SEP 08, 2016 6:16 AM PDT

Study Finds Hints of What's Killing Triathletes

Triathletes are some of the fittest people on the planet. For the Summer Olympics in Rio, Gwen Jorgensen became the first American triathlete to win gold by swimming 1,500 meters, then biking for 40 kilometers, and finally running for another 10 kilometers.
But this intense level of physical exercise is not without great tragedy. Researchers have noted that triathletes have about a two to three time higher death rate than that of marathon runners. And, curiously, most of the deaths occur during the swimming portion of the race, which is typically the first of the three legs.

Athlete's heart and fluid in lungs could be behind triathletes' deaths | Image:
Investigating this link further, scientists at Duke University say that the deaths may be due to a rush of fluid to the lungs – a condition known as immersion pulmonary edema (IPE).
Between 2008 and 2015, there were 58 recorded deaths from participants of triathlons. Over 70 percent of these deaths (42) occurred during the swim, which, with crowding and other unseen factors, makes it harder to pinpoint the true cause of death.
In examining the autopsy reports available for 23 of the 42 deaths, Duke researchers noted that more triathletes had left ventricular hypertrophy (LVH), a condition where the heart is enlarged or the muscle walls thicken. This physiological change is a direct response to increased workload on the heart, which is often the case for people who have high blood pressure, or for athletes who push their body to the extreme. This is why LVH is commonly referred to as “athlete’s heart.”

“Among the autopsy reports of the deceased triathletes, we found a much higher prevalence of LVH than the healthy athletes in Dr. Douglas' study," said Richard Moon, professor at Duke University and first author of the study. "The degree of enlargement was also much greater in the triathletes who died." The Douglas study was conducted in 1997 wherein investigators also attempted to find a correlation in LVH in 225 athletes.
Where does LVH fit in with triathlete deaths? LVH is a susceptibility marker for immersion pulmonary edema – a condition where fluid fills the lungs during activities in cold water. When this happens, the patient has difficulty breathing, which, during a swimming event, can be rapidly fatal.
So far, the team is cautious to say that the heart condition LVH caused the immersion pulmonary edema, or whether immersion pulmonary edema was indeed the cause of the triathletes’ deaths. The results point to a trail of smoke, but more studies are needed before a definitive conclusion can be made. But ultimately, Moon said, "The message is that if people have untreated hypertension or they're known to have ventricular hypertrophy, they need to get evaluated and treated before they embark on this sport.”
Additional source: Duke University via Newswise
About the Author
Doctorate (PhD)
I am a human geneticist, passionate about telling stories to make science more engaging and approachable. Find more of my writing at the Hopkins BioMedical Odyssey blog and at
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