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Heart Disease Health Center

Triathlons More Risky Than Marathons

Swim-Bike-Run Events Carry Twice the Risk of Sudden Death
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WebMD Health News
Reviewed by Louise Chang, MD

March 31, 2009 (Orlando) -- Ironmen, beware: Triathlons can be downright deadly.

Participants in the swim-bike-run competitions face twice the risk of sudden death as marathoners, according to the first study to look at the issue.

The most risky leg of the events is the swimming leg, says study leader Kevin Harris, MD, of the Minneapolis Heart Institute.

Overall, the rate of sudden death was 15 per million participants, the study showed. “While not a large risk, this is not an inconsequential number,” he tells WebMD.

In contrast, the risk associated with running in a marathon is eight per million, Harris says.

The findings were presented at the annual meeting of the American College of Cardiology.

Swimming Leg Most Dangerous Part of Triathlon

Triathlons have been around since the days of ancient Greece, and today their popularity is skyrocketing. Membership in USA Triathlon, the official governing body of the events in the U.S., grew from 15,000 in 1993 to more than 100,000 in 2007.

For the study, Harris and colleagues tracked 2,846 events sanctioned by USA Triathlon during the 33-month period from January 2006 to September 2008. A total of 922,810 triathletes, 60% of whom were male, joined in the races.

Overall, there were 14 deaths, 13 of which occurred during the swimming portion of the events. The other death involved a biking accident.

Those who died ranged in age from 28 to 55, and 11 were men.

Autopsy reports on six of the swimming victims showed that four had underlying heart problems. The other two victims appeared to have normal hearts and may have died from drowning or from heart rhythm problems induced by cold water, Harris says.

He says it’s unclear why the swimming leg was so dangerous, “but it could have to do with the difficulty of resting or signaling for help in the water. Rescue personnel may have trouble spotting someone in trouble in the waves of swimmers in the lakes, rivers, and oceans where these events are usually held,” Harris says.

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