human beings walk upright and maintain their postures with a narrow base of support and 
 with the center of gravity of the upper trunk . even if muscle tension slightly loosens , low 
 back pain occurs because of stress from the mechanical posture of the muscle involved1 . this causative factor of low back pain can 
 lead to problems in sense and timing of muscle contraction awareness , sense of heaviness , 
 acting force , and acting load force2 . of 
 the cases of low back pain syndrome , 80% are related to the lumbar disk ; and herniation of 
 disk material is known as a secondary inflammatory response to stimulation of the dorsal 
 root ganglion and nerve root is known as the cause of low back pain . the remaining 20% of 
 cases are directly related to posterior elements such as lumbar facet joint , ligament , 
 lamina of the vertebral arch , and fascia . in addition , the action of the local muscles 
 attached directly to the spine plays an important role in maintaining spinal segmental 
 stability3 and providing trunk stability 
 generally4 . in particular , lumbar disk 
 herniation causes herniation of part or all of the nucleus pulposus by rupture of the mid , 
 internal , or lateral fiber of the annulus fibrosus through an external force or lumbar disk 
 degeneration . it is a disease that induces neurological signs such as hypoesthesia , muscle 
 weakness , and radiating pain in the constricted innervation area , with back pain in the 
 local part by pressing the dura mater or nerve root . generally , thermotherapy and electrotherapy have been used in physical therapy as 
 interventions for low back pain syndrome . in addition , application of surface heat such as a 
 hot pack and infrared light , and deep heat such as ultrasonography , short waves , and 
 microwaves has been used in thermotherapy6 . spinal stabilization exercise is another widely used intervention 
 method that improves muscle strength and trunk endurance , and stabilizes nervous system 
 control of muscles and muscle coordination . therapeutic 
 methods for herniated intervertebral disks are divided into conservative and operational 
 therapies . excluding 5% of patients , most undergo conservative therapy but anti - inflammatory 
 drugs , joint mobilization , acupuncture , traction , and so on are being used as interventions 
 to recover degenerative disks and improve neurological symptoms8 . among these interventions , traction therapy is essential in 
 clinical therapy , but its effect is not clear and differences in viewpoints at home and 
 abroad are evident9 . recently , spinal 
 decompression therapy is being performed to improve the limitations of traction therapy , as 
 it does not have to set a direction and traction force unlike traction therapy . adjusting 
 the angle and direction of the traction force by adjusting the position of the disk by using 
 a computer program therefore , this study measured disk height after decompression therapy and measured the 
 activities of muscles that provide overall trunk stability by overcoming the gravity applied 
 to the body . in addition , we aimed to 
 clarify the difference between the therapeutic effect of traction therapy and that of 
 decompression therapy , and their clinical therapeutic significance by comparing low back 
 pain disability index between the two intervention groups . this study was approved by the bioethics committee ( institutional review board ) of sehan 
 university center ( approval no . the subjects were 31 patients 
 aged 35 to 50  years who had unilateral or bilateral lumbar and radicular leg pains , who 
 attended a medical institution located in jeollanamdo , south korea , between february 4 , 
 2016 , and april 3 , 2016 , for 2 months . they showed more than one bulging of the 
 intervertebral disks on magnetic resonance imaging mri , had had the onset of illness for 
 less than 6 months , and did not receive spinal depression therapy . in addition , their 
 complaint of pain matched the neurological symptoms , and their mean score in the oswestry 
 disability index ( odi)korean version questionnaire was > 30 points ( table 1table 1.characteristics of the study subjectsitemsexperimental group ( n=15)control group ( n=16)age ( years)42.5  6.345.2  7.3height ( cm)167.1  4.7168.3  3.9weight ( kg)61.7  6.865.4  7.1odi ( point)34.4  3.935.3  4.7gender ( male / female)8/77/9data are presented as mean  sd , obtained by using the shapiro - wilk test . data are presented as mean  sd , obtained by using the shapiro - wilk test . odi : oswestry disability index in this study , an intervention program was conducted in 31 patients with lumbar herniated 
 intervertebral disks . fifteen subjects were randomly selected for the experimental group and 
 received decompression therapy and trunk stabilization exercise . sixteen subjects were 
 randomly selected for the control group and received traction therapy and trunk 
 stabilization exercise . these intervention programs were conducted for 3 weeks , and the disk 
 heights at l4 and l5 were measured by using mri . moreover , trunk muscle activities were 
 measured by using surface electromyography ( semg ) , and the lumbar pain disability index was 
 calculated by using the odi and then analyzed and compared between the groups . the 
 participants understood the purpose of this study very well and agreed to participate in 
