Influence of complete spinal cord injury on skeletal muscle within 6 mo of injury. Impact of Very Early Physical Therapy During Septic Shock on Skeletal Muscle: A Randomized Controlled Trial Neuromuscular electrical stimulation attenuates thigh skeletal muscles atrophy but not trunk muscles after spinal cord injury. Neuromuscular electrical stimulation prevents muscle wasting in critically ill comatose patients. Vastus Medialis Obliquus Atrophy Effects of systemic hypoxia on human muscular adaptations to resistance exercise training Single muscle fiber adaptations to resistance training in old (>80 yr) men: evidence for limited skeletal muscle plasticity. The effects of three different training modalities on the cross-sectional area of the paravertebral muscles. Protein Supplementation Does Not Further Increase Latissimus Dorsi Muscle Fiber Hypertrophy after Eight Weeks of Resistance Training in Novice Subjects, but Partially Counteracts the Fast-to-Slow Muscle Fiber Transition Resistance Training Alters Cytokine Gene Expression in Skeletal Muscle of Adults with Type 2 Diabetes Muscle fiber hypertrophy, hyperplasia, and capillary density in college men after resistance training. Throwing performance after resistance training and detraining Effects of supplement timing and resistance exercise on skeletal muscle hypertrophy. Effects of strength training on muscle cellular outcomes in prostate cancer patients on androgen deprivation therapy. Acute skeletal muscle wasting in critical illness. Hip, thigh and calf muscle atrophy and bone loss after 5-week bedrest inactivity Skeletal muscle structure and function in response to electrical stimulation in moderately impaired COPD patients. PREVENTION OF DISUSE MUSCLE ATROPHY BY MEANS OF ELECTRICAL STIMULATION: MAINTENANCE OF PROTEIN SYNTHESIS Changes in the Cross-Sectional Area of Multifidus and Psoas in Patients With Unilateral Back Pain: The Relationship to Pain and Disability The effects of exercise training on muscle atrophy in haemodialysis patients. Applications of vascular occlusion diminish disuse atrophy of knee extensor muscles. A creatine-protein-carbohydrate supplement enhances responses to resistance training. Supplementation of L-Alanyl-L-Glutamine and Fish Oil Improves Body Composition and Quality of Life in Patients With Chronic Heart Failure
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 Objectives : As the catabolic state induced by septic shock together with the physical inactivity of patients lead to the rapid loss of muscle mass and impaired function , the purpose of this study was to test whether an early physical therapy during the onset of septic shock regulates catabolic signals and preserves skeletal muscle mass . Design : R and omized controlled trial . Setting : Tertiary mixed ICU . Patients : Adult patients admitted for septic shock within the first 72 hours . Interventions : Patients were assigned r and omly into two groups . The control group benefited from manual mobilization once a day . The intervention group had twice daily sessions of both manual mobilization and 30-minute passive/active cycling therapy . Measurements and Main Results : Skeletal muscle biopsies and electrophysiology testing were performed at day 1 and day 7 . Muscle biopsies were analyzed for histology and molecular components of signaling pathways regulating protein synthesis and degradation as well as inflammation markers . Hemodynamic values and patient perception were collected during each session . Twenty-one patients were included . Three died before the second muscle biopsy . Ten patients in the control and eight in the intervention group were analyzed . Markers of the catabolic ubiquitin-proteasome pathway , muscle atrophy F-box and muscle ring finger-1 messenger RNA , were reduced at day 7 only in the intervention group , but without difference between groups ( muscle atrophy F-box : –7.3 % ± 138.4 % in control vs –56.4 % ± 37.4 % in intervention group ; p = 0.23 and muscle ring finger-1 : –30.8 % ± 66.9 % in control vs –62.7 % ± 45.5 % in intervention group ; p = 0.15 ) . Muscle fiber cross-sectional area ( µm2 ) was preserved by exercise ( –25.8 % ± 21.6 % in control vs 12.4 % ± 22.5 % in intervention group ; p = 0.005 ) . Molecular regulations suggest that the excessive activation of autophagy due to septic shock was lower in the intervention group , without being suppressed . Markers of anabolism and inflammation were not modified by the intervention , which was well tolerated by the patients . Conclusions : Early physical therapy during the first week of septic shock is safe and preserves muscle fiber cross-sectional area The current study examined the effects of 12weeks of surface neuromuscular electrical stimulation ( NMES ) and ankle weights on the cross-sectional areas ( CSAs ) of three thigh [ Gracilis ( Gra ) , Sartorious ( Sar ) and Adductor ( Add ) ] as well as two trunk [ hip flexor ( HF ) and back extensor ( BE ) ] muscle groups in men with spinal cord injury ( SCI ) . Seven individuals with chronic motor complete SCI were r and omly assigned into a resistance training + diet ( RT+diet ; n=4 ) or diet control ( n=3 ) groups . The RT+diet group underwent twice weekly training with surface NMES and ankle weights for 12weeks . Training composed of four sets of 10 repetitions of leg extension exercise while sitting in their wheelchairs . Both groups were asked to monitor their dietary intake . Magnetic resonance images were captured before and after 12weeks of interventions . Gra muscle CSA showed no change before and after interventions . A significant interaction ( P=0.001 ) was noted between both groups as result of 9 % increase and 10 % decrease in the Gra muscle CSA of the RT+diet and diet groups , respectively . Sar muscle CSA increased [ 1.7±0.4 - 2.5±0.5cm(2 ) ; P=0.029 ] in the RT+diet group with no change [ 2.9±1.4 - 2.6±1.3cm(2 ) ] in the diet group ; with interaction noted between both groups ( P=0.002 ) . Analysis of covariance indicated that Add muscle CSA was 38 % greater in the RT+diet compared to the diet group ( P=0.025 ) after 12weeks ; a trend of interaction was also noted between both groups ( P=0.06 ) . HF and BE muscle groups showed no apparent changes in CSA in both groups . The results suggested that surface NMES can delay the process of progressive skeletal muscle atrophy after chronic SCI . However , the effects are localized to the trained thigh muscles and do not extend to the proximal trunk muscles Fully se date d patients , being treated in the intensive care unit ( ICU ) , experience substantial skeletal muscle loss . Consequently , survival rate is reduced and full recovery after awakening is compromised . Neuromuscular electrical stimulation ( NMES ) represents an effective method to stimulate muscle protein synthesis and alleviate muscle disuse atrophy in healthy subjects . We investigated the efficacy of twice-daily NMES to alleviate muscle loss in six fully se date d ICU patients admitted for acute critical illness [ n=3 males , n=3 females ; age 63 ± 6 y ; APACHE II ( Acute Physiology and Chronic Health Evaluation II ) disease-severity-score : 29 ± 2 ] . One leg was subjected to twice-daily NMES of the quadriceps muscle for a period of 7 ± 1 day whereas the other leg acted as a non-stimulated control ( CON ) . Directly before the first and on the morning after the final NMES session , quadriceps muscle biopsies were collected from both legs to assess muscle fibre-type-specific cross-sectional area ( CSA ) . Furthermore , phosphorylation status of the key proteins involved in the regulation of muscle protein synthesis was assessed and mRNA expression of selected genes was measured . In the CON leg , type 1 and type 2 muscle-fibre-CSA decreased by 16 ± 9 % and 24 ± 7 % respectively ( P<0.05 ) . No muscle atrophy was observed in the stimulated leg . NMES increased mammalian target of rapamycin ( mTOR ) phosphorylation by 19 ± 5 % when compared with baseline ( P<0.05 ) , with no changes in the CON leg . Furthermore , mRNA expression of key genes involved in muscle protein breakdown either declined [ forkhead box protein O1 ( FOXO1 ) ; P<0.05 ] or remained unchanged [ muscle atrophy F-box ( MAFBx ) and muscle RING-finger protein-1 ( MuRF1 ) ] , with no differences between the legs . In conclusion , NMES represents an effective and feasible interventional strategy to prevent skeletal muscle atrophy in critically ill comatose patients Background : Quadriceps atrophy and in particular atrophy of the vastus medialis obliquus ( VMO ) muscle have been frequently related with patellofemoral pain syndrome ( PFPS ) , despite very little objective evidence . Hypothesis : Patients with PFPS exhibit atrophy of the VMO in comparison with healthy controls . Study Design : Case-control study ; Level of evidence , 3 . Methods : Forty-six patients with PFPS and 30 healthy control persons with similar age , gender , body mass index , and activity index distributions underwent magnetic resonance imaging ( MRI ) of the quadriceps .  