active cervical range of motion ( rom ) is frequently used to assess pain , and cervical rom 
 is reportedly one of the best estimators of cervical disability1 . previous reports have suggested that early changes in 
 cervical rom and muscle endurance could be interpreted as risk factors for the development 
 of neck discomfort2 , 3 . in modern society , neck discomfort is regarded as one of the most 
 prevalent types of pain among computer workers4 . sustained computer work requires constant tension of the 
 musculature of the rear neck region and can easily result in adoption of a forward - head 
 posture3 , 4 . previous work has suggested that cervical rom during neck flexion 
 could be a predictive factor for changes in neck posture and muscular dysfunction after 
 sustained computer work5 , 6 . when assessing rom of the cervical region , however , 
 cervical flexion should be differentiated into total neck flexion and upper cervical 
 flexion , because a forward - head posture is defined as the posture that adopts upper cervical 
 extension and lower cervical flexion7 . therefore , the purpose of the present study was to identify changes in cervical rom after 
 sustained computer work , especially with respect to upper cervical flexion , total neck 
 flexion , and the ratio between these parameters . they were aged 24 to 
 29  years ( 263.2 ) , and their mean height and weight were 174.56.2  cm , and 75.34.1  kg , 
 respectively . the inclusion criterion was regular office workers who used a computer at 
 least four hours per day . exclusion criterion was a history of upper or lower extremity 
 injury or disease that might have affected computer work . this study was approved by the inje 
 university faculty of health sciences human ethics committee . the total and upper cervical 
 flexion angles were measured using a crom instrument ( performance attainment associates , st . the instrument can measure the movements performed 
 by the cervical spine , using inclinometers and a compass goniometer . a pressure biofeedback 
 unit was placed at the lower cervical region , between the back rest and participant s head , 
 below the c4 level , which is used for regulating lower cervical flexion , to provide pressure 
 information . each participant was asked to sit on a standard chair with a high backrest and 
 maintain a neutral spinal alignment as perceived by an experienced physiotherapist . for 
 measuring total cervical flexion , each subject was asked to flex the head until a feeling of 
 muscle tightness or pain was occurred . for measuring upper cervical flexion , each subject 
 was asked to flex the head until the pressure biofeedback unit showed a decrease in 
 pressure . three measurement trials were conducted at 60-s intervals , pre - and post - computer 
 work . each participant was 
 allowed 5-min of adjustment time to regulate the work circumstances to those most 
 comfortable for them . the mean values of both measured values of the total cervical flexion 
 and upper cervical flexion angles , and their ratios in the three trials , pre - and post - test , 
 were calculated for statistical analysis . significance was accepted for values of p<0.05 , and spss version 18.0 was 
 used for statistical analyses . the upper cervical flexion , and the ratio between the upper cervical flexion and total 
 cervical flexion were significantly reduced after computer work , compared to pre - measurement 
 ( p<0.05 ) ( table 1table 1.comparison of the angles of the total and upper cervical flexion , and 
 ratiomeasurementsmean  sdbefore workafter worktotal cervical flexion ( )60.64.859.43.4upper cervical flexion ( )17.72.211.82.9*ratio0.290.020.190.04 * * significant difference , p<0.05 ) . the total cervical flexion angle was not significantly different between 
 pre - and post - measurement ( p>0.05 ) ( table 
 1 ) . reduced rom in the cervical region can disturb functional activities and elicit protective 
 responses , affecting changes in the muscular responses and passive structures of the 
 cervical spine1 , 2 . the present results show that upper cervical flexion and its 
 relationship to total cervical flexion were significantly reduced . yoo et al.6 reported a positive correlation between the 
 magnitude of neck flexion and dysfunction of the cervical erector spinae . a previous work 
 suggested that a prolonged abnormal posture results in impaired proprioception of  good 
 posture  and repositioning sense8 , 9 . although posture during computer work was 
 not evaluated in the present study , the nine subjects usually performed computer work with a 
 forward - head posture , which might have influenced our results . the forward - head posture is 
 defined as extension of the upper cervical region and flexion of the lower cervical region , 
 which requires sustained activation of the cervical erector spinae at the c4 level2 , 6 . this manifests as muscular dysfunction of the cervical erector spinae in the rear neck , 
 especially the upper cervical region .
[ purpose ] the purpose of this study was to evaluate the effect of sustained computer 
 work on cervical flexion , especially the upper cervical region . 
 [ subjects ] we recruited 11 
 sedentary workers who used a computer for at least 4 hours a day . [ methods ] total range of 
 cervical flexion , upper cervical flexion , and their ratio were measured before and after 1 
 hour of computer work . 
 [ results ] the total range of cervical flexion was not significantly 
 different between pre - and post - measurement . 
 however , upper cervical flexion , and the ratio 
 between the upper cervical flexion and total cervical flexion significantly decreased 
 after 1 hour of computer work , compared to pre - measurement . 
 [ conclusion ] sustained 
 computer work affects the range of cervical flexion , especially in the upper cervical 
 region .