Treadmills were historically used as a method of reforming offenders in prison, an innovation introduced by Sir William Cubitt in 1817. these were also termed treadwheels. The first private health club in the U.S. was started by Professor Louis Attila in 1894. Cardio workout machines entered the clubs much later and were developed initially for the hospital. The first medical treadmill designed to diagnose heart and lung disease was invented by Dr. Robert Bruce and Wayne Quinton at the University of Washington in 1952. Dr. Kenneth Cooper's research on the benefits of aerobic exercise, published in 1968, provided a medical argument to support the commercial development of the home treadmill and exercise bike.