Actor Andy Serkis says his film Planet of the Apes left him in "agony".
Serkis played the chimpanzee, Caesar, in the 2011 sci-fi movie and its sequel, 2013's Dawn of the Planet of the Apes.
He says he was relieved that the ape was older in the second movie because he couldn't physically handle putting as much "extraordinary pressure" on his "shredded" knees for a second installment, reports femalefirst.co.uk.
"I was so thankful that playing Caesar this time around he was more bipedal, I'm sure that was informed by the fact that my knees are shredded.
"I think the most physically challenging role, apart from Gollum, was actually Caesar as an infant because the pressure on the knees was pretty extraordinary. Doing that hour after hour I was screaming in agony," he said.
Playing small characters like Gollum and Caesar has left him unable to move following long scenes.
"When I was training for Caesar I actually bumped into an actor friend of mine, I was jogging furiously, it was Danny Mays. He'd just landed this job in South Africa and he was about to move all this family out there.
"I bent down to talk to him at his windscreen and I was telling him to go for it. But when he drove off I was literally stuck on the pavement. I couldn't move," the actor said.