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How Much Water Should A Runner Drink?

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 alreadywater joggling 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.

This Post Has 4 Comments
  1. I think that while hyponatremia is very dangerous and very real, it is also not very likely if you have a sensible diet and fueling plan. Dehydration is much more likely to be a problem than hyponatremia. If you eat as well as drink, then it is difficult to drink too much water.

  2. Im new to running, and do both road running and treadmill running at home. Im never sure how much water i should have while doing this!! This page indicates that i should drink when im thirstyt, but i always feel like i should be drinking often to replenish what i feel my body is losing.

    Any ideas on this matter?

  3. I can only report on what I do myself. I drink infrequently and usually finish a workout dehydrated. But when I’m done working out, I drink to satisfy my thirst. Then I just naturally drink more the rest of the day.

    In my view drinking when you are thirsty is the only thing that makes sense. Don’t worry about replenishing exactly what you’re losing. It’s ok to be a little dehydrated when you work out.

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