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It’s a busy times for the U.S. Anti-Doping Agency this Olympic year.

The group has recently charged four sprinters with using steroids and has demanded access to grand jury testimony.

Since being created in 2000 after the Sydney Games, the agency has caught 85 athletes using a wide array of performance enhancing drugs, including hormones used to bulk up livestock and water pills for race horses.

The doping agency's current fight is over drugs that go undetected The agency is responsible for keeping Olympic athletes drug-free.