low back pain ( lbp ) is a representative musculoskeletal disease with a current prevalence 
 of 6090% ; more than 80% people will experience lbp at least once in their lifetime .
lbp occurs when a poor lifestyle weakens the muscular strength of the waist and excessive 
 loads on and tensions of the muscles create pain .
mediating muscle weakening to stabilize 
 the trunk is an important aspect in the recovery of body function in patients with lbp2 .
structural changes of the waist muscles and 
 histomorphological changes lead to chronic lbp ; in particular , weakening and atrophy is more 
 common in the muscle fibers that stabilize the waist3 .
in addition , if pain develops in the muscles , weakening and atrophy 
 will occur , the ligaments and joints will become stiff , and activity will decrease . a 
 vicious circle of worsening pain repeats by muscle rigidity and sprain4 .
therefore , it is important to maintain mechanical alignment 
 of the trunk muscles to prevent lbp .
it is necessary to keep an upright pattern of muscle 
 activity as well as proper muscle length and strength5 .
intra - abdominal pressure that is produced by the connection of 
 trunk stabilization and respiratory muscles affects waist stability and protects the trunk 
 muscles6 .
effective mediation is 
 reportedly accomplished using simultaneous breathing exercises to relax excessive muscle 
 tension7 .
in addition , if 
 intra - abdominal pressure increases by diaphragm stimulating activity by performing breathing 
 exercises , even the pelvic floor muscles will be activated . as such , contraction of the 
 abdominal muscles during breathing can easily activate even the deep stabilization 
 muscles8 .
clinicians recognize that 
 stabilization exercises to strengthen the waist and abdominal muscles are very important . 

mediating breathing exercise activates the trunk muscles more effectively and decreases lbp . 
 as such
, this study intended to induce activity of the trunk muscles that contribute to 
 spinal stabilization and increase intra - abdominal pressure by performing exhalation 
 exercises as well as to investigate the effects on trunk muscle activity and oswestry 
 disability index ( odi ) by comparing spinal stabilization and exhalation exercises .
we intend 
 to utilize this exercise method to effectively treat lumbar pain in the future .
subjects were 20 male patients ( age 3145  years ) with chronic lbp who visited b hospital 
 located in jeollanamdo , south korea , and complained of lbp over 12 weeks .
patients with 
 acute pain , continuous severe pain , spondylolysis , or spondylolisthesis were excluded from 
 the study .
those who had paresthesia , myoparalysis , or psychological problems as well as 
 those who had difficulty in performing exercise due to lack of comprehension were also 
 excluded .
subjects who understood the purpose of this study and consented to participate 
 were selected ( table 1table 1.subjects characteristicsitemsexperimental group(n=10)control group(n=10)age ( years)42.5  5.340.1  5.3height ( cm)168.5  5.7166.3  4.9weight ( kg)64.3  9.865.4  8.2odi ( points)26.2  4.225.3  3mean  sd , shapiro - wilk test .
odi : oswestry disability index this study was approved by the bioethics committee of sehan university center ( approval 
 number : 2015 - 7 ) .
this study included 20 male patients with chronic lbp , and 10 subjects each were randomly 
 allocated to the exhalation exercise group ( experimental group ) and trunk stabilization 
 group ( control group ) .
the intervention program consisted of daily 30-minute sessions once 
 daily 4 times a week for 6 weeks .
the trunk muscle activities and odi were calculated , 
 compared , and analyzed before versus after the intervention program by using surface 
 electromyography ( semg ) . a surface electromyography ( emg ) mp
100 system ( biopac system inc , goleta , usa ) was used to 
 measure trunk muscle activities , with a sampling rate of 1,000  hz . the frequency band - pass 
 filter was set at 20450  hz .
each subject s hair was removed and dead skin cells were 
 removed using a thin sandpaper to minimize skin resistance to the emg signal .
