EXPLAINER: The drug behind Russia's Olympic doping case

Kamila Valieva, of the Russian Olympic Committee, competes in the women's team free skate program during the figure skating competition at the 2022 Winter Olympics, Monday, Feb. 7, 2022, in Beijing. (AP Photo/Natacha Pisarenko)

FILE - In this file photo dated Thursday, Sept. 20, 2018, Russian National Anti-doping Agency RUSADA building in Moscow, Russia. The agency is trying to re-establish credibility in world sports. During ongoing fallout in the scandal of state-backed Russian doping and cover-ups, RUSADA was ruled non-compliant by WADA. (AP Photo/Alexander Zemlianichenko, FILE)

FILE - In this Feb. 18, 2014 file photo, Nadezhda Sergeeva, of Russia, prepares for the first run during the women's two-man bobsled competition at the 2014 Winter Olympics, in Krasnaya Polyana, Russia. Sergeeva tested positive for trimetazidine at the 2018 Pyeongchang Olympics. She was disqualified from the two-woman bob event and served an eight-month ban.(AP Photo/Natacha Pisarenko, File)

Kamila Valieva, 15, of the Russian Olympic Committee, reacts after the women's team free skate program during the figure skating competition at the 2022 Winter Olympics, Monday, Feb. 7, 2022, in Beijing. Valieva is at the center of the biggest doping story of the Beijing Games after the Russian newspaper RBC reported that the figure skater tested positive for a banned heart medication before the Olympics. Valieva is a “protected person” according to the World Anti-Doping Code, which includes athletes who have not yet turned 16 at the time of a doping violation. (AP Photo/Natacha Pisarenko)