- Fix the chair back to support the torso
- Measure elbow height
- Position the surface above elbow
- Allow forearm to relax on the surface
Locate Work Surface Height
The work surface height is determined after the torso is in the strongest upright sitting posture.
Fix the chair back to support the upright torso, and measure the elbow height with shoulders relaxed and the hands together in the lap.
Note that the elbow height rises as the arm swings forward to the work surface
Position a trial work surface height approximately one inch above that measured elbow height.
Move the chair in close to the work surface, and allow the forearm to relax on the work surface. The hands should be able to move over the work surface without raising the shoulders, and the forearms can fully relax on the work surface without slumping at the shoulders.
A video follows with a more detailed look at the shoulder