Being fit in your 40s and 50s could add years to your life — and meaningful life to those years.
That’s the implication of a comprehensive new study of the links between midlife aerobic fitness and subsequent lifespan and health span among a group of almost 25,000 aging men and women.
Lifespan, obviously, means the number of years we live, in any condition, while health span consists of those years we live without serious disability or disease.
Ideally, the two would match. But they rarely do. Instead, most people’s lifespans extend well beyond their health spans. We often accumulate one chronic condition after another, increasing our odds of frailty and dependence during aging.
But the new study, which was published in April in the Journal of the American College of Cardiology, suggests we might be able to alter that trajectory. It found that being in good shape during middle age was associated with about a 2 to 3 percent improvement in both health span and lifespan, translating to about a year and a half to two years of longer, healthier living.
“I think most people want to live not just a long time but live those years in good health,” said Clare Meernik, an assistant professor at the Kenneth H. Cooper Institute and Texas Tech University Health Sciences Center and the study’s lead author.
The new findings suggest that spending a little time now improving our fitness might be central to achieving both of those goals as we age.
The health span gap
At the moment, Americans have one of the world’s largest gaps between healthspan and lifespan, according to a large-scale 2024 study. When researchers in that study checked health and death records for citizens in 183 nations, they found that, on average, older people’s health spans globally were nine years shorter than their lifespans. But in America, that gap was 12.4 years, the longest in the study, meaning most older Americans spend their final 12-plus years living with illness.
Of course, it’s possible to spin that statistic as desirable, since it suggests American health care keeps people alive, even after they’ve developed serious illness.
But most of us probably would prefer to avoid or delay disease and disability as long as possible and extend our health spans.
Could aerobic fitness help, Meernik and her colleagues wondered?
Does fitness affect health span?
“We’ve known for decades that high fitness is associated with longer lives,” Meernik said. “We’ve also known it’s associated with less risk for individual diseases.”
But would fitness play a role in precisely whether and when people first become ill during aging and how many separate chronic conditions they develop, as well as how long they live?
Conveniently, Meernik and her colleagues had access to a unique dataset to start delving into those questions. For decades, thousands of men and women have visited the Cooper Clinic in Dallas for checkups, most of which included treadmill tests to estimate aerobic capacity. Their health records are maintained, with permission, for research purposes.
The researchers turned to that database, gathering records for 24,567 men and women who had visited the clinic during middle age, usually in their 40s, and later joined Medicare while still relatively healthy, without any major illnesses.
The researchers categorized these people’s midlife fitness as low, moderate or high, based on their treadmill tests. The fittest weren’t necessarily marathon runners or other extreme exercisers, Meernik said; they probably walked briskly most days. The least-fit group likely didn’t exercise much, if at all.
An extra two years
The scientists followed people’s Medicare records deep into retirement and usually until death, noting if and when they developed any of 11 common and serious age-related conditions, such as cardiovascular and kidney disease, several types of cancer, and dementia.
Then they created complex statistical models of how people’s midlife fitness related to their late-life health.
And it did relate. The people who had been the most fit in middle age lived longer in old age than less-fit people, with fewer diseases that appeared later. The moderately fit likewise outlived the least fit, with less disease burden.
Specifically, the men and women in the fittest group tended to develop their first major illness, if any, about 1½ years later in life than people in the least-fit group. They also developed subsequent major diseases at a much lower rate than the less-fit group. And they lived about two years longer, on average.
Both their health spans and lifespans “shifted to the right,” Meernik said, lengthening and improving.
What the study doesn’t say
The gains weren’t enormous. “Some will dismiss a 2 percent health span extension,” said Eric Topol, a cardiologist, founder of the Scripps Research Translational Institute and author of the 2025 bestseller “Super Agers.” He wasn’t involved with the new study.
But no longevity drug or related high-tech interventions have yet shown comparable improvements to health spans in studies in people, he said.
“Is 1½ to two additional years” of health span and lifespan “a big deal?” asked I-Min Lee, a professor of epidemiology at the Harvard T.H. Chan School of Public Health and study co-author. “I would say yes. These are additional years after age 65. The average life expectancy in the U.S. is 79 years. So we live on average 14 years after age 65. Two added years on top of that sounds good to me.”
The study was also associational, meaning it shows links between being fit in middle age and living healthier and longer but can’t prove that fitness is the main driver. Genetics, income, diet, luck and other factors probably play roles.
Perhaps most important, the study doesn’t tell us just how to get more fit or if it’s too late for us to bother if we’re already past middle age.
But a wealth of other evidence shows “it’s never too late” to get into shape, Meernik said, and it’s also never too early. “Whatever your age, it’s worthwhile to be up and moving,” she said. A brisk walk today might help string out our health spans decades from now.
Do you have a fitness question? Email [email protected] and we may answer your question in a future column.
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