***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: AIMS Patients with chronic heart failure ( CHF ) exhibit detrimental changes in skeletal muscle that contribute to their impaired physical performance . This study investigates the possibility of counteracting these changes by chronic low-frequency electrical stimulation ( CLFS ) of left and right thigh muscles . METHODS AND RESULTS ( mean+/-SD ) 32 CHF patients ( 53+/-10 years ) with an LVEF of 22+/-5 % , NYHA II-IV , undergoing optimized drug therapy , were r and omized in a CLFS group ( CLFSG ) or a control group ( controls ) . The groups differed in terms of the intensity of stimulation , which elicited strong muscle contractions only in the CLFSG , whereas the controls received current input up to the sensory threshold without muscle contractions . Functional capacity was assessed by peak VO(2 ) , work capacity , and a 6-min-walk ( 6-MW ) . Muscle biopsies were analyzed for myosin heavy chain ( MHC ) isoforms , citrate synthase ( CS ) and glyceraldehydephosphate dehydrogenase ( GAPDH ) activities . Peak VO(2)(mlmin(-1)kg -1 ) increased from 9.6+/-3.5 to 11.6+/-2.8 ( P<0.001 ) in the CLFSG , and decreased from 10.6+/-2.8 to 9.4+/-3.2 ( P<0.05 ) in the controls . The increase in the CLFSG was paralleled by increases in maximal workload ( P<0.05 ) and oxygen uptake at the anaerobic threshold ( P<0.01 ) . The corresponding values of the controls were unchanged , as also the 6-MW values , the MHC isoform distribution , and both CS and GAPDH activities . In the CLFSG , the 6-MW values increased ( P<0.001 ) , CS activity was elevated ( P<0.05 ) , GAPDH activity decreased ( P<0.01 ) , and the MHC isoforms were shifted in the slow direction with increases in MHCI at the expense of MHCIId/x ( P<0.01 ) . CONCLUSIONS Our results suggest that CLFS is a suitable treatment to counteract detrimental changes in skeletal muscle and to increase exercise capacity in patients with severe CHF The effect of different training intensities of electro-motor stimulation ( EMS ) on strength gains produced in the quadriceps femoris muscle group was investigated . Twenty-four subjects were r and omly assigned to one of three groups : Control ( C ) , Low Intensity ( LI ) trained at 25 % of their maximum voluntary isometric contraction ( MVIC ) , and High Intensity ( HI ) trained at 50 % of MVIC . Results indicated a significant strength improvement in both training groups ( p<0.01 ) following a three-week EMS training program . The HI group showed significantly greater strength gains ( 48.5 % ) than the LI group ( 24.2 % ) ( p<0.01 ) . A significant carry-over effect was also demonstrated in a three-week follow-up period , specifically in the HI group . Positive isokinetic strength changes in the concentric mode were observed in both training groups . In addition , a significant cross transfer effect was demonstrated in the contralateral homologous muscle group ( p<0.01 ) for both HI and LI groups OBJECTIVE To analyze the physiological effects of electrical stimulation with voluntary muscle contraction exercise in postmenopausal women . MATERIAL S AND METHODS Thirty-two females aged 62 to 75 years were r and omly assigned to three groups to perform four activity sessions for six weeks : group ME ( N = 11 ) climbed up and down stairs , group ES ( N = 11 ) practised electrostimulation , and group ME + ES ( N = 10 ) undertook both activities . Physiological adaptations of body composition ( lean and fat masses and bone mineral density ) , muscular strength ( isometric and dynamic ) , vertical jump and posturokinetic activities ( balance and gait ) were analysed . RESULTS For the three groups , the isometric strength at angle 100 degrees ( average increase right and left legs , ME : 19 N.m ; ES : 4.5 N.m ; ME + ES : 11.5 N.m ) , the dynamic strength at speed 60 degrees.s(-1 ) ( average increase right and left leg , ME : 15 N.m ; ES : 14 N.m ; ME+ES : 18.5 N.m ) and the vertical jump ( ME : 23 mm ; ES : 16 mm ; ME + ES : 34 mm ) increased contrary in the body composition and posturokinetic activities . Nevertheless , the group ME + ES adapted differently on some parameters of bone mineral density ( P < 0.05 ) and dynamic strength ( P < 0.01 ) in relation to the groups ES and ME . CONCLUSION Electrostimulation with voluntary muscle contraction exercise could induce different physiologic adaptations compared with electrostimulation or voluntary muscle contraction exercise