Marathon
Great Britain
Age: 34
Less than 10 months after the birth of her daughter, Radcliffe dazzled New York City with a sprint finish to win the city's marathon in November, 2007, her first major race as a mother. Add that feat to the British runner's long list of victories, including a world-record marathon time in 2003, and gold medals at the Commonwealth Games and the World Championships in 2002 and 2005. In fact, in Beijing, Radcliffe will look to rectify the only blight on her record: In three Olympic Games, she's never won a medal. Radcliffe dropped out of the marathon at the 2004 Games with just a few miles to go, exhausted in the Athens heat. It looks as if capturing a medal won't be any easier this year. She's training now despite a stress fracture that's kept her from running for much of the spring. Then again, Radcliffe has already redefined her physical limits once.