Computer Ergonomics - Avoiding MSD and RSI

What Is MSD & RSI? Logo
What Is MSD & RSI?
Preventing MSD/RSI
Preventing Eye Strain
Healthful Work Habits
Safety & Comfort Checklist (Summary)
Copyright © 2012-2017 by Matthew S Harris

Matthew S Harris is a software & database designer, contract programmer & consultant.

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Musculo-Skeletal Disorder (MSD) is a blanket term for illnesses and diseases of the muscles, tendons, skeleton, and connective tissues, such as tendonitis. Repetitive Stress Injury (RSI) is a type of MSD, and refers to injuries to the muscles, bones, or connective tissues caused by repetitive motions. Carpal Tunnel Syndrome is an example of a common RSI. MSD and RSI injuries can take many forms, and can affect any part of the human structure; typically in the hands, shoulders, neck, spine, knees, or ankles.

What Causes MSD/RSI?

Repetitive Stress Injury (RSI) occurs when a person performs the same motion over and over; especially if the motion is performed intensely over a long period of time and involves awkward body positions and/or application of force. Long periods of typing, improper workstation setup, incorrect work habits and/or problems in your personal health may be linked to MSD or RSI.

When you work muscles intensely, the individual cells in your muscles produce waste products faster than your circulatory system can carry them away. The cell waste products, called fatigue poisons, build up in the muscle and other body tissues, and cause swelling. In turn, the swelling reduces circulation, and causes a further build-up of fatigue poisons, resulting in further swelling which reduces circulation even more, and so on in a vicious cycle. Swelling in muscles and connective tissues often puts pressure on nerve pathways, resulting in temporary or permanent damage to the nerves.

As an example, a common type of RSI is Carpal Tunnel Syndrome. The tendons that move your fingers pass through small tunnels in the carpal bones at the back of your hands (hence the name carpal tunnel syndrome). When your hands are overworked, the tissues around the carpal tendons swell, and the tendons become too large to move freely through their bone tunnels; the tendons then scrape against the bone and pinch the nerves that share the carpal tunnel with the tendons. The result is a painful, crippling loss of mobility and control of the hands.

Other types of MSD have similar causes, mostly related to a lack of circulation. For example, constant vibration can drive blood away from the part of the body experiencing the vibration, resulting in tissue and nerve damage.

Some types of MSD, however, are caused by a lack of motion. The joints of the human body, like the moving parts of machinery, must be lubricated for the joint to move freely. Although the human body produces its own internal lubrication for the skeleton's joints, movement of the joint is necessary for the lubrication to be spread over the bearing surfaces. If you don't move the various joints in your body through their full range of motion, the available range of motion tends to become less.

Who gets MSD/RSI?

Young or old, anyone in any occupation can get MSD or RSI. Although we currently most hear about RSI related to computer work, you can get RSI or other MSD from any sort of work, and even from your hobby and recreational activities.

For example, RSI has been a problem afflicting assembly-line workers for over a century now. Piano players have been known to get Carpal Tunnel Syndrome, and there is an MSD known as "bassoon finger" caused by the fact that bassoon players support most of the weight of their instrument with one finger of one hand when playing. Motorcyclists are subject to an MSD known as "tingle-finger" which is caused by vibration in the handlebars— the vibration drives blood out of the fingers, resulting in nerve and tissue damage in the hands. In recent years, teenagers are being diagnosed with a malady known as "texter's thumb", caused by using one's thumbs for too much typing.

Carpenters, engineers, painters, sculptors, drafters, programmers, designers, students — anyone at all can be at risk for MSD/RSI.

MSD/RSI Symptoms & Warning Signs

The symptoms and warning signs of MSD/RSI usually appear in the hands, wrists, arms, shoulders, neck, or back. Symptoms include:

  • Pain
  • Numbness
  • Tingling
  • Throbbing
  • Weakness
  • Swelling
  • Burning
  • Soreness
  • Aching
  • Cramping
  • Stiffness

You may feel such symptoms when typing, using a mouse, drawing, or any number of other activities.

You may also experience these symptoms when you're not engaged in the activity responsible for the injury, such as at night.

If you experience any of the symptoms listed, or any other pain or discomfort you think is related to an RSI, you should promptly consult a doctor.

Additional Risk Factors For MSD/RSI

Your ability to avoid MSD/RSI while working or pursuing recreational activities can be affected by your general state of health. Some factors that have been shown to increase an individual's risk for MSD/RSI are listed below.

In the preceding list, notice that most of the complicating factors are related to conditions that may impede blood circulation. Use of tobacco products, for example, puts nicotine in your system. Nicotine is a vasoconstrictor drug, and reduces blood circulation in the extremities, hence increasing the risk of RSI such as Carpal Tunnel Syndrome.

The remainder of this article describes proper computer workstation setup, posture, and work habits to help you avoid MSD/RSI.

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