One easy way to lessen your risk of injury is to get the right chair (or adjust the one you have) and set up your hardware correctly. But while most ergonomists concur that certain arrangements are particularly hazardous, they don’t always agree on what’s best. That makes it difficult to suggest a perfect setup, so consider these recommendations as guidelines. As you read, refer to the illustration.
Customize your chair
Your chair determines the posture of your back, arms, and legs, so finding one that fits your body size is essential. Office chairs run the gamut, from economical models with a few adjustable features to thousand-dollar seats that sport more levers and buttons than a 747’s cockpit. Here are some things to pay attention to, whether you’re buying a chair or customizing your current seat:
A. Back Support The seat’s back should be tall enough to support at least your lower and middle back, especially in the lumbar area (the lower part that curves inward). Also, make sure it tilts forward and backward. Adjust the back so that the angle between your trunk and legs is a bit more than 90 degrees.
B. Good Armrests Choose a chair with padded armrests. You should be able to rest your arms comfortably, without having to extend them too far or tuck them tightly against your body. Many chairs sport armrests that you can raise or lower so that you don’t end up shrugging or stooping your shoulders. If you can’t find a comfortable armrest position, remove them altogether or find another chair.
C. Solid Cushioning The chair should have a padded cushion that’s long enough from front to back to support your buttocks and thighs without touching the back of your knees. Look for a cushion that’s smoothly rounded in front to avoid putting pressure on the backs of your thighs.
Work Smart Creating a healthy, ergonomically correct workspace doesn’t have to be expensive. Often, simply adjusting the equipment you already have is enough. You shouldn’t have to reach out or crane your neck to perform repetitive tasks.
D. Height Adjustment Adjust the chair so that your forearms and wrists are about desktop height when your elbows are at 90 degrees. Your feet should be flat on the floor—if they dangle, use a footrest.
E. Rollability Chairs that are wobbly or don’t roll smoothly force you to bend or twist to reach your equipment. Look for a chair with five legs, and make sure that it rolls easily. If you work in a carpeted area, get a floor pad that won’t buckle as you move.
Adjust input devices
RSI problems are often compounded by poor hardware design, which forces you to use awkward positions and excessive force while typing or using your mouse. Fortunately, your setup can help minimize the risk of injury.
F. Trays and Wrist Rests Adjustable keyboard trays help on several levels. They keep your keyboard in a flat or slightly backward-tilted position, which is safer. They also help you tweak the height of your input devices so you don’t have to angle your wrists to reach them. Tray or no tray, try to avoid propping up your keyboard on its retractable feet. Although that makes it easier to see the keys, it also forces you to bend your wrists.
Also, beware of wrist rests: they help keep your wrists straight, but they put pressure on the nerves and tendons at the back of your wrist. Look for a wrist rest that’s smoothly contoured and padded, and only use it during rest periods, not when you’re typing.
G. Typing Technique Pounding on keys increases the impact on your fingers. Instead, try to keep your hands in a relaxed, natural position as you type, with your fingers arched smoothly, floating over the keys. If your keyboard requires that you press the keys extra hard to elicit a response, try a different one.
H. Mouse Position Situate the mouse as close to the keyboard as possible, so you don’t have to extend your arm and shoulder as you move between the two. If you use a keyboard tray, it should be large enough to accommodate both a keyboard and a mouse.
Move your monitor
The position of your LCD or CRT is crucial, as poorly placed monitors tend to put extra strain on your eyes and upper spine. Here’s what to consider:
I. Height and Angle Conventional wisdom says that the top of the monitor should be slightly below eye level, so you don’t have to glance up or crane your neck. While this advice works well for most people, some experts recommend an even lower position, so you’re actually looking down at the monitor. As for tilt, make sure the monitor is angled backward slightly so that the top of the screen is farther from your eyes.
Distance It’s less stressful for your eyes to focus on a distant visual target, so try to place your monitor 18 to 24 inches away, farther if there’s room. (If necessary, enlarge the on-screen text size to compensate.) If you wear glasses and spend more than a couple of hours a day at your Mac, consider getting lenses with a midrange focal zone that’s tailored for computer users—ask your optometrist about them.
Body Positioning Your body, monitor, and keyboard should form a straight line—you shouldn’t have to rotate your trunk or neck to type or to read your screen.
[ Dr. Franklin N. Tessler is a radiologist in Birmingham, Alabama. He writes about ergonomics regularly for Macworld.]