By: Glenn Ketcham, CIH and Vince McLeod, CIH
Issue: April/May 2007
Office Ergonomics 101 – Part 2
In the last issue we began to explore the ergonomic risk factors associated
with the use of computers. Three of the fundamental ergonomic risk factors
are: position/posture, repetition/duration, and force. These can all be influenced
by the work area setup and the activities being performed. The good news is,
these risk conditions that may cause pain and potential injury, can often be
easily controlled if one understands basic ergonomic concepts and how to apply
them.
To recap, the take-home message in Part 1 was “balanced” and “neutral.” Your
monitor should be directly in front of you with the upper edge of the screen
at eye-level or slightly below. Any hardcopy you work from should be placed
in front of you on a document stand (not on the desk at your side) 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 generally as close as practical to
prevent over-reaching. Your wrists should be straight in both the vertical
and lateral axes.
In this issue we will discuss repetition/duration and force
as it applies to ergonomic risk in the office setting and some possible solutions
to get you through the day pain-free.
REPETITIVE MOTION
Repetition by definition involves doing things over and over again. In repetitive
work, these same types of motions are performed using the same parts of the
body in the same fashion, time and time again. In activities such as typing,
using a mouse, or referencing paper source documents, the affected muscles, tendons,
and joints can be used thousands of times a day, week after week, year after
year. The risk of injury is even greater when repetitious jobs involve awkward
posture (e.g. bent or flexed wrists) or forceful exertions such as repetitive
overreaching for the mouse (shoulder and neck pain).
Now in conjunction with
neutral and balanced as discussed in Part 1, our goal from an ergonomic standpoint
is to reduce the number of repetitions experienced by each set of muscles,
tendons, and joints throughout the workday and to allow time for recovery.
The body has great capacity to repair itself. Problems arise however when
the amount of damage or stress accumulated over the course of time outpaces
the body’s ability to repair. This is when we experience pain and if
the cumulative damage continues, the potential for serious injury.
Short
breaks in repetitive tasks can be of significant benefit. Break up data
entry with the variations in activity such as filing, reading, using the copier,
or any other type task that uses different muscles and motions than computer
use. It is good to include micro-breaks of just a minute or two every half
hour or so during data entry campaigns. There is good software now available
that tracks keystrokes and mouse movement and alerts you when breaks are
appropriate. It is often better to take many small breaks than one long
work
break during the day.
It is important to examine and analyze the work being performed. Look at
this along the same lines as a job hazard analysis where the parts of the
job are
examined on a task-by-task basis. In many cases we have seen, there is much
unnecessary repetitive work because of poor process design (or the process
was really not designed at all – it just grew). Questions that should
be considered: can parts of this process be automated? Can equipment be linked
directly to CPUs for data collection? Can databases be programmed to “talk” to
each other? In some instance perhaps barcodes and readers might be used to
reduce data entry or in other types of information collection and entry readable/scan-able
forms. It is often well worth investing a little time to engineer a solution
that will save significant time and effort in the long run.
Often we can trace
pain to mouse over-use. This is often combined with poor mouse location. The
conventional mouse requires a great amount of work to be directed through one
arm, shoulder, and hand. It is often best to try to distribute this work and
share it between both sides. One approach is the use of keyboard commands.
Most of the commands commonly used can be accomplished by using keyboard commands
(for those of you that remember those keyboard commands from the DOS days,
they still work. For example in Windows, Ctrl-A will “select all,” Ctrl-C
can be used to copy text and Ctrl-V will paste. Look at the menu bar at the
top of your document next time you are on the computer; all the selections
have one letter is underlined (e.g. File, Edit, View, Table etc.). If you hit
Alt and the underlined letter, the drop down menu will expand just as if you
mouse clicked on it. Cntl and underlined letter on the commands in the drop
down menu will perform that function. This can greatly reduce mouse use and
once you get familiar with them will actually speed up your work.
There are
now actually at least a couple of “alternative-mice” that place
the tracking device between you and the spacebar. This allows one to use both
hands for mousing again sharing work between hands.
Some software programs also allow you to automate common tasks (such as inserting
your address) with scripts called macros. These can significantly reduce
the amount of typing you need to do.
FORCEFUL EXERTION
Force is the amount of muscular effort expended to perform work. Exerting large
amounts of force can result in fatigue and contribute to injury. The amount
of force exerted depends on a combination of factors, including:
The
effort with which one strikes an object (e.g. pounding the keyboard).
The shape and dimensions of an object you are working with.
How you
grip an object or tool.
The preciseness of motion required doing the task.
Duration of force applied by the muscles (e.g., the amount of time
spent without a muscle-relaxation break).
Awkward postures (over-reaching).
In addition to the pounding the keyboard example, some areas where we find
unnecessary force applied are in writing and filing/shelving. There are two
general types of grips people use; a “pincher grip” where you press
your finger against you thumb and a “power grip,” like you would
hold a suitcase. The pincher grip requires much more force and should be avoided
when possible (e.g. instead of pulling large files out of a cabinet by grasping
with a pincher grip from the top, slide your hand beneath the folder and lift
it from the bottom using a power grip).
People often use quite a bit of force holding those standard skinny pens
and pencils. Because writing is precise work (you must be able to read
what you
wrote), there is some resistance between the writing surface and your pen,
and the difficulty gripping a thin barrel, you must hold it tightly to maintain
control. Much better are those wide-barrel pens and mechanical pencils with
the soft grip at the end. One does not need to grip nearly as hard thereby
reducing strain on the muscles and tendons. Personal preference does come
in here so you might audition a couple of different types to see what feels
most
comfortable to you. Try to hold the pen as loosely as practical yet still
maintain control.
In conjunction with a neutral and balanced posture as
discussed in
Part 1, our goal from an ergonomic standpoint is to reduce the number of
repetitions or duration of exertion experienced by each set of muscles,
tendons, and joints
throughout the workday and to reduce the force applied to perform the task.
There is not usually a single golden bullet that will be a panacea for ones
ergonomic woes. OSHA provides an excellent review through their eTool on ergonomics.1The
State of Washington also has some very good self-evaluation checklists and
guides.2One has to recognize and be cognizant of reducing all these risk factors
both on and off the job to effectively reduce the potential for pain and injury.
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.
We welcome your comments and questions.
