treadwheel

The word treadmill, originally a type of mill operated by a person treading steps of a wheel to grind grain, now designates a piece of indoor sporting equipment for running without moving any distance. A treadwheel is a form of animal engine powered by humans. It may resemble a water wheel in appearance, and can be worked either by a human treading paddles set into its circumference (a treadmill), or by a human standing inside it. Uses of treadwheels included raising water, to power cranes, or grind grain. They were also used in prisons as a form of punishment. A treadwheel was also used in a submarine in 1851 to pump air to change buoyancy and thus make the vessel dive or rise.
See more at Wikipedia.org...

Noun
1. a mill that is powered by men or animals walking on a circular belt or climbing steps
(synonym) treadmill, tread-wheel
(hypernym) mill, grinder

(n.)
A wheel turned by persons or animals, by treading, climbing, or pushing with the feet, upon its periphery or face. See Treadmill.