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Every spring, runners emerge from hibernation to run races, and local media are there to cover the throngs of athletes crossing finish lines. Inevitably, there are headlines documenting runners who don’t make it to the end—and who face the most feared outcome: a cardiac event during the race.
Even if you’ve never witnessed it, it’s a familiar image, ingrained in the minds of many—a collapsed runner near the finish line receiving CPR. And though research has shown that, without question, being active decreases both disease-related morbidity and all-cause mortality compared to those leading a more sedentary lifestyle, these heart episodes can leave us with the impression that maybe, just maybe, running is more of a danger than we might like to admit.
A recent study in the Journal of the American Medical Association helps to shed some light on this question. Specifically asking whether the incidence of cardiac arrests at races is rising, who is experiencing these events, and what the outcomes are from those events.
More Cardiac Events, Same Rate of Occurrence
The authors from Emory and Georgia State University used a robust data set that has been maintained for more than 20 years to compile cardiac events at major running races across the United States. The Race Associated Cardiac Event Registry (RACER) data set showed that since 2010, there have been 29.3 million finishers of half marathons and marathons—an almost three-fold increase over participation from 2000 to 2009. The researchers wanted to know if the increase in participation numbers was associated with any change in the rate of cardiac events or outcomes.
The findings of this long-term study are pretty interesting. With the dramatic increase in participation, there was also an increase in the absolute number of cardiac arrests documented on race courses. However, the risk of cardiac arrest during these races hasn’t increased. During the earlier time period, one cardiac event occurred for every 185,185 runners, while in the later time period, it was one for every 166,697 runners. In other words, the rate has stayed about the same, even with a huge increase in participation since 2010.
The defining characteristics of those who were experiencing cardiac events were unchanged from one time period to the other; namely, older men with coronary artery disease. Researchers had thought that hypertrophic cardiomyopathy, a disease that causes the heart to thicken, would have a bigger role to play in the development of cardiac events. That hypothesis was not supported in this study: only seven percent of all cardiac events were attributable to that cause.
Survivor Rates Improve
The most impressive finding in the study was the dramatic improvements in survivability seen in the RACER database. In 2000-2009, only 34 percent of victims of a cardiac arrest survived, whereas 71 percent did in the period between 2010-2023. This reflected race organizers improving emergency action plans with near-immediate deployment of automatic external defibrillators (AED) and an ever-growing uptake of CPR by the general population since early bystander CPR and shorter time to AED are the two most important predictors of survival in cardiac arrest.
The authors also pointed out how running races differ from triathlons in where and when cardiac events generally occur and why that is important in understanding how it impacts outcomes. In running events, cardiac events are seen most frequently towards the end of an event or just after the finish, when athletes increase their intensity and put themselves at the highest risk. In triathlons, athletes tend to run at a lower intensity because of accumulated fatigue, and it is therefore unusual to see cardiac events late in those events. The most common place for a cardiac event in triathlons is during the swim, when athletes are under the most stress and least likely to be identified for early CPR and AED application.
This study serves both as a comfort and a reminder to all runners. First, it’s comforting to know that cardiac events remain exceedingly rare during running races and have become increasingly survivable. But it serves as a good reminder that everyone, especially older men, should be on the lookout for signs and symptoms of occult, or silent, coronary artery disease. This includes unexpected fatigue or shortness of breath at lower-than-expected effort levels, and runners should take symptoms of chest discomfort very seriously.
