Scientists have found why moving your body helps older muscles stay strong. A study from Duke‑NUS Medical School shows that exercise can bring back the natural repair tools that get weaker with age.
Working with partners from Singapore General Hospital and Cardiff University, the team discovered that exercise fixes an important imbalance inside aging muscle cells. Their findings were published in the Proceedings of the National Academy of Sciences (PNAS). The new knowledge could help create ways to stop age‑related muscle loss.
Why Muscles Get Weaker Over Time
Muscles do more than let us move. They help control metabolism, blood sugar, and overall health. Around middle age, muscle strength slowly drops. This raises the chance of falls, broken bones, and slower healing after sickness.
When many people get older, the growing need for care and medical help can strain families and health systems. Keeping muscles strong is key to staying independent and happy.
A major controller of muscle health is a pathway called mTORC1. It tells cells how much protein to make. In older muscles, mTORC1 can become too active. The muscle then makes new proteins but forgets to clear out broken ones.
The junk proteins pile up, stress the cell, and cause strength loss. Until now, researchers didn’t know what started this imbalance.
DEAF1: A Gene Linked to Muscle Aging
The study pointed to a gene named DEAF1. In older muscles, DEAF1 levels rise. Higher DEAF1 pushes mTORC1 to work harder, tipping the balance toward protein buildup and less cleanup.
Normally, a group of proteins called FOXOs keeps DEAF1 low. But FOXO activity drops as we age, letting DEAF1 climb and the repair system slip.
How Exercise Sets the Balance Right
Exercise can lower DEAF1 and calm the over‑active mTORC1 pathway. When the pathway is balanced, muscles can throw out damaged proteins, rebuild properly, and stay stronger.
However, if DEAF1 becomes extremely high or FOXOs are very weak, exercise alone may not fully rescue the muscle. This may explain why some seniors see bigger benefits from working out than others.
Tests in Flies and Mice Confirm the Idea
Researchers raised DEAF1 in fruit flies and older mice and saw muscles weaken faster. Lowering DEAF1 in the same animals improved protein balance and made the muscles stronger. The result suggests DEAF1 works the same way in many species.
Beyond Normal Aging
DEAF1 also affects muscle stem cells, which help repair tissue. As we age, these stem cells lose power, and high DEAF1 makes recovery even harder.
The discovery could help people who cannot exercise much, such as after surgery, illness, or cancer treatment. Targeting DEAF1 might give some of the good effects of exercise at the molecular level.
"Exercise tells muscles to clean up and reset," said the researchers. "Lowering DEAF1 lets older muscles regain strength, almost like hitting a rewind button." With millions facing muscle decline, understanding DEAF1 may lead to new ways to protect strength and improve life quality.