Impact forces following the unexpected removal of a chair while sitting

This report documents the impact forces measured during trials of dropping an anthropometric dummy (80.3 kg) (Hybrid III, First Technologies Corporation) in three different positions onto it's pelvis (gluteal region) from a seated height, which was meant to simulate a chair being pulled out from an individual in the process of sitting. Peak forces on the pelvis were measured by a force plate covered with industrial carpet. These impact forces were translated to the compressive and shear forces on the lumbar spine. The peak impact forces during the different body postures were 20000-29900 N (torso upright); 13000-22200 N (torso-legs 45 degrees to floor); 6000-15200 N (layout position). The impact forces generated from falling onto the pelvis from a seated height, appear to be sufficient to cause injury as the forces well exceed documented injury tolerance levels.