A treadwheel, or treadmill, is a form of engine typically 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 (treadmill), or by a human or animal standing inside it (treadwheel). These devices are no longer used for power or punishment, and the term "treadmill" has come to mean an exercise machine for running or walking in place..
Penal treadmills were used in prisons during the early-Victorian period in the UK as a form of punishment. According to Penal treadmills were used in prisons during the early-Victorian period in the UK as a form of punishment. According to The Times in 1827, and reprinted in William Hone's Table-Book in 1838, the amount prisoners walked per day on average varied, from the equivalent of 6,600 vertical feet at Lewes to as much as 17,000 vertical feet in ten hours during the summertime at Warwick gaol. In 1902, the British government banned the use of the treadwheel as a form of punishment.