An Ergonomics Overview
Here is a brief discussion of specific cumulative trauma injuries, and the basic concepts of ergonomics which help prevent them.
The Injuries
A common injury is tendonitis - inflammation of tendons, which connect muscle to bone. They are prone to damage when overstrained by repetitive use or tense muscles. Since there is little blood flowing in tendon tissue, healing takes a very long time, thus the potential for extended disability.
Nerves may be injured by repetition, friction, and pressure. Carpal tunnel syndrome (CTS) involves injury from pressure on the median nerve that travels through a tight space in the wrist - the carpal tunnel. This nerve delivers impulses to much of the hand, and returns sensory information to the brain. Symptoms include loss of coordination, weakness, tingling and numbness, and cold hands and fingers.
CTS is often misdiagnosed. For instance, if there is tingling in the pinkie finger, it would not be carpal tunnel syndrome, because the media nerve does not distribute to the pinkie. That would be an ulnar nerve compression. If you have pain in your wrist, that is not carpal tunnel. Symptoms are always in the hand. Surprisingly, many general practitioners still use CTS as a broad term for all computer discomforts. It is a very specific injury, and it is crucial that you understand the real anatomy of these maladies.
At the root of it, these problems begin with circulation. The bloodstream must supply fuel to the muscles and cleanse the wastes they produce. This process is disturbed by overuse. The blood can't keep up with the demand being made by constant muscular use in the arms, aggravated even more by slumping, which can limit circulation into the arms through the shoulders.
Freely flowing blood is also limited by uninterrupted or "static" contractions. When a muscle is exerted, the bloodflow is greatly reduced. At the computer, we do many static contractions, but because they don't involve great effort we tend not to notice them until we feel the pain. Holding the shoulders up, keeping the head in fixed positions, keeping the hands raised over the keyboard, keeping the trunk supported in a chair that doesn't support us. All of these are cumulative static muscular effort that leads to tightening of muscles, pulling on tendons, pressing on nerves. When it is the pattern in the way you work, hours each day, multiplied by stress, this is the formula for injury.
Or at least considerable discomfort. This pattern is avoidable simply by learning some simple work habits, and taking the time to make comfort a priority in your workspace.
Where to Start
Prevention of these problems begins with "Ergonomics," the science of adapting our bodies to our tools.
- Proper seating and desk arrangement.
Without proper seating and desk arrangement, regular computer users are at risk. The head should be over the shoulders to ease strain on the neck, shoulders and back, the lower back needs support from a proper chair, and the feet need to reach the floor to give the body overall support. Having the top of the monitor at eye level promotes these postures.
- Keyboard position.
The keyboard position should allow the wrists to remain as straight as possible. Research has clearly shown that pressure in the carpal tunnel increases when the wrists are bent during repetitive motions. The present keyboard design is itself suspect because of the strain inherent in the act of flattening the hands ("pronation") while we type. New designs are attempting to avoid this position. Yet ergonomics is not the whole solution. Prevention requires adjusting individual work habits.
- Stress.
Stress is an enemy. It depletes oxygen and blood to the body, tenses the muscles, and compromises the immune system. Managing stress means taking breaks - big ones and little ones. The going advice is to be away from the computer for at least fifteen minutes every two hours. Just as important is to take "micro-breaks" several times an hour. These are small moments to simply close the eyes, take a deep breath, rest the hands and arms, get up and stretch, and so on. These micro-breaks not only prevent injury, research clearly shows that they actually increase productivity.
- Control.
How much control does a person have over their job? Do people in the office get along well together? Does the supervisor or manager encourage ideas and openness? Are there mandated quotas or job surveillance systems? All of these are factors that can promote stress that can contribute to injury.
- General health.
Ultimately, the best prevention strategy is good general health. Eat well, get sleep, have some fun in your life. Have breakfast, take vitamins. All of this results in good blood, and that's the key. Our bodies need the nutrients the blood supplies to our tissues and metabolism.
Cumulative trauma injuries are truly preventable. Prevention does not have to be expensive. The investment required is tiny compared to the costs of lost time and productivity, medical and insurance costs, and rehiring and training that too many businesses have already suffered. More to the point, safe computing means healthier employees in an environment of higher morale and creativity. The time you take to learn more and make adjustments is the best investment you can make.
Additional ergonomics articles from Onsight
Initial Thoughts on Cumulative Trauma
Why is Cumulative Trauma Happening Now?
Ergonomics - A Brief Definition
