Disc pressure and myoelectric activity decrease when the backrest inclination is increased and the low back support is used [25]. Annular tears due to prolonged simulated sit- ting postures and cyclic compressive loading has been doc- umented in young calf spines [26] and indicated a potential source of LBP in humans [27]. The low back injury process is not only associated with very high loads but even more often with lower repeated or continuous loads. Therefore it is important to study not only fast and high load but also longer lasting tissue loading [28].