By: Vince McLeod, CIH and Glenn Ketcham, CIH
Issue: February/March 2007
You go home each day with a pain in your shoulder or neck, perhaps you wake up
at night with tingling in your wrist or hand. You used to feel good all day
long but now you hurt after just a few minutes at the computer. What to do?
You have
budget information to enter in spreadsheets, you have a stack of reports to
do, and it seems you get two emails to respond to for every one you send. This
means
hours and hours glued to your keyboard and mouse.
More and more, jobs require
a substantial portion of the day working with a computer. Very often pain and
discomfort experienced at work or at home can be tied to easily identified
risk factors. Most of us have heard the term ergonomics. Simply put, ergonomics
is
the study of how people physically interact with their work environment to
perform their required tasks. A phrase often heard to describe ergonomics is “fitting
the task to the worker.” Poor ergonomic conditions and practices cause
more losses in terms of employee suffering, lost time, and productivity than
most other types of injury in the workplace.
Three fundamental ergonomic risk
factors are: position/posture, repetition/duration, and force. These can
all be influenced by the work area setup and the activity being performed.
The
good news is these at-risk conditions that can cause pain and potential injury,
can
often be easily controlled if one understands basic ergonomic concepts and
how to apply them. In this article and the next we will take a look at these
factors
and provide some practical solutions to help get you through the day pain-free.
Position/Posture: The goal here is a neutral and balanced position. “Neutral” is
typically thought of as the midpoint of range of motion for most joints (e.g.
your wrist should be straight in both the up/down and side-to-side axis, your
upper arm should hang comfortably from the shoulder, your back and neck should
be straight and not twisted or bent). Balanced in the ergonomic sense is when
a posture or position is such that one does not have to fight (much) gravity
to maintain that posture or position.
Let’s look at some of the most common position-related complaints we
see. These are often the easiest to correct and can have very dramatic improvement
in discomfort in a relatively short timeframe.
Neck Pain: Your head weighs about as much as a bowling ball. Holding a bowling
ball straight upright takes some effort. Now visualize you are balancing a
bowling ball (your head) on a cylinder (your neck). If you begin to tip the
cylinder, it becomes harder and harder to support. When you sit upright and
are looking directly ahead your skeletal structure supports most of the weight.
If you deviate from vertical, your muscles must come increasingly into play
to support your head. Now imagine tipping and lifting that bowling ball hundreds
of time a day – that is exactly what you are doing when working from
hardcopy placed on your desk. Similarly, if your monitor is placed on the CPU
so you must tip your head back to read (particularly problematic for those
of you wearing bifocals) your muscles must support this off-balance posture.
A much better approach is to place your hardcopy on a document stand between
the keyboard and monitor. The monitor should be directly in front of you with
the top of the screen just at or slightly below eye level. This way instead
of repetitive up/down and side-to-side head motion one can look back and forth
between paper and screen almost by using your eyes alone allowing you to remain
in a neutral, balanced position.
Holding the telephone receiver cradled between
your ear and shoulder while doing other tasks is also a classic cause of
neck pain if you do so on a regular basis. Hold the receiver in your hand if
possible.
Use a speakerphone or a headset if you must speak on the phone while working,
such as reviewing written materials or computer files while conversing.
A keyboard/mouse platform should easily adjust for height
and angle and have the mousing surface in about the same
plane as the keyboard. Photo courtesy of Humanscale.
An example of a poorly set-up workstation that presents a
variety of postural risks. How many of these can you identify?
Photo courtesy of Humanscale.
Shoulder and Neck Pain: Hold your arm straight out in front of you
for a couple of minutes. Now try drawing your shoulders up a couple inches
towards your
ears and hold them there for a minute or two. In both cases, you should begin
to feel discomfort and fatigue relatively quickly. Both these examples illustrate
stresses that can occur when one is working with a keyboard and/or mouse on
a surface that is too high or too far away from an ergonomic standpoint. For
many people this is a result of using a keyboard and/or mouse on top of a standard
height desk or having an older keyboard tray that doesn’t have room for
the mouse (this also can cause contact stress issues we will discuss later).
You must reach up, over the edge, and out in front to use the input devices.
This may not be an issue for really tall individuals but we see it is problematic
for many average and shorter people. Ideally when using a keyboard or mouse,
your upper arms should hang comfortably at your side. The approach we most
often take in a case such as this is to recommend installation of a combination
keyboard/mouse tray.
A word of caution: a cheap tray will often not solve any
problems; it may create new ones. We often see poorly designed trays collecting
dust in storerooms because they just didn’t help. Look for a tray that
has a tilt to lift or a large release button to move it up and down. Stay away
from units with twist knobs to move; these can be troublesome especially for
people that are already having wrist and hand issues.
The mousing surface should
be in about the same plane as the keyboard, even better when it can rotate
over the keyboard or move towards you to reduce your reach and allow you
to keep your elbows in while working. The keyboard platform should be kept
level
or sloped slightly away from you to so your wrists are straight while typing.
We have begun to explore the ergonomic risk factors associated with the use
of
computers. The take-home message in this issue is “neutral” and “balanced.” Your
monitor should be directly in front of you with the upper edge at eye-level or
slightly below. Any hardcopy should be placed in front of you on a document stand
either between the keyboard and monitor or immediately to the side of the monitor.
The keyboard and mouse should be in front of you and as close as practical to
prevent over-reaching.Your wrists should be straight in both axes. OSHA provides
an excellent review through their eTool1on ergonomics. The State of Washington
also has some very good self-evaluation checklists and guides.2Look for Part
2 of this series, where we will discuss the repetition and force and solutions
to get you through the day pain-free.
Vince McLeod is a Certified Industrial Hygienist by the American Board
of Industrial Hygiene and the senior IH with the University of Florida’s
Environmental Health and Safety Division. He has 15 years of experience in
all facets of occupational health and safety and specializes in hazard evaluation
and exposure assessments.
Glenn Ketcham is a Certified Industrial Hygienist
with 20 years experience in the health and safety field. He is currently
the Risk Manager for the University of Florida. He has worked as a USDOL/OSHA
compliance
officer and has program management experience in general OSHA compliance,
laboratory and chemical safety, workplace ergonomics, loss prevention, disaster
preparedness,
and classical industrial hygiene.
