AceShowbiz - Jake Gyllenhaal bulked up for his role in upcoming action movie "Prince of Persia: Sands of Time" by mastering the French martial art of Parkour. The Hollywood hunk completely transformed his body to take on the role as Prince Dastan in the big screen adaptation of the popular video game, and prepared for the shoot by training with professional athletes and gymnasts.

He tells People, "(I) never did anything this intensive before (as a workout). It's a physical role. And when I commit to playing a part, it's 110 per cent. We worked really closely with David Belle, who invented Parkour."

"I worked with a lot of gymnasts. I started jumping off of a lot of things that were padded and learned the fundamental stuff, and then slowly started working on harder surfaces, really carefully. And I'd say, 'OK, I'll try it', and then I'd say, 'Oh God. Oh, please.' But then I'd get it, and we'd go a little further and a little longer and a little higher and just kept it up."

But Gyllenhaal admits his insistence on doing all of his own stunts caused a few headaches for the film's producers, recalling "It got a little bit dicey there near the end, when they saw that I liked doing things that were dangerous. I tried my hand at things that were pushing it a little bit. There was this big 35 foot jump that I did that got a little hairy."

And the "Brokeback Mountain" star has embraced his new muscular look so much, he's decided to keep up the workouts to maintain his ripped figure. He adds, "I enjoy being active as part of my daily insanity anyway, so I'll keep doing that."