We've all heard the stories about marathoners and soldiers who have died due to consuming too much water. Clearly, overhydration can be as dangerous to your health as underhydration.
So what does a sweaty endurance runner need to know about staying adequately hydrated without stomach sloshing? Dr. Timothy Noakes' book Waterlogged: The Serious Problem of Overhydration in Endurance Sports is an interesting yet controversial resource that addresses that question.
According to Dr. Noakes, the sports drink industry has effectively marketed a positive image (successful athletes), despite having an over-hyped product (salted sugar-water). Noakes believes the sports drink industry has brainwashed athletes to over-hydrate—and this has created life-threatening problems.
More: Hydration 101
For example, between 1983 and 1998, more than 700 cases of exercise-induced hyponatremia (overhydration that leads to low blood sodium, brain swelling, coma and even death) were documented in the Gatorade-sponsored Ironman Hawaii Triathlon. The participants had been encouraged to drink copiously.
Did that advice backfire? For the Comrades Marathon, participants were told to drink according to thirst. Race organizers placed aid stations every 5 km (3 miles), and cases of hyponatremia dropped.
The information in Waterlogged challenges the theory drink before you get thirsty.
Noakes believes elite athletes who become champions can tolerate significant sweat loss without intolerable thirst. He contends the associated weight lost via sweating enhances performance. Others question if those athletes could run better with better hydration.