ROWLETT, Texas - Terry Schuchany prefers to exercise indoors these days, especially after a frightening episode on a hot tennis court nearly killed her.
Schuchany has been a runner and in good shape all her life. She is used to working out in the heat.
So, on a sweltering August day, she prepared for tennis by drinking plenty of water before and during play.
"During the tennis lesson, I thought that I was going to pass out," Schuchany recalled. "I thought I was dehydrated."
All told, before, during and after the workout, Schuchany may have consumed a gallon of water.
"By the time I got home, terrible headache, dizziness, felt like I was going to pass out and started vomiting," she said.
She remembers asking her husband to call an ambulance, but does not remember being taken to the emergency room at Baylor Medical Center Dallas, where she was later diagnosed with hyponatremia. It's a condition that occurs from over-hydration.
"You retain the water," said Dr. Michael Emmitt, Baylor internal medicine. "And, if you've drank too much water, then it causes sodium levels to drop and all the cells in your body to swell."
Emmett said the condition can be deadly because brain cells begin to expand and press against the skull. The cells swell so much, the wrinkles in the brain essentially disappear.
"The mild condition is probably a lot more common than we think it is because it only produces a headache and maybe mild confusion," Emmitt said. "The severe condition results in you becoming really delirious, unconscious and then being brought to the hospital."
The cure is salt, in serious cases administered by IV in the hospital.
Sports drinks, which contain salt, are designed in part to avoid conditions like hyponatremia. But, experts say sports drinks don't have a bigger benefit than water, if people drink too much of the liquid.
Schuchany thought it was impossible to drink too much water when you were sweating.
"I was in ICU for three days and was unresponsive for 24 hours," she said. "It apparently was touch and go. It was definitely life and death."
Now, she makes sure she drinks enough water during exercise, but she doesn't go overboard.