Heart 411: Is Running Dangerous for Your Heart?

They wear space-age shoes and sweat-resistant, brightly colored shorts as they hit the roads at 6 a.m., fill the treadmills at health clubs, and line up with over 35,000 like-minded individuals at the start of the New York City Marathon. Runners are everywhere. We are in the middle of a running boom.

Seeking to lose weight, tone their legs, or experience “the runner’s high,” millions of Americans are in love with running. Last year alone, nearly two million people completed a marathon or half-marathon. Proving that long-distance running is possible for nearly everybody, even contestants on The Biggest Loser faced off in a marathon at the end of the last season.

Although enthusiasm abounds, some question the wisdom of running to achieve health. The critics’ focus on the risks of heart attack and sudden cardiac death associated with running. Every year, we hear at least one tragic story describing an athlete who died during or shortly after a marathon. These chilling tales raise an important question for the millions who run: is running actually dangerous for the heart?

Tragedy at a Marathon

This year, millions of Americans will line up to compete in hundreds of marathons and half-marathons across the country. Most will finish the races, a sense of supreme accomplishment helping them to forget their exhaustion and aching legs. Unfortunately, not everybody will survive to bask in the glow of high achievement.

North Carolina firefighter William Caviness was a veteran runner who often trained by running the 18 miles from his home to the firehouse. He entered the 2011 Chicago Marathon with the plan of running the race to raise money for burn victims. But the thirty-five-year old never finished the race. He suffered cardiac arrest and collapsed just 500 yards short of the finish line. Although doctors were able to get his heart started again, he died hours later at a nearby hospital. As the national media reported this tragedy, runners everywhere wondered: “Could this happen to me?”

The Risk Is Low

Spurred by stories like that of William Caviness, researchers at Harvard Medical School set out to quantify the risk of long-distance running. Focusing on athletes who completed a half-marathon or full marathon, they found that 59 of 10.9 million runners suffered cardiac arrest during or soon after the race. Overall, the risk of cardiac arrest was 1 in 100,000 for marathon runners and approximately 1 in 400,000 for half-marathon participants.

The risk was highest among male marathon runners, with 2 in every 100,000 suffering cardiac arrest; the risk in women was only about one-fifth the risk in men. Of particular concern was the finding that the risk in men has increased nearly threefold in recent years. Researchers speculated that this increased risk in men suggests that more men with dangerous cardiac profiles are taking up running for its health benefits.

What Causes Cardiac Arrest in Runners?

The Harvard researchers answered this question. While coronary heart disease (blockages in arteries of the heart that can limit blood flow and cause heart attacks) was responsible in 16% of arrests, the most common culprit was a condition called hypertrophic cardiomyopathy.

Hypertrophic cardiomyopathy is a genetic condition that affects approximately 1 in 500 people; it causes overgrowth of a portion of the heart muscle and renders people susceptible to abnormal heart rhythms, particularly during times of physical stress.

Should Runners Worry?

Overall, the benefits of regular exercise far outweigh the risks. Exercise helps with weight loss and maintenance, improves cholesterol levels, lowers blood pressure and helps with control of Type II diabetes.

But if you are an endurance runner or poised to train for a half-marathon or marathon, answer these four questions to ensure your safety.

1)     Do you have known coronary heart disease or peripheral arterial disease (blockages in arteries of the legs or neck)?

2)     Do you experience chest pain or shortness of breath with exertion (e.g., walking rapidly or climbing stairs)?

3)     Do you have two or more of these risk factors for heart disease: smoking, high blood pressure, high cholesterol, diabetes, family history of early heart disease (before age 50)?

4)     Do you have a family history of sudden cardiac death, particularly in a relative less than 50 years of age, which could be a clue that hypertrophic cardiomyopathy runs in your family?

If the answer to any of these questions is yes, see your doctor before you begin your training program. If you answer no to each of these questions, lace up your running shoes and enjoy your run!

Visit the Cleveland Clinic’s Heart 411 page to learn more tips for a healthy heart.

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