In the course of the study, one group of mice, whose lifespan was nearing the end, was forced to perform strength exercises (they had access to a wheel with additional weights). The second group of aging animals was genetically reprogrammed through the expression of Yamanaki factors. Yamanaki factors are four protein transcription factors (Oct3/4, Sox2, Klf4, and c-Myc, often referred to by the acronym OKSM) by which an old cell is reprogrammed into a young, pluripotent state. Japanese scientist Shinya Yamanaka was awarded the Nobel Prize in 2012 for their discovery. With proper mechanics, the induction of Yamanaka factors throughout the body in rodents can smooth out and even completely remove the signs of aging. It is known that one of the four factors, c—Myc, is induced by skeletal muscle training. The researchers compared the muscles of old mice that were allowed to exercise with those of animals with overexpression of OKSM, as well as those with only overexpression of c-Myc. As a result, the scientists found that strength training promotes a molecular profile consistent with partial cell reprogramming. In other words, muscles that have undergone physical activity acquire the molecular profile of muscle tissue exposed to Yamanaki factors (and thus acquire the characteristics of younger cells). This beneficial effect of exercise, as the authors of the article report, may be partially related to the specific actions of c-Myc in muscles. Thus, exercise can really rejuvenate the body — its effect is comparable to genetic manipulation. The first author of the study, Ronald J. Jones III believes that physical activity is the most powerful medicine that a person has — it not only improves health, but also prolongs life.