walking is the most frequent movement in the daily lives of humans , and stable walking is a 
 basic element of a healthy and pleasant life1 .
maintaining stability is most important in moving the body forward 
 through repeated use of the legs2 .
the 
 muscles of the hip joint are responsible for stabilizing the pelvic and lumbar regions and 
 play an important role in kinematic control during walking3 .
the increased incidence of a sedentary lifestyle and the lack of exercise among modern 
 people has resulted in an increased incidence of back pain , and a habitual sedentary 
 lifestyle decreases abdominal muscle strength and increases the degree of body 
 imbalance4 .
an excessive biomechanical 
 load on the lumbar area can induce pain in the lumbar region , due to abdominal muscle 
 atrophy and weakening , and spinal joint instability , and decrease joint endurance , 
 flexibility , and range of motion5 .
lumbar 
 muscle weakness and imbalance are major factors in reduced exercise performance , and 
 strengthening the muscles in the lumbar region reportedly facilitates efficient functioning 
 of the upper and lower body6 .
back pain decreases an individual s walking speed and pain - related gait disturbances 
 typically appear association with in back pain7 .
the walking characteristics of patients with back pain include 
 decreased walking speed and an asymmetrical gait posture8 . to prevent and treat these conditions , strength training and 
 stabilization exercises are performed , including mat , ball , and sling exercises , and 
 plyometric and circuit training .
ultimately , the purpose of stabilization exercises is to 
 recover movement control and balance by increasing spinal and pelvic stability during 
 functional posture and movement9 . to increase the exercise performance rate , an exercise that can easily be performed by 
 anyone
walking is a simple exercise with a low probability of injury that 
 requires no special technique and can be performed by anyone10 . however
, walking is a representative aerobic exercise , and 
 improper walking form with body imbalance may cause pain .
therefore , in this study , we 
 investigated the effects of running in place accompanied by the abdominal maneuver , a basic 
 stabilization exercise , on gait characteristics .
this study selected 30 male and female college students who were randomly assigned to 
 either the training group ( tg ) ( male , 2 ; female , 13 ) , which performed a walking in place 
 exercise , or the control group ( cg ) ( male , 2 ; female , 13 ) , which did not perform the walking 
 in place exercise .
the selection criteria included people with no spinal abnormality , lumbar 
 pain , or neurological disorders , who did not drink before the experiment , and who were 
 neither overweight nor taking medicine .
people who regularly performed weight training or 
 other exercises were excluded , because these exercises may affect gait characteristics .
this 
 study was approved by the korea nazarene university s institutional review board and the 
 subjects were safely protected throughout the experiment .
all of the subjects understood the 
 purpose of this study and provided their written informed consent prior to participating in 
 accordance with the ethical principles of the declaration of helsinki .
the mean age , height , and weight of the tg participants in this study were 21.50.5  years , 
 162.47.1  cm , and 55.46.7  kg , respectively , while those of the cg participants were 
 20.50.8  years , 163.34.9  cm , and 57.69.2  kg , respectively .
sex data were analyzed using 
 the  test , while age , height , and weight data were analyzed using the 
 independent t - test .
there were no intergroup differences ( p>0.05 ) . to maintain posture during the running in place exercise
, the students were placed at the 
 very center of a marked 30-cm square space .
the jaw was withdrawn to maintain the cervical spine in the 
 neutral position and the transverses abdominis and multifidus muscles were contracted using 
 the abdominal drawing - in maneuver to maintain the waist and pelvis in the neutral position . 

the participants feet were positioned 10  cm apart and one knee was bent 90 and elevated to 
 reach the hip joint ; the elbow opposite to the elevated leg was bent 90 and elevated to eye 
 level .
participants ran with arms and legs crossed in the sagittal plane , and the procedure 
 was repeated for a set number of times .
while exercising , the subjects were advised to 
 maintain their posture with minimum deviation in all directions ( left and right or to and 
 fro ) within the restricted space .
a total of three exercise sets were performed , and each 
 set consisted of 20 times running in place , a 15-s rest , 20 times running in place , a 15-s 
 rest , 30 times running in place , a 20-s rest , 30 times running in place , a 20-s rest , and 30 
 times running in place .
the rest between sets was 3  min long and one performance time was 
 defined as when both feet touched the ground .
each participant made 17 running motions every 
 10 s. to apply the optimal exercise intensity setting for the students and to increase the 
 load during the total 6-week exercise program , two sets were performed in the first and 
 second week , and three sets were performed in the third to sixth weeks .
one 30-min round of 
 exercise was performed three times a week for 6 weeks .
the cg participants did not perform 
 any particular exercise and they were assessed twice at the beginning and end of the 
 exercise intervention .
gait analysis was performed using the optogait gait analysis system ( microgate italy , 
 bolzano - bozen , italy ) , a device consisting of an optical detection system .
the transmitter 
 bar has 96 light - emitting diodes ( leds ) that communicate in the infrared spectrum , the 
 receiver bar , which is positioned opposite it , has the same number of leds .
the transmitter 
 and receiver bars of the optogait were installed on both sides of a treadmill .
communication 
 between the bars is blocked by the subjects movements during walking , and the interference 
 is used to derive the step length difference ( sld ) , stance phase difference ( stpd ) , swing 
 phase difference ( swpd ) , single support difference ( ssd ) , and step time difference ( std ) are 
 evaluated . using a data capture rate of 1,000 transmissions / receptions per second , running , 

