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Despite being the first leg and covering the shortest distance in any triathlon, swimming has proved to be the most deadly. Minneapolis Heart Institute cardiologist Kevin Harris last year published a study in JAMA: The Journal of American Medical Association analyzing the results of 2,971 USA Triathlon-sanctioned events held between January 2006 and September 2008, during which 14 participants died—13 of them while swimming and one while biking. […]
Nearly all of the deaths you studied occurred during the swimming events. Did this surprise you, given that swimming is the first leg of the triathlon and, presumably, the athletes are not suffering from the heat or from exhaustion at this point in the competition?
Yes, exactly. We were first surprised by this but I note this trend continues beyond the end of our study (also in several non-sanctioned races we did not formally look at). While at first I was surprised, it does make sense for a number of reasons: first, the adrenaline surge and pure number of athletes entering the water at the same time; second the fact that I suspect many athletes come from a background in running or other sports and may be less adept at swimming; third, swimming in a triathlon is totally different sport than doing some laps in the pool due to variability of extremes of waves [as well as] people swimming around you and on top of you; fourth, the inability to rest properly if needed (or call for help) as you could do in the marathon and bike [segments]; and, fifth, the difficulties in being noticed if the swimmer is in trouble due to the number of athletes in a body of water, which is not transparent. I think these are some of the factors that are related.