children with spastic hemiplegia experience decreased balance ability and abnormal gait 
 because of decreased weight - bearing in the paretic leg1,2,3 . diminished motor ability in the paretic leg causes weakening of the 
 quadriceps , ankle plantar flexors , and ankle dorsiflexors4 , 5 . to enhance balance and 
 motor ability in the paretic leg in children with spastic hemiplegia , a therapeutic approach 
 promoting weight - shifting to the paretic side and strengthening of paretic leg muscles is 
 required4 , 6 . muscle - strength - enhancement exercise in children with cerebral palsy results in an increase 
 in stride length and gait velocity , decreased crutch gait , and improvement in the gross 
 motor function measure7 . brown et al.8 reported that muscle strength of the ankle 
 plantar flexors and dorsiflexors of the paretic leg in children with spastic hemiplegia was 
 respectively 75% and 72% of that of the unaffected side . horvat9 reported that muscle strength of knee extensors and flexors 
 in the paretic leg in cases of spastic hemiplegia was respectively 42% and 52% of that of 
 the unaffected side . horvat9 applied a 
 gradual resistance exercise program in children with spastic hemiplegia for 8 weeks and 
 reported that knee flexor and extensor muscle strength increased 100% and 129% , 
 respectively . this suggests that knee - muscle  strength exercise is necessary to improve 
 walking function in children with spastic hemiplegia ; the benefits include gross motor 
 function enhancement , faster walking , and increased energy efficiency after knee extensor 
 training10 . hwang11 implemented eccentric muscle strength exercise for the 
 paretic leg in patients with hemiplegia and reported improvement of muscle strength , 
 cadence , gait velocity , and weight - bearing on the paretic side during walking . research on the positive impact of eccentric muscle strength exercise on daily life is 
 ongoing . however , most studies involved muscle strength exercise in supine , prone , and 
 sitting positions . few studies have evaluated the impact of weight - bearing 
 muscle - strength  enhancement training of an independent and controlled paretic ankle and knee 
 on balance ability and gross motor function . hence , this study examined the effects of 
 weight - shifting to a standing paretic leg and concentric and eccentric muscle strength 
 exercise on balance and gross motor function in children with spastic hemiplegia . the inclusion criteria were as follows : diagnosis of spastic hemiplegia , gross motor 
 function classification system ( gmfcs ) level i  ii and able to walk and jump12 , modified mini - mental state examination 
 score over 2513 , absence of vision or 
 hearing deficits , and no medicine or surgery that affects balance . all protocols were 
 approved by the university of daejeon . before participation , the procedures , risks , and 
 benefits were explained to the participants , who gave informed consent . the pediatric balance scale ( pbs ) and gross motor function measure ( gmfm ) were used in the 
 study . the pbs can be applied in children with brain damage and consists of a total of 14 
 items in 3 domains , including sitting , standing , and changing of position . the highest score 
 is 56 and a higher score indicates better standing balance ability14 . the participants performed 88 kinds of motions in 5 domains 
 without assistance by the tester . among the 5 domains , total scores in domain d ( standing ) 
 and domain e ( gait , running , and jumping ) were compared in this study . 20  min of 
 neurodevelopmental therapy and 20  min of muscle - strength - enhancement training were applied 
 to the paretic leg . in the control group , the method of concentric and eccentric muscle - strength - enhancement training for the paretic 
 leg is as follows . a subject stands on a height - adjustable table where he / she is able to 
 bear weight on the paretic leg while holding a stall bar with the upper limb on the paretic 
 side . the subject pushes a ball back and forth on the ground using the non - paretic leg by 
 controlling the ankle and knee joints of the paretic leg . the motion is repeated 10 times 
 for one set followed by 1  min of rest . general characteristics of the research subjects were examined by cross - tabulation analysis 
 and independent t - tests using descriptive statistics . a paired t - test was used to compare 
 differences before and after the experiment in each group . an independent t - test was used to 
 compare differences before and after the experiment between the 2 groups . the statistical 
 package for the social sciences for windows , version 18.0 ( spss , chicago , il , usa ) was used 
 for statistical analysis . a statistical significance level was set at =0.05 for all data 
