It used to be standard advice that marathon runners should drink as much as and as often as they could. Experts said “if you wait until you’re thirsty, it is too late. You are already dehydrated.”
But then you started hearing stories about people who drank too much and actually died from hyponatremia (EAH) or water intoxication. Heartbreaking stories like this one from the Boston Marathon or this one from the most recent London Marathon seemed to crop up more frequently.
A couple of years ago the New York Times wrote a summary “scare” story about how water was killing athletes. They based their exaggerated conclusions on the results of a study published in the New England Journal of Medicine. But despite their exaggerations, the study did show that hyponatremia is a real concern for runners, jogglers and endurance athletes.
Now, a group of experts has issued a number of papers and recommendations about how much water runners should drink.
Drinking and running
According to the group’s spokesman Joseph Verbalis, the idea of continually drinking water has been erroneously promoted in our society. The advice to drink 8 ounces of water 8 times a day is much more than any normal person would need.
He also says that the notion that waiting until you are thirsty to drink means you’re already dehydrated. His group says that “thirst is a good indicator of your body’s need for fluids, and that there is a window of time over which you can rehydrate safely.” He adds that people should use their thirst meter or the sweat test to determine whether they need more water or not.
To be healthy and avoid dehydration you need to have less than 4-6% loss of body water. Since you get thirsty after only losing 1-2% this should be a good indicator of when you should drink.
Advice for marathon jugglers
While you should be aware of EAH, remember that it is still much less common than dehydration. When doing a long run or racing a marathon let thirst be your guide. If you are thirsty, drink. If you aren’t, don’t.