Regular exercise helps aging muscles stay stronger by restoring key cellular repair systems that decline over time, according to new research. Scientists found that physical activity can rebalance important molecular pathways inside muscle cells, allowing older muscles to clear away damaged proteins more effectively and maintain their strength.
The study, conducted by researchers from Duke-NUS Medical School in collaboration with Singapore General Hospital and Cardiff University, was published in the Proceedings of the National Academy of Sciences. The findings identify a molecular pathway that becomes disrupted with age and suggest new targets for therapies aimed at slowing age-related muscle loss.
Why Muscles Weaken With Age
Muscles are essential not only for movement but also for metabolism, blood sugar regulation, and the body’s ability to recover from illness or injury.
Beginning in midlife, muscle mass and strength gradually decline, increasing the risk of falls, fractures, disability, and prolonged recovery following surgery or disease.
This age-related process, known as sarcopenia, is becoming an increasingly important public health concern as populations continue to age.
One of the major regulators of muscle health is a cellular signaling pathway called mTORC1, which normally coordinates protein production, growth, and maintenance.
In aging muscle, however, mTORC1 can become excessively active, causing cells to prioritize building new proteins while neglecting the removal of damaged ones. As defective proteins accumulate, cellular stress increases and muscle function gradually deteriorates.
Researchers Identified a Key Gene
The researchers identified a gene called DEAF1 as an important regulator of this process.
They found that DEAF1 levels increase in aging muscles, further stimulating mTORC1 activity and disrupting the normal balance between protein production and protein recycling.
Under healthy conditions, DEAF1 is kept under control by proteins known as FOXO transcription factors, which help coordinate cellular repair and growth.
As people age, FOXO activity naturally declines, removing this regulatory control and allowing DEAF1 levels to rise.
According to the researchers, this molecular imbalance appears to accelerate muscle deterioration, making DEAF1 an attractive target for future therapies.
Exercise Helps Restore Cellular Balance
The study found that regular physical activity can partially reverse these age-related molecular changes.
Exercise activates proteins that suppress DEAF1 activity, reducing excessive mTORC1 signaling and restoring a healthier balance between building new proteins and removing damaged ones.
This allows aging muscle cells to clear away defective cellular components more efficiently while rebuilding healthy tissue.
As a result, physically active older adults are better able to maintain muscle strength and resilience than individuals who remain inactive.
The researchers also discovered that this natural repair mechanism has its limits.
In muscles where DEAF1 levels become extremely high or FOXO activity is severely diminished, exercise alone may not fully restore normal cellular repair.
Why Exercise Does Not Affect Everyone Equally
The findings may help explain why some older adults experience larger improvements from exercise than others.
When the DEAF1-FOXO regulatory system remains relatively functional, physical activity appears capable of reversing much of the molecular damage associated with aging.
However, when this pathway has become more severely disrupted, exercise may eventually need to be combined with future treatments that specifically target these molecular mechanisms.
The researchers suggest that measuring activity within this pathway could one day help identify which patients are most likely to benefit from particular exercise programs or future therapies.
Evidence From Animal Studies
To confirm their findings, the research team investigated the DEAF1 pathway in both fruit flies and older mice.
Increasing DEAF1 activity caused muscles in these animals to weaken more rapidly and lose function, closely resembling normal age-related muscle decline.
Conversely, reducing DEAF1 activity restored healthier protein balance within muscle cells and improved muscle strength.
Because similar results were observed across multiple species, the researchers believe this mechanism is likely to be evolutionarily conserved and may also play an important role in human muscle aging.
Nevertheless, they emphasize that clinical studies in people will be necessary to confirm these findings.
Potential Applications Beyond Healthy Aging
The researchers believe the findings could have implications beyond age-related muscle loss.
DEAF1 also influences muscle stem cells, which are responsible for repairing damaged muscle tissue after injury or illness.
These stem cells naturally become less effective with age, and excessive DEAF1 activity appears to further impair their function.
Targeting this pathway could therefore improve muscle recovery in older adults following surgery, prolonged illness, or medical conditions that limit mobility.
The researchers also suggest that future drugs capable of modulating DEAF1 activity might reproduce some of exercise’s beneficial molecular effects, helping preserve muscle strength in people who are unable to participate in intensive physical activity.
Looking Ahead
The findings reinforce the importance of regular physical activity throughout middle and older age while also providing a clearer biological explanation for why exercise helps preserve muscle health.
At the same time, the researchers note that biology may limit how much benefit some individuals can achieve through exercise alone.
Future clinical trials will be needed to determine whether therapies targeting DEAF1 can safely complement exercise programs or help patients who cannot exercise adequately.
The research was supported by Singapore’s Ministry of Education, the National Medical Research Council, and several institutional funding programs. According to the researchers, understanding how exercise restores cellular repair mechanisms could ultimately lead to new strategies for maintaining muscle health and independence as people age.
