As we age, the body’s ability to repair damaged tissue also deteriorates. A new study by the Stanford School of Medicine in California (USA) now indicates that endurance exercise can reverse this process and thus have a rejuvenating effect on muscle repair. The study was published on April 13 in the journal ” Nature Metabolism “.

Thomas Rando, professor of neurology and lead author of the study, and his research team let mice of different ages run extensively on exercise bikes for the study. There was an effect on muscle mass, particularly in the older animals. “We have found that regular exercise restores the youthfulness of tissue repair. Their muscle stem cells look and behave like those of much younger animals, ”explained Rando in a statement from the Standford School of Medicine .

“Like reversing the aging process in older people

Applied to humans, this would mean that jogging, swimming, cycling, and other endurance activities could help older people recover as quickly and efficiently as the younger selves once did. Rando explains: “In a way, this is like reversing the aging process in an older person who already suffers from age-typical diseases.” According to the researchers, this is made possible through endurance exercises. As a result, old body cells behaved like young cells and acquired their properties.

Stem cells affect muscle repair

Embryonic or pluripotent stem cells are able to replicate any tissue in the body. For the study, however, the researchers examined so-called muscle stem cells, which are limited in their potential. Until they are activated, these cells remain in a kind of resting state along the muscle fibers. They are only activated when the corresponding molecular signals are received and begin to repair muscles.

“Studies carried out by us and those of other scientists have shown that tissue regeneration declines with age and that this is due to a declining function of the adult stem cells,” explains study leader Rando. “Many researchers are looking for a way to restore youthfulness.”

Rando points out that exercise has long been known to reduce age-related health problems, “including cardiovascular disease, cancer and possibly even Alzheimer’s disease. There is great interest in understanding how exercise brings these health benefits. ”

How did the researchers go about the study?

Rando’s team of scientists investigated whether and how voluntary training influences the function of muscle stem cells in mice. For this purpose, the animals were divided into two groups: The older mice in the first group were 20 months old, which corresponds to an age of 60 to 70 years in humans. The average age of the mice in the second group was three to four months (corresponds to 20 to 30 years for humans).

Both groups had access to an exercise bike, on which the animals were allowed to run to their hearts’ content. While the older mice covered around five kilometers per night, the young animals covered an average of ten kilometers. In two further control groups with older and younger animals, however, the wheels did not turn.

“The animals trained at the intensity they felt comfortable with,” says Rando. A subsequent study showed that the muscle stem cells of the training mice remained in a resting position and that the animals had not yet built up a significant number of new muscle fibers in response to the training.

After three weeks there was a clear difference between the groups

After three weeks of running at night on the running bike, there were significant differences between the mouse groups. The untrained and barely active older mice of the first control group were less able to repair muscle damage than the younger untrained control group. So far as no surprise – the researchers had roughly expected this result.

With the older trained animals, however, the picture was different. In the senior mice who regularly got on the exercise bike at night, the muscle repair looked significantly better than in their peers who did not exercise. In the younger animals, however, the exercise advantage was not shown.

The researchers also obtained similar results when they transplanted muscle stem cells from older, trained mice into younger animals. The stem cells of the training animals therefore contributed more to regeneration than those of the inactive mice.

Positive effects can also be transmitted via blood

Rando’s research team continued to investigate whether the effect could also be achieved by injecting blood. To do this, they injected the blood of older but trained mice into old, untrained animals. Here, too, there was an improvement in the function of tissue-specific stem cells.