WHEN Tom Glavine, a star pitcher for the New York Mets, earned his milestone 300th victory on a hot and humid night last month, he had a secret weapon.

It was not illegal. It was so safe a baby could use it. In fact, many babies do.

Between innings, Mr. Glavine sipped Pedialyte, a liquid sold alongside diapers in drugstores that is meant to quickly rehydrate toddlers experiencing diarrhea. The neon-tinted fluid that comes in grape and other child-friendly flavors contains electrolytes such as sodium, potassium and glucose, which happen to be the basic ingredients in most sports drinks.

Without an iota of marketing effort from Abbott Laboratories, the maker of Pedialyte, the over-the-counter remedy with a teddy bear on its label has developed a small and devoted following among professional and amateur athletes, a trend that long-distance runners seem to have started sometime in the 1980s.

Athletes are always looking for an edge, even the macho ones who would rather be seen off the field with a Cadillac Escalade than with a teddy bear. But despite that cuddly label, Pedialyte continues to pop up in locker rooms.