Maria Sharapova returns the ball during the semifinals of the French Open on June 5. She used platelet-rich plasma to treat a shoulder injury. Miguel Medina/AFP/Getty Images hide caption

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Ray Copeland, a football coach at Bishop McGuinness High School, puts his players through a workout in Oklahoma City in 2007. As is often the case in much of the U.S., the first day of high school football practice that year began in a heat wave. AP hide caption

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University of Louisville cheerleaders hurled into the air during the first half of the NCAA Final Four tournament college basketball semifinal game against Wichita State in April. Charlie Neibergall/AP hide caption

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