Some embodiments provide an abdominal training machine that uses an adapted reverse crunching motion to minimize stress to the knees, back, shoulders, and neck when training the abdominal muscles. The machine combines weight resistance training with a replicated natural motion of each leg to produce...http://www.google.com.au/patents/US20110287912?utm_source=gb-gplus-sharePatent US20110287912 - Abdominal Training Machine and Method
