Our muscles aren’t simply reactive tissues; they possess a surprising capacity to “remember” both strength and weakness, according to new research. This discovery, building on earlier work identifying “epigenetic memory” in muscle, suggests that past experiences – from rigorous training to periods of illness or injury – can have lasting effects on how our muscles respond to future challenges.
The Science of Muscle Memory
Adam Sharples, a molecular physiologist formerly a professional rugby player, first observed this phenomenon in his own athletic experience. He and his research lab at the Norwegian School of Sport Sciences in Oslo were the first to demonstrate in 2018 that exercise can induce long-term changes in how our muscle-building genes function. These changes, while not altering the genes themselves, turn genes “on” to build muscle more efficiently.
Now, Sharples’s team has uncovered evidence that muscles also retain a “memory” of weakness. “Our new data shows that muscle does not just remember growth—it also remembers wasting,” Sharples stated, referring to a study currently under peer review for publication in Advanced Science. The more often muscles experience atrophy due to injury or illness, the more vulnerable they become to future weakening.
Implications for an Aging Population
This finding carries significant weight as many countries face rapidly aging populations. Norway, Japan, Germany, and the United States are all projected to have over 20% of their populations age 65 or older in the coming years. Age-related muscle weakness is a major contributor to falls, a leading cause of injury and death for older adults.
Studies involving both young humans and aged rats revealed that repeated periods of disuse lead to epigenetic changes that impair mitochondrial function – the energy production centers within muscle cells. While young muscle demonstrated some ability to adapt and recover, aged muscle showed a worsened response with each episode of atrophy.
What’s Next?
Researchers have already determined that epigenetic memories in muscle can last at least three to four months, and protein changes can be retained for even longer – up to 10 years in some cases, as observed in cancer survivors. Further research could explore whether exercise can counteract the negative effects of past muscle weakness. Identifying genes associated with muscle growth could also pave the way for pharmaceutical interventions, though scientists caution that stimulating muscle growth requires careful consideration due to potential unintended consequences.
Frequently Asked Questions
What is epigenetic memory in muscle?
Epigenetic memory refers to changes in how genes are expressed, rather than changes to the genes themselves. Repeated exertion can turn on genes that promote muscle growth, creating a lasting effect where muscles respond more favorably to future exercise.
Does age affect muscle’s ability to recover from weakness?
Yes, the research indicates that aged muscle becomes more sensitive to atrophy after repeated periods of disuse, showing a worsened response with each episode. Young muscle, however, demonstrates some resilience and a better ability to adapt.
How long do these “muscle memories” last?
Epigenetic memories in muscle can last at least three to four months, and protein changes can be retained for even longer, potentially up to 10 years in some cases.
Given these findings, how might understanding the interplay between muscle memory for strength and weakness change our approach to fitness and healthy aging?