Abstract: A pneumatic variable resistance rehabilitation/therapy apparatus for the balanced strengthening of musculature surrounding injured, weakened, and post-operative ligaments associated with the major joints of the lower extremities. In a preferred embodiment, a leg press machine is provided comprising a frame, a foot rest assembly including a foot rest pad, and a reciprocating carriage having a patient supporting bed surface thereon. A pneumatic circuit comprising a cylinder having a reciprocating piston therein, an accumulator, an air supply and a pressure regulator is provided for the variable progressive resistance against the movement of the carriage during the working stroke (where the patient straightens his/her leg(s)). The reciprocating piston rod is linked to the reciprocating carriage by a cable and pulley system to provide a longer and more physiologically tolerable working stroke.