After the film "300" hit the screen in 2006, Google trends showed a threefold increase in searches for "six-pack abs." And every magazine with the word "muscle" in its title shared a version of a "Secrets of the '300'" workout.

But there are no secrets to seeing your abs. Methods vary, but they sum up as: Train hard. Eat fewer calories than you burn. The end.

The sequel, "300: Rise of an Empire," is now in theaters, and the actors recently gathered at a Century City hotel to talk about their physical transformation from ordinary humans to chiseled glory.

Considering the effect the rippling midsections of "300" had on popular culture, it might be surprising to learn that aesthetics took a distant second to developing the actors' physical performance. Mark Twight, the trainer for the movie and owner of Gym Jones in Salt Lake City, said, "Appearance is the consequence of fitness. We very rarely work from anything but a performance-based perspective."

And the actors echoed that. The roles are physically demanding, and that's what they were trained for. The physiques would come as a result of developing the strength, stamina and skill for mock battle.

But still: those abs.

"With '300.' I said everyone needs to be buff," screenwriter and producer Zack Snyder said. "When you look at the drawings from the graphic novel, that's what they look like."

"It's very hard," said Eva Green, who plays the female lead Artemisia. "It's scary at the beginning to do all the squats and lunges, and it's painful, but then it helps you for the fights."

She learned to move quickly and smoothly and to get "into lower fighting stances, because it looks cool."

Green learned to run, and to cleave heads while doing so. Unlike the first film, "Rise of an Empire" has two lethally efficient female leads.

The other is Lena Heady, who reprises her role as Gorgo the Spartan queen.

"I'm a masochist," she said. "I love Mark. I would say, 'I can't,' and he proves that you can. He designs the program in such a way that you can do it, and afterward you say, 'Wow, I did 900 of those, and I feel great!' "

And Twight pushed Heady to the wall. "The harder the workout, the better she liked it," he said. "I kept dialing up the intensity. She loved punching and kicking and wrecking stuff. She was always willing to get down and dirty and work hard in the gym."

That may be because Heady was waiting for her turn to kick some butt. "In the first movie I didn't get to do what the boys did, and I was envious of that," she said. "I love physical work. I respond to it."

That doesn't mean it wasn't challenging.

"If you're not getting hammered, you're not working hard enough," said Callan Mulvey, who plays Greek soldier Scyllias.

Mulvey, who nearly lost a leg in a 2003 car crash, emphasized that the training was designed to keep the film's cast from harm. "They were so safe, and we warmed up so thoroughly. I never had to worry about any injuries."

Twight also pushed the cast with resistance training.

"It was barbell squats and box jumps and kettle bells and pull-ups and push-ups — and you have 25 minutes to complete it all," Mulvey said. "I did it in 22 minutes, and I was stoked!"

Rodrigo Santoro is reprising his role as Xerxes and looks leaner than in the first movie. "Mark has the ability to make the training incredibly hard but fun at the same time. It's a total combination of suffering that needs to be endured," Santoro said.