office and training center is set to span some

摘要

The invention concerns a sitting surface (3), in particular for a work chair, driver's seat or the like, which has a central recess (14) in the rear region and is secured on a subframe (2). In order to adapt the sitting surface (3) to different sitting habits or alternatively to use it as a training surface for training the user to sit in the "two-point" position, the recess (14) can be closed at least partially by a corresponding insert (13) such that the difference in height between the sitting surface (3) and the insert (13) can be varied gradually and/or continuously. The introduction of an insert (13) into the recess (14) in the sitting surface (3) can be used alternatively for a person who prefers to sit in the "three-point" position known hitherto or who only sits in the "two-point" position from time to time in order to become accustomed thereto.