(CBS) - With heat hovering near and above the triple digit mark, doctors are reminding residents that their bodies need more than water; they need electrolytes. “Electrolytes, if they’re out of balance, will kill you. And lead to heat stroke out on the court. So keep hydrated and keep your salts up,” said Dr. Bryan Wasson of the Baylor-Irving Medical Center.

When humans sweat, we lose more than water; especially after the first hour. “You begin to decrease the amount of sodium, chloride, potassium, as well as calcium,” Wasson says. “What you’ll notice initially is cramping, you’ll then follow with fatigue, tiredness. In the initial stage of heat exhaustion, you’ll simply be unable to continue.”

But then, he says, it gets worse. “Following that, your temperature begins to rise, sweating stops, you’re going to have mental confusion and other issues that ultimately could lead to death,” he said. Woody Smith knows what Dr. Wasson is describing. The Richardson Bike Mart employee “hit the wall,” as bicyclists say, during a summer race years ago.

“You don’t realize it until once your hair starts standing up,” he said, “then it’s too late.” He urges fellow bicyclists or anyone outdoors to either rely on commercial products or make something they like at home. He and Dr. Wasson urge water for the first hour then, “We’re doing alternates: water, electrolytes; water, electroylytes. Every other break they get. You need both in this heat.”