The effect of sitting on a lateral X-ray. In these two radiographs of the same girl (12 year, bad posture, fatigue, Scheuermann in elder brother) taken in two different ways of sitting, some confronting chances can be seen. At the left an active way of sitting on the edge of a coach. At the right sitting in a complete relaxed way, showing an increase in the kyphotic curve Th1-Th12 from 49° to 69°. It was known in German literature as a “Sitzbuckel”, but nowadays “gameboyback” looks more appropriate. The anterior compressing forces that will lead via the deformation of soft structures ( Volkmann Hueterprinciple) and deformation of bone ( Wollf’s Law) in a given (genetically) resilience of structures are indirectly illustrated in this manner. Flattening of discs, stiffening of motion segments and wedging of vertebrae will occur if not treated. Loss of muscular condition at the posterior side can lead to further secondary or degenerative changes.