cervical and shoulder dysfunction in office workers is usually due to the work environment , 
 including job and sociopsychological risk factors1 .
the resulting pain and functional impairment affect the muscles , 
 skeleton , ligaments , cartilage , and nervous system , and result in musculoskeletal 
 dysfunction2 .
shoulder pain and 
 functional disorders are related to abnormal motion and the position of the scapula when it 
 is stabilized3 .
cervical pain leads to 
 impaired function , decreased occupational performance , and quality of life dissatisfaction 
 including social and economic loss4 .
weakness of the lower trapezius has a negative effect on scapular movement , with an 
 increase in shoulder joint weakness , because the lower trapezius is the primary muscle 
 maintaining the appropriate posture and alignment of the shoulder joint5 , 6 .
therapeutic interventions for shoulder pain include hyperthermia , cryotherapy , 
 transcutaneous electrical nerve stimulation , strengthening exercises8 , and stabilization exercises9 .
most of these interventions can relieve pain but are inefficient at 
 preventing the recurrence of pain and maintaining normal function3 .
the stability of the shoulder joint is important ; however , 
 the stability and strength of the muscle are more important because the shoulder is very 
 mobile3 .
postural stabilization is the state of maintaining a balanced body position , with the 
 muscle and skeleton in a specific space , and the ability to maintain the center of mass10 .
exercise stabilizes the scapula through 
 active movements of the muscles surrounding the scapula , and maintains the effective length 
 and tension of upper arm movement11 . 

rehabilitative ultrasound images ( rusi ) evaluate muscle mass , structure , and composition . 

it is easy to control 
 and accurately visualizes muscle structure and movement12 . in this study ,
a stability exercise was prescribed for normal scapular location and muscle 
 balance in order to determine the effect on scapular stability and rusi , and to provide 
 basic information for the rehabilitation of patients with shoulder pain .
a total of 38 office workers receiving physical therapy at seoul h hospital , who 
 voluntarily agreed to active participation , were included in this study .
the stability exercise for the shoulder was performed two 
 times per week , at 40  min per session , for a total of 6 weeks .
the general characteristics 
 of the subjects in the stability exercise group were as follows : 19 office workers ( 6 males 
 and 13 females ) , mean age 36.2  5.5  years , mean height 168.0  8.1  cm , and mean weight 57.8 
  11.3  kg .
on the other hand , the subjects in the manual therapy group had the following 
 characteristics : 19 office workers ( 6 males and 13 females ) , mean age 35.8  4.1  years , mean 
 height 167.2  7.3  cm , and mean weight 60.2  14.2  kg .
the present study was approved by the sahmyook university 
 institutional review board ( syuirb2015 - 014 ) .
the objective of the study and its requirements 
 were explained to the subjects , and all participants provided written consent , in accordance 
 with the ethical principles of the declaration of helsinki .
the scapular exercise for the shoulder joint was designed to correct the abnormal location 
 of the scapula3 .
the exercise involved the 
 upper trapezius , levator scapulae , suboccipital , sternocleidomastoid , and pectoralis major 
 and minor muscles ( all in a shortened state ) in lengthening and stretching , with 10 sets of 
 10-s sessions .
the following exercises were performed : isometric contraction in the supine 
 position , retracting the subject s chin for deep cervical flexor enhancement ; closed chain 
 knee push - up for the serratus anterior ; cow position and cat position for 10 sets of 10  s 
 each to increase mobility of thoracic and cervical musculature ; prone row and modified prone 
 cobra , as suggested by arlotta et al.13 , 
 to deactivate the upper trapezius and maximize lower trapezius activation ; cow position , cat 
 position , modified cat position , dead bug position , and plank , at 10 sets of 10  s each for 
 cervical , thoracic , and shoulder movement .
the manual therapy program consisted of 23  min of soft tissue mobilization of the upper 
 trapezius , levator scapulae , suboccipital , sternocleidomastoid , pectoralis major and minor , 
 deep cervical flexor , serratus anterior , rhomboid , and middle and lower trapezius muscles , 
 with prone thoracic mobilization , prone selected thoracic mobilization , cervical 
 mobilization , and thoracic mobilization . the forward head horizontal distance ( fhhd ) for cervical stability
was measured with the 
 exbody somatometric system ( pa-2010sm ; steps system inc . ,
the subjects were measured from the side in a natural position while wearing 
 shorts and shirts ; a marker was placed on the tragus and acromion process , and the forward 
 head position was evaluated by measuring the distance between the tragus and acromion 
 process . to assess changes in the rounded shoulder posture ( rsp ) ,
the length was measured to 1/20  mm 
 by using a vernier caliper . with the supine method ,
this was used to measure the length of the 
 pectoralis major ; however , it has good reliability ( intraclass correlation coefficient , 
 0.88 ) with or without symptoms in the shoulder related to the effect of the scapular 
 location on the shoulder joint14 .
