Treadmill

Treadmill: A machine with a moving strip on which one walks without moving forward. A treadmill was originally a wide wheel turned by the weight of people climbing on steps around its edge, used in the past to provide power for machines or as a punishment in prisons.

The treadmill today serves as a device to maintain physical fitness. It is an essential component of the exercise treadmill test (sometimes simply called a treadmill test or exercise test).