The benefits of an active lifestyle are far-reaching and increasingly known, but there is still much to learn as we explore the long-term effects on the human body in detail. A new study has filled a gap in our knowledge of how sustained physical activity can protect against age-related muscle loss. It has been shown that regular exercise increases the number of important stem cells that keep muscles young and healthy.

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While it is generally known that regular exercise keeps our muscles fit and efficient, the authors of this new research paper wanted to investigate how a lifetime of physical activity can halt their decline in old age. It is intended to be the first study to examine the relationship between muscle weakness, which leads to loss of mass and function, and the decline of muscle stem cells in old age.

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Muscle stem cells are cells in skeletal muscle tissue that are capable of self-renewal and can transform into muscle cells. They are therefore of crucial importance for the body's response to injuries or damaged tissue and for protecting against nerve atrophy. It should be investigated how lifelong sports activities such as swimming, cycling, running and ball games can counteract the decline of muscle stem cells and thus the loss of muscle fibers.

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The researchers from the University of Copenhagen enrolled 46 male participants, who were divided into three groups: “young people who sit a lot,” “older people who exercise for a lifetime,” and “older people who sit a lot.” Everyone then had to perform a heavy resistance exercise that assessed their muscle function during a knee-stretching movement.

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The scientists took blood samples and muscle biopsies from both legs and were thus able to create a picture of the muscle stem cell population and muscle function. The regularly exercising volunteers had greater resistance to fatigue during exercise, a greater amount of muscle stem cells associated with fast-twitching muscle fibers, and a favorable state of muscle innervation compared with the old and young inactive volunteers.

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“This is the first human study to show that lifelong recreational exercise can delay some harmful effects of aging,” said lead author Casper Söndenbroe. “Using muscle tissue biopsies, we have identified positive effects of exercise on the general aging population. This has not been considered in the literature so far, as previous studies focused primarily on competitive athletes, who represent a minority.”

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Even though the study is limited to a small sample and an average age of 73 years among exclusively male participants, the scientists believe it is more representative of the general population and their typical mix of regular activities than previous studies. They are planning further studies with women to see if these benefits are maintained later in life.

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“The most important message from this study is that even little exercise appears to make a significant contribution to protecting against age-related decline in muscle function.”

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“This is an encouraging result that can hopefully inspire more people to engage in an activity they enjoy. We still have a lot to learn about the mechanisms and interactions between nerves and muscles and how they change as we age. Our research takes us one step further.”