It's been a rough couple of days for the sport of track and field. A trio of track superstars has tested positive for performance-enhancing drugs. Tyson Gay, the American record holder in the 100m dash, admitted to failing a drug test, saying "I basically put my trust in someone and I was let down." He has already withdrawn from next month's World Championships in Moscow. Asafa Powell, the former 100m world record holder, and sprinter Sherone Simpson, a silver medalist in the Olympic 4x100m relay, also tested positive.