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Ergonomics
Keyboard
When you use the keyboard, your shoulders should be relaxed. Your upper arm and forearm should form an angle that is slightly greater than a right angle, with your wrist and hand in roughly a straight line.
Use a light touch when typing and keep your hands and fingers relaxed. Avoid rolling your thumbs under your palms.
Change hand positions often to avoid fatigue. Some computer users may develop discomfort in their hands, wrists, or arms after intensive work without breaks. If you begin to develop chronic pain or discomfort in your hands, wrists, or arms, consult a qualified health specialist.
Chair
An adjustable chair that provides firm, comfortable support is best. Adjust the height of the chair so your thighs are horizontal and your feet flat on the floor. The back of the chair should support your lower back (lumbar region). Follow the manufacturer’s instructions for adjusting the backrest to fit your body properly.
You may have to raise your chair so your forearms and hands are at the proper angle to the keyboard. If this makes it impossible to rest your feet flat on the floor, you can use a footrest with adjustable height and tilt to make up for any gap between the floor and your feet. Or you may lower the desktop to eliminate the need for a footrest. Another option is to use a desk with a keyboard tray that’s lower than the regular work surface.
Mouse
Position the mouse at the same height as your keyboard and within a comfortable reach.
Computer
Arrange the computer so the top of the screen is slightly below your eye level when you’re sitting at the keyboard. The best distance from your eyes to the screen is up to you, although most people seem to prefer 18 to 28 inches (45 to 70 cm).
Position the computer to minimize glare and reflections on the screen from overhead lights and windows.
For More Information
Go to www.apple.com/about/ergonomics.
Appendix B Care, Use, and Safety Information