PC Users Bible

As the name suggests, repetitive strain injury (RSI) is a class of physical damage caused by performing the same awkward, prolonged, or forceful physical action many times. Medical professionals call this a cumulative trauma disorder (CTD). It can appear in the hands, neck, shoulders, or arms as pain, numbness, weakness, or loss of motor control.

RSI hurts. The symptoms are not always the same-they could be sharp pains in your shoulders or forearms, sore or numb hands, or loss of fine motor control, among other things-and can appear while you're using the computer or hours later. The best-known type of RSI is carpal tunnel syndrome, which appears as numb or tingling fingers and a painful wrist, but other forms of RSI can affect other groups of nerves, tendons, and muscles. Depending on the specific form, the pain can be severe enough to wake you in the middle of the night.

Obviously, this is something you want to avoid if you possibly can. The best way to prevent RSI is to understand its causes:

• Constant muscle contraction: Typing, clicking mouse buttons, and dragging a mouse, as well as sitting in one position for prolonged periods of time, all keep your muscles contracted, and keep them from receiving fresh blood when they are relaxed. Over time, your muscles adapt by remaining in the contracted position. This forces your tendons to stretch, which causes pain and inflammation.

• Cumulative trauma: As you repeat the same motions for hours, days, and months, your muscles, tendons, and other tissue wear because of friction and excessive motion. When this starts, the damage is slight and your body can repair the damage with rest and relaxation. But if you repeat the same activity before you have recovered from the original injury, the damage builds upon itself and becomes susceptible to even more damage.

• Poor posture: If your body is twisted into an awkward position, you're forcing it to work harder and to move your muscles in potentially damaging ways. Even good posture, if kept in one position too long, can be detrimental.

• Excessive force: When you grasp your mouse or pound on a keyboard harder than necessary, or if you hold the keys down too long with too much pressure, you can decrease the circulation in your fingers and increase the tension in your muscles.

• Pressure against a nerve: Leaning a wrist or elbow against the edge of a table, or even wearing a tight wristwatch, can compress certain nerves that run close to the skin.

This is all frightening stuff. You can reduce the likelihood of RSI by following the advice earlier in this chapter. But many of us are creatures of habit, and it's often difficult to remember to keep your wrists up and your feet on the floor if you have been doing things differently for years.

So if you do happen to wake up some morning with early symptoms of RSI, talk to your doctor as soon as possible. It's a lot easier to treat RSI before it becomes more intense. If you don't take steps to reverse or eliminate the problem, it continues to get worse until it becomes a major disability. At that point, you may be facing an extended period away from your computer, combined with drug treatment and a long schedule of physical and occupational therapy.