The muscle size was determined by calculating the cross-sectional area of the total quadriceps and its components . Results : The cross-sectional area ( CSA ) of the VMO was significantly smaller in the PFPS group than in the control group ( 16.67 ± 4.97 cm2 vs 18.36 ± 5.25 cm2 ) ( P = .040 ) . A tendency was noted for a smaller total quadriceps CSA for the PFPS patients at midthigh level ( 66.99 ± 15.06 cm2 vs 70.83 ± 15.30 cm2 ) ( P = .074 ) . Conclusion : This is the first study to examine VMO size in PFPS patients by MRI . Patients with patellofemoral problems exhibited atrophy of the VMO . Although it is not clear whether this atrophy is a result or a cause of PFPS , the results of this study do show that atrophy of the VMO is a contributing factor in PFPS . Longitudinal , prospect i ve studies are needed to establish the cause-effect relation of VMO atrophy and PFPS Abstract Hypoxia is an important modulator of endurance exercise‐induced oxidative adaptations in skeletal muscle . However , whether hypoxia affects resistance exercise‐induced muscle adaptations remains unknown . Here , we determined the effect of resistance exercise training under systemic hypoxia on muscular adaptations known to occur following both resistance and endurance exercise training , including muscle cross‐sectional area ( CSA ) , one‐repetition maximum ( 1RM ) , muscular endurance , and makers of mitochondrial biogenesis and angiogenesis , such as peroxisome proliferator‐activated receptor‐γ coactivator‐1α ( PGC‐1α ) , citrate synthase ( CS ) activity , nitric oxide synthase ( NOS ) , vascular endothelial growth factor ( VEGF ) , hypoxia‐inducible factor‐1 ( HIF‐1 ) , and capillary‐to‐fiber ratio . Sixteen healthy male subjects were r and omly assigned to either a normoxic resistance training group ( NRT , n = 7 ) or a hypoxic ( 14.4 % oxygen ) resistance training group ( HRT , n = 9 ) and performed 8 weeks of resistance training .  Blood and muscle biopsy sample s were obtained before and after training . After training muscle CSA of the femoral region , 1RM for bench‐press and leg‐press , muscular endurance , and skeletal muscle VEGF protein levels significantly increased in both groups . The increase in muscular endurance was significantly higher in the HRT  group . Plasma VEGF concentration and skeletal muscle capillary‐to‐fiber ratio were significantly higher in the HRT group than the NRT group following training . Our results suggest that , in addition to increases in muscle size and strength , HRT may also lead to increased muscular endurance and the promotion of angiogenesis in skeletal muscle The purpose of this study was to investigate whole muscle and single muscle fiber adaptations in very old men in response to progressive resistance training ( PRT ) .  Six healthy independently living old men ( 82 + /- 1 yr ; range 80 - 86 yr , 74 + /- 4 kg )  resistance-trained the knee extensors ( 3 sets , 10 repetitions ) at approximately 70 % one repetition maximum 3 days/wk for 12 wk . Whole thigh muscle cross-sectional area ( CSA ) was assessed before and after PRT using computed tomography ( CT ) . Muscle biopsies were obtained from the vastus lateralis before and after the PRT program . Isolated myosin heavy chain ( MHC ) I and IIa single muscle fibers ( n = 267 ; 142 pre ; 125 post ) were studied for diameter , peak tension , shortening velocity , and power . An additional set of isolated single muscle fibers ( n = 2,215 ; 1,202 pre ; 1,013 post ) was used to identify MHC distribution . One repetition maximum knee extensor strength increased ( P < 0.05 ) 23 + /- 4 kg ( 56 + /- 4 to 79 + /- 7 kg ; 41 % ) . Muscle CSA increased ( P < 0.05 ) 3 + /- 1 cm2 ( 120 + /- 7 to 123 + /- 7 cm2 ; 2.5 % ) . Single muscle fiber contractile function and MHC distribution were unaltered with PRT . These data indicate limited muscle plasticity at the single-muscle fiber level with a resistance-training program among the very old . The minor increases in whole muscle CSA coupled with the static nature of the myocellular profile indicate that the strength gains were primarily neurological . These data contrast typical muscle responses to resistance training in young ( approximately 20 yr ) and old ( approximately 70 yr ) humans and indicate that the physiological regulation of muscle remodeling is adversely modified in the oldest old The purpose of this study was to determine the effect of different training schedules on the cross-sectional area ( CSA ) of the paravertebral muscles ( PA ) in chronic low back pain ( CLBP ) patients . To achieve this goal 59 patients were r and omly assigned to three different 10-week rehabilitation programs : stabilization training ( group 1 , n=19 ) , stabilization training combined with dynamic resistance training ( group 2 , n=20 ) and stabilization training combined with dynamic-static resistance training ( group 3 , n=20 ) . The CSA of the PA was derived from st and ard computerized tomography ( CT ) images at three different levels . The CSA of the PA was found to increase statistically in group 2 ( upper end-plate of L4 ) and group 3 ( upper end-plate of L3 and lower end-plate of L4 ) . In contrast , no statistical differences over time were found in group 1 . Since stabilization exercises have no effect on the CSA of the PA , intensive lumbar resistance training seems to be necessary to restore the size of the PA in CLBP patients with atrophied back muscles . No systematic difference in hypertrophy between dynamic and dynamic-static strengthening training modes was found The