It was an artificial nervous system that gave the comic book version of Iron Man his powers, but for the "Iron Man" movie, it was personal trainer Brad Bose who forged actor Robert Downey Jr. into the steel titan.

"I was already training with Brad," Downey said, "and so during the whole time of waiting to see and then screen-testing for, and then getting 'Iron Man,' I've been training with Brad."

Bose, who lives in Marina del Rey, is the kind of trainer you'd imagine getting celebrities and athletes into top shape. His expertise -- 20 years in the fitness business, experience in sword work and wrestling, and a doctorate in physiology -- justifies the $175 per session he charges.

Under Bose's guidance, Downey gained more than 20 pounds of muscle in five months.

Since the actor already was an avid jogger and kung fu student, he wasn't in bad shape. The challenge here was to keep Downey from looking too much like a superhero.

"They wanted someone unique," Bose said. "His character is an alcoholic and a womanizer, and he's an arms dealer. They didn't want a six-pack or bulging muscles, but they wanted to see that he had the power to forge iron."

Bose's new gym, Anatomi, sits in the industrial section of Santa Monica. It's a low-key building with dingy brick walls, but inside is an astonishing collection of state-of-the-art exercise equipment. There's no sign of basic elliptical trainers and chest press machines here.

Iron Man has his techy weapon-wielding suit; Bose has his collection of imported gadgetry, nothing you're likely to see at even the most high-end fitness clubs.

One of the prime machines Downey used was the Jacob's Ladder. Bose calls it a "glamorized," high-cardio revolving ladder. Think of it as a step up from revolving stairs.

Then there is the Pineapple, one of the strangest pieces of equipment at Anatomi. It looks more like a scruffy coffee table than a fitness machine. But stand on it, push a button and this contraption jiggles like it's having a seizure, forcing the leg muscles into use to maintain balance.

Some days, Downey would drag himself out of bed before the first blink of sunlight to work out, Bose said. Other times, he would come in to train after 14 hours of shooting, bruised and battered from doing his own stunts.

"A lot of people don't realize how demanding it is," Bose said. "The training would be a challenge for anyone."