Medal quest drives Tyson Gay after serving ban

(Photo: Robert Hanashiro, USA TODAY Sports)LOS ANGELES — Tyson Gay crouches his body, knee on the ground, as he loads his feet into the blocks. He explodes forward, his black pants flapping briskly in the breeze generated by his short burst down the track. John Smith, the sprinter’s coach, says he has his snap back as he trains under the Southern California sun at UCLA just days before the U.S. Olympic trials.

At 33, Gay has maintained his form and speed after training with Smith for the last 15 months. But with hopes of going to Rio de Janeiro for one final shot at an Olympic medal, Gay faces a tougher challenge in changing how people perceive his character after a year-long suspension for…