How do our bodies remember?

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The phrase “like riding a bike” is shorthand for the wonderful 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 the coordinated movement pattern that lives in the motor neurons, which control our muscles.

But scientists have discovered this in recent years Our muscles themselves They have a memory for movement and exercise.

When we move a muscle, the movement may seem to begin and end, but all of these small changes are actually continuing to happen inside our muscle cells. The more we move, such as when riding a bike or other types of exercise, the more those cells begin to form a memory of that exercise.

When we move a muscle, the movement may seem to begin and end, but all of these small changes are actually continuing to happen inside our muscle cells.

We all know from experience that a muscle gets bigger and stronger with repetitive work. As leading muscle scientist Adam Sharples — a professor at the Norwegian School of Sports Sciences in Oslo and a former professional rugby player for the UK — explained to me, skeletal muscle cells are unique in the human body: they are long and thin, like fibres, and have multiple nuclei. Fibers grow larger not by division but by recruiting satellite myocytes—muscle-specific stem cells that are dormant until they are activated in response to stress or injury—to contribute their own nuclei and support muscle growth and regeneration. These nuclei often remain for a while in muscle fibres, even after periods of inactivity, and there is evidence that they may help speed up the return to growth once you start training again.

Sharples’ research focuses on so-called epigenetic muscle memory. “The term “epigenetic” refers to changes in gene expression caused by behavior and environment – ​​the genes themselves do not change, but the way they function does. In general, exercise turns on genes that help muscles grow more easily. When you lift weights, for example, small molecules called methyl groups separate from the outside of certain genes, making them more likely to turn on and produce proteins that affect muscle growth (aka hypertrophy). These changes continue; If you start lifting weights again, you will add muscle mass more quickly than before.

In 2018, the Sharples Muscle Lab was the first to show that human skeletal muscle has a genetic memory for post-exercise muscle growth: muscle cells are primed to respond more quickly to future exercise, even after a pause of months (and perhaps even years). In other words: your muscles remember how to do it.

Subsequent studies by Sharples et al have replicated similar findings in mice and older humans, providing further evidence supporting epigenetic muscle memory across species and in later life. Even aging muscles have the ability to remember when to exercise.

Meanwhile, Sharples points to interesting new evidence suggesting that muscles also remember periods of atrophy, and that both small and large muscles do. differently. While young human muscle appears to have what he calls a “positive” memory of atrophy — “they recover well after the initial period of atrophy and do not experience greater loss in the recurrent period of atrophy,” he explains — aged muscle in mice appears to have a more pronounced “negative” memory of atrophy, as they appear “more susceptible to greater loss and an exaggerated molecular response when muscle wasting is repeated.” Essentially, young muscles tend to recover from periods of muscle loss — “ignore” them, in a sense — while older muscles are more sensitive to them and may be more vulnerable to further muscle loss in the future.

Illness can also lead to this type of “negative” muscle memory. In a study of breast cancer survivors more than a decade after diagnosis and treatment, participants showed a genetic profile of people much older than their chronological age. But you have to understand this: After five months of aerobic training, the participants were able to reset the epigenetic profile of their muscles back toward the muscularity seen in an age-matched control group of healthy women.

What this shows is that “positive” muscle memories can help counteract “negative” memories. Takeaway? Your muscles have their own kind of intelligence. The more you use it, the more you can harness it to become a lasting resource for your body in the future.

Bonnie Tsui is the author of On muscle: The things that move us and why they matter (Algonquin Books, 2025).

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2025-10-10 10:00:00