Women's Health March 23, 2026 0 Comments

Is Marathon Running Really Strengthening Your Heart—or Secretly Putting It at Risk?

Ever wondered what happens when the heart of a seasoned marathoner hits an unexpected speed bump? In early 2024, Madison DiBattista, a dedicated runner grinding towards her first Ironman, faced a baffling series of symptoms—shortness of breath, chest pains, and fainting spells—that no amount of grit or coffee could shake off. After over a decade of pounding the pavement with zero hiccups, she chalked it up to stress or overtraining while juggling her flourishing running gear company, Sprints. But the shocking truth was far from a simple workout burnout. It turns out her heart was harboring a rare, invisible defect—one so uncommon it had never been diagnosed in a living adult before. Madison’s journey from dismissal by her doctors to demanding “an Olympic-level heart” post-surgery is a compelling wake-up call for every runner out there. So, are marathons the heart-healthy exercise we all believe them to be—or is there a hidden risk beneath those finish line cheers? Let’s dive deep into the heart of the matter and unravel the real impact of pounding out those miles. LEARN MORE

12 min read

IN EARLY 2024, marathon runner Madison DiBattista was in the midst of training for her first Ironman race when she started experiencing alarming symptoms, like shortness of breath, chest pain, and episodes of passing out, among others. After running for over 11 years without any major problems, the 24-year-old wrote off her symptoms as anxiety or overworking while building her running gear company, Sprints. Soon, however, she realized she wasn’t getting any stronger amid rigorous training. “If anything, I was making my body so much weaker,” she says. “There were a couple of weeks where I tried to get myself to run and just couldn’t.”

Her dad shared her symptoms with a cardiothoracic surgeon friend who advised she see a doctor immediately. And yet, the doctors she saw initially wrote her off as healthy. “My primary care physician at the time looked me up and down and said, ‘if you had heart disease, we would know by looking at you’—and I think that’s an easy box for athletes to be put into, because they’re healthy people. But heart disease can take a lot of different shapes.”

After DiBattista’s symptoms worsened (extreme weight loss, an abnormally high heart rate, etc.), doctors conducted additional tests and discovered she had a rare congenital heart defect—so rare, in fact, that it had never been diagnosed or identified in a living adult, only through autopsies.

She had surgery in August of 2024, and shared one clear request for the surgeon: “I want an Olympic-level heart,” she says. “I don’t want to get to the other side of this and have restrictions.” She waited six weeks and six days before lacing up her sneakers again—and now, she’s working her way back up to racing, slowly but surely.

DiBattista’s story is alarming, but it’s certainly not an isolated case. There are a number of nerve-racking stories out there about runners who thought they were in perfect health, only to discover heart issues while training for marathons or other endurance running events. And, in some instances, mid-race cardiac complications arise for people without any underlying conditions at all.

While cardiac arrests during races are very rare (a recent study estimates just 0.54 per 100,000 participants in the U.S., with cardiac deaths only accounting for 0.20 per 100,000) it is nevertheless alarming. In fact, some physicians even advise their patients against running longer endurance races to eliminate the possibility of excess strain on the heart.

With the numbers so low (for context, you’re statistically more likely to die in a car accident than while running a marathon), completely abstaining from running marathons may seem overzealous. After all, isn’t running supposed to be one of the best things you can do for your heart health?

But even with minimal marathon incidents, it does beg the question: Are marathon races really safe? Are they net positive or negative when it comes to cardiac health? And is it worth the potential risks?

What We Know—and Don’t—About How Distance Running Impacts the Heart

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First off, let’s get one thing clear: According to all of the experts we interviewed, running is good for your health—and for your heart. “Running, similar to any exercise, is helpful from both the cellular and macro physiological level,” says Tamanna Singh, MD, clinical cardiologist and director of the Sports Cardiology Center at the Cleveland Clinic.

