***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: The purpose of this study was to determine whether strength training could reduce the deficit in plantarflexion ( PF ) maximal voluntary contraction ( MVC ) torque observed in previous studies in older subjects relative to young adults . Accordingly , the effects of a 6-month strength training program on the muscle and neural properties of the major muscle groups around the ankle were examined . PF and dorsiflexion ( DF ) isometric MVC torques were measured and surface electromyographic activity of the triceps surae and tibialis anterior muscles was recorded . The strength training program was very effective in improving strength in PF ( + 24.5 % ) , and it thus reduced the DF-to-PF MVC torque ratio ; in addition , it also induced gains in DF ( + 7.6 % ) . Thus , there must be an improvement in ankle joint stability . In PF , gains were due particularly to a modification of the agonist neural drive ; in DF , the gains appeared to be the consequence of a reduction in antagonist coactivation . Our findings indicate that the investigation of one muscle group should always be accompanied by examination of its antagonist muscle group Effects of 6 mo of heavy-resistance training combined with explosive exercises on neural activation of the agonist and antagonist leg extensors , muscle cross-sectional area ( CSA ) of the quadriceps femoris , as well as maximal and explosive strength were examined in 10 middle-aged men ( M40 ; 42 + /- 2 yr ) , 11 middle-aged women ( W40 ; 39 + /- 3 yr ) , 11 elderly men ( M70 ; 72 + /- 3 yr ) and 10 elderly women ( W70 ; 67 + /- 3 yr ) .  Maximal and explosive strength remained unaltered during a 1-mo control period with no strength training . After the 6 mo of training , maximal isometric and dynamic leg-extension strength increased by 36 + /- 4 and 22 + /- 2 % ( P < 0 . 001 ) in M40 , by 36 + /- 3 and 21 + /- 3 % ( P < 0.001 ) in M70 , by 66 + /- 9 and 34 + /- 4 % ( P < 0.001 ) in W40 , and by 57 + /- 10 and 30 + /- 3 % ( P < 0.001 ) in W70 , respectively . All groups showed large increases ( P < 0.05 - 0.001 ) in the maximum integrated EMGs ( iEMGs ) of the agonist vastus lateralis and medialis . Significant ( P < 0.05 - 0.001 ) increases occurred in the maximal rate of isometric force production and in a squat jump that were accompanied with increased ( P < 0.05 - 0 . 01 ) iEMGs of the leg extensors . The iEMG of the antagonist biceps femoris muscle during the maximal isometric leg extension decreased in both M70 ( from 24 + /- 6 to 21 + /- 6 % ; P < 0.05 ) and in W70 ( from 31 + /- 9 to 24 + /- 4 % ; P < 0.05 ) to the same level as recorded for M40 and W40 . The CSA of the quadriceps femoris increased in M40 by 5 % ( P < 0.05 ) , in W40 by 9 % ( P < 0.01 ) , in W70 by 6 % ( P < 0.05 ) , and in M70 by 2 % ( not significant ) . Great training-induced gains in maximal and explosive strength in both middle-aged and elderly subjects were accompanied by large increases in the voluntary activation of the agonists , with significant reductions in the antagonist coactivation in the elderly subjects . Because the enlargements in the muscle CSAs in both middle-aged and elderly subjects were much smaller in magnitude , neural adaptations seem to play a greater role in explaining strength and power gains during the present strength-training protocol Twenty sedentary male university students were r and omly assigned to an experimental or a control group . The experimental group trained the knee extensors of one leg by producing 30 isometric extension maximal voluntary contractions ( MVC ) per day , three times per week for 8 wk . After 8 wk of training , extensor MVC in the trained leg increased 32.8 % ( P less than 0.05 ) , but there was no change in vastus lateralis maximal integrated electromyographic activity ( IEMGmax ) . The most important finding was that the degree of hamstring coactivation during extension MVC decreased by approximately 20 % ( P less than 0.05 ) after the 1st wk of training . Less pronounced adaptations occurred in the untrained leg : extension MVC force increased 16.2 % ( P less than 0.05 ) , hamstring coactivity decreased 13 % ( P less than 0.05 ) after 2 wk of training , and vastus lateralis IEMGmax was unchanged . The same measures in legs of the control group were not changed during the study . There were no changes in flexion MVC , biceps femoris IEMGmax , or the degree of quadriceps coactivity during flexion MVC in either leg of the control or experimental group . A reduction in hamstring coactivity in the trained and untrained legs indicates that these muscles provide less opposing force to the contracting quadriceps . We conclude that this small but significant decrease in hamstring coactivation that occurs during the early stages of training is a nonhypertrophic adaptation of the neuromuscular system in response to static resistance training of this type We compared the effect of a 10‐week resistance training program on peak isometric torque , muscle hypertrophy , voluntary activation and electromyogram signal amplitude ( EMG ) of the knee extensors between young and elderly women . Nine young women ( YW ; range 20–30 years ) and eight elderly women ( EW ; 64–78 years ) performed three sets of ten repetitions at 75 % 1 repetition maximum for the bilateral leg extension and bilateral leg curl 3 days per week for 10 weeks . Peak isometric torque , EMG and voluntary activation were assessed before , during , and after the training period , while knee extensor lean muscle cross‐sectional area ( LCSA ) and lean muscle volume ( LMV ) were assessed before and after the training period only . Similar increases in peak isometric torque ( 16 % and 18 % ) , LCSA ( 13 % and 12 % ) , LMV ( 10 % and 9 % ) and EMG ( 19 % and 21 % ) were observed between YW and EW , respectively , at the completion of training ( P<0·05 ) , while the increase in voluntary activation in YW ( 1·9 % ) and EW ( 2·1 % ) was not significant ( P>0·05 ) . These findings provide evidence to indicate that participation in regular resistance exercise can have significant neuromuscular benefits in women independent of age . The lack of change in voluntary activation  following resistance training in both age groups despite the increase in EMG may be related to differences between measurements in their ability to detect resistance training‐induced changes in motor unit activity . However , it is possible that neural adaptation did not occur and that the increase in EMG was due to peripheral adaptations The aim of this study was to enquire whether older adults , who  continue plantar-flexion ( PF ) strength training  for an additional 6-month period , would achieve further improvements in neuromuscular performance , in the ankle PFs , and in the antagonist dorsi-flexors ( DFs ) . Twenty-three healthy older volunteers ( mean age 77.4 ± 3.7 years ) took part in this investigation and 12 of them followed a 1-year strength-training program .  Both neural and muscular factors were examined during isometric maximal voluntary contraction ( MVC ) torques in ankle PF and DF pre-training , post 6 and post 12 months . The main finding was that 6 months of additional strength training of the PFs , beyond 6 months , allowed further improvements in neuromuscular performance at the ankle joint in older adults . Indeed , during the first 6 months of progressive resistance training , there was an increase in the PF MVC torque of 11.1 ± 19.9 N m , and then of 11.1 ± 17.9 N m in the last 6-month period . However , it was only after 1 year that there was an improvement in the evoked contraction at rest in PF ( + 8 % ) . The strength training of the agonist PF muscles appeared to have an impact on the maximal result ant torque in DF . However , it appeared that this gain was first due to modifications occurring in the trained PFs muscles , then , it seemed that the motor drive of the DFs per se was altered . In conclusion , long-term strength training of the PFs result ed in continued improvements in neuromuscular performance at the ankle joint in older adults , beyond the initial 6 months 1 . The adaptations of the ankle dorsiflexor muscles and the behaviour of single motor units in the tibialis anterior in response to 12 weeks of dynamic training were studied in five human subjects . In each training session ten series of ten fast dorsiflexions were performed 5 days a week , against a load of 30 - 40 % of the maximal muscle strength . 2 . Training led to an enhancement of maximal voluntary muscle contraction ( MVC ) and the speed of voluntary ballistic contraction . This last enhancement was mainly related to neural adaptations since the time course of the muscle twitch induced by electrical stimulation remained unaffected . 