The New York Times
By GINA KOLATA
Published: April 14, 2005
After years of telling athletes to drink as much liquid as possible to avoid dehydration, some doctors are now saying that drinking too much during intense exercise poses a far greater health risk.
An increasing number of athletes - marathon runners, triathletes and even hikers in the Grand Canyon - are severely diluting their blood by drinking too much water or too many sports drinks, with some falling gravely ill and even dying, the doctors say.
New research on runners in the Boston Marathon, published today in The New England Journal of Medicine, confirms the problem and shows how serious it is.
The research involved 488 runners in the 2002 marathon. The runners gave blood samples before and after the race. While most were fine, 13 percent of them - or 62 - drank so much that they had hyponatremia, or abnormally low blood sodium levels. Three had levels so low that they were in danger of dying.
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