After a few years in which it seemed as if the meek would inherit the Earth -- Shia LaBeouf as an action star? really? -- the classic strongman is back in "Thor," "Captain America," "Conan the Barbarian," "Fast Five" and more.

This summer's heroes aren't the first in recent years to bulk up, but there are certainly more now than before. Click through to learn their muscle-bound secrets.

-- Patrick Kevin Day and Noelene Clark