Too Much Water Can Kill You

Hyponatremia, or water intoxication, can be deadly for endurance athletes.

"Overdrinking dilutes the sodium in the bloodstream, causing the brain to swell and push against the skull. Symptoms of hyponatremia include nausea, vomiting, weakness and, in severe cases, seizures, coma and death."

Despite the initial objections of runners, Houston Marathon officials experienced fewer hyponatremic cases after halving the number of water stops.