Don't drink the water
Runners are learning that the old advice to guzzle while racing can be dangerous. It can even kill
Running, for many, is a religion. Its acolytes--35,000 plus of them will line up in two weeks for the Chicago Marathon--have long lived by one commandment: Thou shalt drink a whole lot of water. Physicians and race directors have urged everyone from first-time 5K racers to ultramarathoners to guzzle constantly.
Now, however, doctors are preaching a new gospel. Too much H2O during longer exercise stints can be as dangerous and deadly as Noah's flood. In August, a medical examiner's report revealed that a 28-year-old woman who collapsed and died in April's Boston Marathon had had too much water. In recent years, overdrinking has killed a runner at the Chicago Marathon and sent others to intensive care. "You need a more balanced plan than just drinking water willy-nilly," says Margaret Hsieh, an emergency-room doctor at the University of Pittsburgh Medical Center who has studied the condition behind these problems.
Cells swell. It's an ailment called hyponatremia. That means too much water and too little salt. Overdrinking while exercising for more than four hours in events like a charity AIDS ride or an Ironman triathlon can dilute sodium, or salt, in the blood. Your body needs a certain amount of sodium to help transport nutrients in and out of cells. Too little, and cells can swell dangerously and start to malfunction. Earlier this year, one study found hyponatremia in nearly 6 percent of marathon runners requiring medical treatment. As many as 29 percent of finishers at an Ironman triathlon who got the usual drinking advice had blood levels indicating hyponatremia, but in races advising lower fluid consumption only 1 percent had the condition.
This doesn't mean you should run or jog dry. How to strike a proper balance? Know how much you sweat. Weigh yourself before and after a good workout. The difference represents the fluid you've lost. Replace that amount during exercise, but don't go much beyond it. Runners at big races like the New York City Marathon are specifically warned about hyponatremia and told to drink only about 1 cup of water every 15 to 20 minutes, says Lewis Maharam, medical director for the race. They're also told to carry a salt packet and dip into it if they're sweating a lot.
Hyponatremia is not an issue for the casual jogger. But the estimated 900,000-odd people who will complete half marathons and marathons this year could, if not careful, have themselves a real drinking problem.
This story appears in the October 7, 2002 print edition of U.S. News & World Report.