a stroke is a very serious disease and is accompanied by motor disturbance , sensory 
 disturbance , perceptual disturbance , language disturbance , cognitive disorder , and urinary 
 incontinence depending on the area of the brain lesion1 . stroke patients balance acts as an important factor in impeding their ability to 
 stand or their gait , and their postural sway is twice as high as that of healthy people in 
 their age range2 . limit 
 of stability is defined as the maximal distance to move the center of gravity while 
 maintaining balance without detaching their feet from the ground3 . balance is diminished in people with hemiplegia4 , and hemiplegia can cause a reduction in 
 patients limits of stability , which is defined as the maximal distance that an individual 
 can shift his or her weight in any direction without loss of balance3 . for improving balance ability , the patients have to 
 increase their trunk stabilization . the stabilization of the trunk is necessary for the 
 stability of the spine and the pelvis when they are in a functional position , to increase 
 stability during movement , to enhance muscle strength , and to adjust muscle movements and 
 balance5 . the principal trunk 
 stabilization exercises are pelvic tilt exercises , quadruped exercises , abdominal hollowing 
 exercises , and bridging exercises6 . it can 
 be used as a low intensity weight bearing exercise , as it is an important posture to 
 perform , loading weight on the knee and at the same time it develops coordination from a 
 sitting to a standing position7 . bridging exercises ( be ) are commonly used therapeutically for lumbopelvic 
 stabilization8 . doing be on a plinth 
 lowers the patient s center of gravity , which reduces fear and the instability of weight 
 bearing during gait , and allows exercise in a secure posture9 . although a number of studies on the effects 
 of be with various postures on the activation of trunk muscles and changes in the activity 
 ratio between global and local muscles have been conducted10,11,12 , no studies have been done to prove the effects of weight shifting 
 abilities on the paretic side while on the static state . bridging exercise is a method that is often used clinically , and much research has been 
 conducted using diverse methods and modifications . recently , attention has focused on 
 changes in the activities of the trunk muscles during bridging exercises , and many studies 
 have attempted to identify an efficient method for enhancing the activities of the trunk 
 muscles . the conventional bridging exercise is conducted in a supine position , and most 
 other exercises are modifications of this exercise . to the best of our knowledge , the purpose of this study was to verify the effects of a modified bridging exercise on the 
 static balance of a stroke patient with improvement in weight bearing on the affected side 
 in standing and static balancing ability . the subjects of this study were 30 patients diagnosed with hemiplegia resulting from stroke 
 by a rehabilitation doctor practicing in n hospital located in daegu , south korea . they were 
 randomly and equally assigned to a supine bridge exercise group ( sbg : 4 males , 6 females ) , a 
 supine bridge exercise on a togu balance pad group ( sbtg : 6 males , 4 females ) , and a 
 unilateral bridge exercise group ( ubg : 7 males , 3 females ) . the mean  sd age , height , and 
 weight of the sbg group was 52.440.6  years , 165.09.5  cm , and 66.113.1  kg , respectively . the mean  sd age , height , and weight of the sbtg group was 50.85.5  years , 
 165.98.6  cm , and 63.95.2  kg , respectively . the mean  sd age , height , 
 and weight of the ubg group was 50.85.5  years , 165.98.6  cm , and 63.95.2  kg , respectively . the inclusion criteria were as follows : no visual field defect , no abnormality in the 
 vestibular organs , no orthopedic disease , an unrestricted range of motion , the ability to 
 understand and perform the exercise as instructed by the researcher , and a score of 24 or 
 higher on the mini - mental state examination - korean version . prior to participation , all 
 participants were required to read and sign an informed consent form , in accordance with the 
 ethical standards of the declaration of helsinki . the subjects in the sbg group did the supine bridge exercise . in the starting position of 
 the bridging exercise in the subjects bent their knee joints at 90 degrees and spread both 
 arms at about 30 degrees position with both hands on the ground . they kept their head and 
 neck in a straight position , with their eyes looking at the ceiling . the subjects adopted the same position as 
