cerebral palsy ( cp ) is a disorder of movement and posture that appears during infancy or 
 early childhood .
it is caused by non - progressive damage to the developing brain before , 
 during , or shortly after birth .
spastic cp is the most common form of cp ( accounting for 
 approximately 7080% of cases of cp ) and 50% of children with spastic cp have diplegia . in 
 spastic diplegic cp ,
the lower extremities are severely affected but the upper extremities 
 are only mildly impaired , intelligence is usually normal , and epilepsy is not common1 .
children with cp have neurodevelopmental 
 disorders , such as spasticity , contracture , reduced coordination , selective voluntary 
 control , and muscle weakness2 . among 
 these
muscle weakness is more pronounced distally and the hip extensors , 
 knee extensors , and ankle dorsiflexors are relatively weaker than their antagonists3 , 7 .
muscle strength and resistance training programs have been used as therapeutic 
 interventions to increase muscle strength and to improve muscle function3,4,5,6,7,8,9,10,11,12,13 .
all clinical trials suggest that muscle 
 strength - training programs can increase muscle strength and may improve motor activity 
 without adverse effects in people with cp10 , 11 .
the purpose of this study was to determine whether strength - training programs for hip 
 extensors and knee extensors improve gross motor function of myanmar children with cp .
forty children ( 25 boys and 15 girls ) diagnosed with spastic diplegic cp , were recruited 
 for this study .
the children were both inpatients & outpatients coming for 
 rehabilitation to the national rehabilitation hospital ( nrh ) , yangon , myanmar .
the inclusion 
 criteria were : ages between 4 and 12  years ( mean age : 6.07  2.74  years ) ; gmfcs levels i and 
 ii , with the muscle tone of hip and knee extensors lower than grade + 1 of the modified 
 ashworth scale ( mas ) and the ability to follow verbal commands .
children were excluded if 
 they : ( i ) had received a nerve block injection or orthopedic surgery ; ( ii ) had hip and/or 
 knee flexion contracture greater than 10 degrees ; or ( iii ) had unstable seizures and other 
 medical conditions .
this study was approved by the human research ethics committee of the university of 
 medical technology , yangon ( umty ) , myanmar .
all subjects and parents / caregivers received 
 explanations regarding the purpose and procedures of the study before voluntarily agreeing 
 to participate .
all parents / caregivers were required to give written informed consent for 
 participation before the start of the study procedures , and were reminded that they had the 
 right to withdraw from the study at any time .
all subjects in the study were able to 
 continue their usual therapy at the nrh .
flow diagram of the study the study design was one group pretest - posttest design .
all forty children in this study 
 were categorized into gmfcs levels i and ii according to the original version of gmfcs .
the 
 gmfcs is based on gross motor development of self - initiated movement , and consists of a 
 five - level classification system ( table 
 1table 1.description of gmfcs levels in general for all age bandslevel abilitylevel i walks without restrictionslevel ii walks without assistive devices but limitations in 
 communitylevel iii walks with assistive deviceslevel iv transported or uses powered mobilitylevel v severely limited dependent on wheelchair ) with descriptions of four age bands : before the 2nd birthday ; between the 2nd 
 and 4th birthdays ; between the 4th and 6th birthdays ; and between the 6th and 12th 
 birthdays14 .
the original version of 
 gmfcs used in the present study was in effect prior to the 2007 expended and revised version 
 ( gmfcs - e & r ) with descriptions on five age bands ( younger than 2 , 24 , 46 , 612 and 
 1218 years)15 .
children at level i and 
 level ii learn to walk without aids , children at level iii walk with aids , children at level 
 iv rely mainly on wheelchair mobility and children at level v have no means of independent 
 mobility14 , 15 .
one study also confirmed the reliability and validity of the 
 gmfcs , supporting its use in clinical practice and research16 .
muscle strength can be defined as the ability of skeletal muscle to develop force for 
 providing stability and mobility within the musculoskeletal system , so that functional 
 movement can take place17 .
several types of resistance 
 can be used for strength training19 . the 
 free weights ( adjustable weight cuffs with sand bags and velcro straps ) were used as 
 resistance in this study .
the gmfm is a standardized observational instrument designed and validated to measure 
 change in gross motor function over time in children with cp .
gmfm is a criterion - based 
 observational measure with 88 items that assesses motor function in five dimensions .