Running helps to increase your mitochondrial density, increase the myoglobin in your muscles, and grow new blood vessels—all of which helps increase the amount of oxygen and energy available to use, she says. What’s more, as with most exercise, it reduces blood pressure, helps with cholesterol and blood sugar management. “It’s one of the reasons why we have people do cardiac rehab after a heart attack. We want to get that heart working efficiently,” Dr. Singh says.

And the list of perks certainly doesn’t end there. “Cardio respiratory fitness also is strongly associated with longevity, decreased mortality, decreased cardiovascular events, decreased mental health issues, cancer risk, etc.” says Jonathan Drezner, MD, a family medicine physician who specializes in sports medicine and sports cardiology.

So logic holds: Choosing to go out for a run is ultimately a positive choice for overall health.

However, running does put physiological strain on the heart, particularly when it comes to higher volume and intensity. No matter how well-conditioned an athlete is, plenty of research suggests that following a marathon, individuals experience an increase in inflammatory and abnormal cardiac biomarkers, says Sean Swearington, MD, a cardiologist at Rush, whose research focuses on the cardiovascular effects of intense prolonged exercise.

One biomarker that’s garnered the most attention is the cardiac enzyme troponin—typically associated with heart damage—that is often released into the bloodstream following a marathon, says Dr. Singh.

What’s more, “we’ll typically see some form of strain on the right side of the heart, which has a thinner wall structure. It’s not meant to handle higher pressure loads like the left side of the heart, which is more muscular, and the one responsible for pushing the blood to the rest of your body,” she says.

However, Dr. Singh points out that for individuals with a healthy heart, these effects tend to be transient, meaning “we typically see resolution of that within about 24 to 48 hours.”

The issues tend to arise when people have heart disease, heart failure, or other underlying heart conditions—as those individuals may not be able to sustain the effort required during endurance events, and may become symptomatic as a result, she explains (more on this later). “There is one disease entity where higher volume, higher intensity exercise can actually increase the risk of sudden cardiac arrest and death, and that’s arrhythmogenic cardiomyopathy [an inherited disease characterized by dangerous, irregular heart rhythms]—but it’s rare.”

There’s also some debate over whether or not long-term endurance exercise increases the risk of developing scar tissue buildup in the heart (clinically referred to as myocardial fibrosis). “There [have] been some studies using cardiac MRI that look at lifetime marathoners compared to non-marathoners or the general population, and in lifetime marathoners, there are some areas of the heart that look like they have a little bit of fibrosis in the heart muscle,” says Dr. Drezner, “but there’s absolutely no clinical correlation. There’s no higher risk of arrhythmias or sudden death, or anything in those individuals. And so we don’t know what it means.”

Another potential topic of concern is the occurrence of atrial fibrillation (irregular and often rapid heart rhythm, commonly referred to as AFib) in endurance athletes. AFib can lead to symptoms like palpitations, shortness of breath, and fatigue—or it could be totally asymptomatic. Left untreated, AFib can increase the risk of stroke, heart failure, or other serious complications. “Atrial fibrillation occurs in the general population and occurs in other medical conditions like heart failure,” Dr. Drezner says, “but it is more common in athletes, and specifically endurance athletes.”

He notes that some experts believe this is because, as we exercise, the heart chamber gets larger and stronger; as a result, it dilates with more blood, which can then obstruct the smaller chamber of the atria. “That stretch may throw off the electrical signal of the heart a little bit and increase someone’s predisposition to developing atrial fibrillation,” Dr. Drezner says. “So long term, is there a higher risk of developing AFib? Yes. Is that a reason not to go out and run marathons? I don’t think so.”

When High-Endurance Events Can Become Dangerous

While it’s a wildly unsatisfying answer, Dr. Drezner says those scary cardiac events are often random. “I don’t think there’s anything inherently risky to a marathon event that isn’t present in other forms of exercise, if you push yourself hard enough,” he says. “You could also have random events that occur when you’re shoveling snow in the morning or playing basketball or on the football field.”

