Do you know any novice runners who are planning to take up distance running this summer? Train for an upcoming marathon? Are you thinking about it yourself?

If so, here’s a tip from USA Track & Field, the national governing body for track and field, distance running and race walking: Don’t drink the water.

Or at least, don’t drink too much water. You can wind up with a potentially dangerous case of hyponatremia—perilously low sodium levels, which in extreme cases can lead to respiratory arrest, grand mal seizure, and even death. In fact, two marathoners have died from hyponatremia—one in Boston, one in Washington—in the past year.

This warning is not intended to scare anyone away from getting some very beneficial exercise. Hyponatremia can be easily avoided. You just need to have a sensible plan for hydrating and rehydrating yourself during prolonged exercise.

UT runners weigh in

Two members of the University of Texas Health Science Center at Houston faculty, Dr. Geri L. Wood, associate professor of nursing, and Dr. Herb Fred, professor of medicine in the Department of Internal Medicine, are themselves both accomplished runners—and that’s putting it mildly—and they each have their own thoughts on proper hydration for distance running.

Wood has run “15 or 16 marathons,” usually in a little less than 3:30 (three hours, 30 minutes) which generally puts her first in her age group. (She just turned 55.) As she sees it, serious, experienced runners don’t have much trouble with hyponatremia, because you can’t run a number of marathons without becoming an expert in what your body needs, and how it works.

“Some people gear up and try to run a marathon,” she says. “And people who only run one sometimes aren’t sure how to prepare.”

One of the keys to proper hydration is knowing your own body and having enough experience behind you to know what you need.

Wood herself regularly drinks 8-10 glasses of water daily, so the day before a race she doesn’t need to consume extra fluids. Since humans, unlike camels, don’t store more fluid than we need at a given time, massive pre-race consumption doesn’t improve one’s race stamina.

In the morning before a race, she’ll drink the recommended 30 ounces of water or a diluted sports drink. Wood consumes up to 30 ounces of fluid during a race, depending on the distance she is running. Shorter races demand less hydration. During a race, Wood takes “sips of water at various points” and on hot days she “sips a little more.”

But, according to a report from USA Track and Field recently published in the New York Times, casual marathoners, who may take between 7-9 hours to complete the course, can be in danger of hyponatremia if they stop to drink water at every water stand along the way. (Most marathons provide a stand every mile or two.)

Fred has more first-hand running knowledge than almost anyone alive. He became the first distance runner in Houston in “April 1966,” and since that time has covered some 206,000 miles of running and treadmill walking, according to the log which he’s kept from the beginning.

While he doesn’t want to contribute to any unreasonable fear of water consumption or distance running, he does agree that by drinking water only, a distance runner does dilute or “lose electrolytes—sodium and potassium.” But Fred takes the position that a well-conditioned runner shouldn’t need to consume copious fluids during the course of a marathon. “I rarely took any fluids” during a marathon, "he says". But, he does allow that the 100-mile “super marathons” or ultra-marathons that he used to run were “a whole different story.”

Official guidelines

But if you are a novice runner, gearing up for a first truly long-distance run, such as a marathon or a pre-marathon training run, how can you be sure of how much liquid you need to drink? USA Track & Field urges runners to consume those 30 ounces of fluid before a race, 17-20 of those ounces taken 2-3 hours before the race, and the remaining 10-12 just before its start.

They also recommend drinking fluids (preferably containing some level of sodium) during a race. This is the tricky part. If you’re a novice, how do you know the amount of fluid you personally need to consume?

Dr. John Cianca, medical director for the HP (Hewlett-Packard) Houston Marathon, says that individuals should determine their own “sweat rate,” as it’s the liquids lost due to sweat that need to be replaced.

His test involves running for an hour—without drinking anything—under temperature conditions similar to those you’ll be racing in, and weighing yourself before and after the run. For every pound you lost in sweat, plan to drink 16 ounces of fluid, “preferably with sodium,” during every hour of your marathon run.

So, knowing how much fluid to drink is the easy part. Now all you have to do is…run... 26.2 miles…

UPDATED: 1-03-2006

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