response to resistance training and protein supplementation in the latissimus dorsi muscle ( LDM ) has never been investigated . We investigated the effects of resistance training ( RT ) and protein supplementation on muscle mass , strength , and fiber characteristics of the LDM . Eighteen healthy young subjects were r and omly assigned to a progressive eight-week RT program with a normal protein diet ( NP ) or high protein diet ( HP ) ( NP 0.85 vs. HP 1.8 g of protein·kg−1·day−1 ) . One repetition maximum tests , magnetic resonance imaging for cross-sectional muscle area ( CSA ) , body composition , and single muscle fibers mechanical and phenotype characteristics were measured . RT induced a significant gain in strength ( + 17 % , p < 0.0001 ) , whole muscle CSA ( p = 0.024 ) , and single muscle fibers CSA ( p < 0.05 ) of LDM in all subjects . Fiber isometric force increased in proportion to CSA ( + 22 % , p < 0.005 ) and thus no change in specific tension occurred . A significant transition from 2X to 2A myosin expression was induced by training . The protein supplementation showed no significant effects on all measured outcomes except for a smaller reduction of 2X myosin expression . Our results suggest that in LDM protein supplementation does not further enhance RT-induced muscle fiber hypertrophy nor influence mechanic muscle fiber characteristics but partially counteracts the fast-to-slow fiber shift Resistance training results in muscle hypertrophy and improves glycemic control in patients with type 2 diabetes . Whether resistance training modulates inflammation in muscles of diabetic patients remains unknown . We examined the expression of genes encoding the cytokines , tumor necrosis factor-α ( TNF-α ) , interleukin-1β ( IL-lβ ) and transforming growth factor-β , ( TGF-β , ) as well as the pan-leukocyte marker CD18 . Thirty men and women ( 67 ± 7 years ) were r and omized to either 16 weeks of resistance training and usual diabetes care ( EX ) or to usual diabetes care only ( CON ) . Muscle biopsies were obtained from the vastus lateralis muscle prior to the 16-week intervention , and 72 h following the maximal strength test post-intervention . Fiber cross-sectional area ( CSA ) was determined following ATPase staining . Cytokine and CD18 transcript levels were assessed by real-time PCR . Resistance training increased CSA of type I and II fibers ( both P < 0.05 ) and IL-1β transcript levels ( P = 0.05 ) . TNF-α ( P < 0.05 ) and TGF-β1 transcripts ( P < 0.05 ) increased over time in the EX group , but these increases did not differ from those in the CON group . In both groups , the increase in CD18 transcripts remained minimal . The two groups differ by the relationship between changes in CD18 and changes in cytokine transcripts , suggesting that resistance training affects the source of cytokines in muscle . Our studies establish that resistance training in older adults with type 2 diabetes results in muscle fiber hypertrophy , despite a greater accumulation of inflammatory cytokine transcripts in muscle Twelve male subjects with recreational resistance training background s completed 12 wk of intensified resistance training ( 3 sessions/wk ; 8 exercises/session ; 3 sets/exercise ; 10 repetitions maximum/set ) . All major muscle groups were trained , with four exercises emphasizing the forearm flexors . After training , strength ( 1-repetition maximum preacher curl ) increased by 25 % ( P < 0.05 ) . Magnetic resonance imaging scans revealed an increase in the biceps brachii muscle cross-sectional area ( CSA ) ( from 11.8 + /- 2.7 to 13.3 + /- 2.6 cm2 ; n = 8 ; P < 0.05 ) . Muscle biopsies of the biceps brachii revealed increases ( P < 0.05 ) in fiber areas for type I ( from 4,196 + /- 859 to 4,617 + /- 1,116 microns2 ; n = 11 ) and II fibers ( from 6,378 + /- 1,552 to 7,474 + /- 2,017 microns2 ; n = 11 ) . Fiber number estimated from the above measurements did not change after training ( 293.2 + /- 61.5 x 10(3 ) pretraining ; 297.5 + /- 69.5 x 10(3 ) posttraining ; n = 8) . However , the magnitude of muscle fiber hypertrophy may influence this response because those subjects with less relative muscle fiber hypertrophy , but similar increases in muscle CSA , showed evidence of an increase in fiber number . Capillaries per fiber increased significantly ( P < 0.05 ) for both type I ( from 4.9 + /- 0.6 to 5.5 + /- 0.7 ; n = 10 ) and II fibers ( from 5.1 + /- 0.8 to 6.2 + /- 0.7 ; n = 10 ) . No changes occurred in capillaries per fiber area or muscle area . In conclusion , resistance training result ed in hypertrophy of the total muscle CSA and fiber areas with no change in estimated fiber number , whereas capillary changes were proportional to muscle fiber growth Terzis , G , Stratakos , G , Manta , P , and Georgiadis , G. Throwing performance after resistance training and detraining . J Strength Cond Res 22 : 1198 - 1204 , 2008-The purpose of the present study was to investigate the effect of short-term resistance training and detraining on shot put throwing performance .  