The IOC banned the Russian track team but no other athletes after investigation showed the Russian government helped its athletes use banned substances.
Despite the state-sponsored doping, the IOC ruled that governing bodies for individual sports will make their own decisions on which Russians will compete in the games.
Many athletes say the IOC passed the buck, including Canadians Adam Van Koeverden and Haley Wickenheiser.
"These were unprecedented lengths to dope the great majority of a nation’s athletes, controlled by its state and political powers including at an Olympics it hosted,” tweeted Wickenheiser.
"I’m not sure if banning Russia is the right thing to do but I do know it would have made a bold statement and right now because things aren't working I think something very bold does need to happen," said Olympic medalist Mark Tewksbury.
Pressure is now on the IOC to test athletes more closely than ever.
The games begin in Rio in less than two weeks.