the 
 five dimensions and their respective items and maximum scores are shown in table 2table 2.gmfmdimensionitems maximum scores a. lying and rolling 17 51 b. sitting 20 60 c. crawling and kneeling 14 42 d. standing 13 39 e. walking , running and jumping 24 72 total 88 264 . each item is assessed and scored on four - point ordinal scale :
0 = can not 
 initiate activity , 1 = initiates activity , 2 = partially completes activity and 3 = 
 completes activity20 , 21 . dimension d
( 13 items to measure motor function in standing , 
 scoring from 0 to 39 ) and dimension e ( 24 items to measure motor function in walking , 
 running and jumping , scoring from 0 to 72 ) were used as the outcome measures for this 
 study .
the amount of training weight in pounds , which was maximum amount of weight that the child 
 could lift in one time , gmfm dimension d and e were assessed at baseline before the start of 
 training program and after the completion of six weeks training program .
all forty subjects 
 were given strength - training program , which included progressive resistance hip and knee 
 extension one session ( 45 minutes ) per day , three times a week for total six weeks .
the 
 intervention procedure involved passive stretching of hip flexors , adductors , hamstrings , 
 triceps surae for 15 minutes as warm - up .
the main exercise , extension exercise for both hip 
 and knee extensors with weight cuff , was done ten times for each muscle group on each side 
 for 30 minutes . for hip extensors ,
the subject was lying prone , the weight cuff was placed 
 just above knee joint and the subject was asked to lift the thigh with weight to full 
 extension .
the subject was lying supine with knees slightly bent , a foam roll or a pillow 
 was placed under knees , the weight cuff was placed just above ankle joint and the subject 
 was asked to lift the lower leg with weight to full extension for knee extensors .
the 
 intervention procedure was finished with passive stretching of hip flexors , adductors , 
 hamstrings , triceps surae for 15 minutes as cool - down .
the strength - training program was performed 10 repetitions for each muscle group on 
 each side , one session per day for three days per week up to 6 consecutive weeks .
a daily 
 diary of physical activity of each subject was kept by the parents or caregivers during the 
 study period .
after 6 consecutive weeks training program , the subject was discharged . the 
 parents or caregivers of each subject
were requested to ask the subject to perform the same 
 main exercise program at home by the guidance of a written home exercise program .
all 
 subjects were requested to visit the study area at once per every 2 weeks up to 6 weeks 
 ( three times ) as follow up .
this study was firstly proposed to assess all outcome measures 
 at the end of 6 weeks training and at the end of 6 weeks follow up ( total 12 weeks ) but 
 there were only 7 subjects who were able to come all three times of follow up .
more than 75% 
 of the subjects were not able to completely come all three times of follow up because most 
 of the subjects in this study were from suburbs of yangon and other rural areas of myanmar . 

the subjects who were absent from regular treatment of 3 days for total 6 consecutive weeks 
 were taken as drop - out .
descriptive statistics [ mean , median and standard deviation ( sd ) ] were calculated using 
 independent t - test .
the outcome measures only at the end of 6 consecutive weeks were calculated as final data . 

the general characteristics of the subjects are presented in table 3table 3.general characteristics of subjectscharacteristics mean ( sd)frequency ( % ) age , 412 years years 6.07 ( 2.74 ) 40 ( 100)46 years 23 ( 57.5)612 years 17 ( 42.5)gender boys 25 ( 62.0 ) girls 15 ( 38.0)gmfcs level i 30 ( 75 ) level ii 10 ( 25 ) .
the mean values and standard deviations ( sd ) of pre - test and post - test 
 outcome measures and p values of the participants are presented in table 4table 4.results of strength trainingpre - test ( mean  sd)post - test ( mean  sd)training weight ( lb)hip extensors ( right ) 1.81  1.51 3.50  2.16 * hip extensors ( left ) 1.74  1.20 3.09  1.80 * knee extensors ( right ) 1.86  1.49 3.57  2.1 * knee extensors ( left ) 1.77  1.23 3.23  1.75 * gmfmgmfm - d 28.4  11.1 33.2  11.1 * gmfm - e 42.4  19.3 54.9  22.5 * * p<0.05 .
statistically significant changes were seen in the amount of training weight 
 in pounds and gmfm - d and e.
the purpose of this study was to determine whether strength - training program on hip 
 extensors and knee extensors improves gross motor function of children with spastic diplegic 
 cp ( gmfcs level i & ii ) in myanmar .