Eleven young healthy subjects with basic shot put skills participated in 14 weeks of resistance training , which was followed by 4 weeks of detraining .  Shot put performance in four field tests was measured before ( T1 ) and after ( T2 ) resistance training and after detraining ( T3 ) . At the same time points , one repetition maximum ( 1RM ) was measured in squat , bench press , and leg press . Fat-free mass ( FFM ) was determined with dual x-ray absorptiometry and muscle biopsies obtained from vastus lateralis for the determination of fiber type composition and cross-sectional area ( CSA ) . 1RM strength increased 22 - 34 % ( p < 0.01 ) at T2 and decreased 4 - 5 % ( not significantly different ) at T3 . Shot put performance increased 6 - 12 % ( p < 0.05 ) after training and remained unaltered after detraining . FFM increased at T2 ( p < 0.05 ) but remained unchanged between T2 and T3 . Muscle fiber CSA increased 12 - 18 % ( p < 0.05 ) at T2 . Type I muscle fiber CSA was not altered after detraining , but type IIa and IIx fiber CSA was reduced 10 - 12 % ( p < 0.05 ) . The percentage of type IIx muscle fibers was reduced after training ( T1 = 18.7 ± 4 , T2 = 10.4 ± 1 ; p < 0.05 ) , and it was increased at T3 compared with T2 ( T3 = 13.7 ± 1 ; p < 0.05 ) . These results suggest that shot put performance remains unaltered after 4 weeks of complete detraining in moderately resistance-trained subjects . This might be linked to the concomitant reduction of muscle fiber CSA and increase in the percentage of type IIx muscle fibers PURPOSE Some studies report greater muscle hypertrophy during  resistance exercise ( RE ) training from supplement timing ( i.e. , the strategic consumption of protein and carbohydrate before and /or after each workout ) . However , no studies have examined whether this strategy provides greater muscle hypertrophy or strength development compared with supplementation at other times during the day . The purpose of this study was to examine the effects of supplement timing compared with supplementation in the hours not close to the workout on muscle-fiber hypertrophy , strength , and body composition during a 10-wk RE program . METHODS In a single-blind , r and omized protocol , resistance-trained males were matched for strength and placed into one of two groups ; the PRE-POST group consumed a supplement ( 1 g x kg(-1 ) body weight ) containing protein/creatine/glucose immediately before and after RE . The MOR-EVE group consumed the same dose of the same supplement in the morning and late evening . All assessment s were completed the week before and after 10 wk of structured , supervised RE training . Assessment s included strength ( 1RM , three exercises ) , body composition ( DEXA ) , and vastus lateralis muscle biopsies for determination of muscle fiber type ( I , IIa , IIx ) , cross-sectional area ( CSA ) , contractile protein , creatine ( Cr ) , and glycogen content . RESULTS PRE-POST demonstrated a greater ( P < 0.05 ) increase in lean body mass and 1RM strength in two of three assessment s. The changes in body composition were supported by a greater ( P < 0.05 ) increase in CSA of the type II fibers and contractile protein content . PRE-POST supplementation also result ed in higher muscle Cr and glycogen values after the training program ( P < 0.05 ) . CONCLUSION Supplement timing represents a simple but effective strategy that enhances the adaptations desired from RE-training And rogen deprivation therapy ( ADT ) improves life expectancy in prostate cancer ( PCa ) patients , but is associated with adverse effects on muscle mass . Here , we investigated the effects of strength training during ADT on muscle fiber cross-sectional area ( CSA ) and regulators of muscle mass . PCa patients on ADT were r and omized to 16 weeks of strength training ( STG ) ( n = 12 ) or a control group  ( CG ; n = 11 ) . Muscle biopsies were obtained from m. vastus lateralis and analyzed by immunohistochemistry and western blot . Muscle fiber CSA increased with strength training ( 898 μm(2 ) , P = 0.04 ) , with the only significant increase observed in type II fibers ( 1076 μm(2 ) , P = 0.03 ) . There was a trend toward a difference in mean change between groups myonuclei number ( 0.33 nuclei/fiber , P = 0.06 ) , with the only significant increase observed in type I fibers , which decreased the myonuclear domain size of type I fibers ( P = 0.05 ) . Satellite cell numbers and the content of and rogen receptor and myostatin remained unchanged . Sixteen weeks of strength training during ADT increased type II fiber CSA and reduced myonuclear domain in type I fibers in PCa patients . The increased number of satellite cells