a flexed spine due to poor sitting posture , such as slump sitting posture , results in 
 higher activity in the upper trapezius and erector spinae muscles , in a posture in which the 
 trunk is slightly inclined backward1 . panjabi theorized that spinal instability in the form of laxity around the neutral position 
 of a spinal segment developed because of a significant decrease in the capacity of the 
 stabilizing system that maintains the spine in a neutral position1 . habitually shortened muscle length , which becomes evident when an individual 
 muscle does not travel through a complete range of motion on a daily basis , may cause 
 adaptive changes in muscle length , in turn triggering habitual forward head and slumped 
 sitting postures2 , 3 . use of poorly designed computer workstations may rapidly lead to 
 the development of such postures3,4,5 . the purpose of 
 the present study was not to solve or elucidate the mechanisms of musculoskeletal disorders . rather , this study determined whether a computer workstation individually fixed for standard 
 posture beneficially influences sitting posture . this study compared the forward head angle 
 and the lumbar flexion and rotation angles of computer workers using routine computer 
 workstations and computer workstations individually fixed for standard posture . their average age , height , and weight were 
 31.3  4.3  years , 176.2  3.0  cm , and 70.5  6.3  kg , respectively . this study was approved by the inje 
 university faculty of health sciences human ethics committee . a 3-d motion analysis system , 
 cms - hs ( zebris medizintechnik , isny , germany ) , was used with a sampling rate of 30  hz to 
 measure the angles of the forward head and lumbar flexion during 30 minutes of computer 
 work . single markers for forward head angle were placed on the right tragus of the ear and 
 the 7th cervical spinous process ( c7 ) by the same investigator . the forward head angle was 
 defined as the angle between the line from the tragus to the c7 line and the vertical axis 
 at c7 . the lumbar flexion and rotation angles were measured using two triple - marker sets . triple markers were attached to the lumbar region and the pelvis at l12 and s12 , 
 respectively . lumbar flexion and lateral bending and rotation were calculated relative to 
 movements of the pelvis . the routine computer workstation featured a 23-inch monitor , a 
 keyboard and a mouse on a table , and a swivel chair with five wheels . to allow analysis of 
 lumbar motion , both the table and chair were 
 adjustable in terms of height and were initially set to ensure that elbows , hips , and knees 
 were flexed at 90. the keyboard and mouse were positioned frontally , 30  cm from the trunk , 
 the monitor was reclined by 20 , and the top of the display was set at eye level ( i term 
 these conditions  the standard sitting posture  ) . the computer workstation individually 
 fixed for standard posture used the same hardware , but all products were fixed to encourage 
 the standard sitting posture for each subject . the keyboard was fixed using wedges , and the 
 range of mouse motion was limited ( also using wedges ) . all subjects performed 
 selected computer work for 30 minutes using each type of workstation . the test order was 
 random , and the interval between tests was 30  min . spss version 12.0 ( spss , chicago , il ) was used to assess differences in 
 forward head and lumbar flexion angles . the paired t - test was used to explore the 
 significance of differences in measures obtained using the two workstations . when working at the fixed workstation , the forward head angle ( 18.0  8.5 degrees ) was less 
 than that observed when the routine workstation was used ( 34.4  11.9 degrees ) . at the fixed 
 workstation , the lumbar flexion angle ( 16.3  5.7 degrees ) was less than that observed at 
 the routine workstation ( 29.6  10.6 degrees ) . at the fixed workstation , the lumbar rotation 
 angle ( 10.2  4.9 degrees ) was less than that observed at the routine workstation ( 19.1  
 9.7 degrees ) . when working at the fixed workstation , the forward head angle was less than that observed 
 when the routine workstation was used . at the fixed workstation , the lumbar flexion and 
 rotation angles were less than that at the routine workstation . my hypothesis was that use 
 of a routine workstation might create a habitual leaning posture unless the keyboard , mouse , 
 and chair were used properly . the sitting posture was changed within approximately 10  min to a position that 
 allowed comfortable working . szeto et al.6 
 attributed changes in muscle patterns principally to personal habitual postures rather than 
 postures dictated by workstations . yoo and kim7 also reported that a comfortable seat may induce much more pelvic 
 posterior tilting than a hard or unstable seat , which may in turn decrease lumbar lordosis . also , development of forward head posture may reflect compensation for the posterior 
 movement of the center of gravity . most computer users are well acquainted with the 
 requirements for maintenance of a good or standard posture . however , they commonly fail to 
 maintain such postures , because they involuntarily change good posture to a more relaxed 
 posture to concentrate on computer work . although it could not be 
 affirmed that the effect of computer workstations individually fixed for standard posture is 
 better than ergonomic chair designs and interventions , it has a positive effect which has 
 not been investigated in previous studies . the ultimate goal of this study was not spine 
 straightening , since this can lead to other musculoskeletal disorders . instead , we 
 determined whether workstations individually fixed for standard posture could be used to 
 prevent excessive trunk exion and rotation . also , the fixed computer workstation could be used for 
 education of a good sitting posture for computer workers unfamiliar with the standard 
 sitting posture .
[ purpose ] this study compared the forward head angle and the lumbar flexion and rotation 
 angles of computer workers using routine and fixed computer workstations . 
 [ subjects ] ten 
 male workers voluntarily consented to participate in the study . [ methods ] a 3-d motion 
 analysis system was used to measure the angles of the forward head and lumbar flexion . all 
 subjects performed computer work for 30 minutes using both types of workstation . 
 [ results ] 
 when working at the fixed workstation , the forward head angle was less than that observed 
 when the routine workstation was used . at the fixed workstation , 
 the lumbar flexion and 
 rotation angles were less than that at the routine workstation . 
 [ conclusion ] the computer 
 workstation individually fixed for standard posture may have prevented poor sitting 
 posture .