A-4 Setting Up a Healthy Work Environment Your seat depth should allow your lower back tocomfortably contact the backrest. Make sure that thebacks of your lower legs do not press against the front ofthe chair. Extend your lower legs slightly so that the angle betweenyour thighs and lower legs is 90° or more. Place your feet flat on the floor. Only use a footrestwhen attempts to adjust your chair and workstation failto keep your feet flat. Be sure that you have adequate clearance between thetop of your thighs and the underside of your workstation. Use armrests or forearm supports to support yourforearms. If adjustable, the armrests or forearm supportsshould initially be lowered while all the otheradjustments discussed in this appendix are made. Onceall these adjustments are completed, raise the armrests oradjust the forearm supports until they touch the forearmsand allow the shoulder muscles to relax.ADJUST YOUR INPUT DEVICESNote the following points when positioning your notebookcomputer or any external input devices. Position your keyboard directly in front of you. Avoidreaching when using your keyboard or mouse. If you use a mouse, position it at the same height as thekeyboard and next to the keyboard. Keep your wristsstraight and use your entire arm when moving a mouse.Do not grasp the mouse tightly. Grasp the mouse lightlyand loosely.
