Usain Bolt has described the results of the second instalment of World Anti-Doping Agency's (WADA) report as "quite shocking" as the world of athletics remains in turmoil.
On Thursday, an independent commission set up by WADA published the second part of its report, alleging that the IAAF, athletics' governing body, must have known about the extent of doping within the sport.
Athletics was rocked last November when the first part of the commission's report made allegations of state-sponsored doping in Russia.
The All-Russia Athletic Federation was subsequently suspended by the IAAF and the commission on Thursday stated that the sport's governing body, including former president Lamine Diack, could not have failed to be aware of the doping.
And Bolt, a six-time Olympic gold medallist and the sport's premier superstar, has expressed his disappointment at the recent revelations.
"When I heard it was quite shocking for me to hear that because as far as I was concerned I think they were doing a good job to clean up the sport," the Jamaican told Reuters.
"So for me to hear something like this was quite shocking and you feel let down as an athlete to be wanting to actually help clean up the sport, and then something like this to come up about the body.
"It's kind of a let-down, so hopefully there's no such thing, but we'll see what happens."
Earlier this week, UK Athletics proposed that all world records be reset in a bid to clean up the sport's image, a suggestion Bolt does not agree with.
"As far as I'm concerned it's really pointless," said Bolt, who holds the record in the 100, 200 and 4x100m events.
"What's done is done, you have to just move forward and try to make the upcoming championships and Olympics and the next [world] records as best as we can and just look forward to the future.
"You can't worry about the past, but try to build on the future."