Practical Ergonomics
by
Jeffrey Pearson, D.O.
[Originally published in the San Diego Business
Journal, January 13,1997]
Put aside the notion that workplace ergonomics is only about injuries
- it makes good business sense, as well.
"The fact is," according to Franz Schneider, "that healthy
people work better and sick people perform poorly." Schneider
is the president of Humantech, a
Michigan-based ergonomics and consulting firm. "With all of the
billions of dollars that are invested annually to improve employee
health - smoking cessation classes, employee fitness areas, stress
management, nutritionally balanced menus in the cafeterias, and the like
- it is ironic how little consideration the physical workplace has
received."
This may soon change with the recent adoption of the Repetitive
Motion Injuries (RMI) Standard, by the California Safety and Health
Standards Board.
Speaking recently at the National Ergonomics Conference and
Exposition, in Los Angeles, Schneider plead the case that companies
actually become more productive and profitable when they pay appropriate
attention to ergonomics. Citing his firm’s experience working with
Fortune 500 companies such as Hewlett Packard, an ergonomically sound
workplace also benefits the most important assets of any business - the
employees. By encouraging a safe and work-friendly environment,
employees recognize that they are valued and remain happy, and
relatively injury-free.
"Sports medicine physicians know all too well just how difficult
it is to win the Superbowl with a team of injured athletes." Continuing
the analogy, Schneider noted that the quality of the physical work
environment is analogous to an athlete’s running shoes. "If the
shoes fit the athlete and are correct for the sport, they will enhance
the athlete’s performance; however, if they are the wrong size or don’t
fit the requirements of the sport, performance may be reduced. In the
short term, the wrong shoes may be a hassle or contribute to pain, but
the long term effects may result in foot deformities."
Just as it’s difficult to run a marathon in a pair of golf shoes
that are three sizes too small, you can’t hope to achieve world-class
performance in an ergonomically poor workplace that doesn’t support
your performance needs. Studies have demonstrated how the design of
office furnishings, seating, equipment, and workplace all interact to
support or hinder productivity.
Unfortunately, many companies wait until an employee develops a
cumulative trauma disorder (CTD), and then try dealing with the problem.
Schneider notes that "managing CTD’s is like managing customer
rejects - you’re focusing on the problem very late in the chain of the
events, similar to steering a boat by looking at its wake."
It’s been too easy for employers to ignore the business
implications of workplace ergonomics in the past, because traditionally
it has been difficult to quantify.
He suggests that a company establish goals and measure every element
of human performance. Citing the Hewlett Packard credo "That which
gets measured gets done," if an element of performance is measured,
then management will attend to it.
Also commonly referred to as to repetitive stress injuries (RSI’s),
the true incidence and costs attributed to CTD’s is not known, and is
undoubtedly underreported. In 1994, CTDNews
surveyed 3000 employers and reported that North American businesses
spent nearly $4000 for every reported CTD case. In all, U.S. businesses
paid about $3.6 billion in direct Workers’ Compensation benefits for
injuries such as carpal tunnel syndrome, shoulder tendonitis, and back
strains.
These figures do not account for indirect costs, according to the
North American Ergonomics Resources Guide, an industry publication.
Indirect costs include overtime, employee retraining and production
losses incurred as a result of injured workers. The Guide conservatively
estimates that the financial impact of CTD’s triples to about 10.8
billion or about $12,000 per CTD case.
Therefore, practicing proper ergonomics, as an integral part of the
production process, will save significant amounts of money wasted on the
treatment of avoidable CTD’s, further enhancing a company’s bottom
line. Simply moving objects to within an easier reach may save time and
can minimize the repetitive stresses placed on the worker.
In summary, employers shouldn’t perceive
the new RMI standards as a hassle or a threat to their survival. Rather,
they should consider the proven benefits of ergonomics in the workplace
and watch their bottom lines improve. And, at the same time they will be
protecting their most important resources - their employees.
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Injuries in the Workplace
by
Jeffrey Pearson, D.O.
Recalling the fact that humans are living machines
makes it easier to understand the mechanisms of injury in overuse
conditions. There is an elaborate network of pulleys designed to move
the various parts of our skeleton framework.
In actuality, these pulleys are comprised of two
integral parts: muscle and tendon tissues. While the muscles contract to
initiate movements, they would exert no effects without the tendons
required to attach them to the bones. The muscles need to have elastic
qualities in order to contract and relax. Tendons, on the other hand,
generally remain unyielding in order to transmit the forces across the
joints, inducing movement. In other words, muscle stretches like a
rubber band; tendons behave like paper tape and do not lengthen unless
they begin to tear.