 this study voluntarily by providing written informed consent . vertebral height and disk herniation index were determined by using mri ( signa hde 1.5 t , 
 ge corporate , usa ) . disk height was analyzed by using t2-weighted axial - section mri , and the 
 images were analyzed by using the pacs ( picture archiving and communication system ) . the 
 subject lay supine , and then the researcher put a cushion under the subject s knee and had 
 the subject bend the knee at a 25 angle . in this position , 1.measurement of lumber disk height . a : anterior disk height , b : middle disk height , c : 
 posterior disk height . a : anterior disk height , b : middle disk height , c : 
 posterior disk height . disk height : ( a + b + c)/3 ( mm ) disk herniation index measurement : the disk and intervertebral foramen were measured at 
 intercept of the axial direction . the sagittal distance of the herniated disk was recorded 
 as the maximum anteroposterior disk height ( ab ) , and that of the vertebral foramen was 
 recorded as the maximum anteroposterior canal length ( ef ) . the width of the herniated 
 material was measured by drawing a line at the mid level of the maximum anteroposterior disk 
 length ( cd ) . the width of the spinal canal was calculated at the same level ( gh ) . the 
 formula used for calculating the disk herniation index was ( [ ab cd]/[ef gh ] ) 1,000 ( fig . ab : maximum anteroposterior disk 
 height , cd : width of the herniated material at the level of the mid ab distance , ef : 
 maximum anteroposterior canal length , gh : width of the spinal canal at the level of 
 the mid ab distance . the herniation index is calculated as ( [ ab cd]/[ef gh ] ) 
 1,000)10 , 11 . ab : maximum anteroposterior disk 
 height , cd : width of the herniated material at the level of the mid ab distance , ef : 
 maximum anteroposterior canal length , gh : width of the spinal canal at the level of 
 the mid ab distance . the herniation index is calculated as ( [ ab cd]/[ef gh ] ) 
 1,000 the four - channel semg system mp 100 ( biopac , usa ) was used to measure the activities of the 
 trunk muscles , and the sampling rate for collecting emg signals was set at 1,000  hz . the subjects skin was cleaned by removing 
 hair , and dead skin cells were removed by using thin sandpaper to minimize skin resistance 
 to the emg signals . two 
 ag / agcl surface electrodes were attached to the belly of each muscle in a direction parallel 
 to the muscular fiber at 2-cm intervals . standard electrodes were attached to the spinous 
 process of the 12th thoracic vertebrae and scapula spine , which are the protruding parts . the emg signals from the right rectus abdominis , transverse abdominis , external oblique 
 abdominis , and erector spine muscles were collected . the sampling rate for emg signal 
 collection was set at 1,000  hz , and the notch filter was set at 60  hz . the band pass filter signals from the measured muscles were converted to root mean square 
 ( rms ) , and emg signal analysis was performed by using the acqknowledge 3.9.1 software 
 program ( biopac ) . emg data of the rectus abdominis , transverse abdominis , and external 
 oblique abdominis muscles were collected while the subject was touching the knees with both 
 hands in supine position for 5 seconds . for the measurement at the erector spine muscle , the 
 subjects lay in a prone position and flexed both arms maximally and then extended their 
 trunks maximally for 5 seconds . the emg signal produced while performing this movement was 
 set as a particular action , and the emg signal while standing motionless for 5 seconds was 
 set as the standard action . it was regarded as the reference voluntary contraction ( rvc ) , 
 and the % rvc method standardized based on rvc was used . patients who complained of pain and 
 difficulty in performing movement were excluded from this experiment . the odi was measured by using the korean version of the odi questionnaire to quantify 
 physical difficulty in daily life due to lumbar pain . it is composed of 10 items , and each 
 item was evaluated on a scale of 05 points . in this questionnaire , the higher the score , 
 the more severe the disability . in the korean version , in consideration of the korean 
 culture , the item about sexual life is excluded . thus , it consists of 9 items ; and each item 
 was evaluated with a score from 0 to 5 , and the highest possible total score was 45 points . the total score was divided by the number of items 5 and was converted into a 
 percentage12 . the trunk stability exercise described by lee et al.13 , 14 was used as spinal and 
 pelvic stabilization exercise . it is composed of step 1 ( awareness stage ) , step 2 
 ( associative stage ) , and step 3 ( exercise task stage ) based on the research of ok 
 stage)15 . the exercise method was 
 performed for 30 minutes per session , four times a week , for 3 weeks and was applied step by 
 step in subjects considering their exercise ability ( table 2table 2.intervention program for trunk muscle stabilizationstagetimecontentsprogramwarm - up exercise5  minwhole - body flexibility exerciseupper and lower extremity stretching and joint moving 
 exercisesmain exercise20  mintrunk muscle stabilization exercise1 . pelvic posterior tilting in the supine position with flexion of 
 both kneesstage 12 . abdominal draw - in in the supine position with flexion of both 
 knees3 . pelvic anterior tilting in the supine position with extension of 