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 .
the emg signals of the right rectus abdominis , transverse abdominis , external 
 oblique abdominis , and erector spine muscles were collected .
the sampling rate for the emg 
 signal collection was set to 1,000  hz , the notch filter was set to 60  hz , and the band pass 
 filter was set to 20450  hz . the signals were converted to root mean square ( rms ) values , 
 and an emg signal analysis was conducted using acqknowledge 3.9.1 software ( biopac ) .
emg 
 data were collected while the subjects were performing the stabilization exercise and 6 of 
 the 10 seconds were used .
maximal voluntary isometric contraction ( mvic ) was used to standardize the emg signal 
 during the stabilization exercise9 .
the 
 mvic of the rectus abdominis muscle was measured in the knee - bent position , with both arms 
 on the chest and the trunk bent at 45 at maximum resistance .
the mvic of the transverse 
 abdominis muscle was measured in the knee - bent position , with both arms on the chest and 
 during sit - ups , twisting the trunk from left to right at maximum resistance10 .
the mvic of the external oblique 
 abdominis muscles was measured while rotating the trunk to opposite side with the trunk 
 bending , while the mvic of the erector spinae muscles was measured in a prone position , with 
 both hands on back of the head and the trunk extended at maximum resistance11 .
mvic was measured when the researcher 
 made the subjects perform isometric contraction maximally while a beep was played for 5 
 seconds .
the first and last seconds of the measurements were excluded ; thus , a 3-second 
 measurement was analyzed .
the researcher continuously encouraged subjects to maintain a 
 maximum contraction and the percentage value of the muscle was the highest average value of 
 3 measurements .
the subjects were given a 30-second rest after the mvic of each muscle was 
 measured12 .
the odi was measured using the korean version of the odi to quantify physical difficulties 
 in daily life due to lbp ( cronbach s alpha=0.92 ) .
the original odi is composed of 10 items 
 evaluated as 05 points ( low to high severity ) . in the korean odi ,
considering the korean 
 culture , the item about sex life was excluded , so a total of 9 items were evaluated ( for a 
 highest possible score of 45 ) .
the total score was divided by number of items 5 and was 
 expressed as a percentage13 .
a trunk stabilization exercise , the modifying exercise method of urquhart et al.14 and steven et al.15 , which consists of 3 stages16 , was used .
the exercise was performed for 30 minutes a session 4 times a week for 6 
 weeks at an intensity acceptable to each subject ( table 
 2table 2.trunk muscle stabilization intervention exercise programstagetimecontentsprogramwarming - up exercise5  minflexibility whole - body exerciseupper - lower extremity stretching and joint moving 
 exercisemain exercise20  mintrunk muscle stabilization exercisestage 11 ) pelvic posterior tilting in a supine position with both knees 
 flexed2 ) abdominal draw - in in a supine position with both knees 
 flexed3 ) pelvic anterior tilting in a supine position with both knees 
 extendedstage 24 ) abdominal draw - in in a supine position with both knees 
 extended5 ) bridging in supine positionstage 36 ) ball bridge7 ) unstable bridging : bridging with extension of the left / right 
 legcool - down exercise5  minaerobic exercisebreathing with abdominal muscles ) . the bracing exercise was performed for 20 minutes a session , 5 times a week , for 6 weeks in 
 the group training the exhalation muscles17 . in this exercise method , the subjects bent their knees at 90 and 
 adjusted the alignment of their waist and pelvis in supine position .
a biofeedback system 
 was then attached to the waist and pressure was maintained at 40 mmhg .
the pressure of the 
 manometer increased from 40 mmhg to 70 mmhg and was maintained by quick contractions of the 
 abdominal muscles by the application of abdominal strain .
this exercise was intended to be 
 performed with the feeling that the trunk muscles spread outward and the rectus abdominis 
 muscles did not bulge while the subjects were able to breathe easily17 .
spss 18.0 for windows was used to process the data and the shapiro - wilk test was used to 
 test the normality of the subjects general characteristics , respiratory muscle activities , 
 and body functions of the groups .
