Computer
Workstation Ergonomics
Article Published
By Marc Liron - Microsoft MVP
Computer Workstation Ergonomics
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As we spend
increasing amounts of time at our computer workstation, we need to
be aware of how the design and arrangement of our equipment can
impact our comfort, health, and productivity. |
# Work Area
# Desk/Workstation
# Chair
# Monitor
# Keyboard
# Mouse, Trackball, or Other Pointing Device
# Lighting
# Work Habits
# Laptop Computer
Computer
Workstation Ergonomics - The
WORK AREA
The work area should be large enough to accommodate you, allow the
full range of motions involved in performing required tasks, and
provide room for the equipment and materials that make up the
workstation.
Use a headset for lengthy or frequent telephone work.
Place the items you use most frequently directly in front of you.
Avoid overcrowding computer work areas.
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Computer Workstation Ergonomics - DESK/WORKSTATION
Standard furniture cannot accommodate everyone’s needs. A taller
person may need a one-time adjustment to have his or her work
surface raised somewhat; a shorter person may need a footrest or
other accessories. Adjustable furniture may be needed in situations
where people share or use the same workstation.
The desktop should be organized so that frequently used objects are
close to the user to avoid excessive extended reaching.
The work surface should have a matte finish to minimize glare or
reflections.
The area underneath
the desk should always be clean/uncluttered to accommodate the
user’s legs and allow for stretching.
If a fixed-height
desk is used, add a keyboard tray that adjusts vertically to provide
added adjustability.
A footrest should be
used if, after adjusting the height of the chair, feet do not rest
flat on the floor.
Use a headset or
speaker phone to avoid neck and shoulder discomfort if you use a
phone frequently throughout the day.
Place the phone on
the side of your non-dominant hand (i.e., left side if right-handed,
right side if left-handed)
Position your desk lamp (if you use one) so that it illuminates
source documents without causing either glare on the computer screen
or direct illumination to your eyes.
A document holder
should be used if documents are referred to during keying.
The document holder
should:
Be stable and
adjustable (height, position, distance, and angle of view).
Support your document
on either side of the monitor.
Be at the same distance from your eyes as the display screen to
avoid frequent changes of focus and you should be able you to look
from one to the other without moving your neck or back.
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Computer Workstation Ergonomics - CHAIR ADJUSTMENTS
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Contrary
to popular belief, sitting, which most people believe is relaxing,
is hard on the back. Sitting for long periods of time can cause
increased pressure on the intervertebral discs — the spongy discs
between the vertebra.
Sitting is also hard on the feet and legs.
Gravity tends to pool blood in the legs and feet and create a
sluggish return to the heart. |
The following recommendations can help increase comfort for computer
users:
"Dynamic sitting", don’t stay in one static position for extended
periods of time.
When performing daily
tasks, alternate between sitting and standing or take small walking
breaks throughout the day.
The chair back should
have a lumbar support Adjust height of backrest to support the
natural inward curve of the lower back.
It may be useful to
use a rolled towel, lumbar roll or cushion to support the low back.
The angle of the back
rest is subjective but the trunk and upper legs should form an angle
between 90 to 115 degrees.
Adjust height of
chair so feet rest flat on floor.
Sit upright in the
chair with the low back against the backrest and the shoulders
touching the backrest.
Thighs should be
parallel to the floor and knees at about the same level as the hips.
Back of knees should
not come in direct contact with the edge of the seat pan. There
should be 2-4 inches between the edge of the seat and the back of
the knee.
Arm rests should be
removable and the distance between the arm rests should be
adjustable.
Adjust height and/or
width of armrests so they allow the user to rest arms at their sides
and relax/drop their shoulders while keyboarding.
Don’t use armrests to
slouch. Also, chair arms should not noticeably elevate your
shoulders or force you to move your arms away from your body to use
them.
Elbows and lower arms
should rest lightly on armrests so as not to cause circulatory or
nerve problems.
Use a footrest when
attempts to adjust your chair and the rest of the workstation fail
to keep your feet on the ground.
Ensure that you have
some space (2-3") between the top of your thighs and the underside
of your workstation.
Have enough space
under your work surface so that you can pull your self all the way
up to the edge of the desk with room for your legs and knees to fit
comfortably.
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Computer Workstation Ergonomics - The MONITOR
Once the chair and work surface height are properly adjusted, the
computer monitor should be placed so the top of the screen is at or
just below eye level when seated in an upright position. The
following suggestions can help prevent the development of eye
strain, neck pain and shoulder fatigue while using your computer
workstation:
Make sure the surface of the viewing screen is clean.
