Track and field sprint athlete Allyson Felix of the U.S. , who won an Olympic gold medal in Beijing, trains for the London 2012 Olympics in Los Angeles, California, April 10, 2012. Driven for Olympic gold, Felix began to prepare for the 2012 Olympics by adding the 400m to her signature 200m sprint. Last year she became the first woman to win U.S. national titles in the 100m, 200m, and 400m during a career (via Photo from Reuters Pictures)
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