"You're running against grown men, so you've got to do everything you can to beat them," Erriyon Knighton said. He's had a dramatic rise in track, beating a long-standing record set by Usain Bolt.
It's horrified the racing world and experts say there's no clear answer as to why this is happening, though there are some theories. Santa Anita Park has halted racing to test the track.
The International Association of Athletics Federations said that despite "good progress," Russia hasn't done enough to address a "deeply rooted culture of tolerance — or worse — for doping."
Pappas co-wrote, co-directed and stars in Tracktown, which follows a young runner trying to make it to the Olympics. Pappas will be competing for Greece at this summer's games.