Exercise could be the latest weapon in the fight against skin cancer.
A study conducted by Rutgers University found that mice who had access to a running wheel took longer to develop the deadly disease.
Mice in the study were exposed to ultraviolet B (UVB), the harmful rays of the sun found to be behind the development of skin cancer. Half of the group of mice had access to the running wheels, while the other half did not.
While all of the mice developed skin cancer, those exercising took twice as long to develop signs of the deadly disease, and developed less numerous and smaller cancer tumours.
Lead researcher Dr Allan Conney said that their findings showed that exercise was slowing down the development of the cancer by killing off the cancerous cells.
"While UVB is triggering the development of tumours, exercise is counteracting the effect by stimulating the death of the developing cancer cells," he said.
But the researchers warn that the study should not be used as an excuse to go out in the sun unprotected this summer.
Cancer Research UK said: "Despite the fact that exercise lessened the severity of skin cancer in mice in this study, this doesn't mean people should strip off and start jogging in strong sunlight without proper protection - UV rays from the sun are a major cause of skin cancer and are best avoided when the sun is most intense, especially by the fair skinned."