sitting too close to the desk

A recurring question usually comes when I train office workers: what is the right distance to the desk when sitting? The picture below illustrates 3 situations that I will comment below: at the right distance, a bit too close, much too close.

In situation A the worker is sitting right on the sitting bones (ischial bones). As a result, the back is flat and slightly forward. The shoulders are relaxed, the elbows are hanging naturally alongside the body. The neck and shoulder area is fully relaxed. In this optimal situation, the distance to the desk is determined by the length of the forearms. 

In situation B, the workers started to come a bit closer. At first, the elbows are pulled backwards, creating tension in the rhomboids and the neck. The lower back gets hollow and tenses up.

In situation C, the worker is so close to his desk that the pelvis had to rotate backwards to allow the spine backwards, away from the desk. As a result, the lower back is slouched, as well as the mid back. The shoulders and head are pushed forward, which strongly impairs the blood flow to the arms due to compressions in the thoracic outlet area. Usually, the worker also rests his weight on the forearms, which increases even more the strain in the neck.

In practice, how should you overcome this?

• Step 1 is to sit away from the desk. Find your sitting bones, sit deep in the chair so that the pelvis fully rests against the lumbar support. The back is flat and slightly forward: the shoulder blades are free from the backrest. Let your shoulder be relaxed and your elbow hang loosely against your sides.
• Step 2 is to bend the elbows 90°. The shoulders are still relaxed. Now, slowly move towards the keyboard, which should be placed close to the edge of the desk. Stop when the finger tips naturally come on top of the keys. You should be in situation A.