Excessive fluids may be harmful to athletes

Researchers are taking a second look at risks of drinking too much fluid during exercise.

Hyponatremia, or water intoxication, hit the spotlight after the deaths of two female runners in 2002, one who ran in the Boston Marathon. The women drank excessive fluids.

Hyponatremia happens when the body’s sodium level falls below normal. People lose salt through their sweat, and overdrinking dilutes the sodium in the bloodstream, causing the brain to swell and push against the skull. Symptoms include nausea, vomiting, weakness and, in severe cases, seizures, coma and death.

Research has shown that exercise-related hyponatremia happens only during long periods of exertion, such as in marathons or triathlons, in which athletes are more likely to drink a lot.

Experts agree hyponatremia is a serious problem, but some fear hyping the dangers will cause athletes to dehydrate themselves and lead race officials to limit water stops during long-distance competitions.

The American College of Sports Medicine acknowledges hyponatremia is a concern, but fears too much emphasis may cause athletes to ignore drinking altogether.

Its new recommendations will be to drink only when thirsty and to drink as much as you sweat. The way to know whether you drank too much is if your weight afterward is more than it was before your exercise.

Other groups such as the American Running Association recommend athletes incorporate salty foods like pretzels into their pre-race meal. The International Marathon Medical Directors’ Association urges athletes to drink no more than one cup of fluid every 20 minutes during a race.