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. They have become established as popular small pets. The best-known species of hamster is the golden or Syrian ...

and other

rodents Rodents (from Latin , 'to gnaw') are mammals of the order Rodentia ( ), which are characterized by a single pair of continuously growing incisors in each of the upper and lower jaws. About 40% of all mammal species are rodents. They are n ...

, 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 axle A stub axle or stud axle is either one of two front axles in a rear-wheel drive vehicle, or one of the two rear axles in a front-wheel drive vehicle. In a rear-wheel drive vehicle this axle is capable of angular movement about the kingpin for steer ...

s. 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 principal historical dictionary of the English language, published by Oxford University Press (OUP), a University of Oxford publishing house. The dictionary, which published its first editio ...

, is in a 1949 newspaper advertisement. Squirrel cages featured in an 1885 catalog by Osborn Manufacturing Co''.'' came with running wheels for the squirrels, similar to hamster wheels.

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 d ...

s (''Mesocricetus auratus'') have shown that they prefer larger wheels; the animals chose a wheel diameter of over , which itself was preferred over . 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 a ...

. Choice tests with

mice A mouse (: mice) is a small rodent. Characteristically, mice are known to have a pointed snout, small rounded ears, a body-length scaly tail, and a high breeding rate. The best known mouse species is the common house mouse (''Mus musculus' ...

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 The canyon mouse (''Peromyscus crinitus'') is a species of rodent in the family Cricetidae. It is a species of the genus ''Peromyscus'', a closely related group of New World mice often called "deermice". It is a gray-brown mouse-like rodent fou ...

(''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

lemming A lemming is a small rodent, usually found in or near the Arctic in tundra biomes. Lemmings form the subfamily Arvicolinae (also known as Microtinae) together with voles and muskrats, which form part of the superfamily Muroidea, which also inclu ...

s, for

laboratory mice The laboratory mouse or lab mouse is a small mammal of the order Rodentia which is bred and used for scientific research or feeders for certain pets. Laboratory animal sources for these mice are usually of the species ''Mus musculus''. They a ...

, and for

gerbil The Mongolian gerbil or Mongolian jird (''Meriones unguiculatus'') is a rodent belonging to the subfamily Gerbillinae. Their body size is typically , with a tail, and body weight , with adult males larger than females. The animal is used in s ...

s.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 peptides produced in the brain that block the perception of pain and increase feelings of wellbeing. They are produced and stored in the pituitary gland of the brain. Endorphins are endogeno ...

endocannabinoid Cannabinoids () are several structural classes of compounds found primarily in the ''Cannabis'' plant or as synthetic compounds. The most notable cannabinoid is the phytocannabinoid tetrahydrocannabinol (THC) (delta-9-THC), the primary psychoact ...

release associated with the ' runner's high', 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. In economics "demand" for a commodity is not the same thing as "desire" for it. It refers to both the desire to p ...

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 ...

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. Canyon mice provided with wheels stopped exploring new areas of a complex burrow-simulating maze and spent less time revisiting already-explored areas. 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 oscillation that repeats roughly every 24 hours. Circadian rhythms can refer to any process that originates within an organism (i.e., endogenous) and responds to the environment (is entrai ...

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. Chron ...

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

cockroach Cockroaches (or roaches) are insects belonging to the Order (biology), order Blattodea (Blattaria). About 30 cockroach species out of 4,600 are associated with human habitats. Some species are well-known Pest (organism), pests. Modern cockro ...

es and the cricket

Teleogryllus commodus ''Teleogryllus commodus'', commonly known as the black field cricket, is a cricket species native to Australia. They are significant pests to most plants in Australia and New Zealand.Chen G, Vickery V.R., and Kevan D.K. 1967. A Morphological Comp ...

. 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 Metabolism (, from ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run cellular processes; the co ...

obesity Obesity is a medical condition, considered by multiple organizations to be a disease, in which excess Adipose tissue, body fat has accumulated to such an extent that it can potentially have negative effects on health. People are classifi ...

, and pain. The

neurotransmitter A neurotransmitter is a signaling molecule secreted by a neuron to affect another cell across a Chemical synapse, synapse. The cell receiving the signal, or target cell, may be another neuron, but could also be a gland or muscle cell. Neurotra ...

systems involved in wheel-running behavior have received considerable study. Recent evidence suggests that changes in both

dopamine Dopamine (DA, a contraction of 3,4-dihydroxyphenethylamine) is a neuromodulatory molecule that plays several important roles in cells. It is an organic chemical of the catecholamine and phenethylamine families. It is an amine synthesized ...

rgic and serotonergic tone alter running-wheel activity. For example, one study in mice has shown that several

antidepressant Antidepressants are a class of medications used to treat major depressive disorder, anxiety disorders, chronic pain, and addiction. Common side effects of antidepressants include Xerostomia, dry mouth, weight gain, dizziness, headaches, akathi ...

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

midbrain The midbrain or mesencephalon is the uppermost portion of the brainstem connecting the diencephalon and cerebrum with the pons. It consists of the cerebral peduncles, tegmentum, and tectum. It is functionally associated with vision, hearing, mo ...

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 Steel is an alloy of iron and carbon that demonstrates improved mechanical properties compared to the pure form of iron. Due to steel's high Young's modulus, elastic modulus, Yield (engineering), yield strength, Fracture, fracture strength a ...

wood Wood is a structural tissue/material found as xylem in the stems and roots of trees and other woody plants. It is an organic materiala natural composite of cellulosic fibers that are strong in tension and embedded in a matrix of lignin t ...

plastic Plastics are a wide range of synthetic polymers, synthetic or Semisynthesis, semisynthetic materials composed primarily of Polymer, polymers. Their defining characteristic, Plasticity (physics), plasticity, allows them to be Injection moulding ...

, 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 ...

degus The Degus are a group of octodontid rodents in the Octodontidae family, but historically referred to the common degu (''O. degus''). Degus are placed in two genera: * Genus ''Octodon'' ** ''O. bridgesi'', Bridges's degu, found in Argentina and Chi ...

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

Guinea pigs The guinea pig or domestic guinea pig (''Cavia porcellus''), also known as the cavy or domestic cavy ( ), is a species of rodent belonging to the genus ''Cavia'', family Caviidae. Breeders tend to use the name "cavy" for the animal, but "gui ...

cannot use exercise wheels, and attempting to use one may cause injury to a guinea pig.

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 ideal 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 or 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 at 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