Toronto, Jun 20 (IANS): Here is another reason why you should hit the gym regularly as you grow older. New research has found that regular exercise could help muscles repair themselves as quickly as possible after injury even as you age.

For many mammals, including humans, the speed of muscle repair slows as they grow older, and it was once thought that complete repair could not be achieved after a certain age.

"Exercise-conditioning rescues delayed skeletal muscle regeneration observed in advanced age," said one of the researchers Gianni Parise, Associate Professor at McMaster University in Hamilton, Ontario, Canada.

This study, published online in The FASEB Journal, showed that after only eight weeks of exercise, old mice experienced faster muscle repair and regained more muscle mass than those of the same age that had not exercised.

To make this discovery, the researchers used three groups of mice -- old mice that were exercise trained, old mice that were not exercise trained, and young mice that were not exercised trained.

In the first group, old mice were trained three days/week for eight weeks.

The effect of exercise in ageing muscle was measured by comparing the three groups of mice.

Changes in muscle repair with ageing were determined by injecting the old mice and young mice (neither group exercised) with snake venom commonly used to induce muscle injury in rodent studies.

These mice were compared prior to muscle injury, 10 days following injury and 28 days following injury.

"This is a clean demonstration that the physiological and metabolic benefits of exercise radiate to skeletal muscle satellite cells, the adult stem cells responsible for repair after injury, even in senescent animals," Thoru Pederson, Editor-in-Chief of The FASEB Journal, said.