Results of blood tests of track and field athletes reveal that doping is a widespread problem in the sport, according to NPR.

The Sunday Times and the German public broadcaster ARD/WDR obtained leaked documents containing results of the blood work of 5,000 athletes. The International Association of Athletics Federations (IAAF), track and field’s world governing body, confirmed in a statement that analysis from the news organizations was based on “an IAAF database of private and confidential medical data which has been obtained without consent.”

The BBC reports one-third of medals—including 55 gold medals—from the Olympics and World Championships between 2001 and 2012 were won by athletes with suspicious test results. More than 800 of the 5,000 athletes tested had results highly suggestive of doping.

Test results for track and field stars Mo Farah and Usain Bolt were normal, the article notes.

Robin Parisotto, a scientists who reviews athletes blood tests, told The Sunday Times, “Never have I seen such an alarmingly abnormal set of blood values…So many athletes appear to have doped with impunity, and it is damning that the IAAF appears to have idly sat by and let this happen.”

In a statement, World Anti-Doping Agency (WADA) President Craig Reedie said, “These allegations require swift and close scrutiny to determine whether there have in fact been breaches under the World Anti-Doping Code and, if so, what actions are required to be taken by WADA and/or other bodies.”