an upper limb closed chain exercise test was used for the stability of the upper limb 
 ( sul)15 . in the performance of the 
 closed chain exercise test , the starting position , which had a width of 90  cm , was marked on 
 the floor , and both hands of the subjects were placed on the marker dots in order to form a 
 push - up position . to reduce changes in position ,
placement of one hand over the other 
 was counted as one , performed for 15  s , and the number was counted . between test 
 performances , the subjects were allowed a 1-min break ; measurements were performed two 
 times , and the mean value was used16 . in this study , a portable rusi device ( ugeo h60 ; samsung medison , seoul , korea ) was used to 
 examine the structural properties of muscles .
ultrasound examination was performed at 
 612  mhz in two - dimensional b - mode linearity , at t8 level , r=0.77 ( muscle thickness ) for the 
 lower trapezius structural examination17 ; 
 an average of two repetitions was used to measure values . the spss 18.0 program ( spss inc .
the 
 shapiro - wilk test was used to determine the distribution of the general properties and 
 outcome measures of the subjects .
the paired t - test was used to compare the pretest and 
 posttest results of fhhd , rsp , sul , and rusi within each group , and the independent t - test 
 was performed to compare the two groups before and after training
in the scapular stability exercise group , the fhhd was 9.5  cm before the training and 
 7.8  cm after the training , which was statistically significant ( p<0.001 ) .
the right - side 
 rsp showed a statistically significant decrease of 0.6  mm ( p<0.001 ) .
the left - side rsp 
 showed a statistically significant decrease of 0.5  mm ( p<0.001 ) .
the sul showed a 
 statistically significant increase of 4.3 ( p<0.001 ) . in the manual therapy group ,
the right - side rsp showed a statistically 
 significant decrease of 0.1  mm ( p<0.001 ) .
the left - side rsp showed a statistically 
 significant decrease of 0.1  mm ( p<0.001 ) .
the scapular stability exercise group showed greater improvements than the manual therapy 
 group in fhhd , left and right rsp , sul , and left and right lower trapezius in rusi ( table 1table 1.comparison of shoulder stability and rusi within and between groups 
 ( n=38)parametersvalueschange valuessseg ( n=19)mtg ( n=19)sseg ( n=19)mtg ( n= 9)beforeafterbeforeafterbefore - afterbefore - afterfhhd ( cm)9.5  2.47.8  1.98.4  2.38.2  2.31.7  0.80.2  0.2rt rsp ( mm)10.9  1.910.3  1.89.7  2.09.5  2.00.6  0.30.1  0.1lt rsp ( mm)10.5  2.09.9  1.89.2  2.19.0  2.10.5  0.30.1  0.1sul ( numb)9.5  3.213.7  2.88.8  3.59.3  3.74.3  1.20.5  0.5rusi in rt lt ( mm)3.6  0.93.9  0.93.3  1.23.4  1.20.3  0.20.1  0.1rusi in lt lt ( mm)3.4  0.83.7  0.83.1  1.13.2  1.10.3  0.20.1
p<0.05 , * * p<0.001 : significant 
 difference within the group , p<0.05 , p<0.001 : 
 significant difference between groups ; sseg : scapular stability exercise group ; mtg : 
 manual therapy group ; fhhd : forward head horizontal distance ; rsp : rounded shoulder 
 posture ; sul : stability of the upper limb ; rusi : rehabilitative ultrasound images ; lt : 
 lower trapezius ; lt : left ; rt : right ) .
