In recent years, at least 14 deaths of marathon runners, American football players and other athletes have been attributed to exercise-associated hyponatremia, a condition that results from drinking too much water or sports drinks.
But there’s an easy way to prevent hyponatremia: drink only when you’re thirsty. That’s according to a 17-member international expert panel in their new guidelines on preventing and treating hyponatremia, published in the Clinical Journal of Sport Medicine.
“Using the innate thirst mechanism to guide fluid consumption is a strategy that should limit drinking in excess and developing hyponatremia while providing sufficient fluid to prevent excessive dehydration.”
Exercise-associated hyponatremia (EAH) occurs when drinking too much overwhelms the ability of the kidneys to excrete the excess water load.
Sodium in the body becomes diluted which can lead to swelling in cells, which can be life-threatening.
Symptoms of severe EAH include vomiting, headache, altered mental status (confusion, agitation, delirium, etc.), seizure, and coma.
EAH has occurred during endurance competitions such as marathons, triathlons, canoe races and swimming, hiking, football and even yoga and lawn bowling, the guidelines said.
Athletes often are mistakenly advised to “push fluids” or drink more than their thirst dictates by, for example, drinking until their urine is clear or drinking to a prescribed schedule. But excessive fluid intake does not prevent fatigue, muscle cramps or heat stroke.
“Muscle cramps have nothing to do with dehydration,” said panel member, Dr. James Winger. “And you don’t get heat stroke because you’re dehydrated. You get heat stroke because you’re producing too much heat.”
Modest to moderate levels of dehydration are tolerable and pose little risk to otherwise healthy athletes. An athlete can safely lose up to 3 percent of his or her body weight during a competition due to dehydration, Dr. Winger said.
The guidelines say EAH can be treated by administering a concentrated saline solution that is 3 percent sodium – about three times higher than the concentration in normal saline solution.
The guidelines are published in an article titled “Statement of the Third International Exercise-Associated Hyponatremia Consensus Development Conference, Carlsbad, California, 2015.”