Computer Work Postures and Injury: The Stress of Reaching for the Mouse, A
Doctors' Perspective
by Dr. Steven R. Jones, DC
As we spend increasing amounts of time at our computer workstations, we need
to be aware of how the design and arrangement of our equipment can impact our
chances of injury. Computer ergonomics is the study and / or implementation of
work station design with the purpose of reducing or eliminating physical stress.
My interest in repetitive stress syndromes began approximately 10 years ago when
my practice started seeing a much greater number of people suffering from the
effects of computer work.
Despite all of my training and continuing education related to these types of
injuries, I quickly realized that short of surgery and radical changes in the
patient's lifestyles, treatment for this type of injury was marginally
successful at best.
The real solution had to be prevention and it was going to involve the
application of basic ergonomic principals.
This article will address the specifics of injury resulting from postural
stress secondary to use of the computer mouse.
Specifically, the following will be addressed:
1) What repetitive stress injuries are
2) What role do work station ergonomics play in injury
3) How reaching for the mouse sets the stage for injury
4) What are the symptoms of repetitive stress injury
5) How one can avoid mouse reaching injuries
What Exactly is a Repetitive Stress Injury?
Repetitive Stress Injury is a kind of catch all phrase for many conditions.
Carpal Tunnel Syndrome, Tenosynovitis / DeQuervain's Syndrome, Tendonitis,
Thoracic Outlet Syndrome, Trigger Finger, Myofascial Pain Syndrome and Chronic
Sprain / Strain are some of the actual diagnosis that are rendered in my office.
All of these conditions are serious and in many cases can cause great pain,
permanent disability and sometimes loss of employment.
Repetitive Stress Injuries occur from repetitive movements involving a
specific set of muscles and joints. RSI injuries are the result of an
accumulation of stress and strain that causes irritation, inflammation, and
eventually pain or other disability. A good analogy used to characterize the
onset of RSI would be the "straws on the camels back" saying.
Initially, RSI affects the soft tissues of the involved joint(s). Soft
tissues include muscles, nerves, ligaments and tendons. However, if left
untreated for long periods of time, the involved joint can become arthritic and
form bone spurs resulting in permanent damage to the joint.
While various occupations ranging from meat cutters to construction workers
develop RSIs that result from the typical duties of their professions, the most
frequent cause of these injuries involve computer work.
The constant demand of keyboarding and mousing combined with the postural
stress of confinement in an office chair with one's neck and back held in
prolonged fixed positions has resulted in an epidemic of injuries that includes
hand pain, wrist pain, arm pain, neck pain, back pain and shoulder pain.
Work Station Ergonomics
The study of workstation ergonomics tells us that the objects that are used most
often should be located closest to your body and accessed easily, without
awkward body positions. Repeated reaching or prolonged postures that involve
leaning forward from your chair are particularly stressful and fatiguing.
Many people are aware of computer ergonomics and thus have an ergonomic
mouse. An ergonomic mouse is of little use if it is positioned in an area that
requires reaching and stretching in order to operate it. Limiting reaching and
stretching for desk items is essential to maintaining a healthy ergonomic
environment.
The most frequent complaint that I have seen in my office is due to computer
work is the combination of mousing and its' inherent postural stress.
Most computer stations are designed in a way that involves the worker
operating the computer mouse on a pad on the desk. Reaching to the desk for the
mouse places direct stress on the joints and soft tissues of the neck, shoulder,
elbow, wrist and hand. Additionally, reaching forward for the mouse stresses the
lower and middle back.
So How Does Reaching for the Mouse Set the Stage for Injury?
Reaching for the mouse causes you to lean forward in your chair, extend your
arm and support the weight of your body through your extended arm. The following
section will discuss the particulars of each of these positions.
The stresses placed on the human frame when reaching for the mouse are easily
explained. 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 of the spine.
In recent years, ergonomisist have told us that proper sitting posture would
have us sitting upright with our hips flexed at 90 degrees. As it turns out, the
most up to date studies show that a slightly reclined sitting posture with the
hips flexed at 100 to 115 degrees is ideal if you have to sit at a desk. If your
mouse is not positioned close enough to your body, you will have to reach for
it. Reaching for your mouse stresses your back by reducing the angle of your
hips.
Next, we have to look at the effects of reaching on the neck and shoulder.
When the mouse is being operated at a distance that makes the operator reach,
the shoulder extends forward and the shoulder blade abducts (rotates forward).
This position stretches the muscle groups that connect the medial portion of
your shoulder blade to your spine and the superior portion of your shoulder
blade to your neck. In the short term, this stretch aggravates the affected
muscle groups causing spasm, fatigue, headaches and stiffness in the neck and
shoulder. In the long term, this position creates a condition called a "stretch
weakness" resulting in muscular imbalance, trigger points and chronic variations
of the conditions listed in the prior sentence.
Lastly, placing the mouse too far away, too low, or too much on one side can
cause shoulder, wrist, elbow, and forearm discomfort. When the operator is
forced to reach for the mouse, his / her body weight shifts forward and
ultimately results in weight bearing stress on the extended arm. Spending
prolonged periods of time leaning on an extended arm is an unnatural and
destructive posture that will eventually lead to the development of a repetitive
stress syndrome; likely resulting disorders would include tendonitis of the
wrist, elbow or shoulder.
What are the Common Symptoms?
- Tightness, discomfort, stiffness, soreness or burning in the hands,
wrists, fingers, forearms, or elbows
- Tingling, coldness, night pain or numbness in the hands, especially
around the base of the thumb
- Clumsiness or loss of strength in the hands
- Pain in the neck, shoulders, wrists, hands or back that is associated
with using the computer
How Can You Avoid Injuries Related to Reaching for the Mouse?
The following recommendations are applicable to both home office ergonomics as
well as ergonomics in the office.
1) Placing the input device directly in your immediate reach zone offers
natural comfort and maximum hand-eye coordination. The use of a platform for the
mouse is preferable. Some models of mouse platforms attach directly to your
chair.
2) Your chair should have arm rests that are adjustable.
3) Your wrist should be either in a neutral position or flexed slightly
downward when operating both your mouse and your keyboard. For this reason, if
you select a mouse platform that attaches to your chair, adjustability of the
platform is of primary importance.
4) Consider using a high quality office chair with adjustable armrests and
lumbar supports. It should also allow some degree of recline.
5) Make sure that the upper arm and elbow are as close to the body and as
relaxed as possible for mouse use - avoid overreaching.
6) Hold the mouse lightly, don't grip it hard or squeeze it. Place the
pointing device where you don't have to reach up or over very far to use it. The
closer you can place it to your body the better.
Dr. Steven R. Jones DC (Steve), is a licensed Chiropractor
in the state of California. Dr. Jones completed his pre-med education at
California State University Hayward. He finished his doctorate work at Palmer
College of Chiropractic-West. Dr. Jones has treated his patience for 15 years at
his own practice Jones
Chiropractic Clinic. He holds a U.S. Patent on the ergonomic device, the
"Ergo Nav", the only fully
adjustable mouse platform on the market.
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