Runners or any long-distance athletes who drink too much water during a race could put themselves at jeopardy for developing hyponatremia, a condition marked by a loss in the body's sodium content that can result in physical symptoms such as lethargy, disorientation, seizures and even respiratory distress.
In a perspectives article in the current issue of The New England Journal of Medicine, Dr. Benjamin Levine, professor of internal medicine at UT Southwestern, said competitive runners are less likely to suffer from hyponatremia.
"Those who are running to finish the race very fast don't have time to drink a lot of water along the way," Dr. Levine said. "Those who are not running the race competitively tend to stop at every water station and take a drink. Over the course of a long race, they can dilute themselves."
In addition popular sports drinks don't always include enough sodium to offset the body's loss of the mineral during exercise. The drinks often carry more water with smaller concentrations of salts than are normally found in the human body; therefore, they do not replace salts adequately, said Dr. Levine, medical director of the Institute for Exercise and Environmental Medicine, a collaboration between UT Southwestern and Presbyterian Hospital of Dallas.
The NEJM perspectives article accompanies a study in the same journal by researchers at Children's Hospital in Boston and Harvard Medical School. The study evaluates the blood concentration of sodium in runners both before and after a long race and examines their risk factors for developing hyponatremia. It recommends individualized fluid-replacement consumption by all competing athletes.
"Researchers of the study found a surprisingly large number of runners had actuall