Ben Foster says that he started taking performance-enhancing drugs to prepare for the role of Lance Armstrong in an upcoming movie.

Actor Ben Foster has fully committed to the role of playing former seven-time Tour de France champion Lance Armstrong in the upcoming film The Program to the point where he started taking performance enhancing drugs, he toldThe Guardian.

“I don’t want to talk about the names of the drugs I took,” Foster said. “Even discussing it feels tricky because it isn’t something I’d recommend to fellow actors. These are very serious chemicals and they affect your body in real ways. For my own investigation it was important for me privately to understand it. And they work.”

Foster, 34, is no stranger to taking his acting practices to extreme measures after eating dirt during the filming of Lone Survivor to get an idea of life on the battle front U.S. Navy Seals. In preparation for his role as Armstrong, Foster consulted with cycling experts to get his physical appearance on and off the bike to resemble Armstrong.

“It was important to get his gait, his riding style.” Foster told the Guardian. “I talked to people who had the aerodynamics of his body on a computer system so I could get the hump in the back, the heels slightly out. It’s almost a duck pedal. It’s not a delicate ride. It’s violent, which is also why he’s such an exciting rider. It’s like he wants to break the bike.”

Armstrong declined Foster’s request for a meeting, according to The Guardian.

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The Program, directed by two-time Academy Award nominee Stephen Frears, will be released in theaters on Oct. 13 and is based off The Sunday Times journalist David Walsh’s book Seven Deadly Sins. Walsh is played in the film by actor Chris O’Dowd.

“I was interested in making a crime film,” Frears toldThe Hollywood Reporter​. “In January, Armstrong did an interview with the BBC where he was much more straightforward and used the word ‘criminal’ for the first time. I think this is a modern crime story. It’s a very American tragedy.”

Watch the trailer for The Program:

- Christopher Chavez