In 1818, British prisons adopted William Cubitt's treadmill as a tool of hard labor. 208 years later, the machine is a fitness staple, but its modern medical and exercise history evolved separately from the original punishment device

The treadmill has an unsettling place in the history of exercise: its story includes Victorian prisons, forced labor, physiological research and modern cardiac medicine. In the early 19th century, engineer William Cubitt adapted an older treadwheel into a machine that required prisoners to climb continuously, sometimes generating useful power and sometimes simply increasing exhaustion.