Adjust brightness and
contrast to optimum comfort.
Position the monitor
directly in front of the user to avoid excessive twisting of the
neck.
User must position
the monitor at a comfortable viewing distance, approximately 18-30
inches from the user.
Position monitors at
right angles from windows to reduce glare. Close window blinds as
needed to reduce glare from sunlight.
Position monitors
away from direct lighting which creates excessive glare or use a
glare filter over the monitor to reduce glare.
Adjust the monitor
tilt so that ceiling lights do not reflect on your screen.
If a document holder
is used, it should be placed at approximately the same height as the
monitor and at the same distance from the eyes to prevent frequent
eye shifts between the monitor screen and reference materials.
Get regular eye
check-ups.
Adjust as needed for
larger screens. You may need to sit farther away and increase the
font size to take full advantage of the larger screen.
Bifocal and trifocal
wearers have to pay particular attention to the placement of their
monitor. Wearers of bifocals and trifocals often unknowingly tilt
their heads backwards so they can read the screen through the lower
portion of their glasses. This can sometimes lead to neck, shoulder,
and back discomfort. Potential solutions include either lowering the
computer monitor or purchasing glasses designed specifically for
working at the computer.
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Computer Workstation Ergonomics - The KEYBOARD
Many ergonomic problems associated with computer workstations occur
in the shoulder, elbow, forearm, wrist, and hand. Continuous work on
the computer may expose soft tissues in these areas to repetition,
awkward postures, and forceful exertions, especially if the
workstation is not set up properly.
The following adjustments should be made to your workstation to help
prevent the development of an ergonomic problem in the upper
extremities:
First adjust your chair as mentioned above, then with your arms
resting comfortably at your side, raise your forearms to form a 90
degree angle with your upper arms.
Adjust keyboard
height so shoulders can relax and allow arms to rest at sides. An
articulating keyboard tray is often necessary to accommodate proper
height and distance.
Position the keyboard
directly in front and be close to the user to avoid excessive
extended reaching.
Forearms parallel to
the floor (approximately 90 degree angle at elbow).
Mouse should be
placed adjacent to keyboard and at the same height as the keyboard.
Avoid extended and elevated reaching for keyboard and mouse. The
back of the wrist should be kept flat (in a neutral position). Do
not rest the hand on the mouse when your are not using it. Rest
hands in your lap when not entering data.
A padded wrist rest
will help to keep your wrist in a straight and neutral position
while typing and keep your arms off the sharp edges of the work
surface.
Do not rest your
wrists or hands on a palm or wrist rest when you are keying. These
rests are designed to provide support only during breaks from
keying.
The slope of the
keyboard may need to be adjusted so that it is flat in order that
your wrists are straight, and not bent back while you are typing.
Press the keys
gently; do not bang them or hold them down for long periods. Keep
your shoulders, arms, hands, and fingers relaxed.
If your work surface
is too high and not adjustable, adjust your chair to bring your arms
to the proper position. If you raise your chair make sure your feet
are properly supported.
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MOUSE, TRACKBALL, OR OTHER INPUT DEVICE
The mouse is present in virtually every office environment. Handed
versions of mouses are designed specifically to the contours of
either the right or left hand.
Placing the mouse,
trackball, or other input device too far away, too low, or too much
on one side can cause shoulder, wrist, elbow, and forearm
discomfort. Placing the input device directly in your immediate
reach zone offers natural comfort and maximum hand-to-eye
coordination.
Do not bend your
wrist upward. Make sure you are sitting high enough for the
workstation to be slightly below elbow height so that your hand
rests naturally on the mouse.
Mousing demands a
certain level of surface stability; if used on a keyboard tray, the
tray should not wobble or tip.
A trackball has an
exposed ball that you manipulate with your fingers. It requires the
use of different muscle and tendon groups than does a mouse, and can
add variety to your manipulation of computer information. Some
trackball designs, however, may cause discomfort and possible injury
to the area around your thumb, which stretches and reaches to
maneuver the trackball.
Test different models
of mousing devices, trackball or other input devices. Consider the
shape and size of the devices, how comfortably it fits into your
hand, ease of operation, and any special features that might make
your job easier.
In addition to the
mouse and trackball, a variety of other input devices are available.
Consider your task requirements and physical limitations.
