Could Running a Marathon Hurt Your Heart?

The sudden deaths of several marathoners in recent years due to cardiac events has raised important questions about the impact of training for and running a marathon on your heart. Coupled with the well-known high rates of injuries distance runners tend to suffer, it's easy to wonder if marathon training isn't just arduous, but actually dangerous.

Adding fuel to the anti-marathon fire is a study presented at the American College of Cardiology meeting last week that evaluated the blood pressure and artery elasticity in 49 men who regularly trained to run marathons and 46 people who were not marathon runners. Researchers found that marathoners had higher blood pressure than the control group as well as increased stiffness of the large arteries, suggesting that the intensity of marathoning can potentially lead to hardening of the arteries, heart attack and even death.

Despina Kardara, a researcher from the Athens Medical School and Hippokration Hospital in Athens and lead author of the report, said in a statement, "The cardiovascular system is like a sports car engine. If you do not use it, it will decay, but if you run it too fast for too long, you might burn out."

With so much evidence seemingly mounting against marathon running, should you abandon your pursuit of running the distance?

Kerry J. Stewart, director of clinical research and exercise physiology at Johns Hopkins University School of Medicine, said that the take-home message from the study is not entirely clear. "There have been similar findings in people with weightlifting, so there is some evidence that intense exercising may lead to greater artery stiffness," Stewart said. "But it's just an indicator. What we need to understand is -- what are the morbidity and mortality rates of people who exercise? That would require long term trials that followed marathon runners."

What is crystal clear about the research on exercise is that it is beneficial to your overall health. "When you compare long term exercisers to couch potatoes, clearly the exercisers live longer and suffer fewer cardiac events," said Stewart. "Even though the intensity of exercise may cause cardiac changes, that doesn't necessarily translate into having an event. But we know that someone who doesn't exercise and has these markers [stiffness of the arteries and high blood pressure] is at an increased risk of a cardiac event."

While there have been several highly-publicized deaths of runners during marathons, it is considered rare and blamed on underlying and undetected heart conditions. Stewart doesn't believe that this study or even the unfortunate marathon deaths are enough to declare marathon running dangerous. "Studies have examined this and there is an increased risk of dying while running a marathon compared to someone sitting in a chair," he said, "but exercise still decreases your overall risk of death."

That's not to say everyone should run a marathon. "It is possible to identify people who are at risk of cardiac events," said Stewart. People who have a history of heart disease, high blood pressure, high cholesterol, elevated blood sugar, who smoke or lead a sedentary lifestyle should get medically cleared before exercising. If you are a man aged 45 or older or a woman aged 55 or older and have any of the previously mentioned risk factors, you should see a doctor before embarking on a training program.

And if you have any concerns about your heart health even if you are not in a risk category, talk to your doctor before you start training.

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