From Simple English Wikipedia, the free encyclopedia
A horse grinds olives in a treadmill in the Atlas Mountains
Donkey-powered grinding mill, in Oxaca, Mexico
Sportspeople are being tested on a treadmill

A treadmill is a device for walking or running, while staying in the same place. Before there was steam power, such treadmills were used to power machines. That way, the work of animals or people could be used in the machines. Such treadmills were also used as a form of punishment in prisons.