The New England Journal of Medicine released a study today about hyponatremia and runners in the Boston Marathon. The study confirms much of the speculation regarding over-hydration during vigorous activity.
Here's the kicker quote from the NY Times' piece on the study:
"Everyone becomes dehydrated when they race. But I have not found one death in an athlete from dehydration in a competitive race in the whole history of running. Not one. Not even a case of illness."
LINK: New England Journal of Medicine
LINK: New York Times