The purpose of this study was to determine the efficacy of resistance exercise in reversing skeletal muscle myopathy in heart transplant recipients . Myopathy , engendered by both heart failure and immunosuppression with glucocorticoids , is a post-transplant complication . The sequelae of myopathic disease includes fiber-type shifts and deficits in aerobic metabolic capability . We r and omly assigned patients to either 6 months of  resistance exercise ( training group ; n = 8) or a control ( control group ;  n = 7 ) group . Exercise was initiated at 2 months after transplant . Biopsy of the right vastus lateralis was performed before and after the 6-month intervention . Myosin heavy chain ( MHC ) composition was assessed using sodium dodecyl sulfate-polyacrylamide gel electrophoresis . Biochemical assays were performed to determine citrate synthase , 3-hydroxyacyl-CoA-dehydrogenase , and lactate dehydrogenase activity . There were no group differences ( p > or=0.05 ) in MHC composition and enzymatic reserve at baseline . Improvements in the training group for citrate cynthase ( + 40 % ) , 3-hydroxyacyl-CoA-dehydrogenase ( + 10 % ) , and lactate dehydrogenase activity ( + 48 % ) were significantly greater ( p < or=0.05 ) than in the control group ( + 10 % , -15 % , and + 20 % , respectively ) . Oxidative type 1 MHC isoform concentration increased significantly in the training group ( + 73 % , p < or=0.05 ) but decreased in the control group ( -28 % ; p < or=0.05 ) . Glycolytic type 2x MHC isoform increased significantly ( 17 % ; p < or=0.05 ) in the control group but decreased ( -33 % ; p < or=0.05 ) in the training group . This is the first study to demonstrate that resistance training elicits myofibrillar shifts from less oxidative type II fibers to more oxidative fatigue-resistant type I fibers in heart transplant recipients .  Resistance exercise initiated early in the post-transplant period is efficacious in changing skeletal muscle phenotype through increases in enzymatic reserve and shifts in fiber morphology This study examined the influence of  spinal cord injury ( SCI )  on affected skeletal muscle . The right vastus lateralis muscle was biopsied in 12 patients as soon as they were clinical ly stable ( average 6 wk after SCI ) , and 11 and 24 wk after injury . Sample s were also taken from nine able-bodied controls at two time points 18 wk apart . Surface electrical stimulation ( ES ) was applied to the left quadriceps femoris muscle to assess fatigue at these same time intervals . Biopsies were analyzed for fiber type percent and cross-sectional area ( CSA ) , fiber type-specific succinic dehydrogenase ( SDH ) and alpha-glycerophosphate dehydrogenase ( GPDH ) activities , and myosin heavy chain percent . Controls showed no change in any variable over time . Patients showed 27 - 56 % atrophy ( P = 0.000 ) of type I , IIa , and IIax+IIx fibers from 6 to 24 wk after injury , result ing in fiber CSA approximately one-third that of controls . Their fiber type specific SDH and GPDH activities increased ( P < /= 0.001 ) from 32 to 90 % over the 18 wk , thereby approaching or surpassing control values . The relative CSA of type I fibers and percentage of myosin heavy chain type I did not change . There was apparent conversion among type II fiber subtypes ; type IIa decreased and type IIax+IIx increased ( P < /= 0.012 ) . Force loss during ES did not change over time for either group but was greater ( P = 0.000 ) for SCI patients than for controls overall ( 27 vs. 9 % ) . The results indicate that vastus lateralis muscle shows marked fiber atrophy , no change in the proportion of type I fibers , and a relative independence of metabolic enzyme levels from activation during the first 24 wk after clinical ly complete SCI . Over this time , quadriceps femoris muscle showed moderately greater force loss during ES in patients than in controls . It is suggested that the predominant response of mixed human skeletal muscle within 6 mo of SCI is loss of contractile protein . Therapeutic interventions could take advantage of this to increase muscle mass This study investigated changes in elderly muscle joint angle-torque relation  induced by  resistance training . Older adults were assigned to either training ( n = 9 , age 74.3 + /- 3.5 years ; mean + /-s.d . ) or to control groups ( n = 9 , age 67.1 + /- 2 years ) .  Leg-extension and leg-press exercises were performed three times per week for 14 weeks . Maximal isometric knee extension torque was measured across the knee joint angle range of movement . Vastus lateralis muscle architecture was examined in vivo using ultrasonography . The vastus lateralis muscle fascicle force was estimated from the measured joint torque , enabling construction of the fascicle length-force relation . Electromyographic ( EMG ) activity was measured from representative agonist and antagonist muscles . Training altered the angle-torque relation : ( a ) displacing it by 9 - 31 % towards higher torque values ( P < 0.05 ) ; and ( b ) shifting the optimal angle from 70 deg ( corresponding torque : 121.4 + /- 61 N m ) before to 60 deg ( 134.2 + /- 57.2 N m ; P < 0.05 ) after training . Training also altered the fascicle length-force relation : ( a ) displacing it by 11 - 35 % towards higher force values ; and ( b ) shifting the optimal fascicle length from 83.7 + /- 8 mm ( corresponding force : 847.9 + /- 365.3 N ) before to 93.2 + /- 12.5 mm ( 939.3 + /- 347.8 N ; P < 0.01 ) after training . The upward displacement of the angle-torque relation was mainly due to a training-induced increase in agonist activation , whilst the shift in the optimal angle was associated with changes in muscle-tendon properties
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 .