Should Runners Constantly Drink Water during a Marathon?

In an effort to stay healthy and hydrated, long-distance runners often drink significant amounts of water before, during, and after grueling races such as marathons. However, water can sometimes be too much of a good thing. In 2002, a runner in the Boston Marathon died from hyponatremia, a condition brought on by over-hydration. Drinking too much water without replacing electrolytes such as sodium, chloride, potassium, and calcium can cause disorientation, bloating, nausea, and, if left untreated, it can be fatal. And although several exercise-associated hyponatremia fatalities have been recorded, there are no known cases of a marathon runner dying from dehydration.

Water alone is not enough:

• Long-distance, marathon, and triathlon runners are most at risk of hyponatremia, fitness experts say. Danger signs include being unable to take in more water and being unable to urinate.
• To avoid hyponatremia, experts suggest drinking sports drinks with sodium and potassium, and eating salty snack foods, such as pretzels or chips.
• If you consume too much water and not enough electrolytes, your body can’t use the water you're giving it, explains fitness expert Karen Ghiron, adding, “You're virtually drowning your body.”