I think it's a posture thing.
You could get one of these, and position it so that the thin end of the wedge is in the crack between seat and back. A roll of duct tape and hey presto, your upper body would be tilted forward at 25 degrees
http://www.advantagemedical.com/prod...h-x-24w-x-28l/
It is very bloody expensive though, as is that chair. My office chair cost 29.99