WHEN Lance Armstrong publicly confessed to using performance enhancing drugs, he was ousted and shamed.

But that is exactly what actor Ben Foster did in his preparations to play the disgraced cyclist in the upcoming film The Program.

Foster told The Guardian that he had used performance enhancing drugs while shooting the film, in order to try to “get (Armstrong) into his system.”

The 34-year-old was hesitant to divulge the type of drugs he used, however he said their affect was dramatic.

“I don’t want to talk about the names of the drugs I took,” he 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.”

Taking the same substances Armstrong admitted to abusing throughout a prolific cycling career, Foster said he nearly lost his mind while under the influence of the drugs.

“There’s a fallout,” he said.

“Doping affects your mind. It doesn’t make you feel high. There are behaviours when you’ve got those chemicals running through your body that serve you on the bike.

“I’ve only just recovered physically. I’m only now getting my levels back.

“I don’t know how to separate the chemical influence from the psychological attachment I had to the character. If it’s working, it keeps you up at night. This is losing your marbles, right? They’re definitely rolling around. They’re under the couch but they’re retrievable.”

Lance Armstrong publically confessed to using performance enhancing drugs in a 2013 interview with TV host Oprah Winfrey, after fighting doping allegations for over a decade.

In the same interview, Armstrong told of the specific “cocktail” of drugs that led him to seven Tour de France titles.

“I viewed it as very simple. You had things that were oxygen boosting drugs — for lack of a better word or way to describe it — that were incredibly beneficial for performance or endurance sports, whether it’s cycling or running or whatever. And that’s all you needed. My cocktail so to speak was only EPO, but not a lot, transfusions and testosterone. Which in a weird way I almost justified [referring to testosterone] because of my history. I thought, surely I’m running low,” Armstrong said.

Having spent the most recent period of his career living and breathing everything Lance Armstrong, Foster developed a cautious admiration for the former Nike athlete.

“He started training within a culture that was doping — you’d have to go down 18 riders to find a clean one. He survives death, the story catches fire and he recognises that,” Foster said.

“He’s a smart man. He says, ‘I can do some good with this’. He raised half a billion for cancer research. We just don’t like him because he was Jesus Christ on a bicycle. We’re mad he came back from the dead, saved the sick and then turned out to be full of s***. And we’re punishing him because he didn’t apologise in the way we’d like.”

The Program made its debut appearance at the Toronto Film festival on Sunday, and is due to be released first in the UK on October 16 this year.