 that of the sbg group , but they placed their feet on togu balance pads . again , adopting the same position as that of the sbg 
 group , the subjects raised their hemiplegic - side leg . the exercises were done for 20 minutes each time , five times per week , for a total of four 
 weeks . for the measurement of balance ability , a biofeedback analysis system ( ap1153 biorescue , 
 france ) was used to determine weight bearing , anterior length in limit of stability , and 
 posterior length in limit of stability on the affected side in a static standing 
 position . the experimental results were statistically analyzed using spss 12.0 ko ( ibm , il , usa ) . after the general characteristics of the subjects were determined , a one - way anova was used 
 to compare the variation in the weight bearing on the affected side in standing , the 
 anterior length in limit of stability following standing , and the posterior length in limit 
 of stability following standing . the significance of the differences between the three groups 
 was investigated using the independent t - test . the analysis results of each group s weight bearing rate on the paretic side are as 
 follows . according to the analysis results of the weight load rate on the paralyzed side , 
 there were significant differences in each group before and after the experiment , and there 
 were significant differences in the ubg after the experiment ( p>0.05 ) ( table 1table 1.comparison of change in balance function in the training groups with values 
 presented as mead  standard deviationsbgsbtgubgpretestposttestpretestposttestpretestposttestwb ( % ) 45.91.246.21.4 * 41.32.047.01.2 * 42.81.547.01.3*al ( mm)980.8186.21,020.6210.11,072.7550.4895.9678.5 * 971.7348.5689.5269.7*pl ( mm)914.9139.5992.3141.71,389.7345.01,294.0198.2 * 1,059.6429.5788.5124.6**significant difference from pre - test at < 0.05 . sbg : supine bridge exercise group , sbtg : 
 supine bridge exercise on togu group , ubg : unilateral bridge exercise group , wb : 
 weight bearing in affected side on standing , al : anterior length in limit of stability 
 following on standing , pl : posterior length in limit of stability following on 
 standing ) . according to the results of the comparison of the forward and backward 
 movement range in limit of stability in a standing position before and after the experiment , 
 there were significant differences between the sbtg group and the ubg group after the 
 experiment ( p>0.05 ) ( table 1 ) . sbg : supine bridge exercise group , sbtg : 
 supine bridge exercise on togu group , ubg : unilateral bridge exercise group , wb : 
 weight bearing in affected side on standing , al : anterior length in limit of stability 
 following on standing , pl : posterior length in limit of stability following on 
 standing balance is the ability to maintain body equilibrium and influences most motions performed 
 in daily living13 . balance can be defined 
 as the ability to maintain the body s center of mass over its base of support and maintain 
 equilibrium constantly during body movements14 . stroke patients , who are at a relatively early stage post - onset , show a marked deficit in 
 weight shifting to the affected leg15 . shin et al.15 noted that stroke patients 
 weight support ability was correlated with functional performance ability , and moving the 
 weight left or right in a standing position was related to motor function , an independent 
 life , and the amount of time it took to go back home from the hospital . the reason was that 
 stroke patients ability to move their weight left or right was directly related to gait . in 
 the current study , weight bearing on the affected side in standing and the forward and 
 backward movement range in limit of stability in a standing position were compared , and the 
 results showed a significant effect in the unilateral bridge exercise group and 
 statistically significant differences between the three groups . latash et al.16 used the center of pressure ( cop ) as a 
 measure of postural control , and measuring the variables of cop represented changes in the 
 locations where the ground reaction forces were composite , which referred to the weight 
 average of all the pressure points that contacted the ground . kim et al.17 reported that the characteristics of 
 cop - based variables were utilized widely as a tool to diagnose a patient s prognosis related 
 to balance disabilities and to assess treatment effects . bridging exercises with the feet on an unstable surface are effective for increasing 
 dynamic balance , especially for the prevention of spinal damage11 . kavcic et al.18 reported that a bridging exercise with the right leg lifted was 
