Athletes drinking too much water during exercise can be very risky. It can cause fatal water intoxication.
Hyponatremia, also called water intoxication, is generally the result of drinking excessive amounts of plain water which causes a low concentration of sodium in the blood needed for the organ to function. There is much more fluid in the body than the kidney can excrete. Once a rare occurrence at sporting events, it is becoming more prevalent as participation increases and more novice exercisers are entering endurance events.
One recent study found that 13 percent of Boston marathon runners suffered from Exercise induced Hyponatremia (EAH), though most cases were mild. But since 1985, there have been at least eight documented fatalities from EAH related to long-distance events.
The publics impression of the amount of water that is necessary to drink for good health is not based on real factual data, said Dr. Joseph Verbalis at Georgetown University Medical Center. Many in our society have promoted the idea that you need to continually drink a large amount of fluid, such as 8 ounces of water eight times a day. But most people dont really need that much.
When the body is inundated with water, hyponatremia (abnormally low sodium) can result, and in extreme cases, the brain swells like a balloon inside the skull, producing confusion, dizziness, nausea, coma, and in extreme cases, death; a constellation of symptoms that together are known as water intoxication.