 both knees4 . abdominal draw - in in the supine position with extension of both 
 kneesstage 25 . unstable bridging : bridging with extension of the left / right 
 legcooling - down exercise5  minbreathing and aerobic exercisesbreathing with the abdominalis muscle ) . the automatic electric traction equipment rehatrac rc-100 ( sakai , japan ) was used for 
 traction therapy . the duration of traction was 15 minutes , and the ratios of hold and rest 
 times were 2:1 and 60:30 sec , respectively . the traction force for resting time was set to 
 half of the traction force used in hold time . traction force was started at one fourth of 
 each weight and gradually increased in each session until the subjects did not feel 
 uncomfortable . in the last week , the standard of the maximum traction force was half of the 
 subjectsthweights . the pelvis was fixed with a pelvic stabilization belt , and the thorax was 
 fixed with a thorax stabilization belt . spinal decompression therapy was performed by using a lumbar decompression device max - d 
 ( medirex , korea ) , and the subjects lay on a traction table in the supine position . their 
 knees were naturally positioned in a 90 angle on the knee support fixture installed in the 
 device . the ankle was fixed with a hydraulic device according to the subject s body type . traction force and movement of the low extremity were supposed to be delivered through the 
 fixed ankle . the upper extremity was fixed by using a trunk stabilization belt and an air 
 pumping apparatus to maintain lumbar lordosis . a pelvic tilt of 15 was applied for patients 
 with a lumbar herniated intervertebral disk at the l4 and l5 levels . the subjects were 
 comfortably positioned in the device ; then , their lower limbs were pulled within range so as 
 not to make them feel uncomfortable during steps 1 to 5 of delivering traction force through 
 the hydraulic device . the subject s upper extremities were pulled within range so as not to 
 make them feel uncomfortable during steps 1 to 5 , using a trunk stabilization belt . first , 
 the multi - mode of an automatic program of a decompression therapy device was used for steps 
 1 to 5 . this multi - mode was programmed to make the lower part move in multiple directions . traction force was started at one fourth of the subjects weight and increased by 2  kg at a 
 steady rate daily . when pain occurred according to the increase in traction force , the 
 traction force was lowered or maintained . the traction force 
 for rest time was set to half of the traction force used in hold time . both the traction and 
 decompression therapy groups received their respective therapies once a day and five times a 
 week for the first week and then once a day , four times a week ( total 8 times ) for the next 
 2 weeks . the normality of the general 
 characteristics of the subjects , and the respiratory muscle and physical activities of both 
 groups were tested by using the shapiro - wilk test . no special variables related to the general characteristics of the subjects were found 
 between the groups , thus indicating normality ( table 
 1 ) . the activities of the rectus abdominis , transverse abdominis , and external 
 oblique muscles increased significantly in both the experimental and control groups 
 ( p<0.05 ) . the activity of the erector spinal muscle decreased significantly in comparison 
 with the changes in both groups ( p<0.05 and p<0.01 , respectively ; table 3table 3.comparison of changes in muscle activity and disk height within and between the 
 experimental and control groupsgroupprepost%rvcraexperimental group50.8  4.754.1  3.2*control group51.2  5.153.8  5.2*taexperimental group 47.1  3.649.7  4.1*control group45.9  3.748.7  4.9*eaoexperimental group 45.3 2.247.5  2.4*control group45.7  3.248.1  2.1*esexperimental group 59.4  5.253  5.4***control group55.1  4.852.7  5.2*disk height ( mm)experimental group 7.1  2.77.3  1.9control group6.8  2.36.8  1.7disk herniation indexexperimental group284  12.3198  22.6**control group264  9.5248  16.3**p<0.05 , * * p<0.01 . ra : rectus abdominis muscle , ta : transverse abdominis muscle , 
 eao : external abdominal oblique muscle , es : erector spine muscle ) . this was the only significant difference between the groups ( p<0.05 ; 
 table 3 ) . the disk herniation index in the 
 experimental group decreased significantly ( p<0.01 ) in comparison with the changes in 
 both groups . the difference in the changes in disk herniation index between the groups was 
 significant ( p<0.05 ; table 3 ) . ra : rectus abdominis muscle , ta : transverse abdominis muscle , 
 eao : external abdominal oblique muscle , es : erector spine muscle in this study , 31 patients with lumbar herniated intervertebral disk were randomly assigned 
 to receive either trunk stabilization exercise and decompression therapy or traction therapy 
 and trunk stabilization exercise . the 
 disk heights of the l4 and l5 segments were measured before and after the intervention by 
 using mri . in addition , trunk muscle activities were measured by using semg , and lumbar pain 
 disability index was calculated by using the odi questionnaire and then analyzed and 
 compared between the groups . guehring et al.16 reported that while 
 decompression by distraction in an animal model with degenerative disk was conducted for 28 
 days , the detection rate of degenerative change on mri decreased , gene expression levels of 