Touch pads allow you to move the cursor on the computer screen by
simply gliding your finger across a small pad. Unlike mouses,
trackballs, and other pointing devices, touch pads have no moving
parts to clog or breaks, so they never require disassembly for
cleaning.
Touch screens allow
you to point directly at an object. They require little or no
training, are faster than other pointing devices, and require no
extra work surface. However, the disadvantages of touch screens
include arm fatigue, smudges, optical interference, and increased
glare.
Voice input allows
you to "talk" to your computer. Currently, such programs can
understand and respond to natural speech delivered at rates of up to
160 words per minute.
Pen-like devices use
pressure, light, electromagnetic disruption, or radio frequencies to
enter and manipulate information through contact with the computer
screen or a horizontal pad. A pen pad requires about as much room on
the work surface as does a mouse. If pen technology is used on a
horizontal pad, a workstation must provide adequate non-glare
lighting for both it and the computer screen.
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Computer Workstation Ergonomics - LIGHTING
Lighting not suited to working with a computer is a major
contributing factor in visual discomforts including eyestrain,
burning or itching eyes, and blurred or double vision.
The lighting in most office environments is too bright for optimal
VDT screen viewing. The illumination may be reduced by removing 2
bulbs in a 4-bulb fluorescent fixture, removing the bulbs in every
other fixture, or turning off overhead lights altogether.
Supplemental desk lighting is better than overhead lighting for
reading or printed copy.
Use the following recommendations to reduce eyestrain and eye
fatigue:
Close drapes/blinds to reduce glare.
Adjust lighting to
avoid glare on screen (light source should come at a 90 degree
angle, with low watt lights rather than high).
Avoid intense or
uneven lighting in your field of vision.
Place monitor at 90
degree angle to windows (where possible).
Reduce overhead
lighting (where possible).
Use indirect or
shielded lighting where possible.
Walls should not be
painted with a reflective finish.
Use a glare screen or
monitor shield to reduce glare from overhead lighting.
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Computer Workstation Ergonomics - WORK HABITS
Repetitious static work (working at the computer) is very fatiguing
on your upper extremities as well as your eyes. It is important that
breaks from working at the computer be taken every 20 to 40 minutes
in order for your body to rest and recover. Taking a short break (3
to 5 minutes) does not mean you have to stop working, other
activities such as talking to a co-worker, making copies, filing,
etc. could be done during breaks from typing.
It is also important to change positions periodically. Sitting in
one position or leaning on your arms for an extended period of time
can interfere with circulation.
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Computer Workstation Ergonomics - Laptop Computers
NOTE: LAPTOP COMPUTERS ARE NOT RECOMMENDED AS PRIMARY
COMPUTERS. IN THE OFFICE OR WHILE AT HOME, A DOCKING STATION IS
RECOMMENDED TO PROVIDE ADJUSTABILITY WHICH WILL ENHANCE NEUTRAL
POSTURES.
Computing
Maintaining neutral postures will reduce stress and strain to the
musculoskeletal system.
Incorporate mini-breaks every 20 to 30 minutes to break up
repetition and static postures.
Maintain a
comfortable viewing distance from your screen; about 18-30 inches.
Keep your head and
neck in a neutral posture; avoid excessive neck flexion or rotation.
Angle the screen so
that it is perpendicular to your line of sight, if lighting permits.
Position the keyboard
at elbow height, and keep your wrists straight while keying.
Experiment with table height, chair height and keyboard angle to
maintain neutral wrist postures.
Remember: if you
raise your chair use a footrest to support your feet. When seated
your hips should be slightly higher than your knees.
If you are seated in
a side chair or couch, use a pillow to support your arms while
keying. This will help you maintain neutral arm, wrist, and hand
postures.
Attach an external
mouse instead of using the small constricted touchpad or trackball.
Clean the screen
regularly using appropriate antistatic cleaning materials.
The hands and wrists
should be kept in a straight wrist posture when typing and should
not be resting on a pal rest, table, or lap while typing. Wrist and
palm rests are designed to provide support during breaks from
typing.
Transporting the
Computer
Keep these ideas in mind while carrying your laptop from place to
place:
Eliminate unnecessary baggage from your briefcase, the less demand
placed on the body the better.
Carry your laptop in
a case with a padded shoulder strap and handle. Frequently shift
hands or shoulders to balance the load.
Use a wheeled luggage cart when possible.
I hope this article on computer workstation ergonomics helped...
Enjoy the rest of site!
Kind Regards

Marc Liron -
Bio
Microsoft MVP
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