Arnold Schwarzenegger has had to change his fitness regime because his "knees are shot"

Speaking to Men's Health magazine, he said: "Squatting and all those kind of like heavy leg exercises, I can't do anymore. My knees are shot. I have to protect my knees because I want to go skiing.

"I do mostly bicycling, so that's why I want to bicycle all over the world. When I travel, I get around in the bicycle.

"When I go shopping or something, I go on the bicycle, because then you can exercise in the legs and you see the town in a totally different way."

Arnie, 71, also opened up about his son Patrick's own training, and he explained he doesn't have a big influence on the way his offspring gets in shape.

He added: "My sons train themselves and sometimes they train with other trainers. I'm really proud of them.

"Patrick, he works out every day, but he doesn't want to get too big because of the acting, because he's being sought after now for romantic roles, not action roles.

"But eventually, when he gets to be like 30, 35, he will go get bigger and then do more action movies. But I love seeing them work out and being into it. It's a great feeling."

Meanwhile, the star is envious of the equipment people have access to nowadays, compared to what he had available to him when he was younger.

He said: "The machines that you have today, I wish that I could have used them in addition to what I did, because they're really amazing (what has happened with the gym equipment business).

"A guy like myself who had shoulder surgery, hip surgery, knee surgery--they can always find an exercise around the injury that I could do."