normally seen following strength training was not observed IMPORTANCE Survivors of critical illness demonstrate skeletal muscle wasting with associated functional impairment . OBJECTIVE To perform a comprehensive prospect i ve characterization of skeletal muscle wasting , defining the pathogenic roles of altered protein synthesis and breakdown . DESIGN , SETTING , AND PARTICIPANTS Sixty-three critically ill patients ( 59 % male ; mean age : 54.7 years [ 95 % CI , 50.0 - 59.6 years ] ) with an Acute Physiology and Chronic Health Evaluation II score of 23.5 ( 95 % CI , 21.9 - 25.2 ) were prospect ively recruited within 24 hours following intensive care unit ( ICU ) admission from August 2009 to April 2011 at a university teaching and a community hospital in Engl and . Patients were recruited if older than 18 years and were anticipated to be intubated for longer than 48 hours , to spend more than 7 days in critical care , and to survive ICU stay . MAIN OUTCOMES AND MEASURES Muscle loss was determined through serial ultrasound measurement of the rectus femoris cross-sectional area ( CSA ) on days 1 , 3 , 7 , and 10 . In a subset of patients , the fiber CSA area was quantified along with the ratio of protein to DNA on days 1 and 7 . Histopathological analysis was performed . In addition , muscle protein synthesis , breakdown rates , and respective signaling pathways were characterized . RESULTS There were significant reductions in the rectus femoris CSA observed at day 10 ( −17.7 % [ 95 % CI , −25.9 % to 8.1 % ] ; P < .001 ) . In the 28 patients assessed by all 3 measurement methods on days 1 and 7 , the rectus femoris CSA decreased by 10.3 % ( 95 % CI , 6.1 % to 14.5 % ) , the fiber CSA by 17.5 % ( 95 % CI , 5.8 % to 29.3 % ) , and the ratio of protein to DNA by 29.5 % ( 95 % CI , 13.4 % to 45.6 % ) . Decrease in the rectus femoris CSA was greater in patients who experienced multiorgan failure by day 7 ( −15.7 % ; 95 % CI , −27.7 % to 11.4 % ) compared with single organ failure ( −3.0 % ; 95 % CI , −5.3 % to 2.1 % ) ( P < .001 ) , even by day 3 ( −8.7 % [ 95 % CI , −59.3 % to 50.6 % ] vs −1.8 % [ 95 % CI , −12.3 % to 10.5 % ] , respectively ; P = .03 ) . Myofiber necrosis occurred in 20 of 37 patients ( 54.1 % ) . Protein synthesis measured by the muscle protein fractional synthetic rate was depressed in patients on day 1 ( 0.035%/hour ; 95 % CI , 0.023 % to 0.047%/hour ) compared with rates observed in fasted healthy controls ( 0.039%/hour ; 95 % CI , 0.029 % to 0.048%/hour ) ( P = .57 ) and increased by day 7 ( 0.076 % [ 95 % CI , 0.032%-0.120%/hour ] ; P = .03 ) to rates associated with fed controls ( 0.065%/hour [ 95 % CI , 0.049 % to 0.080%/hour ] ; P = .30 ) , independent of nutritional load . Leg protein breakdown remained elevated throughout the study ( 8.5 [ 95 % CI , 4.7 to 12.3 ] to 10.6 [ 95 % CI , 6.8 to 14.4 ] μmol of phenylalanine/min/ideal body weight × 100 ; P = .40 ) . The pattern of intracellular signaling supported increased breakdown ( n = 9 , r = −0.83 , P = .005 ) and decreased synthesis ( n = 9 , r = −0.69 , P = .04 ) . CONCLUSIONS AND RELEVANCE Among these critically ill patients  , muscle wasting occurred early and rapidly during the first week of critical illness and was more severe among those with multiorgan failure compared with single organ failure . These findings may provide insights into skeletal muscle wasting in critical illness Unloaded inactivity induces atrophy and functional deconditioning of skeletal muscle , especially in the lower extremities . Information is scarce , however , regarding the effect of unloaded inactivity on muscle size and function about the hip . Regional bone loss has been demonstrated in hips and knees of elderly orthopaedic patients , as quantified by computerized tomography ( CT ) . This method remains to be vali date d in healthy individuals rendered inactive , including real or simulated weightlessness . In this study , ten healthy males were subjected to 5 weeks of experimental bedrest and five matched individuals served as ambulatory controls . Maximum voluntary isometric hip and knee extension force were measured using the strain gauge technique .  