New research explains how movement helps older muscles repair themselves.
Spoiler alert: No amount of exercise can turn back your chronological age. But regular physical activity may help reverse some of the biological changes that contribute to age-related muscle weakness, so you feel stronger (and younger) even as the calendar ticks forward.
Recent research published in the Proceedings of the National Academy of Sciences has identified a new biological pathway in the body that may explain how exercise helps aging muscle cells clear away damaged material, thereby preserving strength. The discovery provides scientific evidence for a common observation: namely, that older adults who stay physically active often have better mobility, recover more effectively, and continue doing everyday activities independently, compared with folks the same age who are sedentary.
While the results are preliminary, they are nevertheless encouraging, offering a possible explanation for why movement remains one of the most powerful tools available for maintaining muscle health as we age.
Why Muscles Change With Age
Age-related muscle loss is sometimes called sarcopenia. With sarcopenia, muscle mass, strength, and coordination can all decline over time. These changes may make it harder to climb stairs, get up from a chair, carry groceries, maintain balance, or recover after an illness or hospital stay. Weakness can also increase the risk of falls and fractures and make it more difficult to live independently.
In younger people, healthy muscle tissue is constantly remodeling itself. Cells build new proteins while breaking down and removing old or damaged ones. This ongoing maintenance process is known as proteostasis, or protein balance. A major controller of this process is a cellular pathway called mTORC1. Under the right circumstances, mTORC1 helps muscles build proteins, grow, and respond to nutrients and exercise. But more activity is not always better.
In the study, which was conducted on lab animals, the researchers found that mTORC1 can become chronically overactive in aging muscle. When that happens, muscle cells may continue producing new proteins without efficiently clearing away damaged ones along with other cellular debris. Over time, that imbalance can place the cells under stress and contribute to muscle deterioration.
It’s in the Genes
What causes mTORC1 to go into overdrive as you get older? The study identified DEAF1, a regulator gene that helps moderate how certain genetic instructions are turned on and used, as a primary culprit. Higher DEAF1 activity increased the production of mTOR, leading to overactivity of the mTORC1 pathway. This was associated with impaired protein balance, signs of cellular aging, and declining muscle function.
While DEAF1 controls mTORC1 stimulation, DEAF1 itself is controlled by regulatory proteins known as FOXO. These proteins help cells respond to stress, manage energy, and activate maintenance processes. As muscles age, however, FOXO activity may decline. That appears to allow DEAF1 levels to rise and mTORC1 activity to increase.
Exercise Helps Aging Muscles to Reset
Working backwards, then: If mTORC1 controls muscle building, and DEAF1 controls mTORC1, and FOXO controls DEAF1, what controls FOXO? In their lab studies, researchers found the proverbial keys to the kingdom. Exercise in older animals caused FOXO activity to increase, leading to a decline in DEAF1 levels. This brought mTORC1 activity closer to a healthy range and improved the muscles’ ability to remove damaged proteins.
“Exercise can reverse this process, correcting the imbalance,” said study leader Hong-Wen Tang, Ph.D., an assistant professor in the Cancer and Stem Cell Biology Program at Duke-NUS Medical School, in a news release .
“Physical activity activates proteins which lower DEAF1 levels, bringing the growth pathway back into balance,” Tang explained. “This allows ageing muscles to clear out damaged proteins, rebuild themselves properly, and helps them stay stronger and more resilient.”
First author Priscillia Choy Sze Mun described the process as a cellular cleanup signal. “Exercise tells muscles to ‘clean up and reset,’” Choy said in the Duke-NUS news release. “Lowering DEAF1 helps older muscles regain strength and balance, almost like hitting the rewind button.”
To be clear, exercise does not make the muscles of an older adult young again. But activating the FOXO-DEAF1-mTORC1 axis essentially restores muscles maintenance processes that have become less efficient with age, thereby improving strength and mobility in physically active seniors, compared with their sedentary counterparts.
All Signs Point to Staying Active
Because the study was conducted in a lab, it’s too soon to definitively say that exercise alone can reverse muscle aging. One day, researchers speculate that the DEAF1 pathway could become a target for therapies designed to reproduce exercise benefits in people who cannot be physically active. But the findings still need to be proven in the real world, with real people.
For now, the study’s message is more straightforward: Regardless of how old you are, your muscles retain a meaningful capacity to respond to movement. Current public health recommendations offer a practical starting point. The Centers for Disease Control and Prevention recommends that adults age 65 and older work toward at least 150 minutes of moderate-intensity aerobic activity each week, along with muscle-strengthening activity on at least two days and exercises that improve balance. Adults who cannot meet the full recommendations because of a chronic condition should be as active as their health and abilities allow.
For muscle health, resistance exercises are especially important. Some examples include:
• Doing wall push-ups
• Lifting light hand weights
• Practicing supported squats or step-ups
• Repeated standing and sitting from a sturdy chair
• Using resistance bands
• Using strength-training machines with appropriate instruction
Walking, swimming, cycling, gardening, and dancing can support endurance and overall health, but strength work gives muscles a direct reason to adapt. Balance activities such as tai chi or yoga can complement strength training and help reduce fall risk.
Someone who has previously been inactive doesn’t need to begin with a lengthy routine. Even five-minute activity periods throughout the day can be useful; duration and intensity can be increased gradually.
Older adults with heart or lung disease, severe arthritis, osteoporosis, balance problems, or other health issues should speak with a healthcare professional before starting a new program.
Movement Today Keeps Aging at Bay
Sources:
Study: Proceedings of the National Academy of Sciences. (2025.) “Exercise suppresses DEAF1 to normalize mTORC1 activity and reverse muscle aging.” https://www.pnas.org/doi/10.1073/pnas.2508893122
Duke Press Release: Duke NUS Medical School. (2026.) “Duke-NUS scientists uncover how exercise helps ageing muscles repair themselves.” https://www.duke-nus.edu.sg/newshub/media-releases/deaf1
Study Recap: Duke University Medical School. (2026.) “Why Muscles Weaken With Age—and How Exercise Fights Back.” https://medschool.duke.edu/news/why-muscles-weaken-age-and-how-exercise-fights-back
Activity Guidelines: Centers for Disease Control and Prevention. (2025.) “Older Adult Activity: An Overview.” https://www.cdc.gov/physical-activity-basics/guidelines/older-adults.html
