While we’re all at home and practicing social distancing during this global pandemic, it has become a challenge to get in daily exercise. Aside from outward physical appearance, what other benefits does exercise hold? Dr. Thomas Rando and his team at Stanford University explored this question in more detail in a CIRM supported animal study.

The Stanford research team found that exercise played a key role in restoring the youthful properties in the muscle stem cells of old mice. Muscle stem cells play an important role in tissue regeneration. They are usually on standby alongside muscle fibers in a resting state known as quiescence until called upon to repair damage.

For this study, the researchers wanted to see if voluntary exercise had an effect on the muscle stem cells in mice. Older mice that were 20 months old, the equivalent of 60-70 human years, were given an exercise wheel where they were allowed to run at will. Younger mice that were 3-4 months old, the equivalent of 20-30 human years, were also given an exercise wheel and allowed to run at will. A separate group of younger and older mice were given a wheel that didn’t rotate to compare them with the groups of mice that exercised.

They found that the older animals that had exercised regularly were significantly better at repairing muscle damage compared to their counterparts that did not exercise. However, this exercise benefit was not observed between the younger group of mice.

The researchers also transplanted the muscle stem cells from the older mice that had exercised into younger mice that had not exercised. They found that the muscle stem cells from the older mice contributed more to the repair process than did those from the non-exercising mice.

What was also surprising is that injecting blood from an old mouse that had exercised into an old mouse that hadn’t created a similar benefit in the muscle stem cells. This finding suggests that exercise simulates the production of some factors that then circulate in the blood and enhance the function of older stem cells.

Lastly, the researchers were ably to identify a molecular pathway that activates the resting muscle stem cells in response to damage.

In a press release, Dr. Rando discusses how this discovery could potentially lead to the development of a drug that could rejuvenate muscle stem cells.

“If we could develop a drug that mimics this effect, we may be able to experience the benefit without having to do months of exercise.”

The full results of this study were published in Nature Metabolism.