Drink to Your Health

Sure, you should drink regularly. But exactly how much water do you need? And why are some runners dying from excessive fluid consumption

by: Amby Burfoot

Your Daily Drinking Requirement

The old formula--everyone needs eight glasses of water a day--is out. It has been replaced by formulas based primarily on your gender and body weight. Here are the formulas for moderately active men and women:

Male Drinking Requirement, in fluid ounces:
Body Weight x .35

Female Drinking Requirement, in fluid ounces:
Body Weight x .31

Example: A 132-pound women needs to drink 41 ounces of water a day (132 x .31= 41). She'll get the rest of her daily water supply from food and metabolic processes. Runners need to drink extra to cover daily sweat losses.
As she passed her coach and friends at the 15-mile mark of the 2002 Boston Marathon, Cynthia Lucero smiled and waved cheerily. It was typical behavior for the petite Ecuadorian native. According to all who knew her, Lucero loved life, loved to help others, and loved running. Seven miles later, however, something went horribly wrong.

It should have been the best of times for Lucero. The previous week she had defended her doctoral dissertation to become, in effect, Dr. Cynthia Lucero. The dissertation studied the positive effect of marathon training on cancer victims and their families. A member of Team in Training herself, Lucero had run her first marathon 2 years earlier, finishing in 5:19 at the Rock 'N' Roll event in San Diego.

Now Lucero was running her first Boston Marathon. She had trained well, and eagerly anticipated the day. Things seemed to go smoothly until the 22-mile mark, where she stopped to drink a cup of fluid. Another runner remembers hearing Lucero say that she felt dizzy and disoriented.

A few steps later, Lucero staggered briefly, then fell to the pavement, unconscious. She never regained consciousness, becoming just the second runner ever to die in the Boston Marathon, and the first to die of hyponatremia, which is caused by excessive fluid consumption.

We live in a water-obsessed culture. Every soccer kid has a water bottle or two. Mothers haul around gallon jugs in their minivans. And every business exec clutches a 20-ouncer while dashing through airports with a laptop and overnighter. Why? At least in part because every fitness article in every newspaper and magazine insists that you absolutely, positively must drink eight big glasses of water a day.

But where's the proof? Amazingly, there isn't any. Even in marathons, the available evidence indicates that overhydrating is a bigger health threat than underhydrating, with Cynthia Lucero's story serving as an unfortunate exclamation point.

Yes, we runners need to drink generously. No one questions that. But we need to drink with a fuller understanding of the facts, the medical science, and the potential risks.

I've been interested in this subject since early 1968 when I was a subject in one of the first experiments on hydration and performance. First, I ran a hard 2 hours on a laboratory treadmill while chugging fluids every 10 minutes. Then exercise physiologist David Costill sat me down on a chair and attempted to thread a long plastic tube through a nostril, down my throat, and into my stomach. I gagged and protested, but Costill persisted. He said he needed to drain my stomach to see how much of the fluids had actually been absorbed into my bloodstream. "Relax your throat," he said. "Just pretend you're swallowing some spaghetti."

Two months later Costill weighed me before (138 pounds) and after (129 pounds) that April's warm Boston Marathon. I had lost an alarming 6.5 percent of my body weight. And I felt like crap. Except for the winner's laurel wreath on my head.

Last winter, I spent several months talking to experts and reading everything I could find on the subject of human hydration needs. Here's the most interesting and useful stuff that I learned.

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