When you use the keyboard and mouse, 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 or using the trackpad and keep your hands and fingers relaxed. Avoid rolling your thumbs under your palms.
Change hand positions often to avoid fatigue. Some computer users might 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.
External mouse. If you use an external mouse, position the mouse at the same height as the keyboard and within a comfortable reach.
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 are 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.
Built-in display. Adjust the angle of the display to minimize glare and reflections from overhead lights and windows. Do not force the display if you meet resistance. The display is not designed to open past 135 degrees.
You can adjust the brightness of the screen when you take the computer from one work location to another, or if the lighting in your work area changes.
For more information about ergonomics, see the Apple Support article Ergonomics.