Cross-sectional area ( CSA ) of hip , thigh and calf muscles , and radiological density ( RD ) of the proximal tibial bone were measured using CT . Bedrest decreased ( P < 0.05 ) average ( SD ) muscle strength by 20 (8)% in knee extension , and by 22 (12)% in hip extension . Bedrest induced atrophy ( P < 0.05 ) of extensor muscles in the gluteal region , thigh and calf , ranging from 2 to 12 % . Atrophy was more pronounced in the knee extensors [ 9 (4)% ] and ankle plantar flexors [ 12 (3)% ] than in the gluteal extensor muscles [ 2 (2)% ] . Bone density of the proximal tibia decreased ( P < 0.05 ) by 3 (2)% during bedrest . Control subjects did not show any temporal changes in muscle or bone indices ( P > 0.05 ) , when examined at similar time intervals . The present findings of a substantial loss in hip extensor strength and a smaller , yet significant atrophy of these muscles , demonstrate that hip muscle deconditioning accompanies losses in thigh and calf muscle mass after bedrest . This suggests that comprehensive quantitative studies on impaired locomotor function after inactivity should include all joints of the lower extremity . Our results also demonstrate that a decreased RD , indicating bone mineral loss , can be shown already after 5 weeks of unloaded bedrest , using a st and ard CT technique 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 The effect of percutaneous electrical stimulation in preventing immobilisation-induced muscle atrophy was determined from measurements of quadriceps mass , composition , and rate of protein synthesis in seven men who had a fracture of one tibia immobilised in a long-leg cast for 6 weeks . These features were compared with those of fourteen men with similar injuries who did not use an electrical stimulator .  In men who did not use the stimulator , quadriceps cross-sectional area ( CSA ) at midthigh , measured by ultrasonography , fell by a mean ( SD ) 17 (10)% and the rate of muscle protein synthesis was 23 (10)% lower on the immobilised than on the control side ( 0.037 [ 0.016 ] vs 0.048 [0.02]%/h ) . In contrast , in those who used the stimulator , quadriceps CSA ( 55.5 [ 7.3 ] ) cm2 control leg , 50.9 [ 9.0 ] cm2 immobilised leg ) and the rate of muscle protein synthesis ( 0.053 [ 0.009 ] % /h control leg , 0.059 [ 0.012 ] % /h immobilised leg ) were similar on the two sides . The results suggest that brief periods of low-voltage percutaneous electrical stimulation will reduce quadriceps atrophy secondary to knee immobilisation , and that the mechanism includes prevention of the fall in muscle protein synthesis that usually occurs on immobilisation Study Design . Prospect i ve , cross-sectional observational study . Objectives . The aim of this study was to determine if there was an association between wasting of psoas and multifidus as observed on MRI scans and the presenting symptoms , reported pathology , pain , or disability of a cohort of patients presenting with unilateral low back pain . Summary of Background Data . Current physiotherapy practice is often based on localized spine stabilizing muscle exercises ; most attention has been focused on transversus abdominus and multifidus with relatively little on psoas . Method . Fifty consecutive patients presenting to a back pain triage clinic with unilateral low back pain lasting more than 12 weeks were recruited . The cross-sectional surface area ( CSA ) of the muscles was measured . Duration of symptoms , rating of pain , self-reported function , and the presence of neural compression were recorded . Results . Data analysis compared the CSA between the symptomatic and asymptomatic sides . There was a statistically significant difference in CSA between the sides ( P < 0.001 ) . There was a positive correlation between the percentage decrease in CSA of psoas on the affected side and with the rating of pain ( rho = 0.608 , P < 0.01 ) , reported nerve root compression ( rho = 0.812 , P < 0.01 ) , and the duration of symptoms ( rho = 0.886 , P < 0.01 ) . There was an association between decrease in the CSA of multifidus and duration of symptoms . Conclusions . Atrophy of multifidus has been used as one of the rationale s for spine stabilization exercises . The evidence of coexisting atrophy of psoas and multifidus suggests that a future area for study should be selective exercise training of psoas , which is less commonly used in clinical practice 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 PURPOSE We have previously shown that the combination of low-intensity resistive exercise and moderate vascular occlusion induces in humans a marked increase in growth hormone secretion and muscular hypertrophy . The present study investigated the effects of vascular occlusion on the size of thigh muscles in patients who underwent an operation for the reconstruction of the anterior cruciate ligament to see whether it attenuates the disuse muscular atrophy without any exercise combined . METHODS Two sessions of occlusive stimulus , each consisting of five repetitions of vascular occlusion ( mean maximal pressure , 238 mm Hg ) for 5 min and the release of occlusion for 3 min , were applied daily to the proximal end of the thigh from 3rd to 14th days after the operation . Changes in the cross-sectional area ( CSA ) of thigh muscles were analyzed with magnetic resonance images taken on the 3rd and 14th day after the operation . RESULTS Without occlusive stimulus ( control ) , the CSAs of knee extensors and flexors decreased by 20.7 + /- 2.2 % and 11.3 + /- 2.6 % ( mean + /- SEM , N = 