 very closely associated with the activity of the rectus abdominis in the side bridging 
 exercise when healthy adults performed lumbar stabilization exercise . park et al.19 reported that a bridge exercise using 
 vibration training under an unstable support that used sling equipment significantly 
 increased the muscle activities of the internal and external oblique muscles of healthy 
 subjects . the results of the current study suggest that the position adopted in the ubg group is 
 useful for weight bearing on the feet and increasing balance ability . in this study , three 
 groups performed modified bridging exercises , thereby determining the weight bearing ability 
 on the affected side , changes in forward weight shifting , and changes in backward weight 
 shifting . with regard to weight bearing , all three groups ( sbg , sbtg , and ubg ) increased 
 weight bearing to 46.21.4 , 47.01.2 , and 47.01.3 . with regard to the com shifting effect , 
 not only the al direction but also the pl direction showed that sbtg 895.9678.5 and ubg 
 689.5269.7 had more significant results than sbg 1020.6210.1 . in particular , the ubg group 
 experienced the highest body weight bearing ability and com shifting of pl and al . that is , 
 the ubg group s exercise was concluded to be the most suitable balance control ability . bridging exercise has been applied in many previous studies already , and it has been 
 modified variously . hong et al.20 
 reported that changes in muscle activity and muscle endurance can be obtained over unstable 
 ground surfaces more than on stable ground surfaces , based on their studies on the 
 application of bridging exercises over various support surfaces . this result is consistent 
 with those of the current study in which bridge exercise on the unstable base significantly 
 increased ( p<0.05 ) dynamic and static lumbar stability relative to bridge exercise on the 
 unstable base21 . many patients have difficulty bearing weight on the hemiplegic side and in forward and 
 backward body movement . because patients with hemiplegia after stroke normally use a hip 
 strategy instead of an ankle strategy due to changes in the ground reaction force and the 
 increased muscle tone of the hip flexors , they feel they will fall down when moving a little 
 bit forward or backward . therefore , regaining the ability to move forward and backward is 
 very important for maintaining posture in standing as well as in walking . in the final 
 assessment , the increases in the subjects anterior and posterior stability limits were 
 meaningful , indicating that they had gained more efficient postural control . the subjects 
 especially needed more strength and proprioceptive senses in the ankle joints when they did 
 the bridge exercise with the balance pad and the unilateral bridge exercise . there were only 30 participants , making it difficult to 
 generalize the results to the general population . moreover , not only anterior and posterior 
 cog adjustments , but internal and external adjustments were also important for balance 
 abilities . thus , future studies will be conducted to determine how the correlation of 
 internal and external shifting and anterior and posterior shifting as well as weight bearing 
 increases on the affected side and postural control improvement are functionally related to 
 one another .
[ purpose ] the purpose of this study was to verify the effects of a modified bridging 
 exercise on stroke patients with improvement in weight bearing on the affected side in 
 standing and static balancing ability . 
 [ subjects ] thirty patients who had a stroke were 
 randomly allocated into a supine bridge exercise group ( sbg , n=10 ) , a supine bridge 
 exercise on a togu balance pad group ( sbtg , n=10 ) , and a unilateral bridge exercise group 
 ( ubg , n=10 ) . 
 [ methods ] the sbg patients underwent supine bridge exercise , the sbtg 
 patients underwent supine bridge exercise with a togu balance pad , and the ubg patients 
 underwent unilateral bridge exercise . 
 all groups received 20 minutes of training per day , 
 five times per week , for four weeks . 
 [ results ] all groups showed significant changes in 
 weight bearing in a standing position after the intervention . 
 the sbtg and ubg groups 
 showed significant changes in balance ability . 
 [ conclusion ] according to the results of 
 this study , bridge exercise was effective in improving weight bearing in a standing 
 position and improving balance on stroke patients . 
 the bridge exercise with a togu balance 
 pad and the unilateral bridge exercise were especially more effective in anterior , 
 posterior length in limit of stability following on standing .