Downey is back in the third installment of Marvel's "Iron Man."
Playing a superhero requires super conditioning. Downey's trainer for all three "Iron Man" films, Brad Bose, created an ironclad workout to keep in line with the new plot.
"It's really him doing the stunt work, so that's really kind of an important aspect," said Bose.
At Bose's Anatomi Functional Performance Center gym in Santa Monica, he used innovative equipment like the Surge 360 trainer to get results.
"The Surge has pistons on it that gives you resistance, so what happens is the harder you push against it or the faster you push, the more resistance it gives," said Bose.
It provides lean yet ripped muscles for a businessman-turned-Iron-Man look.
Then there are Beast Battle Ropes: Ropes made of rubber tubing, not heavy rope, which should be easier, but there's a catch.
"When you're pulling back on them, they're trying to pull you forward, so what's happening is that you have to really work to keep your feet on the ground," said Bose.
Bose and Downey also created a contraption to maximize bench-pressing with elastics and kettlebells.
And for fight scenes, the Bot Trainer helped out.
"This was made for professional boxers in the MMA to set up a fight scenario so that you can practice the same punches or kicks over and over again," said Bose.
Bose and Downey worked together two-hour sessions three to four days a week. They also incorporated kung-fu and functional training in the mix. Downey put on 5 pounds of lean muscle and lost 10 pounds of fat.
"Just like an athlete has to perform so it gets your body in great, great shape, but it also helps you in everyday life to perform," said Bose.