(AP Photo/Ashley Landis, File)

United States sprinter Sha’Carri Richardson is questioning Olympic and anti-doping officials on whether there is a double standard following Russian figure skater Kamila Valieva’s return to competition Tuesday. Valieva tested positive for a banned substance last week.

Richardson was barred from competing in the Tokyo Olympics this past summer after testing positive for THC, the intoxicant in marijuana. Conversely, Valieva was reinstated Monday despite testing positive for trimetazidine, a banned heart medication that is also known to affect endurance and blood flow.