Nevertheless, they do happen, and one of the best protective measures is simply bodily awareness—during a race, yes, but also throughout training. “I would say probably the majority of the time, if you were to go back and talk with [people who were having cardiac issues during a race], they would probably tell you that they were having some symptoms of chest pain or lightheadedness or abnormal shortness of breath that they may have tried to ignore,” says Dr. Swearington. “A lot of times, individuals who are highly active won’t always tell you when they’re experiencing things, and they’ll try to push through those symptoms,” as demonstrated by DiBattista’s experience. Case in point: Pay attention to your symptoms, and alert a cardiologist if anything feels abnormal.

And while running for long periods is not necessarily dangerous, at a certain volume, the cardiac benefits hit a point of diminishing returns, Dr. Swearington notes. “Typically what I say is, once you get to the point of doing six to eight hours per week, beyond that, you are limiting any significant benefit,” he says.

That’s not to say once you get into that zone that it’s hazardous (Dr. Swearington says there is no definitive evidence of a negative impact on your heart, beyond the potential increased risk of AFib). But if you’re running with the goal of improving your heart health, know that you’re not necessarily doing your body any additional favors at that point.

Before Blaming the Marathon, Look at the Machinery

As with any facet of your well-being, heart health is determined by a number of variables—all of which may influence risk of complications (during a race or otherwise).

There’s a saying that goes, “you can’t outrun a bad diet,” and that’s true. “A lot of people think, ‘I’m exercising like crazy, I can eat and drink whatever I want,’ and that’s really not the case,” says Dr. Swearington. “We do see, not uncommonly, that people can be high intensity athletes and develop significantly blocked heart arteries from cholesterol buildup over a long period of time.” And the downstream effects of said bad diet might rear its ugly head during training or even a big race.

That same principle applies to other lifestyle choices—smoking, drinking, and even a lack of good sleep hygiene. In short: If you’re not taking care of the motor, the car isn’t going to run very smoothly, and could even break down.

And, perhaps the most influential factor when it comes to heart health is none other than the one factor that’s uncontrollable: genetics. You may be predisposed to an underlying condition, even at a young age, despite checking all the boxes to take care of your health. That’s why it’s crucial to know your personal and your family history, Dr. Singh says, so you can understand what your cardiovascular risk is in the long run. “Know what your labs are, know what your baseline labs are, and continue with surveillance there,” she says. “That way, you’re always in the know of where your body is, how it’s changing as you age, and what you can do to prevent bad things from happening.”

Women May Have an Edge When Going the Distance

Speaking of genetics, it’s no secret that cardiovascular disease tends to affect men sooner than women. By that estimation, does that mean female athletes’ hearts are actually better-suited for endurance running?

As with most health research, there are very few studies specifically about female runners’ heart health. Because of that “it’s hard to say whether it’s low data or there’s actually low incidence of things like sudden cardiac arrest and death, cardiomyopathy, cardiovascular disease,” with female marathoners, says Dr. Singh. What we do know is that estrogen is very cardioprotective, which explains why cardiovascular disease might show up later for women (generally after perimenopause or menopause).

Anecdotally, however, Dr. Singh has heard many cases of women becoming stronger marathoners after having children. To her, this makes complete sense: “I don’t have any science to back why we’re seeing a lot of women pull off amazing feats at these longer endurance events in their late 30s,” she says, “but I do think the challenge of of growing the fetus and the physiological changes to your heart, into your vasculature, into your blood volume, and that’s an endurance sport.”

The New Rules of Signing Up for a Marathon and Training Safely

As the saying goes: It’s about the journey and not the destination, and that sentiment is certainly true when it comes to heart-friendly race prep.

