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“Like riding a bike” is shorthand for the remarkable way our bodies remember how to move. Most of the time when we talk about muscle memory, we are not talking about the muscles themselves, but about the memory of a coordinated movement pattern that lives in the motor neurons that control our muscles.
However, in recent years, scientists have discovered that our very muscles have memory for movement and exercises.
When we move a muscle, the movement may seem to begin and end, but all these small changes actually continue to occur inside our muscle cells. And the more we move, such as cycling or other forms of exercise, the more these cells begin to remember that exercise.
When we move a muscle, the movement may seem to begin and end, but all these small changes actually continue to occur inside our muscle cells.
We all know from experience that a muscle becomes larger and stronger with repeated use. Being an innovator muscle scientist Adam Sharples— a professor at the Norwegian School of Sports Science in Oslo and a former professional rugby player in the UK — explained to me that skeletal muscle cells are unique in the human body: they are long and thin, like fibers, and have multiple nuclei. Fibers grow not by dividing, but by recruiting muscle satellite cells—muscle-specific stem cells that lie dormant until activated in response to stress or injury—to contribute their own nuclei and support muscle growth and regeneration. These nuclei often remain in muscle fibers for a while, even after periods of inactivity, and there is evidence that they can help speed the return to growth when you start training again.
Sharples' research focuses on something called epigenetic muscle memory. ““Epigenetics” refers to changes in gene expression that are caused by behavior and environment – the genes themselves don't change, but the way they work does. In general, exercise turns on genes that help muscles grow more easily. For example, when you lift weights, small molecules called methyl groups become detached from the outside of certain genes, making them more likely to turn on and produce proteins that influence muscle growth (also known as hypertrophy). These changes are saved; if you start lifting weights again, you will gain muscle mass faster than before.
In 2018, Sharples' muscle laboratory was the first to show that Human skeletal muscle has an epigenetic memory of muscle growth after exercise.: Muscle cells are ready to respond faster to exercise in the future, even after a pause of many months (or maybe even years). In other words: your muscles remember how to do it.
Subsequent studies by Sharples and others replicated similar findings in mice and older humans, providing further evidence of epigenetic muscle memory across species and in later life. Even aging muscles can remember when you exercise.
At the same time, Sharples points to intriguing new evidence that muscles also remember periods of atrophy, and that young and old muscles remember this. differently. While young muscle appears to have what he calls a “positive” memory of depletion—“in the sense that it recovers well from the first period of atrophy and does not experience much loss during a second period of atrophy,” he explains—old muscle in rats appears to have a more pronounced “negative” memory of atrophy, in which they appear to be “more susceptible to greater losses and a more exaggerated molecular response when muscle wasting is repeated.” Essentially, young muscles tend to recover from periods of muscle loss – in a sense “ignoring” it – while older muscles are more sensitive to this and may be more susceptible to further muscle loss in the future.
Illness can also lead to this kind of “negative” muscle memory; In a study of breast cancer survivors more than ten years after diagnosis and treatment, participants showed the epigenetic muscle profile of people much older than their chronological age. But here's the thing: after five months of aerobic training, the participants were able to reset the epigenetic profile of your muscles back to the muscles observed in a control group of age-matched healthy women.
This shows that “positive” muscle memories can help counteract “negative” ones. Conclusion? Your muscles have an intelligence of their own. The more you use them, the more they can be used to become a long-lasting beneficial resource for your body in the future.
Bonnie Tsui – author About muscles: The Things That Move Us and Why It Matters (Algonquin Books, 2025).
