A hamster wheel or running wheel is an exercise device used primarily by

hamsters Hamsters are rodents (order Rodentia) belonging to the subfamily Cricetinae, which contains 19 species classified in seven genera.Fox, Sue. 2006. ''Hamsters''. T.F.H. Publications Inc. They have become established as popular small pets. The ...

and other rodents, but also by other cursorial animals when given the opportunity. Most of these devices consist of a runged or ridged wheel held on a stand by a single or pair of stub axles. Hamster wheels allow rodents to run even when their space is confined. The earliest dated use of the term "hamster wheel", located by the

Oxford English Dictionary The ''Oxford English Dictionary'' (''OED'') is the first and foundational historical dictionary of the English language, published by Oxford University Press (OUP). It traces the historical development of the English language, providing a co ...

, is in a 1949 newspaper advertisement.

Preferences

Choice tests with

Syrian hamster The golden hamster or Syrian hamster (''Mesocricetus auratus'') is a rodent belonging to the hamster subfamily, Cricetinae. Their natural geographical range is in an arid region of northern Syria and southern Turkey. Their numbers have been de ...

s (''Mesocricetus auratus'') have shown that they prefer larger wheels; the animals chose a wheel diameter of 35 cm (14 in) over 23 cm (9 in), which itself was preferred over 17.5 cm (7 in). Hamsters showed no preference between a relatively uniform running surface made of plastic mesh and a surface made of rungs spaced 9 mm apart, although they did prefer the mesh compared to rungs spaced 12 mm apart, most likely because of the wider space between the rungs allowed their legs to slip through. The hamsters neither preferred nor avoided wheels that had small "speed bumps" installed along the running surface to provide

environmental enrichment Environmental enrichment is the stimulation of the brain by its physical and social surroundings. Brains in richer, more stimulating environments have higher rates of synaptogenesis and more complex dendrite arbors, leading to increased brain ac ...

. Choice tests with mice have also shown a preference for larger wheels (17.5 cm over 13 cm in diameter) and a preference for plastic mesh over rungs and over solid plastic as a running surface. More acrobatic species, such as the canyon mouse (''Peromyscus crinitus'') and the

deer mouse ''Peromyscus'' is a genus of rodents. They are commonly referred to as deer mice or deermice, not to be confused with the chevrotain or "mouse deer". They are New World mice only distantly related to the common house and laboratory mouse, ''Mu ...

(''Peromyscus maniculatus'') can develop preferences for wheels that force the animals to jump, such as square wheels or wheels with hurdles along the running surface.

Use by animals

Like other rodents, hamsters are highly motivated to run on wheels; it is not uncommon to record distances of being run in one night. Other 24-h records include for rats, for wild mice, for lemmings, for laboratory mice, and for gerbils.Sherwin, C.M., 1998, Voluntary wheel running: A review and novel interpretation, Animal Behaviour, 56: 11–27 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. Alternatively, various experimental results strongly indicate that wheel-running, like play or the

endorphin Endorphins (contracted from endogenous morphine) are chemical signals in the brain that block the perception of pain and increase feelings of wellbeing. They are produced and stored in an area of the brain known as the pituitary gland. Hist ...

endocannabinoid Cannabinoids () are several structural classes of compounds found in the cannabis plant primarily and most animal organisms (although insects lack such receptors) or as synthetic compounds. The most notable cannabinoid is the phytocannabinoid tet ...

release associated with the '

runner's high The neurobiological effects of physical exercise are numerous and involve a wide range of interrelated effects on brain structure, brain function, and cognition. A large body of research in humans has demonstrated that consistent aerobic exerci ...

', is self-rewarding.Novak, C.M., Burghardt, P.R. and Levine, J.A., 2012, The use of a running wheel to measure activity in rodents: Relationship to energy balance, general activity, and reward, Neuroscience and Biobehavioral Reviews, 36: 1001–1014 Wheel use is highly valued by several species as shown in

consumer demand In economics, demand is the quantity of a good that consumers are willing and able to purchase at various prices during a given time. The relationship between price and quantity demand is also called the demand curve. Demand for a specific item ...

studies which require an animal to work for a resource, i.e. bar-press or lift weighted doors. This makes running wheels a popular type of enrichment to the captivity conditions of rodents. Captive animals continue to use wheels even when provided with other types of enrichment. In one experiment, Syrian hamsters that could use tunnels to access five different cages each containing a toy showed no more than a 25% reduction in running-wheel use compared to hamsters housed in a single cage without toys (except for the running wheel). 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. Laboratory mice were prepared to perform more switch presses to enter a cage containing a running wheel compared to several meters of

Habitrail Habitrail is a brand name for a hamster cage made by the Hagen corporation. It is a series of translucent plastic tubes and "houses" for use in home terrariums, designed specially for hamsters. The design of the Habitrail is modular and can be co ...

tubing or a torus of Habitrail tubing.Sherwin, C.M., 1998, The use and perceived importance of three resources which provide caged laboratory mice the opportunity of extended locomotion, Applied Animal Behaviour Science, 55: 353-367. 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. Such paw wounds rapidly scab over and do not prevent hamsters from continuing to run in their wheel. A hamster in a running wheel equipped with a generator can generate up to 500 mW electric power, enough for illuminating small LED lamps.