the results of this study supported the 
 effectiveness of prescribing strength - training program on hip and knee extensor muscle 
 groups of lower limbs in patients with spastic diplegic cp as a method to enhance their 
 functional abilities and to increase their gross motor function .
after 6 consecutive weeks 
 of strength - training program , the subjects were found to achieve increased mean values of 
 maximum weight for training for all muscle groups and gmfm dimension d and e. many studies 
 reported that muscle strength and gross motor function activities significantly improved 
 after strength - training program .
reported that children with spastic diplegia 
 increased quadriceps femoris muscle strength through heavy resistance exercise , three times 
 per week for 6 weeks using ankle weights at load of approximately 65% of each child s 
 maximum isotonic force production3 , 4 .
macphail & kramer stated that there was 
 a direct relationship between knee extensor strength and gross motor ability , which meant 
 improvement in muscular strength , was associated with improvement in walking efficiency and 
 functional abilities in adolescents with cp5 , 6 . in the study of functional outcomes of 
 strength training in spastic cerebral palsy by domiano and abel ,
the results of their study 
 reinforced the relationship of strength to motor function in children with cp and further 
 demonstrated the effectiveness of strengthening in this population8 .
in the randomized clinical trial of strength training in 
 young people with cerebral palsy by dodd et al . , home - based , 6 weeks strength training 
 program on knee extensors and ankle plantar flexors was effective in increasing muscle 
 strength and gmfm - d and e of young people ( mean age 13  years 1 month , sd 3years 1 month : 
 range 8 to 18  years ) with spastic diplegic cp ( gmfcs level i to iii)9 .
dodd et al . also reported that strength training programs 
 could increase strength and may improve motor activity in people with cp without adverse 
 effects in their study of a systematic review of the effectiveness of strength training 
 programs for people with cp10 . a pilot 
 study using repeated measure design of the effects of progressive resistance training for 
 children with cp by morton et al . also found that muscle strength and gmfm dimension d and e 
 increased immediately after 6 weeks training program using free weights11
increased muscle strength ( increased amount of 
 training weight in pounds ) and gmfm dimension d and e from baseline to the certain extent 
 until the end of 6 weeks strength training program .
although this study was first proposed 
 to assess the outcomes measures at the end of 6 weeks training and at the end of 6 weeks 
 follow up ( total 12 weeks ) but there were only 7 subjects who were able to come all three 
 times of follow up and the result of those 7 subjects were not calculated in the results . 

the results of the present study supported the effectiveness of prescribing strength 
 training program on muscles of lower limbs in patients with spastic diplegic cp as a method 
 to enhance their functional abilities and to increase their gross motor function .
the 
 current physical therapy program including strength training program was as effective as the 
 previous studies , but with much shorter time and utilized unsophisticated and inexpensive 
 equipment which was available in the most of the physiotherapy departments in our country . 

the limitations 
 of this study were absence of control group , not using standardized assessment of muscle 
 strength , not using gmfm-66 with gross motor ability estimator ( gmae ) software , not 
 involving other physiologic types of cp and presence of weakness that the subjects were able 
 to take usual therapies from the nrh that might have influenced the outcome measures . in 
 conclusion
, the results of this study suggested that a simple method of strength training 
 program might lead to improve muscle strength and gross motor function in children with 
 spastic diplegic cp .
this simple methodology could provide powerful motivation to these 
 patients group to encourage more active lifestyle and allow increased activity and 
 participation within family and community settings .
 [ purpose ] the purpose of this study was to determine whether strength training programs 
 for hip extensors and knee extensors improve gross motor function of children with 
 cerebral palsy in myanmar . 
 [ subjects and methods ] forty children ( 25 boys and 15 girls , 
 mean age : 6.07  2.74  years ) from national rehabilitation hospital , yangon , myanmar , who 
 had been diagnosed with spastic diplegic cerebral palsy , gross motor classification system 
 i and ii participated in a 6-week strength training program ( 45 minutes per day , 3 days 
 per week ) on hip and knee extensors . 
 assessment was made , before and after intervention , 
 of the amount of training weight in pounds , as well as gross motor function measure ( gmfm ) 
 dimensions d ( standing ) and e ( walking , running , jumping ) . 
 [ results ] all scores had 
 increased significantly after the strength - training program . [ conclusion ] 
 a simple method 
 of strength - training program for hip and knee extensors might lead to improved muscle 
 strength and gross motor function in children with spastic diplegic cerebral palsy . 
INTRODUCTION
SUBJECTS AND METHODS
RESULTS
DISCUSSION