When dealing with cumulative trauma types of overuse,
the tendons incur microscopic connective tissue fiber tears at points of
stress. One such point is their bony origin attachment. The best example
of this is probably lateral epicondylitis - more commonly referred to as
"tennis elbow." In this condition, the point of maximum
tenderness is where the tendon for the wrist extensor muscle group (top
of the proximal forearm) originates off of the lateral epicondyle of the
elbow. (Incidentally, unloading the pressure off of this bony origin
can help to prevent/worsen injury, hence the rationale for the use of
counterforce, or "tennis elbow," bracing.)
It had been long thought that inflammation ("-itis")
played a major role in the discomforts associated with overuse injuries,
e.g. tendonitis. However, while it often accompanies injuries, there are
overuse conditions in which no inflammation was detected in biopsy
studies. Hence, physicians may refer to some of these problems as
overuse tendinosis.
It should be noted that there are many factors affecting the degree
of force placed upon these tissues. These variables include the
intensity and duration of activity, inherent flexibility of the tissues
and allowance of adequate recovery time (for the fibers to heal
themselves), as well as the myriad of ergonomic issues (workstation
design, activity technique, etc.). Addressing each of these is a
prerequisite for the treatment and prevention of overuse injuries.
Sports medicine physicians
grade overuse injuries based upon the symptoms and
impact upon the athletes performance. This grading helps to guide the
treatment and rehabilitation process.
Grade 1 No pain with activity, but some
discomforts afterwards (either immediately or during the
evening/following days).
Grade 2 Some discomfort with activity
but does not interfere with performance.
Grade 3 Discomfort with activity and
interferes with performance (body mechanics altered).
Grade 4 Discomforts so intense that
activity cannot be performed at all.
Treatment Guidelines:
Grade 1 Usually reducing the intensity or
duration of the activity by 25% is all that's required. Activity can
be gradually increased as symptoms allow. A runner, for example, should
never increase his or her weekly mileage by more than 10%. Similarly, an
assembly line worker should gradually increase his or her production to
avoid re-injury. Sudden, excessive overtime is a sure-fire recipe for
overuse complaints because the workers do not have an opportunity to
build up their endurance prior to the extra work.
Grade 2 Reduce intensity or duration
of the activity by 50%.In addition to ice and stretches, consider
the use of non-steroidal anti-inflammatory agents in appropriate
individuals. Physical therapy can be considered, but is not absolutely
necessary at this point. When pain is gone, have therapist teach an
endurance program, in addition to concentrating on eccentric
strengthening exercises.
Grade 3 "Active" rest: the
worker should stop performing the offending tasks, but is allowed
to move the affected part for his daily activities. Physical
therapy is used to speed resolution of the discomforts, as well as
rehabilitate, i.e. strengthen, increase endurance, restore coordination
and proprioception. In addition to the oral non-steroidal
anti-inflammatory agents, a corcoteroid injection may be considered at
this time.
Grade 4 Complete rest of the affected part, usually
involving the use of some sort of sling or splint (even casting is
considered in severe cases). All of the above options applicable here.
If worker fails to improve, or condition recurs despite adequate
treatment, then surgical intervention may be required, e.g. removal of
subacromial spur affecting a rotator cuff tendonitis.
Primary Prevention Tips: Unlike
sports, there is no "off-season" for workers to recover from a
season of overuse, nor is there a "pre-season" to warm up
prior to beginning employment. Industrial athletes perform all year
round. Therefore, it is extremely important to emphasize a continued
flexibility program; otherwise, the tissues will be "tight"
with reduced flexibility which will make it easier for the microscopic
tears to occur, leading to injury. Only after the tissues have achieved
a certain degree of flexibility should a strength training and endurance
program be initiated. Starting strength exercises too soon will often
result in worsening of the condition.
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Regarding your posture, there is no optimal position, but the
following guidelines will help the body to adjust better to fit a
particular situation:
Adjust the chair first, the keyboard second,
and then the monitor.
Traditionally, ergonomists have advised:
Your feet should be flat on the floor.
Knees bent at about 90°.
The seat of your chair should be flat. The back of the chair should
be straight upright (rather than leaning backwards) and the lower back
should be supported.
Avoid sitting in positions that place sharp pressure on your legs or
wrists. There should be at least 2 fingers clearance between the front
edge of the chair and the back of the knee. Arm and shoulder muscles
should be relaxed.
Your elbows should be bent at about 90°, wrists should be straight,
rather than cocked up or bent downwards.
