Video Displays, Work, and Vision (1983) / Chapter Skim
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6. Anthropometry and Biomechanics in VDT Applications
6. Anthropometry and Biomechanics in VDT Applications
Pages 129-142
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From page 129... ...
Unless the proper balance between job demands and operator capabilities is established, there may be adverse health consequences, as indicated by physical complaints and symptoms, absenteeism, and so forth. Problems must be studied at the level of subsystems (e.g.
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From page 130... ...
This chapter addresses anthropometry and biomechanics in VDT applications and the ways in which they influence appropriate design of workstations, particularly the choice of chairs, support stands for keyboard and display tables, footrests, wristrests, armrests, and document holders. The first part of this chapter reviews several field surveys of postural strain in VDT work.
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From page 131... ...
Branton and Grayson (1967) studied train passengers and found that there were cyclic postural changes, which they interpreted as necessary to prevent postural strain.
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From page 132... ...
(1981) VDT users Data entry 11 9 9 13 Dialogue 5 6 11 6 Non-VDT Typists 6 9 10 5 Traditional office work 1 2 2 6 Smith et al.
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From page 133... ...
This condition may cause acute pain in the statically loaded muscle. Excessive static loads may also lead to rheumatic diseases that affect the joints, ligaments, and tendons and to the development of arthrosis of an inflammatory and degenerative nature (van Wely, 1970~.
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From page 134... ...
It is also important to provide seats that allow operators to bend their knees since the decrease in lumbar lordosis while sitting is further emphasized if a seated person stretches his or her leg. Stretched legs cause a rotation of the pelvis due to the pull action of the hamstring muscle.
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From page 135... ...
population apply to various military populations and cannot be readily used for estimating body dimensions of the working population. Since the military population is a subsample of the entire population, civilian body dimensions have recently been extrapolated from data on military populations.
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From page 136... ...
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From page 137... ...
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From page 138... ...
potentials from the muscles in the lower back are affected by various sitting postures (Nachemson and Elfstron, 1970; Andersson and Ortengren, 1974, 1979~. Disc pressure was measured by inserting a needle with a strain-gauge measuring device into the third lumbar disc, and the EMG was recorded using skin electrodes.
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From page 139... ...
Disc pressures decreased monotonically with backrest inclination and the size of the lumbar support. Complementary investigations showed that a seat inclination of 6° towards the back decreased disc pressure in comparison with a horizontal seat.
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From page 140... ...
These recommendations have obvious effects on the height of the keyboard and its support stand and also on the seat height to be selected. The first recommendation, having the elbows at right angles and the upper arms hanging vertically, is reflected in the proposed German regulation for VDT operators (Helander, 1981~.
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From page 141... ...
This is indicative, again, of the various interactions between components of workstation and work habits. Effects of Display Position on Postural Strain Human engineering guidelines agree on a preferred downward slope of the line of sight of from 15° to 30° (Cakir et al., 1980; Rupp, 1 98 1; U.S.
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From page 142... ...
A modern workseat allows good support and a relaxed seating posture that uses a full backrest and permits an operator to lean back. This is likely to bring about a working height slightly above elbow rest height (measured while sitting)
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