First and foremost, if you have even an inkling of concern about your cardiac health, go get checked out. Watch out for chest pain, lightheadedness, abnormal shortness of breath, or really any new, alarming symptoms during exercise. In DiBattista’s case, warning signals also extended to episodes of passing out, 25 pounds of weight loss in a two-month period, rashes all over her body, and night sweats. She notes that, for her, wearing an Apple Watch was an extremely valuable tool for detecting and validating that something was off (she had a resting heart rate of 115 BPM, and during exercise it sometimes surpassed 200). Ultimately, this data convinced gave her the final nudge to seek medical attention.

In hindsight, DiBattista realizes how important it is to take all symptoms seriously—and beseeches others to do the same. “It’s very easy to gaslight yourself into thinking that you’re okay, or you’re tough enough to handle it, or you don’t need to ask for help,” she says. “But I beg people to take every symptom very seriously, even if you feel like a hypochondriac or you feel like you’re blowing things out of proportion.”

Now, because of her experience, DiBattista’s friends and family have started getting preventative scans for their own hearts—an action that Dr. Drezner also stands by. “People should know their cardiovascular risk,” he says. (Testing might include imaging, stress testing, and an electrocardiogram—and the doctor may also evaluate lifestyle risk factors.) “No matter what age you are, there is an appropriate screen that can give you information.”

For female-bodied distance runners, specifically, it’s a good idea to get checked for anemia—as this can impact heart health by forcing the heart to work harder, leading to increased heart rate. Chronic anemia can even lead to structural changes like an enlarged heart muscle, arrhythmia, and heart failure.

And even if you’re completely asymptomatic, it certainly doesn’t hurt to know your heart health baseline. “Empower yourself and rip the band-aid off,” Dr. Singh says. “Some people think ignorance is bliss, but it truly is not. Ignorance leads to a lot of poor outcomes.”

From that point, a cardiologist can help determine if there are any underlying health concerns, and offer any recommendations for lifestyle adjustments to support overall heart health. A sports cardiologist can also determine if you’re safe to participate in any kind of fitness event (including running a marathon), and offer suggestions for how to train most effectively in order to minimize any possible risks.

While those recommendations are highly individual, there are some general guidelines to consider. For instance, Dr. Swearington typically recommends completing some amount of cardio or endurance training four days a week, along with two days of strength training. And, he tells his patients not push themselves towards maximum heart rate on a regular basis. Instead, he suggests sprinkling in high-intensity interval training throughout the week, “to get toward their maximum predicted heart rate intermittently, which can help improve their overall endurance going forward,” he says. “That type of training has been shown to be beneficial in individuals with known coronary artery disease, and hasn’t shown any increased risk as far as them having recurrent cardiac events.”

And remember, recovery is a part of training, says Dr. Singh. That includes sleep, managing stress, hydrating effectively, and getting proper nutrition (the Mediterranean diet is your best bet for heart health). “That kind of holistic approach will lead to the best possible experience with these longer duration events—not just psychologically, but physically and cardiovascularly.”

It really boils down to this: Get a health workup, train smart, and listen to your body. And while running is certainly not the only way to support your heart health (any kind of cardiovascular training will do the trick), it is a great, accessible exercise option.

As for that infamous 26.2 mile race? Well, “you certainly don’t need to run a marathon to get the greatest cardiovascular pain for your buck, but people run these for all different reasons,” says Dr. Singh.

“Whether it’s postpartum or diabetes or heart disease, there’s so many things you can’t see that people bring to the starting line,” says DiBattista. “Whatever it is, it’s given me a much more rounded view on what it means to be a runner.”

Before her diagnosis, DiBattista used to finish a run and fixate on her speed and results. “Now I finish a run and think: Wow, how lucky are we to get to move our bodies in this way.”

Kristine Thomason is a writer and editor with over a decade of experience creating content for print and digital publications. Previously, she was the health and fitness director at mindbodygreen, and the fitness and wellness editor at Women’s Health. Kristine’s work has appeared in Men’s Health, Travel + Leisure, Health, and Refinery29, among others. She holds a journalism degree from New York University, and is certified in personal training by the National Academy of Sports Medicine (NASM).