REPETITIVE STRESS INJURY
Repetitive stress injury (RSI) is a result of repeated movement of a particular part of the body.
A familiar example is "tennis elbow." Of more concern to keyboard users is the form of RSI
called carpal tunnel syndrome (CTS).
CTS is an inflammatory disease that develops gradually and affects the wrist, hands, and
forearms. Blood vessels, tendons, and nerves pass into the hand through the carpal tunnel (see
illustration below). If any of these structures enlarge, or the walls of the tunnel narrow, the
median nerve is pinched and CTS symptoms may result.
Symptoms of RSI/CTS
CTS symptoms include numbness in the hand; tingling or burning in the hand, wrist, or elbow;
severe pain in the forearm, elbow, or shoulder; and difficulty in gripping objects. Symptoms
usually appear during sleeping hours, probably because many people sleep with their wrists
If not properly treated, the pressure on the median nerve, which controls the thumb,
forefinger, middle finger, and half the ring finger, causes severe pain. The pain can radiate into
the forearm, elbow, or shoulder and can require surgery or result in permanent damage or
Causes of RSI/CTS
RSI/CTS often develops in workers whose physical routine is unvaried. Common occupational
factors include: (1) using awkward posture, (2) using poor techniques, (3) performing tasks with
wrists bent (see below), (4) using improper equipment, (5) working at a rapid pace, (6) not
taking rest breaks, and (7) not doing exercises that promote graceful motion and good
Reducing the Risk of RSI/CTS
CTS is frequently a health concern for workers who use a computer keyboard or mouse. The
risk of developing CTS is less for keyboard operators who use proper furniture or equipment,
keyboarding techniques, posture, and/or muscle-stretching exercises than for those who do not.
Keyboard users can reduce the risk of developing RSI/CTS by taking these precautions:
1. Arrange the work station correctly:
a. Position the keyboard directly in front of the chair.
a. Keep the front edge of the keyboard even with the edge of the desk so that wrist
movement will not be restricted.
b. Position the keyboard at elbow height.
a. Position the monitor about 18 to 24 inches from your eyes with the top edge of the screen
at eye level.
a. Position the mouse next to and at the same height as the keyboard and as close to the
body as possible.
2. Use a proper chair and sit correctly:
a. Use a straight-backed chair that will not yield when you lean back.
a. Use a seat that allows you to keep your feet flat on the floor or use a footrest.
a. Sit erect and as far back in the seat as possible.
3. Use correct arm and wrist positions and movement:
a. Keep your forearms parallel to the floor and level with the keyboard so that your wrists
will be in a flat, neutral position rather than flexed upward or downward.
a. Keep arms near the side of your body in a relaxed position.
4. Use proper keyboarding techniques:
a. Keep your fingers curved and upright over the home keys.
a. Keep wrists and forearms from touching or resting on any surface.
a. Strike each key lightly using the fingertip.
5. When using a keyboard or mouse, take short breaks. A rest of one to two minutes every
hour is appropriate.
6. Exercise the neck, shoulder, arm, wrist, and fingers before beginning to key each day and
often during the workday
Ergonomic keyboards are designed to improve hand
posture and make keying more comfortable. Generally they
have a split design with left and right banks of keys and the
ability to tilt or rotate the keyboard for comfort. More
research is needed to determine just how effective er-
gonomic keyboards are in preventing RSI injuries and
carpal tunnel syndrome.
Like the mouse, a trackball is a
pointing device that moves the
insertion point. A trackball enables
the user to control the pointer without
hand or wrist movement. The thumb
or finger moves the ball directly. The
ergonomic design of the trackball
generally features buttons contoured
to the shape of the hand.
Brief daily practice of finger gymnastics will strengthen your finger muscles and increase the
ease with which you key. Begin each keying period with this conditioning exercise. Choose
two or more drills for this practice.
DRILL 2. Clench the fingers as shown. Hold the fingers
DRILL 1. Hands open, fingers wide, muscles tense. in this position for a brief time; then extend the fingers,
Close the fingers into a tight "fist," with thumb on top. relaxing the muscles of fingers and hand. Repeat the
Relax the fingers as you straighten them; repeat 10 movements slowly several times. Exercise both hands
times. at the same time.
DRILL 3. Place the fingers and the thumb of one hand DRILL 4. Interlace the fingers of the two hands and
between two fingers of the other hand, and spread the wring the hands, rubbing the heel of the palms
fingers as much as possible. Spread all fingers of both vigorously.
DRILL 5. Spread the fingers as much as possible, DRILL 6. Rub the hands vigorously. Let the thumb rub
holding the position for a moment or two; then relax the the palm of the hand. Rub the fingers, the back of the
fingers and lightly fold them into the palm of the hand. hand, and the wrist.
Repeat the movements slowly several times. Exercise
both hands at the same time.
DRILL 7. Hold both hands in front of you, fingers
together. Hold the last three fingers still and move the
first finger as far to the side as possible. Return the first
finger; then move the first and second fingers together;
finally move the little finger as far to the side as