Jake Gyllenhaal wasn't allowed to get too muscular for his role in 'Prince of Persia: The Sands of Time'.

The 29-year-old actor got into incredible shape for his action-packed role as Prince Dastan in the Disney movie but producer Jerry Bruckheimer kept the bodybuilding in check.

He said: "Of course I worked out a lot! But we always had to make sure not to overdo it. Jerry kept popping into the gym to check our muscles weren't getting too big, because he didn't want us to look too massive on screen. He said, 'Always remember - no huge biceps!'

"For a whole month I did a lot of climbing and sword fighting."

Jake insists Jerry was a constant inspiration on set and has even made him consider becoming a movie producer himself.

The Hollywood heartthrob added to website Skip.at: "Seeing Jerry producing this film I just thought, 'I want to do this as well!' He knows how to make the most complicated things look easy. And I love films more than anything - so it's only logical for me to work behind the camera as well."