There's a Critical Window in Your 50s for Preserving Body Strength
The fight against frailty can begin decades before physical decline becomes obvious.
Frailty may seem like a problem for old age. But the biological changes that make us more vulnerable to physical decline can begin decades before the first signs appear.
A 2026 study in Cell Metabolism analyzed data from more than 50,000 people and found that changes in proteins associated with frailty clustered around two ages: roughly 50 and 63.
These molecular patterns may help scientists understand how frailty develops before physical signs appear. Researchers also developed a protein-based frailty score that could eventually help identify people at risk, although more research is needed before it can be used clinically.
Around age 50, many of the changes involved proteins related to how the body uses and stores energy and regulates hormones. Around age 63, the changes were more closely linked to immune activity and inflammation.
“The idea that aging isn’t a perfectly linear process, but may involve periods of more pronounced physiological change, is consistent with what many clinicians observe in practice, even if we haven’t previously had the molecular data to confirm it,” says Julia Loewenthal, an assistant professor at Harvard Medical School and a geriatrician at Lutanen Health.
The findings do not mean that everyone experiences a sudden biological shift at 50. But they suggest that midlife may be a useful time to pay closer attention to physical health, rather than waiting until signs of decline become apparent.
Some loss of physical reserve is normal with aging. But losing it faster than expected can increase the risk of frailty, says Terence Favero, a professor of biology and exercise science at the University of Portland in Oregon.
“Genetics and the biology of aging set the pace, but the biggest factor we control is how much we move,” Favero says. “Systems atrophy without use, and we usually notice only when a task demands more than we have left.”
Muscle strength and power begin to decline as early as the late 30s, with losses accelerating later in life, says Kent Langston, an assistant professor of pathology at Yale School of Medicine and a member of the Yale Center for Research on Aging.
(Aging isn‘t just about decline. Here’s how health improves as we grow older.)
As people lose physical reserve, they may progress from robust to prefrail and, eventually, frail. Researchers often assess frailty using five physical signs: unintentional weight loss, exhaustion, low physical activity, slow walking pace, and weak grip strength. One or two signs indicate prefrailty; three or more indicate frailty.
These changes are not limited to old age. A 2018 study in The Lancet Public Health, involving nearly half a million UK Biobank participants aged 37 to 73, found that both frailty and prefrailty were present in middle age.
A 2024 study of adults in Malaysia found that, among participants younger than 60, 67.9 percent were classified as prefrail and 10.4 percent as frail. However, researchers used a broader measure of health problems and limitations than the five physical signs assessed in the UK study.
Several biological changes can help explain this decline. The body gradually loses motor neurons, and muscles become less responsive to the signals that stimulate growth. Changes in mitochondria, which produce energy for cells, and rising levels of low-grade inflammation may also play a role. In women, hormonal changes during menopause can accelerate muscle and bone loss, Favero said.
“None of these is frailty, but they shrink the buffer or reserve that protects you later, when an illness, injury, or hospital stay hits,” he says.
Smoking, poor nutrition, physical inactivity and chronic health conditions can further erode that reserve. Poor sleep, metabolic problems and persistent inflammation may also contribute. Illness and repeated hospitalizations can make recovery more difficult, leaving people struggling to regain their previous strength after each episode, Langston says.
(Your body ages rapidly in two “bursts,” at 44 and 60. Here’s how to prepare.)
The changes can be difficult to notice at first, even for people who remain active and independent. Loewenthal says recovery may take longer, sleep may feel less restorative, or everyday activities may leave someone more tired than they were a few years earlier. These experiences can occur with age, but they do not necessarily indicate frailty. But a sustained decline in physical capacity may warrant closer attention.
“Everyone experiences some decline with age, and ideally, we’d like to avoid tipping into the prefrail or frail categories if possible,” she says.
Frailty is not necessarily a one-way decline. A March 2026 study in Maturitas that followed 3,405 adults aged 50 to 64 found that moderate and vigorous physical activity were associated with improvements in frailty status. Living with others and volunteering were also linked to a lower likelihood of progressing from prefrailty to frailty. Higher hemoglobin levels were also linked to a lower risk of developing frailty.
The findings suggest that physical function can change over time, even in midlife. “Muscle, bone, tendon, and the cardiovascular system are fundamentally adaptive---- at any age,” Favero says. “These systems need regular, manageable stress to maintain themselves.”
Exercise may help people preserve that capacity. A 2024 systematic review examined eight intervention studies involving 2,838 adults aged 40 to 65. Resistance training and multicomponent exercise showed the most promising evidence for preventing or reversing frailty.
(Here’s how to start aging like an athlete.)
A separate 2024 review examined nine trials involving 842 adults aged 60 and older who were robust or prefrail. Those who took part in exercise-based interventions had a 74 percent lower relative risk of developing frailty than those in control groups. Combining exercise with nutrition was also associated with a lower risk, although nutrition interventions alone did not show a statistically significant benefit.
Timing may matter, too. “Frailty is more likely to be reversible when identified early,” Loewenthal says. “People with prefrailty or mild frailty are more likely to return to a robust state than those with moderate to severe frailty.”
Favero recommends strength training two to three times a week, working all major muscle groups and including faster movements to maintain power. Regular aerobic activity and balance exercises can also help, as can breaking up long periods of sitting. Eating enough protein throughout the day and getting adequate sleep support the body’s ability to maintain and repair muscle.
Tracking grip strength, how easily someone rises from a chair, balance, and walking speed over time may help reveal a decline. It is also important to identify and treat conditions such as anemia, depression, and thyroid dysfunction that may affect energy and physical capacity. Social support and daily routines that make healthy habits easier to sustain can help people stay active.
People cannot stop aging, but they can take steps to preserve their strength and independence as they get older while reducing their risk of falls, disability, and several chronic diseases, Favero says.
“In practical terms, it's the difference between carrying your own luggage and climbing stairs at 72 and needing help with them.”