 ( table 1table 1.characteristics of study participantsexperimentalgroup ( n=15)controlgroup ( n=15)gendermale9 ( 60.0)10 ( 66.7)female6 ( 40.0)5 ( 33.3)gmfcs ( l1/l2)11 ( 73.3)/4 ( 26.7)12 ( 80.0)/3 ( 20.0)age ( yr)11.6  2.060.1  12.3height ( cm ) 123.1  14.0 166.8  10.0weight ( kg ) 28.3  7.6 65.7  8.8n(% ) ; mean  standard deviation ; gmfcs : gross 
 motor function classification system ) . n(% ) ; mean  standard deviation ; gmfcs : gross 
 motor function classification system in the experimental group , pbs statistically significantly increased from 53.07 to 54.61 
 after training ( p<0.05 ) . standing in gmfm gait , running and jumping in gmfm 
 statistically significantly increased from 93.58 to 94.65 after the intervention ( p<0.05 ) 
 ( table 2table 2.a comparison of balance and gross motor function before and after 
 trainingexperimentalgroup ( n=15)controlgroup ( n=15)balance ( score)pre - test53.1  3.152.1  2.5post - test 54.6  1.4 * 52.4  2.4standing ( score)pre - test94.5  3.192.9  2.4post - test 95.9  2.5 * 93.3  2.9walking , running and jumping ( score)pre - test93.6 4.391.1  3.6post - test 94.7  3.9 * 91.3  3.7mean  standard deviation . * compared to normal children , even children with spastic cerebral palsy with a high 
 functional level show leg muscle weakening7 , 17 . horvat9 reported that muscle 
 strength in the paretic knee extensors and flexors was 4252% of that on the unaffected side 
 in hemiplegic children . muscle - strength - enhancement training is critical for functional 
 improvement in children with spastic hemiplegia4 . hence , this study examined the effects of concentric and eccentric 
 exercise control training on the paretic leg in children with spastic hemiplegia . damiano and abel4 reported that gross 
 motor function and pediatric balance ability improved after leg - muscle - strength - enhancement 
 training . dodd et al.19 reported that 
 gmfm , gait velocity , and walking upstairs improved in children with spastic diplegia after 
 muscle - strength - enhancement training . dodd et al.19 applied muscle - strength - enhancement exercises to ankle plantar 
 flexors and knee extensors in children with spastic diplegic cerebral palsy and reported 
 improvement in items d and e in gmfm . in this study , control training of the paretic leg 
 resulted in significant improvement in gmfm , similar to previous literature reports . shumway - cook et al.20 applied 5 days of 
 intensive balance training in children with spastic hemiplegia and diplegia and reported 
 significantly improved core stability . in this study , control training of the paretic leg 
 caused significant improvement in balance ability in children . it is possible that control 
 function and balance reaction improved due to stable muscle activity of the hip , knee , and 
 ankle joints through consistent full weight - bearing control in the paretic leg . first , the sample size was small , and it is 
 difficult to generalize the study results to all children with spastic hemiplegia . second , 
 because there is limited literature on weight - bearing muscle - strength - enhancement exercise 
 in children with gmfcs level i  ii , it was difficult to compare study results . hence , 
 research using a larger sample of children with spastic hemiplegia will be needed to 
 determine the long - term effects of muscle strengthening on the paretic lower limb . moreover , 
 multidimensional analysis using appropriate assessment tools will be needed to validate the 
 results of concentric and eccentric weight - bearing exercise . concentric and eccentric control exercise therapy in children with spastic hemiplegia can 
 be used as a means to solve functional problems in a paretic leg .
[ purpose ] this study examines the effect of concentric and eccentric control training of 
 the paretic leg on balance and gross motor function in children with spastic hemiplegia . 
 [ subjects and methods ] thirty children with spastic hemiplegia were randomly divided into 
 experimental and control groups . in the experimental group , 
 20  min of neurodevelopmental 
 therapy and 20  min of concentric and eccentric control exercise were applied to the 
 paretic leg . in the control group , 
 40  min of neurodevelopmental therapy was applied . 
 the 
 pediatric balance scale test and standing and gait items of the gross motor function 
 measure were evaluated before and after intervention . 
 [ results ] in the experimental group , 
 gross motor function measure and pediatric balance scale scores statistically 
 significantly increased after the intervention . 
 the control group showed no statistically 
 significant difference in either score after the intervention . 
 [ conclusion ] concentric and 
 eccentric control exercise therapy in children with spastic hemiplegia can be effective in 
 improving gross motor function and balance ability , and can be used to solve functional 
 problems in a paretic leg .