3 . The motor unit torque , recorded by the spike-triggered averaging method , increased without any change in its time to peak . The orderly motor unit recruitment ( size principle ) was preserved during slow ramp contraction after training but the units were activated earlier and had a greater maximal firing frequency during voluntary ballistic contractions . In addition , the high frequency firing rate observed at the onset of the contractions was maintained during the subsequent spikes after training . 4 . Dynamic training induced brief ( 2 - 5 ms ) motor unit interspike intervals , or ' doublets ' . These doublets appeared to be different from the closely spaced ( + /-10 ms ) discharges usually observed at the onset of the ballistic contractions . Motor units with different recruitment thresholds showed doublet discharges and the percentage of the sample of units firing doublets was increased by training from 5.2 to 32.7 % . The presence of these discharges was observed not only at the onset of the series of spikes but also later in the electromyographic ( EMG ) burst . 5 . It is likely that earlier motor unit activation , extra doublets and enhanced maximal firing rate contribute to the increase in the speed of voluntary muscle contraction after dynamic training Explosive-type strength training may alter kinetics and neuromuscular activity during stair ascent in elderly women . This may improve functional ability . Nineteen women ( 69.7 ± 3.4 yr ) were r and omly allocated to strength training ( TG ; twice per wk , 12 wk ) or a control group ( CG ) . Stair ascent was assessed at self-chosen ( AFV ) , st and ardized ( ASV ) , and maximal velocity ( AMV ) pre- and posttraining . Ground-reaction force ( GRF ) and EMG quantified kinetics and neuromuscular activity . After training , TG increased AMV and AFV velocity by 8 % ( p = .02 ) and 17 % ( p= .007 ) , respectively ( TG vs. CG ; p < .05 ) . This was accompanied by elevated rectus femoris EMG ( from 21 % to 48 % , p < .047 ) . At AFV , TG increased GRF first peak force 4 % ( p= .047 ) , and CG increased second peak force 5 % ( p = .036 ) . Muscle coactivation remained unaltered in both groups . Explosive-type strength training led to enhanced stair-climbing performance at maximal and self-chosen speed , reflecting an improved functional ability PURPOSE To test the ability of a combination high-velocity/high-resistance training program to enhance knee extensor muscle strength , power , nervous activation of muscle , and muscle activation time in inactive women and compare the response to training between young and old women . METHODS The study involved 49 inactive women , with young ( 18 - 33 yr , n = 25 ) and old ( 65 - 84 yr , n = 24 ) distributed to training and control groups using blocked r and omization .  Electrically evoked muscle twitches were measured for the knee extensors ; then maximal , voluntary , isometric knee extensions were performed in a visually cued reaction time ( RT ) task , followed by 8 wk of explosive resistance training . RESULTS Training increased peak torque ( + 12 % , P = 0.03 ) and reduced antagonist coactivation ( -13 % , P = 0.02 ) similarly for both age groups . Young training group increased the rate of torque development by 34 % compared to young controls ( -7 % ) , old training ( + 9 % ) , and old controls ( + 8 % ) ( P = 0.002 ) . Young training group increased impulse by 53 % , which was greater than young controls ( -11 % ) , old training ( + 12 % ) , and old controls ( + 9 % ) ( P = 0.001 ) . Resistance training did not change electrically evoked twitch , RT ( premotor time , motor time , or reaction time ) , or nervous activation measures ( onset EMG amplitude or rate of EMG rise ) . CONCLUSIONS Explosive force training was ineffective at enhancing muscle twitch characteristics , neural drive , or RT in young or old women . It did enhance peak muscle force in both young and old , modulated through a reduction in antagonist coactivation . Older participants showed less of an improvement in the rate of torque development and contractile impulse than young , indicating either that this sample of older women had a reduced capacity to develop muscle 
    Output:
    
Based on our results we can conclude that there is evidence for  exercise-induced increase in voluntary activation related to strength gains in the lower extremities in elderly persons .