Top Runners Test Positive For Banned SubstancesPlay
Tyson Gay, a former Olympic champion, and Asafa Powell, a world record holder in the 100 meters, confirmed on Sunday they have tested positive for banned substances.
There were also reports that Powell was among five Olympic gold medalists from Jamaica who tested positive for performance-enhancing drugs at that country's national championships last month.
These revelations cast a shadow over next month's world championships in Moscow.
- Phil Hersh, writes about sports for the Chicago Tribune. His most recent piece is "Doping issues killing track and field again." He tweets @olyphil.
This segment aired on July 15, 2013.