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Ready to Run a Marathon? Ensure Your Heart Is Up for the Challenge!

Written By Ami Beniaminovitz, MD

As an avid runner and a cardiologist, I try to closely follow the research on endurance running and its effects on the heart. Recent research has raised alarms about the potential for plaque buildup and scarring in the heart in some long-distance runners. Yet other studies have suggested that when marathoners get heart disease, they may be able to weather it better than non-runners.

The truth is that long-distance running is an intense experience that puts stress on multiple organs. In one study from 2012 (O’Keefe et al. 2012), MRIs were used to show the effects of marathon running on the heart. The studies showed that many long-distance runners’ right atrium and ventricle dilated immediately after a marathon and up to 24 hours later. It also included blood tests that showed an elevation in biomarkers that are indicators of heart stress and injury. The study concluded that 25 percent of runners are susceptible to this recurrent heart injury. A smaller subset, about 1 percent, could be prone to scarring. Myocardial fibrosis, or scarring of the heart, can lead to heart failure.

A  study from 2008 (Chakravarty et al. 2008) focused on runners and non-runners in their 50s. The two groups were tracked for more than two decades. At the beginning of the study, the runners ran an average of about four hours a week. After 21 years, their running time declined to an average of 76 minutes a week, but they were still seeing health benefits. Nineteen years into the study, 34 percent of non-runners had died, compared with 15 percent of runners.

A study from 2012 (Kim, Malhotra, Chiampas et al. 2012) looked at the rates of cardiac arrest during long distance races in over 10.9 million runners in the United States. The study found a very low overall risk, 0.54 per 100,000 runners, of cardiac arrest. The study noted that of the runners that had cardiac arrest, nearly all had some underlying cardiac disease, such as hypertrophic cardiomyopathy or atherosclerotic coronary disease. It was noted in the study that cardiac arrest occurs primarily among male marathon participants. 

A  study from 2020 (Bhuva A, D’Silva A, Torlasco C et al. 2020) showed that first time marathon completers, who also went 6 months of pre-marathon training, were able to reduce central blood pressure and aortic stiffness equivalent to a ~ 4-year reduction in vascular age.  The study showed that the greatest rejuvenation or reduction in vascular age was observed in older, slower individuals. 

So, what is a runner to do?

It is important not to scare people. There are more benefits to exercising regularly than there are risks. Exercise is among the best medicines we have. I do not want to discourage athletes who are inclined to do endurance sports. More is not necessarily better, but it is not necessarily harmful either.

Here’s a plan to help you participate safely.

A good idea is to check your heart before you lace up for a marathon. Although sudden cardiac death is rare during or shortly after a marathon, researchers found that most heart attacks occurred in people who had pre-existing heart disease or a congenital heart problem.

Bottom line: Before you ramp up your mileage, get clearance from your doctor.

When seeing your doctor, discuss your health, heart disease risks, and training goals. Your doctor should ask about any symptoms such as chest pain or shortness of breath, ask about a family history of heart disease, measure your blood pressure, and listen to your heart with a stethoscope. He or she can perform the tests needed to determine how to proceed in the safest way possible for you.

Stay safe when training.

Listen to your heart, and do not push through the pain. Some common red flags during exercise include chest pain, excessive shortness of breath, an unusual amount of fatigue, or difficulty completing a workout that was formerly doable. If you experience any of the symptoms, stop training and go see your doctor for a check-up before resuming your training program.