a paired t - test was used to compare intragroup changes , 
 while analysis of covariance was used to compare intergroup changes .
there were significant differences in the rectus abdominis , transverse abdominis , external 
 oblique abdominal , and erector spinae muscle activation and in the odi within the 
 experimental group ( p<0.05 and < 0.001 , respectively ) .
there were significant 
 differences in the rectus abdominis muscle , external oblique abdominal muscle , erector 
 spinal muscle and odi within control group ( p<0.05 ) .
in addition , there was a meaningful 
 difference in the transverse abdominis muscle alone on comparing the change in trunk muscle 
 activity and in odi between the groups ( p<0.05 ) ( table 3table 3.comparison of change of muscle activity and odi within each group and between the 
 groupsgroupprepost%rvcraexperimental group 21.3  5.125.6  4.2*control group21.6  5.225.8  4.3*taexperimental group 16.2  2.419.4  3.1*control group14.3  3.215.7  3.6eaoexperimental group 16  2.520.2  2.1*control group17.3  3.221  3.5*esexperimental group 23  6.4928.2  6*control group26  5.1929.1  4.9*odiexperimental group 27.1  2.723.2  1.9**control group28.2  2.726.2  1.7**p<0.05 , * * p<0.001 .
ra : rectus abdominis muscle ; ta : transverse abdominis muscle ; eao : 
 external abdominal oblique muscle ; es : erector spinae muscle ; odi : oswestry disability 
 index ) .
ra : rectus abdominis muscle ; ta : transverse abdominis muscle ; eao : 
 external abdominal oblique muscle ; es : erector spinae muscle ; odi : oswestry disability 
 index
recently , interest in the use of breathing exercises such as abdominal respiration and yoga 
 breathing to improve vertebral joint stability and motor control is increasing18 .
hodges et al.3 found that the respiratory muscles are an important factor 
 affecting spinal stabilization .
in particular , if respiratory and abdominal muscle 
 activities are uncertain , spinal stabilization will decrease due to decreased 
 intra - abdominal pressure .
urquhart et al.19 reported that 
 activities of the deep abdominal muscles should be evoked using a combination of breathing 
 and stabilization exercises rather than stabilization exercises alone .
marshall et al.20 classified 20 patients with non - idiopathic 
 lbp into a stabilization exercise group with abdominal respiration exercise ( n=10 ) and a 
 general exercise group ( n=10 ) and compared their muscle activity and range of motion .
the 
 muscle activities of the abdominal rectus , external oblique abdominis , and erector spinae 
 muscle increased , as did range of motion of the waist .
this study s findings support 
 advanced research by drawing a conclusion that the activities of the rectus abdominis , 
 transverse abdominis , external oblique abdominis , and erector spinae muscles increased in 
 the experimental group performing breathing exercises .
there was a meaningful intergroup 
 difference in the transverse abdominis alone , in terms of the change of trunk muscle 
 activities .
the transversus abdominis muscle is located in the deepest part of the abdomen 
 and is called the corset muscle because it plays a role in stabilizing the waist and 
 creating abdominal pressure owing to being attached to the thoracolumbar fascia . of all of 
 the abdominal muscles , the transverse abdominis has the widest and closest attachment to the 
 thoracolumbar fascia .
ki and heo21 classified 24 patients with 
 chronic lbp into a spinal stabilization exercise with feedback respiratory exercise group 
 and a trunk stabilization exercise group that they performed 3045 minutes a session , 3 
 times a week , for 6 weeks . the spinal stabilization exercise with feedback respiratory 
 exercise increased stability of the vertebral joints and flexibility of the thoracic 
 vertebrae more than the spinal stabilization exercise only .
ferreira et al.22 reported that improvement in transverse 
 abdominis muscle activity was higer after postural control exercise than after conventional 
 physiotherapy , targeting 34 patients with chronic lbp .
