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INTRODUCTION
At the end of a work day, or after a period of intense work at your
desk, have you ever experienced pain and tension in your neck and
upper back? Discomfort in your lower back, elbows, wrists, or hands?
Headache? Tired eyes? General fatigue and lack of concentration?
Does it occur frequently? Most of you answered yes to at least one
of these questions. This suggests that your work place may not fit
your body as well as it could.
Performance in the workplace is an integral part of the survival and
prosperity of businesses. Creating the correct fit between the worker
and workplace is the most important factor in allowing the worker to
gain maximal performance without creating health problems.
Workplace injury has become a major issue for both employers and employees.
"When there is a mismatch between the physical requriements of the job
and the physical capacity of the worker, musculoskeletal disorders (MSD's)
can result....MSD's are injuries and disorders of the muscles, nerves,
tendons, ligaments, joints, cartilage and spinal discs. They do not
include injuries resulting from slips, trips, falls, or similar accidents.
Examples of MSD's include carpal tunnel syndrome, tendonitis, sciatica,
herniated disc and low back pain."1
"Work-related MSD's account for 34% of all occupational injuries
and illnesses that are serious enough to result in days away from work.
More than 600,000 employees suffer lost-workday MSD's each year.
These injuries cost business over $15 billion in workers' compensation
costs each year and account for $1 of every $3 spent for workers'
compensation."1
"Carpal tunnel syndrome (CTS) results on average to more days away from work
than any workplace injury. The median days away from work for CTS is 25 days,
as compared to 17 days for fractures and 20 days for amputations."1
Low back pain accounts for 1,400 lost work days per 1,000 employees per
year.
The study of ergonomics has arisen form an understanding of
the importance of how our workplace fits our body. Ergonomics
derives from the Greek word Ergo (work) and Nomos (natural laws of).
Ergonomics is the study of designing the workplace to fit the human
body properly to protect it from unnecessary wear and tear. Proper
positioning of both your body and work station is critical in reducing
stress and strain and optimizing job performance. If your work place
is not customized to your body and your job requires repetitious actions,
you are at risk of experiencing musculoskeletal disorders called
Repetitive Stress Injuries(RSIs).
ERGONOMIC DESIGN OF COMPUTER WORKSTATIONS
Since many of you spend much of your work day sitting, let's
consider how to ergonomically design your work station.
Look around your work space. Is there a chair, desk, light,
computer terminal with a keyboard, telephone, typewriter, pens,
pencils, adding machine, books, etc.? Are they all easily
accessible without contorting your body to get them? Proper
sitting posture, seating adjustments, monitor and keyboard positions,
and lighting are especially important for preventing work-related
musculoskeletal disorders and eye discomfort.
Proper sitting posture (for computer use)
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arms comfortably
at sides
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elbows bent at about 90
degrees
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forearms parallel to floor
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knees slightly above hips
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wrists straight
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normal lower back curve
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shoulder blades back and down
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head erect
Your Chair
Your chair should fit the length, size and contours of your body
for maximum support and comfort. It should be lightly padded so
the cushion can evenly distribute the weight of your body. Fabric
upholstery on the cushion helps prevent slipping and sliding and
reduces the amount of effort required to maintain you sitting
posture.
The type of work you perform determines how you should adjust your chair.
If your task requires reading and writing at a desk you need to lean the
seat pan (what you sit on) forward to about 15 degrees so the thigh
can angle downward and help preserve the natural curves of the spine
and reduce the pressure on your thighs. If you operate a computer you
do not need to lean forward. Angle the seat pan up 5 degrees from level
to take advantage of the low back support of the back rest. The back
rest should arch forward and support the small of your back. Pull
your chair in close to the desk so you do not have to lean forward.
Your feet should rest firmly on the floor or on a footrest (angled 15
degrees up toward the toes). If you turn from side to side swivel
capability is essential. Avoid extreme twisting and leaning especially
if it involves reaching for heavy objects like catalogs or manuals.
For many, armrests are useful because they support the forearms which
reduces strain on the shoulders, neck and upper body. Armrests also
provide leverage to help a person get in and out of the chair.
Your Chair should:
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adequately support back and legs.
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be adjusted so that knees are at same
level or slightly higher than hips.
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be adjusted so that there is a space
equal to the breadth of your hand between the seat and calf.
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be adjusted to support the normal
curve in the lower back to prevent fatigue of back muscles.
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have padded but firm cushions.
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have separately adjustable back
and seat cushions.
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allow feet to be supported either
on floor or with foot rest.
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have swivel seats.
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have adjustable arm support.
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have five wheels.