If you use a monitor a lot, it should be placed directly in front of
you. The top of your monitor screen should be slightly (e.g. 20°) below
eye level. If you wear bi-focals, try tilting the lowered screen to
lessen neck strain.
***More recently, the traditional views of sitting have been
challenged and some alternative sitting postures discussed in The
Chair : Rethinking Culture, Body, and Design by Galen Cranz.
[Some excellent reviews of the book can be found at the
Amazon.com site here.]
Feel free to experiment to see what works best for your body e.g.
some people may find "perching" postures more acceptable via
the use of sit-stand
chairs. Other new and exciting chair designs include saddle-shaped
seating such as the Capisco,
the Bambach, and the Salli.
(Beware the sticker shock factor, though!).
Other considerations:
Try taking a break from computer activities at least every 20-30
minutes. Getting up and moving around is ideal; try to break up
computer tasks with alternate work [In fact, many of us would
comment that getting up from chair as often as possible is much more
important than worrying about the type of chair that one sits in.]
Avoid over-reaching and awkward positions. Things that you
use most of the time should be within one forearm’s reach, e.g. keep
the mouse close to the keyboard and move your entire hand. Things that
you use less frequently should be within a full arm’s reach, and
those that you hardly ever use should be out of the way.
Use document holders and telephone headsets to maintain your
neck in a neutral, i.e. stress-free, posture. The prices of good
telephone headsets (e.g. Plantronics)
are coming down. (If you're an employer, it's certainly worth
springing for headsets for your staff as they're infinitely cheaper in
the long run than a Workers Comp claim for a chronic tension neck
syndrome!)
Reduce/eliminate glare by adjusting the monitor location,
closing blinds, using focused light sources, or trying non-glare
screens.
Ergonomic book, software, and website
recommended by Dr. Pearson:
Working Well...? How to Correct the Unhealthy Workplace: The
Ergonomic Approach. Terry McShane, M.A. T&M Associates, P.O.
Box 23-2156, Encinitas, CA 92023-2156; (858) 753-6556;
Ergosentry (now includes Ergo Stretch, too!). http://www.magnitude.com/main/products.html
ErgoWeb. A great resource site for all things ergonomic.
http://www.ergoweb.com
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Working on your feet all day can also lead to RSI’s. For
example, hard concrete surfaces do not absorb the forces from the striking
of the foot against it. Rather, these forces are re-directed back upward
into our bodies. These may result in continued stresses leading to
micro-tears in the tissues of the arches of the feet (Plantar fasciitis),
as well as chronic back fatigue.
Prevention is easy. Providing a means of dampening
the forces between the ground and your feet makes sense. Vibram-soled
shoes, such as those found in work/hiking boots are effective. I
personally recommend Rockport
and Ecco's - they are extremely comfortable and lightweight, yet durable.
(I also
like Spenco shoe inserts
and my $9.99 Dr. Scholl's
arch supports for additional shock absorption in my running shoes.) Shock mats
are recommended for prolonged working in one place.
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THINK before
lifting! THINK before lifting! THINK before
lifting!
- Be familiar with what
you're about to lift. Don't just go ahead and
assume that an object is either heavy or light. Test it gently,
first - no one likes surprises!
- Know where the
object(s) needs to be placed. Don't pick up and
carry a box while you decide where it should go. At the same
time, be sure that you have a clear path to your destination,
avoiding wet floors and junk that you might trip on.
- Ask for assistance.
Don't hesitate to request additional help if an object is perceived
as being either too heavy or awkward for one person to lift/carry in a
safe manner.
Lift/carry using proper
techniques
- Keep your chin up
while lifting and setting objects down. This helps to engage your
legs and spares your back! Also, never keep your knees locked
straight while forward bending
- this places too much stress on the low back and can cause
"locking" of the sacroiliac joints (this hurts!).
Therefore, always try to partially bend at least one knee while
bending - you'll notice the difference.
- Carry objects as close
to your chest as possible to decrease the forces placed
upon the spine.
- Don't twist while
carrying. The lower back (lumbar spine) is not
designed for twisting. Pivot, if you must turn.
- If given the choice, it's
better to push a heavy load than to pull it. Simple
physics dictate this, so why mess with Mother Nature?
Finally...
If you recognize that, despite your best
intentions, you've still managed to overdo your lifting, don't wait for the
symptoms of pain and stiffness to begin later on. Apply ice/cold
packs to the region as soon as possible for about 20-30 minutes.
This can often head off a painful low back syndrome 1-2 days later. Don't
forget: ice is nice!
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