Many runners are probably familiar with the advice to “stay ahead of dehydration” by drinking at designated intervals and following a hydration plan. Nervous runners can be seen gulping water in the days before big races, terrified of dehydration and subsequent “hitting of the wall.”
Recently though, another water-related worry has come into the running world in the form of exercise-associated hyponatremia. This condition occurs when blood-sodium levels become dangerously diluted due to over-consumption of water. Exercise-associated hyponatremia, sometimes known as “water-intoxication” can occur during, or up to 24 hours after exercising and may have mild or no symptoms.
If symptoms occur, they generally include headaches, confusion, or vomiting, as a result of the brain swelling. One study on exercise-induced hyponatremia found that a symptomatic form of the condition was found in one percent of endurance athletes, while the asymptomatic form may occur in up to six percent. Serious cases, when the amount of fluid taken in overwhelms the body’s ability to eliminate through sweat and urine, can be life threatening.
Researchers are encouraging athletes to drink according to their thirst and resist the urge to go overboard during endurance events. Runners should also make sure that they are replenishing their sodium levels, which become decreased during distance races.