Actor Robert Downey Jr. didn’t take the role of Iron man lightly. In fact, he decided to live up the super hero’s name, and gained 20 pounds of muscle for his role in the second installment of the hit Marvel Comics movie franchise.

The star’s trainer, Brad Bose, dishes the dirt on how he got Downey to bulk up in such a dramatic fashion:

“When we did Iron Man 1, we had five months before the shoot to get ready, so we used more traditional, heavy-weight training,” says Bose. “After [the first routine], Robert felt kind of bored with it and wanted to something a little more exciting… so we decided to do what I call a Rocky IV meets high-tech training,”

Robert Downey pushed a custom-built wheelbarrow around an obstacle course. It was modified with 600- to 700-pound weight stacks.

To say that the fitness routine was nontraditional, is an understatement.

Downey juggled Indian clubs, bowling-pin shaped wooden objects of varying sizes and weights. He also used kettle bells.

“We went out and bought truck tires, and we used sledgehammers – anywhere from, two four-pound sledgehammers in each hand, all the way up to a full 20-pound sledgehammer – and we were just beating tires with it. We used fire hoses that we filled with sand and water… and we’d drag and whip them to build the shoulder muscles and pecs back up.”

While you may not have a Hollywood star’s budget for your workouts, maybe the lesson to be learned here is that you don’t have to let yourself get bored with your fitness routine. Change it up, get outdoors and outside your comfort zone.

Iron Man 2 opens today nationwide.

(via: HealthyHollywood.com)