Is Running a Marathon Good For You?

Third in a series of posts recognizing American Heart Month

By Kousik Krishnan, MD

Over the past several years, in very high-profile, large-city marathons, there have occasionally been deaths during races. They have occurred during the Chicago Marathon, the Philadelphia Marathon and even the Olympic Marathon Trials in 2007. These reports often bring to light an unusual paradox, where seemingly very healthy individuals are dying during athletic pursuits, when these same individuals are ostensibly healthy enough to go through the rigors of training for years without any incident.

Why are these individuals dying? Are they living with an undiagnosed condition that leads to the tragic result? Shouldn’t this condition have warning signs or symptoms? Is there something unique about the actual race that triggers an event that doesn’t become evident during normal training?

In the past, I have written about screening for heart disease prior to beginning a vigorous training program. (Read more about symptoms and risk factors that should prompt physician evaluation.)

With this background, I was very interested in a recent article in the New England Journal of Medicine that analyzed the Race Associated Cardiac Arrest Event Registry (RACER). This registry collected data from the most recent decade of long-distance running races to determine the incidence, clinical profile, and outcomes of cardiac arrest in these events. The finding of this study show that the rate of cardiac arrest is actually very low (1 per 184,000 runners) and lower than cardiac arrest rates for college athletes, triathletes and previously healthy middle-aged joggers.

The cause of death was most commonly hypertrophic cardiomyopathy (abnormally thickened heart muscle) which is the same for other athletes. The rate of cardiac arrest in marathons, while low, is increasing: from 0.71 cases per 100,000 runners from 2000 to 2004, compared to 2.03 per 100,000 from 2005 to 2010. The number of deaths has increased over the years, primarily due to the rapid growth of the sport and record participation levels. The number of marathon participants has more than doubled from 2000 to 2010 while the average finish time has gone up from 4:21 to 4:40. This may represent many more casual runners who are not as well-trained as the runners in the past. Despite overall low rates of cardiac arrest, a sobering statistic is the poor outcome of runners who do suffer a cardiac arrest at these events (71 percent fatality rate) despite onsite medical staff and rapid response to a fallen runner.

My take-home messages from this study are:

  • Marathon running is still a very safe athletic pursuit
  • Prior to any training program, it is crucial that a thorough assessment of a runner is made, using the American Heart Association screening guidelines listed above.
  • Further evaluation should be taken for any signs or symptoms found on screening
  • Improvement in first responder training and more access to automatic external defibrillators are needed as well as processes being in place to rapidly transport runners to hospitals where treatment can be instituted.

As a marathon runner and cardiologist, I found this study very helpful in quantifying the risk associated with marathoning. Media attention to marathon deaths is understandably high. Every death is a tragedy, often occurring in a person in peak physical condition. However, the real risk must be based on facts and not by a disproportionate amount of media attention overestimating the real risk to a general population.

The “million dollar” question is whether I will stop running based on these results. The answer is no. However, I will continue to be vigilant about any changes in symptoms that may represent a need for further evaluation. There is an adage in the marathoning community that “training for a marathon is healthy, but running one may not be.” Hopefully this article will assuage some of those fears.

Kousik Krishnan, MD, FACC, a cardiac electrophysiologist, is director of the Arrhythmia Device Clinic and associate director of the Electrophysiology Lab at Rush University Medical Center. He is an assistant professor of medicine at Rush University.

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