Drew Barrymore Rolls with the Punches

By Andi Miller

09/16/2009 at 07:00 AM EDT

Stars usually walk away from a film with a paycheck and a some happy memories – but Drew Barrymore left her new movie, Whip It, with bruises.

Just don't expect much sympathy from fellow castmates Ellen Page, Eve, Kristen Wiig and Juliette Lewis – because they may have been the ones who meted out the punishment in this tale of tough roller-derby girls who grapple, block, and elbow each other mercilessly as they race around the track. Whip It opens Oct. 2.

To get in fighting form, the debut director (who also plays derby girl "Smashley Simpson") and her cast reported to roller-derby boot camp in Ann Arbor, Mich., where they perfected the art of the rail check and other classic derby moves.

"It got easier the more we practiced," Barrymore, 34, said at a screening Friday at the Bonaventure Skating Center in Farmington, Mich., near Detroit. But, she noted, "We got hurt all the time," and the lengthy practice sessions were "painful" and "scary ... Thank God nobody was seriously hurt, but it was rough. We wanted it to look authentic."

To that end, Barrymore even cast real-life skaters from Michigan.

And they didn't take it easy on themselves off camera, either – even after hours of rigorous skaitng on the low-budget shoot. "We didn't have trailers," she said. "We just crashed out on these old couches."

The tough-as-nails story was what attracted Barrymore to the project in the first place. Based on Derby Girl by Shauna Cross, the movie tells the true story of a Texas teen's journey through the roller-derby world. Said Barrymore: "I like movies about girls who are capable."