• Keyboards trays, or other working surfaces that are too high or too low can lead to awkward wrist, arm, and shoulder postures. When keyboards are too low you may type with your wrists bent up, and when keyboards are too high, you may need to raise your shoulders to elevate your arms. Performing keying tasks in awkward postures such as these can result in hand, wrist, and shoulder discomfort.
• A keyboard tray or mouse that is too close or too far away may cause you to assume awkward postures such as reaching with the arms, leaning forward with the torso and extreme elbow angles. These awkward postures may lead to musculoskeletal disorders of the elbows, shoulders, hands, and wrists. 

• The best position is to have your keyboard tray at a negative tilt angle in order to prevent any bending of your wrists, thus reducing strain and tension.
• Elbows should be about the same height as the keyboard and hang comfortably to the side of the body
• Shoulders should be relaxed, and wrists should not bend up or down or to either side during keyboard use
• The work surface should generally be no more than 2 inches thick
• A keyboard tray is needed if the work surface or chair cannot be properly adjusted
• The keyboard tray should be adjustable in height and tilt
• Keyboard trays should provide adequate leg and foot clearance
• The keyboard system should have adequate space for multiple input devices
• Place the keyboard directly in front of you at a distance that allows your elbows to stay close to your body with your forearms approximately parallel with the floor.
• A keyboard tray may be useful if you have limited desk space or if your chair has armrests that interfere with adequate positioning.
  

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