a series of jumping tests , or the time on the ground or in the air can be accurately 
 measured . from these basic data ,
the software analyzes the data measured in real time in a 
 series of movements .
the data collected by the optogait uses the differences in gait 
 variables between the left and right legs ; the smaller the difference , the greater the 
 stability and balancing ability .
the collected data were statistically processed using spss 12.0 ko ( spss , chicago , il , 
 usa ) .
the paired t - test was used to test the significance of the differences between before 
 and after the experiment in each group , and the independent t - test was used to test the 
 significance of the differences between the two groups .
all data are shown as means and 
 standard deviation , and the significance level ,  , was chosen as 0.05 .
when pre- and post - intervention values of tg and cg were compared , sld , swpd , ssd , and std 
 of subjects in the tg were significantly different , but no significant difference in any 
 parameter was found in the cg ( p<0.05 ) ( table 
 1table 1.comparison of pre- and post - intervention sld , stpd , swpd , ssd and std in each 
 group ( meansd ) ( unit : sld - cm , stpd , swpd , ssd , std-%)categorygrouppre - interventionpost - interventionsldtraining group*3.41.51.60.8control group3.53.83.22.1stpdtraining group2.72.91.10.9control group2.21.52.61.4swpdtraining group*3.01.81.80.8control group2.71.73.22.9ssdtraining group*3.32.31.51.0control group2.81.83.02.1stdtraining group*3.21.91.91.0control group3.41.63.01.9 * p<0.05 ; sld , step length difference ; stpd , stance phase difference ; swpd , swing 
 phase difference ; ssd , single support difference ; std , step time difference ) . * p<0.05 ; sld , step length difference ; stpd , stance phase difference ; swpd , swing 
 phase difference ; ssd , single support difference ; std , step time difference when pre - intervention , post - intervention , and the change between pre- and post - intervention 
 of tg and cg were compared , there were no significant differences in any of the 
 pre - intervention parameters ; however , post - intervention sld , stpd , and ssd values were 
 significantly different , and the pre- and post - intervention changes in stpd , swpd , and ssd 
 values were also significantly different between the two groups ( p<0.05 ) ( table 2table 2.comparison of sld , stpd , swpd , ssd and std between the training group and control 
 group ( meansd ) ( unit : sld - cm , stpd , swpd , ssd , std-%)categorytraining groupcontrol grouppre - interventionsld3.41.53.53.8stpd2.72.92.21.5swpd3.01.82.71.7ssd3.32.32.81.8std3.21.93.41.6post - interventionsld*1.60.83.22.1stpd*1.10.92.61.4swpd1.80.83.22.9ssd*1.51.03.02.1std1.91.03.01.9change between pre- and post - interventionsld1.71.90.33.8stpd*1.53.10.31.6swpd*1.11.90.42.5ssd*1.82.60.12.0std1.21.90.42.5 * p<0.05 ) .
, it enables the body to 
 assume a new posture with smooth movement of the center in preparation for the movement of 
 the arms and legs against gravity11 . in 
 particular , when there is a problem in the lumbar region , the walking speed decreases and an 
 asymmetric gait posture develops8 , 
 suggesting that stability of the body center has a large impact on limb movement .
judge et 
 al.12 reported that muscle 
 strengthening exercises , stretching , and balance exercises improve muscle strength and 
 walking speed .
brill et al.13 reported 
 that the walking time and number of steps after exercise improved by 3.9% and 13.6% in 
 elderly individuals , respectively .
the abdominal drawing - in method effectively stabilizes 
 muscles in the lumbar region , including the transversus abdominis14 , 15 , and running in 
 place , which is similar to plyometric exercise , effectively activates the muscles around the 
 hip joint3 . in this study
, we observed a remarkable reduction in the differences in the gait 
 characteristics of the left and right legs in tg compared with those in the cg , which 
 suggests that the combination of dynamic lumbar stabilization exercises and upper and lower 
 extremity movements improved subjects stability and balancing ability .
panjabi16 emphasized the importance of lumbar 
 stabilization exercise in correcting a disturbed gait , and topp et al.17 asserted that a muscle strengthening program effectively 
 improves stable walking speed and balancing capability .
in addition , approximately 80% of 
 the time used for walking is occupied by the body being supported on one foot .
the 
 alternating style of one - foot standing seems to be an important factor in balancing the 
 trunk , and grabiner et al.18 reported 
 that trunk muscle strength is an important factor in gait stability . in conclusion ,
running in place accompanied by the abdominal drawing - in technique helps 
 lumbar stabilization , strengthens and activates the muscles around the pelvis and hip 
 joints , and seems to have a positive effect on gait symmetry .
 [ purpose ] this study was conducted to investigate the effects of running in place 
 accompanied by abdominal drawing - in on the gait characteristics of healthy adults . 
 
 [ subjects ] the total number of subjects was 30 , and 15 were randomly placed in the 
 training group ( tg ) and 15 in the control group ( cg ) . 
 [ methods ] to determine the gait 
 characteristics of tg and cg , step length difference ( sld ) , stance phase difference 
 ( stpd ) , swing phase difference ( swpd ) , single support difference ( ssd ) , and step time 
 difference ( std ) were evaluated using optogait , a gait analysis system . 
 [ results ] when the 
 pre - intervention and post - intervention results of tg and cg were compared , statistically 
 significant differences in sld , swpd , ssd , and std of tg were found . 
 [ conclusion ] running 
 in place accompanied by abdominal drawing - in might help reduce the deviation between left 
 and right gait variables during walking . 
INTRODUCTION
SUBJECTS AND METHODS
RESULTS
DISCUSSION