An exercise machine composed of a frame, a first four bar linkage system, a second four bar linkage system, and a means for transferring an incident force from the legs of a user is disclosed. The first four bar linkage system is operably mounted on the frame and operably connects the transferring means...http://www.google.es/patents/US7608022?utm_source=gb-gplus-sharePatente US7608022 - Leg press and abdominal crunch exercise machine