8) , whereas with the occlusive stimulus , they decreased by 9.4 + /- 1.6 % and 9.2 + /- 2.6 % ( N = 8) , respectively . The relative decrease in CSA of knee extensors was significantly ( P < 0.05 ) larger in the control group than in the experimental group . CONCLUSION The results indicate that the occlusive stimulus effectively diminishes the postoperation disuse atrophy of knee extensors PURPOSE Studies attributing gains in strength and lean body mass ( LBM ) to creatine monohydrate ( CrM ) during resistance exercise ( RE ) training have not assessed these changes alongside cellular and subcellular adaptations . Additionally , CrM-treated groups have seldom been compared with a group receiving a placebo similar in nitrogen and energy . The purpose of this study was to examine the effects of a CrM-containing protein-carbohydrate ( PRO-CHO ) supplement in comparison with a supplement containing a similar amount of nitrogen and energy on body composition , muscle strength , fiber-specific hypertrophy , and contractile protein accrual during RE training . METHODS In a double-blind , r and omized protocol , resistance-trained males were matched for strength and placed into one of three groups : protein ( PRO ) , PRO-CHO , or the same PRO-CHO supplement ( 1.5 g x kg(-1 ) body weight x d(-1 ) ) containing CrM ( Cr-PRO-CHO ) ( 0.1 g x kg(-1 ) body weight x d(-1 ) ) . Assessment s were completed the week before and after a 10-wk structured , supervised RE program : strength ( 1RM , three exercises ) , body composition ( DEXA ) , and vastus lateralis muscle biopsies for determination of muscle fiber type ( I , IIa , IIx ) , cross-sectional area ( CSA ) , contractile protein , and creatine content . RESULTS Cr-PRO-CHO provided greater improvements in 1RM strength . At least 40 % of the strength improvements could be attributed to hypertrophy of muscle involved in this exercise . Cr-PRO-CHO also result ed in greater increases in LBM , fiber CSA , and contractile protein compared with PRO and PRO-CHO . CONCLUSIONS In RE-trained participants , supplementation with Cr-PRO-CHO provided greater muscle hypertrophy than an equivalent dose of PRO-CHO , and this response was apparent at three levels of physiology ( LBM , fiber CSA , and contractile protein content ) Background —Skeletal muscle dysfunction and exercise intolerance are clinical hallmarks of patients with heart failure . These have been linked to a progressive catabolic state , skeletal muscle inflammation , and impaired oxidative metabolism . Previous studies suggest beneficial effects of & ohgr;-3 polyunsaturated fatty acids and glutamine on exercise performance and muscle protein balance . Methods and Results —In a r and omized double-blind , placebo-controlled trial , 31 patients with heart failure were r and omized to either L-alanyl-L-glutamine ( 8 g/d ) and polyunsaturated fatty acid ( 6.5 g/d ) or placebo ( safflower oil and milk powder ) for 3 months .  Cardiopulmonary exercise testing , dual-energy x-ray absorptiometry , 6-minute walk test , h and grip strength , functional muscle testing , echocardiography , and quality of life and lateral quadriceps muscle biopsy  were performed at baseline and at follow-up . Oxidative capacity and metabolic gene expression were analyzed on muscle biopsies . No differences in muscle function , echocardiography , 6-minute walk test , or h and grip strength and a nonsignificant increase in peak VO2 in the treatment group were found . Lean body mass increased and quality of life improved in the active treatment group . Molecular analysis revealed no differences in muscle fiber composition , fiber cross-sectional area , gene expression of metabolic marker genes ( PGC1&agr ; , CPT1 , PDK4 , and GLUT4 ) , and skeletal muscle oxidative capacity . Conclusions —The combined supplementation of L-alanyl-L-glutamine and polyunsaturated fatty acid did not improve exercise performance or muscle function but increased lean body mass and quality of life in patients with chronic stable heart failure . These findings suggest potentially beneficial effects of high-dose nutritional polyunsaturated fatty acids and amino acid supplementations in patients with chronic stable heart failure . Clinical Trial Registration —URL : http://www . clinical trials.gov . Unique identifier : NCT01534663
Our meta analysis of a homogeneous set of studies is the first to provide valuable LLNs for fiber CSA according to fiber type and gender .
Skeletal muscle atrophy is a major systemic impairment in chronic diseases .
Yet its determinants have been hard to identify because a clear research definition has not been agreed upon .
The reduction in muscle fiber cross-sectional area ( CSA ) is a widely acknowledged marker of muscle atrophy , but no reference values for the muscle fiber CSA at the age of the onset of chronic disease have ever been published .