This model houses rats in cages with running wheels starting at 28 days of age, which the animals voluntarily use for the next three to six weeks. (physiologyinfo.org)
As a measure of exercise performance, experimental mice were allowed free access to cage running wheels for a 14 - hour period that included the 12 - hour dark cycle. (jci.org)
Some of the animals were given running wheels in their cages, allowing them to run at will. (rawbarrel.com)