 disk matrix components increased , and the nucleus pulposus was regenerated . formation of the 
 structural material of the matrix increases with the increase in hydrostatic pressure 
 through decompression , moisture content increases through the improvement in the combining 
 ability with moisture , and nutrition supply can be expected to increase owing to the 
 improvement of degenerative change . apfel et al.17 insisted that 30 patients with discogenic low back pain or disk 
 herniation received treatment by using decompression therapy equipment for 6 weeks and 
 conducted a cohort study that compared disk heights by using ct . kwon et al.11 performed 
 acupuncture , cupping therapy , medicine treatment , and decompression therapy in six patients 
 with disk disease . they reported significant differences in disk height and disk herniation 
 index , and positive changes as results of their research . moreover , park and kim18 compared disk herniation index and disk 
 height by using mri after applying traction and decompression therapies in 60 patients . as a 
 result , they observed a significant difference in disk herniation index but no significant 
 difference in disk height . this study supported the results of advanced studies because no 
 significant difference in disk height was found in both groups , but a significant difference 
 in disk herniation index was found in the decompression therapy group . various factors cause 
 the discrepant results between the present study and the advanced study , such as disk 
 disease duration and activities of daily living . in particular , the reasons for having no 
 difference in disk height could be that the patients were exposed to gravity in daily living 
 and that treatment periods differed between the two studies however , a significant 
 difference in disk herniation index was found between the two groups . only 
 disk separation was discussed as the mechanism that explains the effectiveness of 
 conventional traction therapy , and the effectiveness of automatic traction therapy for 
 patients with chronic discogenic back pain in relation to spine decompression remains 
 unclear . by comparison , kwon et al.11 
 suggested that decompression therapy supplemented the limitation of traction therapy and had 
 a great advantage of inducing physical change to the disk . it is known that it can measure 
 load applied to the spine by using an electronic control system and allows delivery of 
 traction force to the spine because based on the result , muscle tone did not occur by 
 controlling the speed of traction therapy . in terms of muscle activity , the activity of the 
 erector spine muscle in the decompression therapy group decreased significantly . inflammation , pain caused by the inflammation , and neurological manifestations were observed 
 in the paraspinal muscles as symptoms of disk disease increased intervertebral foramen 
 diameter by decompression can induce an increase in blood flow in the blood vessel within 
 the foramen and intervertebral foramen , and increased blood flow can lead to decreased 
 muscle tension and pain by removing inflammatory exudation20 . based on these results , the paraspinal muscles were verified to 
 have a positive response to trunk stabilization exercise after decompression therapy , it is 
 considered more effective clinically than conventional traction therapy as intervention 
 method for patients with disk disease . normalizing the general 
 characteristics of the study subjects was difficult because the study period was short and 
 the subjects daily lives were not properly controlled . however , decompression therapy can 
 be considered a more effective intervention method for patients with disk disease in the 
 light of disk height and disk herniation index , change in muscle activity , and many advanced 
 research studies . prospective research on this intervention with adjustment of the study and 
 disease periods will be needed in the future .
[ purpose ] this study was conducted to clarify the difference in therapeutic effects 
 between traction and decompression therapies , and their clinical therapeutic significance . 
 [ subjects and methods ] the subjects were 31 patients aged 35 to 50  years who had 
 unilateral or bilateral lumbar and radicular leg pain . 
 an intervention program was 
 implemented in 31 patients with lumbar herniated intervertebral disks . for the 
 experimental group , 
 15 subjects were randomly selected to receive decompression therapy 
 and trunk stabilization exercise . 
 for the control group , 16 subjects were randomly 
 selected to receive traction therapy and trunk stabilization exercise . 
 [ results ] 
 activities of the rectus abdominis , transverse abdominis , and external oblique muscles 
 increased significantly in both groups . however , the activity of the erector spine muscle 
 decreased , which was the only significant change in muscle activity among those of the 
 other muscles in both groups . 
 the disk herniation index in the experimental group 
 decreased significantly in comparison with that in the control group , and the difference 
 in the change in disk herniation index between the groups was significant . 
 [ conclusion ] 
 decompression therapy was demonstrated to be more effective clinically than conventional 
 traction therapy as an intervention method for disk disease .