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    Frequent fluid stops entice racers to drink more than they need, expert says

    By Alan Mozes

    HealthDay Reporter

    WEDNESDAY, March 9, 2016 (HealthDay News) -- Long-distance triathletes who drink too much water during competition may end up with dangerously low blood sodium levels, new research warns.

    Researchers in Germany who tested nearly 1,100 competitors in the annual Ironman European Championships found more than 10 percent had developed this condition -- called hyponatremia.

    In its most severe form, hyponatremia can be life-threatening, experts say.

    "Hyponatremia among athletes is not a new issue," said study co-author Dr. Stefan Braunecker, of the department of anesthesiology and intensive care medicine at University Hospital of Cologne. But the 2015 death of an athlete who developed hyponatremia during an Ironman competition underscores the "still urgent importance of the topic," he added.

    The condition occurs in a "considerable percentage" of long-distance triathletes, Braunecker and his colleagues said in the March 10 issue of the New England Journal of Medicine.

    A dramatic dilution of sodium (salt) causes an athlete's internal water regulation to go out of whack. Cellular swelling ensues, often accompanied by nausea, headache, a drop in blood pressure and energy, weakness, and even seizures, according to the National Kidney Foundation.

    For this study, the authors tracked hyponatremia cases among nearly 1,100 triathletes who participated in the annual Ironman European Championships between 2005 and 2013. More than 900 were men.

    The competition includes a 2.4-mile swim, 112-mile bike ride and a 26.2-mile run.

    Racers took about 10 to 15 hours, on average, to finish, and blood samples were collected within 20 minutes of completion.

    The investigators found that 115 athletes had developed hyponatremia. Seventeen cases were deemed serious and three critical. These findings led the authors to conclude that hyponatremia is a significant and serious health concern among triathletes.

    The highest risk for hyponatremia was among female athletes and/or those who took comparatively longer to finish the competition, the research team found.

    Some marathon runners also develop hyponatremia, Braunecker said. A previous study found that 12 to 13 percent of marathon participants had the condition, the authors noted.

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