alone ABSTRACT It is known that electromyostimulation ( EMS ) alone or superimposed over voluntary contraction ( EV ) can effectively improve muscle strength . However , the effect of this type of training on the ability to control force production at submaximal levels is unknown . The authors examined the effects of EV training on steadiness in force production of knee extensors and flexors in older adults . Forty participants , including 20 men and 20 women , 60–77 years of age , were r and omly allocated into a  control group ( CG ) and an electromyostimulation superimposed over voluntary contraction ( EVG ) group . The EVG performed 30 bilateral isometric knee extension and flexion contractions per session , 3 training sessions per week , for 6 weeks . The variations in force production , expressed in absolute ( st and ard deviation [ SD ] ) and relative ( coefficient of variation [ CV ] ) terms , were assessed in isometric contractions at 5 % , 15 % and 25 % maximal voluntary contraction ( MVC ) levels . Results indicated that MVC increased in knee extension and flexion in EVG ( p < .05 ) after the training ; steadiness CV also improved at 15 % MVC in knee flexion ( p < .05 ) but no significant changes were found in knee extension and steadiness SD . The training-induced changes in MVC were not correlated to steadiness CV that might indicate different mechanisms underlying these adaptations Since musculoskeletal impairment increases with age , it is important to determine if exercise changes age-related muscle weakness . This study compared the training effects of electrical stimulation and voluntary isometric contraction , the traditional exercise , on the quadriceps femoris in males 65 years and older . Eighteen informed , nondisabled males , 72 + /- 4 years of age , participated in 12 training sessions over 4 weeks . Maximal voluntary isometric contraction ( MVIC ) torque was measured with a Cybex II dynamometer prior to and following training . An interclass correlation coefficient ( 3,1 ) of 0.982 demonstrated repeated reliable torque measurement . The electrical stimulation group trained at an average of 36 % of pretest MVIC ; the traditional exercise group trained at an average of 42 % MVIC . Average ( F = 14.06 , p = 0.004 ) and peak ( F = 14.32 , p = 0.004 ) torque values were increased with both modes of training . Both methods of training using a low training load were effective in increasing torque in this older male sample .  Electrical stimulation has the same potential as traditional exercise to provide improved strength for aged males . Future research should examine electrical stimulation in older persons with compromised ability to exercise using traditional methods OBJECTIVE To test the hypothesis that increased gait variability predicts falls among community-living older adults attending an outpatient clinic . DESIGN Prospect i ve , cohort study . SETTING Three outpatient geriatric clinics . PARTICIPANTS Fifty-two community-living , ambulatory men and women aged > or = 70 years . INTERVENTIONS Not applicable . MAIN OUTCOME MEASURES Subjects walked at a normal pace for up to 6 minutes wearing force-sensitive insoles that measured the gait rhythm on a stride-to-stride basis . Afterward , subjects reported fall status on a weekly basis for 1 year . The primary outcomes were the association between measures of the stride-to-stride fluctuations in gait rhythm and ( 1 ) subsequent falls during a 12-month follow-up period and ( 2 ) potential contributing factors . RESULTS Almost 40 % of the subjects reported falling during the 12-month follow-up period . Stride time variability was 106 + /- 30 ms in subjects who subsequently fell ( n = 20 ) and 49 + /- 4 ms in those who did not experience a fall ( n = 32 ) during the 12-month follow-up period ( p < .04 ) . Logistic regression also showed that stride time variability predicted falls ( p < .05 ) . Stride time variability correlated significantly with multiple factors including strength , balance , gait speed , functional status , and even mental health , but these other measures did not discriminate future fallers from nonfallers . CONCLUSIONS These findings show both the feasibility of obtaining stride-to-stride measures of gait timing in the ambulatory setting and the potential use of gait variability measures in augmenting the prospect i ve evaluation of fall risk in community-living older adults The effect of 12 weeks of resistance