Too much water can hurt athletes

Runners, hikers, bikers, even soldiers on long maneuvers should think twice before reaching for that water bottle. A study confirms that drinking too much can be dangerous, even deadly, for endurance athletes.

Researchers who studied 488 runners in the 2002 Boston Marathon found that 62, or more than one in eight, had a serious fluid and salt imbalance from drinking too much water or sports drinks. Three of them had extreme imbalances.

One 28-year-old woman died after the race from the condition, called hyponatremia, in which the excess water dilutes the salt level in the body too much.

“More is definitely not better when it comes to fluids, but it’s a hard message to get across,” said Leslie Bonci, director of sports nutrition at Pittsburgh Medical Center.

Endurance athletes have long been warned about getting dehydrated, and many tend to drink more on race day than they do during training.

Researchers found hyponatremia was most serious in runners who gained substantial weight – 4 1/2 to 11 pounds – from drinking lots of water along the route. Extremely thin runners also were at high risk. Runners who drank sports drinks, which contain little salt, were not less likely to develop hyponatremia.

Bonci and Almond said a good way to prevent problems is for athletes to weigh themselves before and after training sessions. If they gain significant weight, they should cut back on water intake until they find the right balance – long before race day.

The goal is simply to replace water lost to sweating.

Hyponatremia can begin with confusion and lethargy and progress rapidly to twitching, seizures, stupor, coma and death.