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 Corporati on) in three different positions onto it's pelvis (gluteal region) from a s eated 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 measur ed by a force plate covered with industrial carpet. These impact forces wer e translated to the compressive and shear forces on the lumbar spine. The p eak impact forces during the different body postures were 20000-29900 N (to rso 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 force s well exceed documented injury tolerance levels. (C) 1998 Elsevier Science Ltd. All rights reserved.