p<0.05 , * * p<0.001 : significant 
 difference within the group , p<0.05 , p<0.001 : 
 significant difference between groups ; sseg : scapular stability exercise group ; mtg : 
 manual therapy group ; fhhd : forward head horizontal distance ; rsp : rounded shoulder 
 posture ; sul : stability of the upper limb ; rusi : rehabilitative ultrasound images ; lt : 
 lower trapezius ; lt : left ; rt : right
postural cervical pain decreases muscle endurance , and increases muscle fatigue and 
 functional impairment18 ; thus , working in 
 an upright sitting position affects muscle length and tension to maintain low muscle 
 activation19 . in this study ,
the fhhd was 9.5  cm before the training and 7.8  cm after the training , a 
 decrease of 1.7  cm that was statistically significant ( p<0.001 ) , in the scapular 
 stability exercise group . in the manual therapy group ,
the fhhd was 8.4  cm before the 
 training and 8.2  cm after the training , a decrease of 0.2  cm ( p<0.05 ) .
the scapular 
 stability exercise group showed greater improvement than the manual therapy group in the 
 fhhd .
if the forward head position is severe , the distance between the tragus and acromion 
 process increases ; if the distance decreases , deep cervical flexor activation increases , and 
 sternocleidomastoid and anterior scalene muscle activation decreases , thereby stabilizing 
 the cervical position . in the forward head position and round shoulder position , the upper 
 trapezius and pectoralis major and minor have increased activity , inducing scapular and 
 thoracoscapular position change , which causes abnormal cervical alignment and decreased 
 shoulder stability20 .
the upper , middle , and lower trapezius , and serratus anterior muscles are involved in 
 shoulder joint stabilizing motion21 . 
 therefore , in this study , isometric contraction was applied to enhance the upper , middle , 
 and lower trapezius and serratus anterior strength in shoulder stabilizing exercises . as a 
 result
, the right - side rsp was significantly decreased by 0.6  mm ( p<0.001 ) , and the 
 left - side rsp was significantly decreased by 0.5  mm ( p<0.001 ) .
the sul was 9.5 before the 
 training and 13.7 after the training , a statistically significant increase of 4.36 
 ( p<0.001 ) , in the scapular stability exercise group .
the scapular stability exercise 
 group showed greater improvements than the manual therapy group in the sul and left and 
 right rsp .
these results are considered to be due to the prone row and modified prone cobra , 
 which were performed to minimize the upper trapezius activity and maximize the lower 
 trapezius activity . according to rusi , if lower trapezius muscle activation increases , then 
 the muscle bulk changes22 .
day and 
 uhl22 applied repetitive arm raises on 
 14 normal subjects in their 20s , and found considerable differences in the thickness of the 
 lower trapezius ( p<0.01 ) . in this study ,
the right - side lower trapezius in rusi was significantly increased by 0.3  mm 
 ( p<0.001 ) , and the left - side lower trapezius was significantly increased by 0.3  mm 
 ( p<0.001 ) in the scapular stability exercise group .
the scapular stability exercise group 
 showed greater improvement than the manual therapy group in the left and right lower 
 trapezius in rusi .
the increases in muscle thickness in the scapular stability exercise 
 group indicate increases in muscle mass and strength .
this study provides basic material to 
 aid in the development and promotion of individualized stability exercises , which can be 
 applied in the work environment to improve shoulder stability in office workers .
a limitation of this study is the generalization of the results because the results are 
 based on a selected group of participants office workers with shoulder pain .
 [ purpose ] to examine the clinical effectiveness of scapular stability exercise on 
 shoulder stability and rehabilitative ultrasound images in office workers . 
 [ subjects and 
 methods ] thirty - eight subjects were randomly divided into a scapular stability exercise 
 group ( n=19 ) and a manual therapy group ( n=19 ) . 
 subjects in the scapular stability 
 exercise group performed a scapular stability exercise designed to correct the abnormal 
 location of the scapula , at 40 minutes per session , two times per week , for 6 weeks . 
 
 forward head horizontal distance , rounded shoulder posture , stability of the upper limb 
 for the shoulder , and rehabilitative ultrasound images were evaluated before and after 6 
 weeks . 
 [ results ] after the intervention , both groups showed significantly decreased 
 forward head horizontal distance and rounded shoulder posture , with significantly improved 
 stability of the upper limb and rehabilitative ultrasound images . 
 forward head horizontal 
 distance , rounded shoulder posture , stability of the upper limb , and rehabilitative 
 ultrasound images showed greater improvements in the shoulder stability exercise group 
 than in the manual therapy group . 
 [ conclusion ] scapular stability exercise can improve 
 shoulder stability and the thickness of the lower trapezius in rehabilitative ultrasound 
 images of office workers , and could be useful in clinical rehabilitation . 