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What Happens to Your Heart After Running a Marathon? Insights from Sports Cardiologist
5 min. read
Baptist Health Miami Cardiac & Vascular Institute
Running a marathon is a remarkable physical achievement. It’s an intense test of endurance, strength, and mental fortitude. But what happens to your heart after running 26.2 miles? Is it stressed? Does it take a toll on your body’s most important organ?
Thousands of runners Sunday completed the Life Time Miami Marathon & Half. As the official medical provider for the event, Baptist Health teams were stationed at various first-aid and medical tents throughout the course, providing staffing and equipment to ensure that runners had access to medical care if needed.
Eli Friedman, M.D., director of Sports Cardiology at Baptist Health Miami Cardiac & Vascular Institute, breaks down the effects of marathon running on the heart and provides insights on how to train, race, and recover safely.
The bottom line: If you trained properly and are in good overall health, there’s nothing much to worry about after running a marathon.
“Those who trained and were smart about their training should be fine,” explains Dr. Friedman. “And anybody who might have concerns or abnormal or unusual symptoms, just make sure to seek medical attention.”
For the most part, he adds, “they’ll mostly feel sore and beat up a bit. But they really shouldn't notice a whole lot of things, otherwise.”
How the Marathon Can Stress the Heart
When it comes to marathon running, the heart is undoubtedly one of the hardest-working organs. “We know that the heart can see a lot of stress from running the marathon,” says Dr. Friedman. However, he emphasizes that this is not necessarily a bad thing. Much like the rest of the muscles in the body, the heart undergoes strain during such an intense physical feat.
Eli Friedman, M.D., medical director of sports cardiology at Baptist Health Miami Cardiac & Vascular Institute.
Dr. Friedman explains that “all of our muscles are stressed by running 26.2 miles,” but the degree of that stress varies depending on factors like training, fitness level, and individual health.
For seasoned marathoners, their bodies may be better equipped to handle the strain, while first-timers or under-trained runners might experience disproportionate stress. “For those who don’t train and aren’t smart about it, the stress may be more than it would be in somebody else,” he notes.
One of the key areas of stress has to do with the right side of the heart, which faces unique challenges during endurance events. “The right side isn't used to the volume and pressure challenges that the left side of the heart is used to,” says Dr. Friedman.
The heart works as a dual pump: the left side pumps blood to the body, while the right side pumps it to the lungs. Because of the increased blood flow required during a marathon, the right side can sometimes experience greater strain. For experienced endurance runners, "Athlete's heart" describes physical and electrical changes, or remodeling, to the heart as a result of intense training – raising the risk of an increase in the size of the right ventricle and right atrium (the upper chamber).
The good news? Most of these changes are temporary. “These changes can be reversible,” Dr. Friedman reassures. “We see them in people who’ve run hundreds and maybe even thousands of marathons over time, and they are different than those who may just be running once a year or once every couple of years.”
The Importance of Training and Conditioning
According to Dr. Friedman, one of the most important aspects of running a marathon is the preparation. While the heart is resilient, it is still a muscle. And just like any other muscle in the body, it needs to be trained for the task at hand. He emphasizes that “it’s really important to train and condition that muscle, like any other muscle in the body, for what it’s about to face.”
Training allows the heart to adapt to the increased demands of long-distance running. When runners train properly, their hearts become more efficient at pumping blood, and they build up the necessary endurance to handle prolonged physical exertion. “As you train more and do it smartly, and spend years and years doing this, your risk goes down during the event,” Dr. Friedman explains.
Though the risk is relatively low, Dr. Friedman acknowledges that there is always a chance of heart issues during any physically demanding event. “There is a risk of actually having a heart attack during the event of exercise,” he notes. However, it’s important to remember that this is a risk not just for marathoners but for anyone engaging in strenuous activity, especially if they are untrained or have pre-existing conditions.
For those who train well and understand their bodies, this risk is significantly reduced. “The more you do it, the better prepared you are, the less that risk is,” he says. For seasoned athletes, running a marathon is a well-prepared event, and their chances of a serious heart-related incident during the race are low.
Post-Marathon Heart Health
After crossing the finish line, most runners will feel the physical toll of their efforts, but for the majority, the heart should not present any immediate concerns. “For most people, they’re not going to notice any difference,” Dr. Friedman affirms. “Honestly, if anything, they may have lower blood pressure than normal. That’s because blood vessels would dilate out to help get rid of all the waste products that built up.”
That said, recovery is still a crucial phase of the marathon process. Immediately after the race, runners may feel sore and fatigued.
While heart-related issues are rare after a marathon, some potential risks exist that are not directly related to the heart. For example, overhydration can lead to hyponatremia, where sodium levels dip dangerously low. Additionally, rhabdomyolysis—the breakdown of muscle tissue—can occur due to muscle strain and heat.
Moreover, hyperthermia, or increased body temperature, could be a concern if a runner is exposed to extreme conditions during the race. Fortunately, these issues are typically resolved after the race, but they still present a potential risk.
After completing a marathon, Dr. Friedman encourages runners to take proper care of themselves. He emphasizes: “Anybody who finishes a half or a marathon should be really proud of themselves. It’s as much a mental feat as it is a physical feat.”
Once you’ve completed the race, make sure to allow time for recovery. “Focus on mobility and stretching, and have a couple lazy days afterward and rest,” he adds.
Even after the race, maintaining an active lifestyle is important for heart health. “Don’t stop exercising—always keep exercising. It’s really good for your health,” stresses Dr. Friedman. “Regular physical activity, along with proper recovery, ensures that your heart remains strong and resilient long after the marathon is over.”
Baptist Health is the official medical provider for the Life Time Miami Marathon & Half. The medical director for the event is Thomas San Giovanni, M.D., orthopedic surgeon at the Baptist Health Orthopedic Care and the co-medical director is Michael Swartzon, M.D., primary care and sports medicine physician.
Do You Know Your Coronary Calcium Score? As part of Heart Month this February, many Baptist Health diagnostic imaging locations will be participating in our heart scan promotion. You may be eligible for a CT calcium scoring if you are 40-75 years old and meet certain cardiac risk factors. To learn more and request an appointment visit BaptistHealth.net/HeartScan.
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