Researchers at Stanford University have recently identified a molecular pathway involved in turning back the clock on cells. 

“Exercise is known to reduce the risk of a wide variety of age-related problems, including cardiovascular disease, cancer and perhaps even Alzheimer’s disease,” Rando said. “There’s a lot of interest in understanding how exercise confers these health benefits.”

The study's major goal was to see how voluntary exercise influences the function of muscle stem cells in mice.

They gave mice approximately 20 months old, the equivalent of 60-70 years old in humans, and mice 3 to 4 months old, the equivalent of 20- to 30-year-old humans, access to an exercise wheel and permitted them to run at will.

Young mice traveled approximately 10 kilometers per night, while older mice traveled approximately 5 kilometers. To serve as controls, two other groups of young and old mice were given wheels that did not rotate.

They discovered that, as expected, older sedentary mice were considerably less capable of repairing muscle damage than younger sedentary mice.

However, older animals that had routinely exercised were substantially better at healing muscle damage than their non-exercising counterparts. This benefit of exercise was not demonstrated in the younger animals.

When muscle stem cells from older mice that had exercised were transplanted into younger animals, similar results were achieved.

The exercised animals' stem cells contributed more to the healing process than their sedentary counterparts.