Back pain is a common complaint among computer users. Common causes:
Problem: Chair lacks lower-back support. A chair that fails to support the lumbar (lower) region of the spine is a common cause of back discomfort; 35 percent more pressure can be placed on an unsupported lower back. The normal alignment of the spine is an S-shaped curve: an inward curve at the neck, an outward curve in the middle of the back, and an inward curve at the lower back. When a chair does not provide adequate lumbar support, the lower curve of the back flattens. As a person sits, the bottom of the hipbone contacts the chair first. The hip rotates, flattening the curve in the lower part of the back; the spinal discs stretch from the vertebrae causing back pain.
Solution: Select a chair that provides good low-back support. A chair that maintains the normal alignment of the lower spine will relieve fatigue and discomfort. Adjusting seat pan tilt also helps align the lumbar spine. A straight-back chair provides little or no support. Sitting in such a chair causes back fatigue from the effort required to maintain a comfortable posture.
Solution: Select a chair that has a tiltable backrest; a tiltable backrest permits you to change postures and reduces muscular fatigue. A slight backward tilt helps reduce the flattening of the lower spine.
Problem: Chair is too soft or too hard. If you’re like most computer users, you spend most of your work time sitting. If your chair is too soft, you sink into the seat pan which restricts your movement and causes thigh, buttocks, and lower back fatigue. When your chair is too hard, you may need to change postures frequently to relieve thigh and buttock discomfort.
Solution: If possible, try out different chairs with similar features and select the one that feels most comfortable.
Problem: Monitor is too low. When your monitor is too low, you tend to bend your head forward, slouch, or lower your chair to improve viewing. Tilting the monitor up too much can increase glare from overhead lighting.
Solution: Raise the monitor to the correct viewing height; the topmost active line of text displayed on the screen should be at or just below your eye level.
Neck strain is often related to improper monitor height, poor placement of documents, or improper positioning a document holder.
Problem: Improper monitor height. A monitor that is too high or too low will cause you to bend your neck backward or forward to read text on screen. If you wear bifocals, trifocals, or progressive lenses, you may also tilt your head back to read through the bottom portion of the lenses.
Solution: Lower or raise the monitor so that you don’t have to bend your neck or tilt your head to read text.
Problem: Poor placement of documents. Documents placed flat and off to the side of the work surface cause forward bending and twisting of the neck and trunk. Solution: Use an adjustable document holder. Position it close to and at the same height and viewing distance as the monitor screen — or between the keyboard and monitor if space is available. Improperly positioned document holder The document holder is too far away from the monitor screen.
Solution: The monitor screen and document holder should be close together and the same distance from your eyes so that you can look from screen to document without excessive neck or back movement.
Working with your arms too high or low can cause shoulder pain. When your arms are too high, they pull your shoulders up, straining shoulder and back muscles. When your arms are too low, they pull your shoulders down, putting pressure on the shoulder and back muscles and compressing nerves in the neck and arms.
Problem: Keyboard is too high or too low
Solution: Adjust the keyboard or chair so that your hands are at or just below elbow height; wrists and forearms should be in a reasonably straight line, slightly above the keyboard. Your shoulders should be relaxed, your elbows next to your body.
Problem: Chair armrests are too high or too low
Solution: Remove the armrests if you can’t adjust them to a comfortable height; if they’re permanently attached to the chair, replace the chair with one that has adjustable armrests.
Problem: Shoulder or arm discomfort. You could develop a sore shoulder from prolonged reaching if the mouse is too far away from your keyboard.
Solution: Place the mouse next to the keyboard so that your shoulders are relaxed, your wrists are straight, and your elbows are by your side. If you don’t use the ten-key portion of your keyboard consider a mouse bridge, a simple platform that rests over the keypad. Using the mouse on the bridge reduces the need to reach for the mouse.
Problem: Hand and finger discomfort. How do you move your mouse? Holding the mouse too tightly or resting your wrist on the edge of the work surface can cause pain in your hand or fingers. Solutions:
Forearm and hand
Discomfort can occur if your hands aren’t in line with your forearms or if sharp work surface edges press against your palms, wrists, or forearms.
Problem: Keyboard is too thick, too low, or too high.
Solution: Use a thin keyboard to keep your hands in line with your forearms. Adjustable-height and sloped keyboard platforms make correct hand and wrist posture easier to achieve.
Problem: Wrists rest on the work surface. Some keyboard users support their wrists on the work surface as they type. This can cause backward bending of the wrist and pressure on the wrists and palms.
Solution: Choose work surfaces that have round edges or use a palm rest. A palm rest will support the heel of your hand and minimize wrist bending. The top of the palm rest should not be higher than the first row of keys.
Problem: Edge of the seat pan presses against the thighs.
Solution: Adjust the seat-pan height so that your feet are flat on the floor; use a footrest if your feet aren’t flat on the floor. (The ideal seat-pan length allows two to three finger widths from the front edge to the back of your knee.)
Problem: Excessive knee bending. Avoid using the base of your chair as a footrest. Doing so can cause your knees to bend too much.
Solution: Adjust the height of the chair so that your feet rest flat on the floor. Use a footrest, if necessary.
Problem: Burning eyes, blurred vision, irritated eyes, headaches.
Solution: The minimum distance from your eyes to the screen should be 16 inches. Take a short rest break (3-5 minutes) for each hour of continuous computer work; get up and stretch, move about, or do other work. Periodically focusing on distant objects also relaxes eye muscles.
Problem: Uncorrected or improperly corrected vision. Uncorrected or improperly corrected vision can cause or contribute to vision problems.
Solution: When getting fitted for glasses, tell your eye-care specialist that you do computer work. The following information will be helpful to your specialist: the size of your monitor screen, the distance from your eyes to the screen, average hours per day that you spend using a computer, and the tasks that you do on the computer.
Problem: Wearing bifocals or trifocals. If you wear bifocals or trifocals do you tilt your head back to read text on the monitor screen through the bottom of the lenses? This can strain your neck muscles.
Solution: Adjust the height of the monitor so that you don’t have to tilt your head back or wear lenses made specifically for computer use.
Problem: Poor lighting. Too much light and too little light contribute to vision problems.
Solution: The ideal illumination for computer work should be 20-50 foot-candles for screen viewing; 50-70 foot-candles for reading printed documents. The most practical way to measure illumination is with a light meter.
Problem: Glare. Harsh bright light that reflects off the computer screen can cause eyestrain, headache, and loss of concentration. Typical sources of glare are ceiling lighting, windows, and other bright lights. Glare reflected from flat panel displays may be harder to control than glare from traditional monitor screens.
Copyright ©2000-2016 Geigle Safety Group, Inc. All rights reserved. Federal copyright prohibits unauthorized reproduction by any means without permission. Students may reproduce materials for personal study. Disclaimer: This material is for training purposes only to inform the reader of occupational safety and health best practices and general compliance requirement and is not a substitute for provisions of the OSH Act of 1970 or any governmental regulatory agency. CertiSafety is a division of Geigle Safety Group, Inc., and is not connected or affiliated with the U.S. Department of Labor (DOL), or the Occupational Safety and Health Administration (OSHA).