Death by Marathon

A number of people have asked my opinion regarding the risk of dying during a marathon. I consider myself qualified to comment on this—not because I am a cardiologist—but since I recently ran a marathon and felt like I was dying at about the 15th mile (and the 16th, and the 17th, and the 18th, etc.). Since this is not a posthumous blog entry you can assume that I survived all 26.2 miles and have recovered enough to write about it.

The same can’t be said of the three unfortunate individuals who made the news in Detroit this week. As many of you may know this year’s Detroit Marathon was marred by the sudden deaths of three participants—all within minutes of each other. This tragedy has people wondering about the advisability of doing something as crazy as running a marathon and speculating that long distance running may actually be harmful for you. I’d like to dispel a number of misconceptions surrounding this notion.

The sport of distance running has been around as long as humans have existed, but the popularity of running among the general population really didn’t take off until the mid-1970s. With his best-selling book, The Complete Book of Running, Jim Fixx jumpstarted the jogging revolution and inspired millions of Americans to pull on their knee-high white socks, lace up their Nike Waffle Trainers and hit the open roads. Only 7 years after the publication of his book Jim Fixx, at the age of 52, became the face of controversy when he dropped dead from a heart attack shortly after a daily jog. Couch potatoes everywhere herald this event as vindication for a sedentary lifestyle (never mind the fact that Mr. Fixx, who took up running only after the age of 35, came from a family where his father was dead from heart disease by the age of 42).

Since Jim Fixx’s demise there have been numerous high-profile deaths related to competitive running. Every couple of years a story will hit the news of a previously healthy athlete who dies suddenly during competitive exercise. As an example, just two years ago, elite runner Ryan Shay collapsed in the U.S marathon trials and died despite efforts at resuscitation (the news later came out that Mr. Shay had a history of an enlarged heart and at one point had been advised to curtail his competitive career). When you add to these stories the tragedy of the 3 runners in Detroit it starts to look like a pattern.

Or does it? Every weekend thousands of runners take to the streets for races of one length or another. While most are not marathons, the races are likely long enough to tax the stamina of the participants (incidentally, the 3 victims of the Detroit race were not actually participating in the full marathon, only the 13.1-mile half marathon). Despite these massive numbers we only rarely hear of race-related deaths. So why do we have 3 die in one race?

In an insightful article in The New Yorker magazine about 10 years ago, surgeon and author Atul Gawande took to task the many people who get worked up over “cancer clusters”—communities in which there seems to be an unusual number of cancers. Despite reports of unusually high rates of malignancy in certain areas, aggressive investigation by epidemiologists only rarely turns up anything more than what can be explained by random variation. The problem, Dr. Gawande says, is that we humans tend to see remarkable—but isolated—episodes and then extrapolate erroneous generalizations:

“Human beings evidently have a deep-seated tendency to see meaning in the ordinary variations that are bound to appear in small samples. For example, most basketball players and fans believe that players have hot and cold streaks in shooting. In a paper entitled “The Hot Hand in Basketball,” Amos Tversky and two colleagues painstakingly analyzed the shooting of individual players in more than 80 games played by the Philadelphia 76ers, the New Jersey Nets, and the New York Knicks during the 1980-81 season. It turned out that basketball players—even notorious “streak shooters”—have no more runs of hits or misses than would be expected by chance.”

Another example of this is the Florida shark attack scare of 2001—the so-called “summer of the shark.” East coast beaches went vacant because of the news reports of one shark attack after another. In the end, the rate of shark attacks was only minimally higher that year than usual and within statistically expected variation.

Rather than drawing conclusions from what happened in Detroit let’s look at hard data. A report in the Journal of the American College of Cardiology assessed the risk of death in over 200,000 marathon runners and concluded that the risk of suffering cardiac arrest during a marathon was only 0.002% (1 in 50,000). A more recent study put the risk of marathon death at 0.8 in 100,000. To put this in perspective, death from a lightning strike is just slightly more probable at 1 in 79,746.

Now compare this to healthy but sedentary individuals. The best data we have come from a 1984 publication that suggests that the risk of sudden cardiac death is two and a half times higher in sedentary individuals than those who routinely exercise.

A commentary by a physiologist in the Encyclopedia of Sports Medicine and Science puts these recent deaths in perspective:

“On the day James Fixx died, 1000 other Americans would also have died of heart attacks. Few if any would have received nationwide coverage. Yet almost all of those deaths would have occurred in persons who were sedentary, or were smokers, or who had uncontrolled high blood pressure and elevated blood cholesterol concentrations. If only those sudden deaths occurring in athletes are reported in the press, it is understandable why the public acquires a distorted impression of the relationship between exercise and heart disease.”

So, go train for a marathon, but know this: although you may feel like you’re dying, the odds are pretty good that you’ll survive. Just stay out of the lightning storms.