Mark Hyman

Let's take a break from counting Michael Phelps medals at the Summer Olympics, shall we? Instead, let's count teenagers.

Of the 596 athletes representing the U.S. this month in Beijing, 41 were teenagers. The youngest Americans are synchronized diving partners Haley Ishimatsu and Mary Beth Dunnichay, both 15, and swimmer Elizabeth Beisel, who turns 16 tomorrow. Five of the seven women's gymnasts are teens, as are seven members of the women's swim team, including Baltimore native Katie Hoff, who is 19. The youngest male U.S. athletes are a diver, a cyclist, a boxer, a wrestler and a canoe paddler, all 18. The youngest Olympian of all those gathered in Beijing? A 14-year-old British diver, Tom Daley.

Most of these teen phenoms started in their sports early, before they were old enough even to cross the street alone. (Nastia Liukin, the fabulous American gymnast from Parker, Texas, tells visitors to her Web site that she began her tumbling career "when I started walking!")

They quickly stood out as prodigies. (Gerek Meinhardt, an 18-year-old U.S. fencer, picked up his epee at age 9 and was competing in national tournaments a year later.) Before long, they had cast aside all other sports to become specialists.

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