In the 15 years since she became the American women's National Team Coordinator, Martha Karolyi has overseen the construction of a gymnastics dynasty. Since 2001, the U.S. women have won 87 World and Olympic medals, nearly double the number of anyone else. But for Karolyi, who helped coach Nadia Comaneci to greatness in 1976, the quest for improvement -- the idea that one can always be a little better, a little stronger -- never ends.