High levels of water intake may pose threat
Tim Noakes, a sports medicine expert, reconfirmed that too much water intake during exercise may have fatal consequences in The British Medical Journal. Hyponatremic encepthalopathy (hyponatremia) or "water intoxication," a swelling of the brain due blood sodium concentrations falling to an abnormally low level (a.k.a., lack of salt in the blood), is caused by excess fluid intake.
"To date at least seven fatalities and more than 250 cases of this condition have been described in the medical literature," said Noakes, of the University of South Africa, in Cape Town.
When an athlete consumes large amounts of water during an event the amount of salt available to the body tissues decreases over time to a point where the loss interferes with brain, heart and muscle function including dangerous swelling. The symptoms of hyponatremia can be confused with those of heatstroke, heat exhaustion and dehydration including throbbing headache, nausea, cramps and dizziness.
The standard treatment for dehydration--pushing fluids by mouth or intravenously--can prompt the brain or the lungs to swell, which can produce seizure, coma and death in a person who is severely hyponatremic. Instead, he would require an IV with a concentrated sodium solution, a diuretic medication to speed water loss and an anti-convulsive medication, in case of seizure.
In 2002, Cynthia Lucero of Ecuador, a Boston Marathon runner, drank large amounts of sports drink during the race, which resulted in death. Her death brought attention to the medical condition and the danger of drinking too much water while exercising.
Dr. Lewis Maharam, medical director for the NYC Marathon said, "The people who get in trouble are not the elite runners but the people out there four hours or more and stop at every water station along the route, located at every mile and drink one, two or three cups of fluid that will really have a problem."1
In a commentary in The British Medical Journal, Noakes said that people in the military, hikers and athletes, particularly women marathon runners, are most likely to develop the condition. The condition is preventable and athletes are encouraged to continue drinking to quench their thirst.
Most forms of recreational and competitive exercise would require between 14 fl oz. and 28 fl oz. of liquid per hour.2
Just be aware of how much water you drink. That was the advice from the governing body of runners, an organization called USA Track and Field. Too much water during a long event can cause a runner respiratory failure, seizures and even death. The current advice is to limit yourself to 24 ounces an hour when exercising.
Although hyponatremia usually is associated with long distance events such as running and cycling, there have been recent events that have increased the awareness of the condition.
* Nancy Gayoso, a South Florida woman, is accused of killing a child in her care. Investigators believe she gave 3-year-old Rosita Gonzalez nearly three liters of water in four hours as punishment when she was baby-sitting. According to the medical examiner, the extreme amount of water led to water intoxication, which killed the girl. Gayoso faces first-degree murder charges.3
* Jennete and Richard Killpack are accused of pouring water down their four-year-old daughter's throat for misbehaving. The Killpacks are charged with child-abuse homicide and child abuse. The Springville couple have said they forced Cassandra to drink large amounts of water as psychological therapy for sneaking around and lying. Cassandra vomited, complained of a headache and then "laid down." It was determined that Cassandra died from water intoxication and brain damage. The water lowered her sodium level, which caused her brain to swell and triggered seizures, the doctor said.4
* Eleven fraternity brothers were charged in the death of 18-year-old Walter Jennings, a freshman at Plattsburgh State College in New York pledging the Psi Epsilon Chi fraternity. The fraternity forces pledges to ingest large quantities of water through a funnel. Police say he later died from brain swelling caused by water intoxication.5
4 San Diego Union Tribune
5 WRIC News.com