Computer Ergonomics

Living with computers
Dr. Charles Daniels, D.C. Chiropractor

Introduction

Welcome to my computer ergonomics homepage. I hope the information here can be of some help to you. The big idea is to help you be able to use you computer without health problems sneaking in to ruin your fun or decrease your productivity. The emphases is very much on preventing troubles rather than trying to fix existing conditions. Although some guidance as to what can help will be touched upon, if you have a problem, this page is no substitute for professional help.

The Human Interface

Working with a video display terminal (VDT) and a keyboard can be productive, rewarding and a lot of fun. Unfortunately, prolonged postures, coupled with high levels of concentration and the occasional frustration of things going less than perfectly, can lead to physical problems. Basic understanding in the way you "interface" with your computer can help prevent common health-related VDT and keyboard problems. A little knowledge of the principles of ergonomics, how people interact safely and efficiently with machines and their work environment, can save a lot of discomfort and maximize both productivity and enjoyment.

Machine Set-up

Visibility. Must be able to see what you are doing easily to avoid eye strain and neck pain. Have adequate amounts of light. Florescent lights are not very good, the so called "natural spectra" florescent lights are not quite as bad, incandescent lighting is better and indirect natural (sun) light is best. Reduce glare as much as possible, not only on your screen but also on the rest of your work ares including the keyboard. Hoods, drapes, glare screens and changing the lights can do wonders. Use the control knobs on the monitor, they can help you. Don't be afraid to fiddle around with the tilt and height positions of the monitor. Rearrange things until you can see well and it feels comfortable for you.

Keyboards. Be sure to get the height right to prevent too much bend at the wrist and allow the forearm to have some support. The arms should hang loose to prevent the shoulder muscles from cramping. Many keyboards can tilt; unfortunately, most of them tilt the wrong way. If any thing the keyboard should tilt to help the wrist stay straight, which is to say raising the space bar end and lowering the "top"(the F1, F2 etc.) end. Tilting the key board the other way, (space bar lower and "top" row higher) can predispose you to carpel tunnel syndrome.

Mouse. The continual clicking and small, precise motions involved in mouse use are a repetitive action that can be a health hazard. A few basic rules can help make handling this convenient input devise safer and more comfortable:

Hold the mouse loosely. "White knuckling" the mouse creates too much tension. Use a light touch when you click.
Use you whole arm and shoulder to move the mouse, not just your wrist. Don't rest your forearm on the desk while you move the mouse.
Do not lift your "pinkie", use all of your fingers to lightly hold the mouse.
Keep your wrist relaxed and neutral, not bent. The click button should be about the same height as your keyboard.
Avoid prolonged postures. Rotate your shoulders, gently shake your hands and fingers four or five times per hour.
Left handers should use a "left handed" mouse, or configure the mouse to work best with their different (mirror image) hand shape.

Desks. Make enough space so that you have room to work, especially if your pushing your mouse around. Use a paper holder to keep letters or books semi-vertical and at eye level. Your work space should be set up so that you need not twist your neck. Documents should be positioned at the same height and next to the VDT, especially if a lot of time is to be spent at these tasks. Make your work space user friendly.
Keep your distance. Electromagnetic radiations follows the inverse square rule, which is to say the further away you are from the source, the weaker they get and they do so quickly. You can protect yourself with space. I recommend you stay at least 75 centimeters (30 inches) from your terminal and at least one meter (40 inches) from other terminals.
Keep it fixed. X-ray and other radiation production increases dramatically when the VDT is damaged, improperly maintained, or just plain worn out. PCBs are sometimes released by very old VDT models (ie built before 1970).

Human Set-Up

Posture. No one posture is perfect. You do not have to be "military" but getting comfortable is essential. Footrests help, (or a book or lunch pail or anything handy to rest your feet up a bit), as do cushions if your chair is not providing adequate support. The most important rule is to avoid prolonged positions. Shake your hands and shoulders now and then. Keep lose.

Eyes. After good lighting and avoiding glare, the most important eye consideration is to look away from the screen occasionally. It really helps. Also, don't forget to blink. Blinking moistens the eyes to prevent burning from dryness.

Warm up. Just as an athlete prepares for the game by stretching and loosening the joints and muscles to prevent injury and enhance performance, you too should prepare for a marathon session surfing the Net. Do some shoulder rolls, neck stretches, wrist wiggles and leg stretches before you even log in. Prevention is better than repair.

Breaks. If you hold any part of you in one position for longer than an hour, you set your self up for stiff joints, achy muscles, tendon fatigue and ligament weakness; not to mention decreased efficiency and diminished concentration. If you are focused on what you are doing, you can loose track of time unless you purposely schedule breaks. Have the computer clock on screen, or steal the oven timer out of your kitchen, or set the alarm on your watch, or somehow let yourself know about the passage of time. Then, at least once an hour, (every half hour would be better), get right up off your seat and walk around, stretch, yawn, wiggle, breath, get the blood flowing and stimulate the joints. It is worth the time and trouble as you will feel better, work sharper and get more done. Take advantage of un-scheduled "downtime". Instead of staring at the little hour-glass and wishing it would go faster, do something beneficial for your body.

If you already have mechanical body problems, such as neck arthritis or carpel tunnel syndrome, it is necessary to take breaks more frequently; on the order of three or four mini-breaks per hour. Preventing a flair-up is far superior to irritating these disorders.

Article from http://www.klis.com

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