Gyllenhaal buffs up for 'Persia' lead

Jake Gyllenhaal has packed on five pounds of muscle for his role in Disney's action fantasy Prince Of Persia: The Sands Of Time.

The actor told Entertainment Tonight that he spent a lot of time in the gym to prepare for the film, in which he frequently appears without a shirt.

He said: "I guess I've gotten buff. There's a lot acrobatics in the movie - a lot of running up walls, and jumping on things and Parkour, so it requires muscularity, but it requires a lot of aerobic ability too."

Gyllenhall, who was cast as the lead in the movie in May, stars alongside Alfred Molina, Sir Ben Kingsley and Gemma Arterton.

He plays a prince who must prevent a villainous nobleman (Kingsley) from possessing the Sands of Time, an artifact that can reverse time and allow its possessor to rule the world.

"I over-prepared myself because I never knew how much they were going to ask me to do, so I just made sure I'd be hopefully able to do anything," he said.

Filming is currently underway for the movie, which is scheduled for release next May.