Work Surface
The height to which you adjust your chair depends on the height
of your work surface, the size and slope of your body, and the nature
of your task. A general rule is this - the closer the distance the
hands and eyes must work together, the higher the desk height should
be. This position supports the arms, hands, and upper body without
making the body lean with the head tilted too far forward.
The arrangement of work materials on your work surface should place
these objects within easy view or access, so you will not have to
twist or bend your body while using these items. Arrange these items
in order of their priority to help reduce repetitious or prolonged one
sided movements. If you are right handed, place your phone to the left.
If you use a phone often avoid bracing the receiver between your ear
and shoulder. This position forces the head to tilt causing excess
tension on the neck, shoulders, and upper back which may result in
numbness into the arms and hands as well as headaches. Try using
either a speaker phone or a head set. When you write, place the paper
to your right if you are right handed.
Work surface should:
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be large enough to support keyboard,
mouse, monitor and documents.
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be large enough to put the
screen directly in front of you.
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have rounded edges.
Screen/Monitor Position
Position the screen so that the center is about eye level.
Eye screen distance may vary from 14-30 inches
and should allow you to see all the characters on your video
display terminal without making you lean your head and body forward
or backward. Be aware of any glare caused by sunlight or office
lighting as this may cause you to change your posture.
If your task involves high frequency data entry activities, the
keyboard should be placed directly in front of you with the hard
copy positioned on a stand in front of you. The video display
should be positioned to the side, but angled toward your visual field.
If you key information into the computer, place the keyboard and display
screen directly in front of you with paper and pencil to one side within
easy reach. The angle between your arms and your elbows should be 90
degrees. If you record information from the screen and occasionally
use the keyboard, the screen and writing material should be directly
in front of you with the keyboard conveniently placed to one side.
Angle the screen toward your visual field.
Viewing monitor and documents
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The middle of the screen should be
at eye level to keep neck straight.
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Monitor should be 14-30" away from
worker.
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Use anti-glare screen
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Screen contrast and brightness
should be easily adjustable.
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Documents should be at same height
and distance as screen.
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Screen and document should be in
position to be easily viewed without having to turn to side of
tilt head up or down regularly.
Keyboard
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Keyboard edges should be rounded.
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Wrist/palm rests may be used to
protect wrist and palms from hard or sharp edges and to help
keep wrists in neutral position. It should be made of soft but
supporting material and be same height as front edge of keyboard.
Avoid Vision Problems
Symptoms may include: headaches, blurry vision, burning eyes,
excessive tears, dry eyes, excessive blinking or squinting,
itching eyes, and double vision.
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Take frequent breaks - at least a few minutes every 1/2 hour.
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Make a conscious effort to blink more. Our blinking rate decreases
when we stare at the screen, causing our eyes to become
dryer.
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Use a lubricating eye drop or tear replacement for dry
or itchy eyes.
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Make sure there is minimal glare on your screen. Relocate
lamps; place blinds over windows; and invest in a glare-
reduction filter for your screen (look for the
American Optometric Association seal of approval)
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Sit in your normal working position and examine the dark
screen for reflections - they will be distorted by the
curvature of the screen. Try to arrange your environment
so that you can see no intense light sources reflected
from your screen. Reduce the general surrounding light
level.
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Clean your screen often; water and a soft, clean cloth
work fine.
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Choose a light screen with dark letters because this is
easiest on the eyes. Anything you can do to make the
screen blacker and the area around the screen darker
will reduce eyestrain.
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Eyes are strained more by close viewing than by distant
viewing. Keep viewed material as far away as can be
clearly read. If you can discern individual pixels on
your screen, you are probably sitting too close.
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Use the "20/20 rule" --- every twenty minutes, look
twenty feet away for twenty seconds. Move head and body
periodically for comfort.
For more on vision see
IBM Healthy Computing Guide
Exercises
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Forearms, wrists, and hands:
Extend arm (straight at elbow) in front, palm down. Pull hand toward body with
other hand. Hold 10 seconds. Extend arm in front, palm up.
Pull hand down with other hand. Hold 10 seconds.
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Legs: Standing: Alternate raising
heels and toes 10 times. Sitting: Extend legs (straighten at
knees) and move ankles in circles both clockwise and
counterclockwise. Repeat 10 times.
Remember to take time during appropriate breaks to walk around for a
a few minutes and stretch those parts of you body that are restricted
or tensed while performing your tasks.
Treatment of MSD's
For treatment of injuries like carpal tunnel syndrome, epicondylitis
(tennis elbow), neck strains (whiplash), back pain, see the article
on Active Release Techniques®.
1 OSHA Proposal for an Ergonomics Program Standard Frequently Asked
Questions
For a "how to" checklist on ergonomics, see the article
ERGONOMIC CHECKLIST
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ERGONOMICS