in particular , those findings 
 supported ours since they showed that the transverse abdominis muscle plays an important 
 role in controlling vertebral shearing force .
yoon et al.23 studied 10 
 patients with chronic lbp who performed 3 types of stabilization exercises in the 
 quadrupedal position for 20 minutes and then compared trunk muscle activities .
the 
 activities of the back muscles of the trunk showed a higher increase in the group in which a 
 hand and a foot were asymmetrically lifted in the quadrupedal position than in the group in 
 which a hand was lifted in the quadrupedal position or in the group which a foot was lifted 
 in the quadrupedal position .
however , advanced studies have limited ability 
 to induce abdominal muscle contractions because most agonists were back muscles of the trunk 
 when the stabilization exercise was performed in various quadrupedal positions .
niemisto et 
 al.24 found that odi in the trunk 
 stabilization exercise group decreased meaningfully when trunk stabilization exercise and 
 conventional physiotherapy were mediated in 203 subjects with chronic lbp for 312 months . 

sung25 found that odi decreased 
 meaningfully after mediating spinal stabilization exercise for 4 weeks in 16 subjects with 
 chronic lbp .
kang and jeong26 found that 
 odi decreased in a spinal stabilization exercise group as a result of mediating spinal 
 stabilization exercises for 34 patients with chronic lbp for 4 weeks .
this study drew a 
 conclusion supporting advanced research because there were meaningful differences in odi . 

the reason for this is that the delivery of stimulation on pain receptor tissues such as 
 those around the spine and articular capsules and ligaments decreases as trunk stabilization 
 and breathing exercises strengthen the deep stability muscles and it affects abdominal 
 muscle functional recovery .
we found that they are effective to functional disability of lbp 
 by decreasing the delivery of stimulation to the pain receptor tissue such as that around 
 the spine and articular capsules and ligaments .
son27 found a disability index change , center of body gravity change , and 
 area decrease in both a spinal stabilization exercise group with abdominal respiration and a 
 spinal stabilization exercise group ; however , no intergroup change was seen .
regardless , 
 there was a meaningful difference in this study in direct opposition to that of advanced 
 research .
abdominal respiration mediation in advanced research is a type of breathing 
 exercise used in the resting state . on the other hand ,
exhalation exercise is more effective 
 at reducing odi because compensation in the lumbar region decreases largely as back and 
 waist mobility increase .
breathing exercises effectively increase muscle activity due to 
 training of the gross and fine muscles of the trunk . since it strengthens the muscles that 
 stabilize the body , the breathing exercise proved to be a very important element as it 
 relieves lbp , prevents lumbar pain , and prevents recurrence .
 [ purpose ] this study investigated the effect of exhalation exercises on trunk muscle 
 activity and oswestry disability index by inducing trunk muscle activity through 
 increasing intra - abdominal pressure and activating muscles , contributing to spinal 
 stability . [ subjects and methods ] this intervention program included 20 male patients with 
 chronic low back pain . a total of 10 subjects each were randomly assigned to an exhalation 
 exercise group as the experimental group and a spinal stabilization exercise group as the 
 control group . 
 [ results ] there were significant differences in the activities of the 
 rectus abdominis , transverse abdominis , external oblique abdominal , and erector spinae 
 muscles as well as in the oswestry disability index within the experimental group . 
 there 
 were meaningful differences in the activities of the rectus abdominis , external oblique 
 abdominal , and erector spinae muscles and in the oswestry disability index within the 
 control group . 
 in addition , there was a meaningful intergroup difference in transverse 
 abdominis muscle activity alone and in the oswestry disability index . 
 [ conclusion ] the 
 breathing exercise effectively increased muscle activity by training gross and fine motor 
 muscles in the trunk . 
 moreover , it was verified as a very important element for 
 strengthening body stability because it both released and prevented low back pain . 
INTRODUCTION
SUBJECTS AND METHODS
RESULTS
DISCUSSION