About half of you and your clients may be drinking too much fluid during running races, say results of a recent survey by Loyola University Health System researchers, published in the June 2011 issue of the British Journal of Sports Medicine. The survey revealed the following about runners:

  • While expert guidelines recommend that runners drink only when thirsty, 36.5% of runners reported that they drink according to a preset schedule or to maintain a certain body weight.
  • Of those surveyed, 8.9% said they drink as much as possible.
  • Nearly a third of runners (29.6%) incorrectly believe they need to ingest extra salt while running.
  • More than half (57.6%) said they drink sports drinks because they provide electrolytes that prevent low blood sodium. In fact, the main cause of low sodium in runners is drinking too much water or sports drink.

“Many athletes hold unscientific views regarding the benefits of different hydration practices,” researchers concluded. Drinking too much fluid while running can cause a potentially fatal condition called exercise-associated hyponatremia. It occurs when runners drink even when they are not thirsty. Drinking too much during exercise can dilute the sodium content of blood to abnormally low levels.

Drinking only when thirsty will prevent overconsumption of fluids. “It’s the safest known way to hydrate during endurance exercise,” said Loyola sports medicine physician James Winger, MD, lead author of the study, in a press release.

Symptoms of hyponatremia can include nausea, vomiting, headache, confusion, loss of energy, muscle weakness, spasms or cramps. In extreme cases, the condition can lead to seizures, unconsciousness, coma and even death.

For a closer look at overhydration, read “Hyponatremia: The Other Side of the Hydration Story” in the September 2005 issue of IDEA Fitness Journal: www.ideafit.com/fitness-library/hyponatremia-other-side-hydration-story.