and balance training on strength and gait measures in older persons was tested in a r and omized control trial . Thirty-one residents of two life-care communities volunteered ( mean age , 82.1 years ) . The exercise group ( E ) trained three times per week , performing resistance training to fatigue for knee extension , hip abduction , ankle dorsiflexion , hip extension , and knee flexion , and postural control exercises . The control group ( C ) met weekly for flexibility exercises performed sitting in a chair . The exercise group achieved significant improvements in muscle strength and gait velocity ( p < .05 ) . Knee extension one maximum repetition increased 32 % ( 24 % to 40 % , 95 % confidence interval [ CI ] ) , from 55 + /- to 72 + /- 4N.m . Isokinetic knee extension torque increased 25 % ( 3 % to 47 % ) from 40 + /- 5 to 50 + /- 5N.m at 120 degrees s-1 . Usual gait velocity increased 8 % ( 3 % to 13 % ) in E from 1.04 + /- .07 to 1.12 + /- .06 m/s . There was a trend of improvement in maximal gait speed 4 % ( 0 to 8 % ) from 1.43 + /- 0.1 to 1.49 + /- 0.1 m/s , p = 0.054 . Gait and strength measures in C were unchanged . A short-term exercise program that trained strength and balance achieved a clinical ly significant improvement in gait velocity This study was design ed to determine the effects of pulse frequency ( 20pps , 45pps , 80pps ) on subjects ' voltage tolerance , delayed muscle soreness , and muscle strength gained following 6 weeks of electrical stimulation .  Thirty healthy men ( mean age = 22 years ) were r and omly assigned to three groups . Subjects in group 1 ( n = 10 ) , group 2 ( n = 10 ) , and group 3 ( n = 10 ) had their right quadriceps femoris muscles electrically stimulated with a high-voltage pulsed galvanic stimulator present at pulse frequencies of 20pps , 45pps , and 80pps , respectively . The left limb of each subject served as the control . For all the groups , the duty cycle of the stimulator was set at 10 seconds on and 50 seconds off during the stimulation . At each training session , the maximal tolerable voltage for each subject was monitored . Ten maximum contractions was allowed at each training session . Muscle soreness perception was evaluated 48 hours after stimulation using a 10-point visual analog scale . Electrical stimulation was administered three times a week for 6 weeks . For each subject , the average voltage output and muscle soreness rating were computed at the end of each week . With a cable tensiometer , the knee extension isometric force of both limbs was evaluated before training and at the end of the second , fourth , and sixth weeks of the study and 3 weeks after training . Repeated measure 's analysis of variance was used to determine significant differences in the dependent variables . The results showed that the maximum voltage tolerance , muscle soreness ratings , and muscle strength gained by the three groups are not significantly ( p > .05 ) different . ( ABSTRACT TRUNCATED AT 250 WORDS AIM The present study aim ed to compare the effects of 3 strength development methods on muscular mass and muscular strength in healthy ageing women . METHODS Thirty-two healthy women , 62 to 75 years old were r and omised into 3 groups . The 3 groups performed 4 sessions a week of strength development for 6 weeks . The 1(st ) group ( SC ) climbed up and down 300 stairs per session . The 2(nd ) group ( ES ) followed an electrostimulation programme on the quadriceps muscles . The 3(rd ) group ( SC+ES ) combined stair climbing with electrostimulation . Before and after the 3 programmes , the muscular mass of the leg was assessed using a biphotonic absorptiometry machine . Isometric ( angle 20 degrees and 100 degrees ) and isokinetic ( 60 degrees /s and 240 degrees /s ) knee extension torque was measured using an isokinetic dynamometer . RESULTS None of the programmes changed the muscular mass . All 3 groups increased isometric ( angle 20 degrees , p<0.001 ; angle 100 degrees , p<0.0 
    Output:
    
Indeed , NMES efficiently improved functional and molecular muscle physiology , and , depending on the studies , could lead to better gait and balance performances especially among less active elderly .
HighlightsElectrical stimulation training has a positive effect on the strength of the lower limbs of the elderly .
Electrical stimulation training improves balance of the elderly .
Electrical stimulation could be used to avoid falls among the elderly