The influence of different lateral computer monitor positions on neck and shoulder muscle activities and subjective discomfort during computer use

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The influence of different lateral computer monitor positions on neck and shoulder muscle activities and subjective discomfort during computer use

 

Author: Sham, Siu-wai
Title: The influence of different lateral computer monitor positions on neck and shoulder muscle activities and subjective discomfort during computer use
Degree: M.Sc.
Year: 2004
Subject: Hong Kong Polytechnic University -- Dissertations
Microcomputers -- Health aspects
Video display terminals -- Health aspects
Human engineering
Neck -- Muscles
Shoulder -- Muscles
Department: Dept. of Rehabilitation Sciences
Pages: x, 87 leaves : col. ill. ; 30 cm
Language: English
InnoPac Record: http://library.polyu.edu.hk/record=b1800274
URI: http://theses.lib.polyu.edu.hk/handle/200/4540
Abstract: With the rapid increase in computer use, there is rising concern on the corresponding increase in musculoskeletal disorders among computer users. The viewing of a monitor is almost an essential component in a computer task. Previous studies have focused on examining the effects of vertical locations and heights of monitor, and generate certain ergonomic recommendations for its placement. There is to date no study that has actually investigated the lateral monitor position on musculoskeletal demands, but this position is commonly adopted by office workers. The present study examined the effects of lateral monitor positions in a group of pain-free normal subjects. Ten male and ten female symptom-free subjects within the age of 20-24 volunteered to participate in a typing task for 20 min in 3 different monitor positions: central monitor position (CMP), angled left monitor position (ALMP), and angled right monitor position (ARMP). The electromyographical activities of bilateral cervical erector spinae (CES) and upper trapezius (UT), discomfort score in upper body regions, and the productivity of typing task were determined. The results showed that there were a significant increase in muscle activities of both sides of CES (side x position, p = 0.003) and right UT (side x position, p = 0.030) in both ALMP and ARMR The muscle activity of left UT only increased significantly in ARMP (side x position, p = 0.030). The pattern of increase in muscle activities were also asymmetrical in which the ipslateral CES and contralateral UT muscle activities were increased in response to the change in monitor position from central to either the left or right side. There was also a significant increase in the mean discomfort score in ALMP (p = 0.003) and ARMP (p = 0.009) when compared to CMP. There was also a trend for asymmetrical increase in discomfort score over the neck and shoulder regions when the monitor was placed to either the left or right side. The pattern of discomfort showed a similar pattern with the neck and shoulder muscle activities. For typing performance, there were no significant differences in both gross and net typing speed, but a significant reduction in typing accuracy (p = 0.000) was found in both ALMP and ARMP. The results of this study suggested that subjects may increase the muscle work of neck and shoulder stabilizers in order to look at the monitor that is placed laterally. This may also increase the discomfort in the corresponding neck and shoulder regions. Therefore, both ALMP and ARMP are not a recommended monitor position for computer users and workplace reorganization or redesign is required in order to avoid these positions.

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