Female athlete drinking water on the beach.

Athletes: Drinking too much water can be fatal

September 5, 2014

One always hears about how important it is to drink enough water while exercising, but in rare cases people have actually died from overhydration, according to sports medicine physician James Winger, MD.

Loyola Medicine primary care doctor James Winger, MD. Overhydration by athletes is called exercise-associated hyponatremia. It occurs when athletes drink even when they are not thirsty. Drinking too much during exercise can overwhelm the body’s ability to remove water. The sodium content of blood is diluted to abnormally low levels. Cells absorb excess water, which can cause dangerous swelling in the brain.

Hyponatremia can cause muscle cramps, nausea, vomiting, seizures, unconsciousness and, in rare cases, death. And in recent years there have been more than a dozen documented and suspected deaths from hyponatremia among recreational runners and high school athletes. Dr. Winger said it’s common for coaches to encourage athletes to drink profusely before they get thirsty. But he noted that expert guidelines recommend athletes drink only when thirsty.

Dr. Winger said athletes should not drink a predetermined amount or try to get ahead of their thirst. Drinking only when thirsty can cause mild dehydration. “However, the risks associated with dehydration are small,” Dr. Winger said. “No one has died on sports fields from dehydration, and the adverse effects of mild dehydration are questionable. But athletes, on rare occasions, have died from overhydration."

Dr. Winger is co-author of a 2011 study that found that nearly half of Chicago-area recreational runners surveyed may be drinking too much fluid during races. Dr. Winger and colleagues found that, contrary to expert guidelines, 36.5 percent of runners drink according to a preset schedule or to maintain a certain body weight and 8.9 percent drink as much as possible.

“Many athletes hold unscientific views regarding the benefits of different hydration practices,” Dr. Winger and colleagues concluded. Their study was published in the British Journal of Sports Medicine.

Dr. Winger is an associate professor in the Department of Family Medicine of Loyola University Chicago Stritch School of Medicine.