Q. As a middle-aged male, does marathon running transiently increase my risk for cardiac arrest?
A. Marathon running can increase your risk of cardiac arrest in the short term, but it also lowers the overall likelihood that you will experience cardiac arrest or other heart problems, according to science, statistics and sports cardiologists.
“In general, endurance exercise substantially reduces the risk that someone will develop heart disease,” says Dr. Paul D. Thompson, emeritus chief of cardiology at Hartford Hospital in Connecticut and co-author of a three-volume textbook about sports cardiology.
Exercise does not prevent heart disease altogether, though, he says, and the hearts of marathon runners, like those of sedentary people, can harbor fatty plaques that may break free and block an artery, causing cardiac arrest.
Interestingly, the risks for runners are heightened by racing. According to most estimates, about one of every 100,000 marathon runners will experience a heart attack as an adult, but the incidence almost doubles during a marathon to about one of every 57,000 participants, presumably because the excitement and stress of racing place extra strain on the heart.
Middle-aged male racers also seem to be the most vulnerable. Dr. Thompson was a co-author of a 2012 study that found that, between 2000 and 2010, 59 people racing a full- or half-marathon in the United States experienced a heart attack. Of those, 51 were middle-aged men, almost all competing in the marathon.
Another 2012 study, using survey data from marathon medical directors, concluded that the overwhelming majority of heart attacks during races involve middle-aged men, most of whom collapse in the final four miles of the course.
Still, while middle-aged male runners’ relative risk of a heart attack rises while they are completing 26.2 miles compared to when they are not, their absolute risk of cardiac arrest, even then, remains reassuringly low, Dr. Thompson says.
And over all, running lowers people’s chances of ever developing or dying from heart problems. A 2014 study published in the Journal of the American College of Cardiology found that, no matter how often or infrequently runners trained and raced, they were about 45 percent less likely than nonrunners to die from heart disease.
Obviously, however, talk to your doctor if you are concerned about your heart health, Dr. Thompson says, especially if you notice symptoms such as chest pain, shortness of breath, numbness in your left shoulder or jaw, or unusual fatigue before, during or after a run or race.
