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About Situs
Seating
Accessories
Workstation Information
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About Situs
Seating
Accessories
Workstation Information
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About Situs
Seating
Accessories
Workstation Information
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Liz Dowler OTR/L, CRC
Bruno Kappes Ph.D.
A field research project was conducted by Liz Dowler to evaluate
if adapting work-
station environments to a worker's physical profile facilitates
a reduction in Cumulative Trauma Disorders(CTD), improve safety
and increase efficiency in work performance.
Neutral posture as defined in this study:
1. A forward sloping seatpan set at a worker specific height
puts pelvis, spine and head in full upright position thus reducing
stress on spinal structures and musculoskeletal systems. (Mandal,
Schoberth, Bridger, Bendix)
2. Height of desk, keyboard and monitor is based on individual
seated height in a forward sloping seatpan.
3. The monitor, document and keyboard are in alignment in front
of operator.
4. Keyboard placed at 15° negative slope and elbows at 115°
and wrists in mid-range.
Subjects:
Eighty-seven (87) workers at Alyeska Pipeline Services Co., the
University of Alaska, Anchorage, and the Anchorage School
District participated in the study.
Methods:
Surface electromyography (sEMG) measures the work done by muscles
in terms of micro volts(mv) of activity. Upper trapezius and
forearm extensors were measured
during four, 5 minute typing tests while
subjects worked at four different workstation arrangements. These
positions include: (Position 1) subject's working position
as they were found (Position 2) workstations using the
American National Standard Institute (ANSI HFS 100-1988) as a
guideline (Position 3) positioned height specific, seatpan
tilted forward at the pelvis, keyboard on desk with 90 degrees
at the elbows and wrists in mid-range (Position 4) neutral
posture, as defined above. Subjects were placed in one of four
groups and then tested again 30 days later. Pain was recorded
by each participant during a pre-screening and at the conclusion
of the study.
Results:
A. Results reveal muscle tension during typing activity reduced
significantly (p<.001) when using the Negative Sloping Keyboard
Tray
(Position 4).
B. There were no differences between pre-test and post-test scores
in either control or intervention groups indicating that the
muscles used when doing VDT work responded immediately to changes
in positioning.
C. The intervention group who used the neutral posture workstation
(Position 4) significantly reduced (p<.001) pain levels.
D. Productivity was measured by word count per minute during
typing tasks. The data reveals no decrease in productivity or
efficiency when in neutral position.
Conclusion:
VDT workers responded immediately to neutral posture using forward
tilted seating, midline positioned monitor and document, and
the Negative Sloped Keyboard Tray. This was demonstrated by reduced
muscle use and reduced pain symptoms. These results may produce
potential cost saving by influencing long term benefits to employee
health without decreasing performance and efficiency.
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