Use in science

Voluntary wheel running is one of the most widely used indicators of activity and wake-time in research on

circadian rhythms A circadian rhythm (), or circadian cycle, is a natural, internal process that regulates the sleep–wake cycle and repeats roughly every 24 hours. It can refer to any process that originates within an organism (i.e., endogenous) and responds to ...

and other aspects of

chronobiology Chronobiology is a field of biology that examines timing processes, including periodic (cyclic) phenomena in living organisms, such as their adaptation to solar- and lunar-related rhythms. These cycles are known as biological rhythms. Chronob ...

. Miniature running wheels have even been used to measure the circadian locomotor activity of

cockroach Cockroaches (or roaches) are a Paraphyly, paraphyletic group of insects belonging to Blattodea, containing all members of the group except termites. About 30 cockroach species out of 4,600 are associated with human habitats. Some species are we ...

es. For rodents, running wheels are easier to set up and automate than other techniques of activity recording such as bar-gnawing and spring-suspended or knife-edge balanced cages. In rodents, voluntary exercise is almost always measured by the use of wheels. This makes running wheels the tool of choice in research on the effects of exercise and voluntary activity on metabolism, obesity, and pain. The neurotransmitter systems involved in wheel-running behavior have received considerable study. Recent evidence suggests that changes in both dopaminergic and serotonergic tone alter running-wheel activity. For example, one study in mice has shown that several antidepressant medications (all of which directly or indirectly enhance serotonergic tone) suppress running-wheel activity without suppressing general locomotion. The

system also contributes to wheel running in a sex-specific manner in rodents. Mice from lines that have been selectively bred for high levels of voluntary wheel running have altered responsiveness to drugs that alter dopamine and endocannabinoid signalling, and enlarged midbrains.

Animal welfare considerations

Tierärztliche Vereinigung für Tierschutz (TVT) recommends wheels should be at least 20 cm (8") for dwarf hamsters and at least 30 cm (12") for

s, since smaller diameters lead to permanent spinal curvatures, especially in young animals. They also recommend a solid running surface because rungs or mesh can cause injury. It has been published in several books about small pet care as far back as 2000 that rungs and mesh wheels can cause injuries. Most wheels are constructed of steel,

wood Wood is a porous and fibrous structural tissue found in the stems and roots of trees and other woody plants. It is an organic materiala natural composite of cellulose fibers that are strong in tension and embedded in a matrix of lignin ...

plastic Plastics are a wide range of synthetic or semi-synthetic materials that use polymers as a main ingredient. Their plasticity makes it possible for plastics to be moulded, extruded or pressed into solid objects of various shapes. This adaptab ...

, each having advantages and disadvantages. Solid wheels are safer for all animals because the animal's feet or legs cannot get trapped and injured between rungs. There are wheels in all these materials that are solid. Plastic wheels are fine for some animals. However, some rodents (e.g.

gerbils Gerbillinae is one of the subfamilies of the rodent family Muridae and includes the gerbils, jirds, and sand rats. Once known as desert rats, the subfamily includes about 110 species of African, Indian, and Asian rodents, including sand rats an ...

or degus) will quickly chew and destroy plastic wheels but not steel versions.

Hamster ball

A related exercise device, the

hamster ball Hamster balls are hollow spheres made of clear plastic into which hamsters, gerbils, degus and other small rodent pets are placed, allowing them to run around outside their cages without the risk of running away or getting lost under furniture. ...

, is a hollow plastic ball into which a pet can be temporarily placed. The ball allows the pet to freely roll around on the floor to explore and exercise while preventing escape. Recent theory suggests that hamster balls are not recommended for exercise outside of the cage. The balls prevent the rodent from using touch (whiskers) and smell to navigate the area. It also restricts airflow and can catch toes/tails in the slits meant for airflow.

Running disc

A related exercise device is a running disc. This is a rotatable shallow bowl, or slightly concave disc, which is set an angle to the horizontal.De Bono, J. P., D. Adlam, D. J. Paterson, and K. M. Channon. 2005. Novel quantitative phenotypes of exercise training in mouse models. American Journal of Physiology. Regulatory, Integrative and Comparative Physiology 290:R926–R934. Some commercial refuges for caged rodents have a disc mounted on the roof at a slight angle. The rodents run on the rim of the disc in a similar way to running in hamster wheels.

References

External links

{{Commons category, Hamster wheels Ethology Animal welfare Articles containing video clips Hamster equipment Wheels