Summer is in full swing, which means an all-out onslaught of high-energy fantasy films.

Perhaps no film embodies summer escapism more than "Reign of Fire," a post-apocalyptic dragon-slaying tale full of explosions, muscles and courageous bravado courtesy of Matthew McConaughey and Christian Bale. Set roughly 20 years from now, "Reign of Fire" depicts a world ravaged by a centuries-old dragon and her offspring, accidentally awakened by construction in London.

For McConaughey, who earned his reputation taking on heavy-duty subject matter in 1996's "A Time to Kill" and 1997's "Amistad," making "Reign of Fire" was a chance to blow off some steam.

"It was a lot of fun," Matthew said of playing dragon-slayer Denton Van Zan. "I mean, there was no rules to it, slaying dragons in the future — go be the man of action, the badass, the get physical, run through something instead of around it, eat it instead of smell it [type of character]."

On the other hand, getting in shape to meet the physical demands of playing Van Zan wasn't all fun and games.

"I worked out on the ranch a couple of months," he said, referring to the property he owns in Texas. "[I] did a lot of running, did a lot of building, wrestled with the cows a little bit. Anything I could pick up or carry somewhere, I would do that instead of put in the back of a truck. ... Boxing, running around barefoot. And when it was 110 degrees in the sun, I started running miles and miles barefoot to get the soles of my feet toughened up."

McConaughey's co-star, who portrayed a deranged yuppie obsessed with his physique in the Bret Easton Ellis novel-turned-movie "American Psycho," had other ideas about what the role would require.

"I actually dieted," Bale said. "Because I can't imagine [my character] as being pretty [big], because I thought they are going through a food shortage, these people are probably going to be scrawny. I arrived in Ireland, though, and I saw Matthew [as] Van Zan. And I just looked at him and just went, 'Holy sh--!'

"You know a whole dynamic of this movie is the two of us clashing and us both being leaders and sort of control freaks. And I have to really look like I can be psychologically and physically a challenge to his character. And he was in such incredible shape. I kind of desperately worked out for a couple of weeks, to try and look like I could, you know, face off against him."

Audiences will be able to see Bale face off against McConaughey and a whole mess of fire-breathing dragons when "Reign of Fire" hits theaters July 12.