Hamster wheel

[3] The hamsters neither preferred nor avoided wheels that had small "speed bumps" installed along the running surface to provide environmental enrichment.

[9] Hypotheses to explain such high levels of running in wheels include a need for activity, substitute for exploration, and stereotypic behaviour.

However, free wild mice will run on wheels installed in the field, which speaks against the notion of stereotypic behavior induced by captivity conditions.

[10] Alternatively, various experimental results strongly indicate that wheel running, like play or the endorphin or endocannabinoid[11] release associated with the 'runner's high', is self-rewarding.

[9][12][13] Wheel use is highly valued by several species as shown in consumer demand studies which require an animal to work for a resource, i.e. bar-press or lift weighted doors.

[15] In another study, female Syrian hamsters housed with a nestbox, bedding, hay, paper towels, cardboard tubes, and branches used a wheel regularly and benefitted from it as indicated by showing less stereotypic bar-gnawing and producing larger litters of young compared to females kept under the same conditions but without a wheel.

[17] Running in wheels can be so intense in hamsters that it may result in foot lesions, which appear as small cuts on the paw pads or toes.

[citation needed] Voluntary wheel running is one of the most widely used indicators of activity and wake-time in research on circadian rhythms and other aspects of chronobiology.

[21][22] For rodents, running wheels are easier to set up and automate than other techniques of activity recording such as bar-gnawing[23] and spring-suspended or knife-edge balanced cages.

This makes running wheels the tool of choice in research on the effects of exercise and voluntary activity on metabolism, obesity, and pain.