Drinking excessive water is not good for your health as this weakens the ability of the kidneys to excrete excess water load and sodium in the body becomes diluted. This leads to swelling in cells, which can be life-threatening. According to new guidelines from an international expert panel, you should drink only when you are thirsty in order to avoid exercise-associated hyponatremia (EAH).
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. Symptoms of mild EAH include lightheadedness, dizziness, nausea, puffiness and gaining weight during an athletic event. 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, swimming and military exercises. 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 and heatstroke are not related to dehydration,” said James Winger, sports medicine physician at Loyola University Medical Center and a member of the 17-member expert panel. “Modest to moderate levels of dehydration are tolerable and pose little risk to otherwise healthy athletes. An athlete can safely lose up to three percent of his or her body weight during a competition due to dehydration without loss of performance,” Winger said.
The guidelines say EAH can be treated by administering a concentrated saline solution that is three percent sodium – about three times higher than the concentration in normal saline solution. The guidelines were published in the Clinical Journal of Sport Medicine.