The Incredible Hulk, the Thing, He-Man, Superman—these cartoon heroes must fulfill some kind of longing. And as yearnings go, it’s an old one: the Hebrew tradition has Samson, the Greek Heracles, the Anglo-Saxon Beowulf, the Irish Cú Chulainn. Every culture has its dreams of superhuman strength, often divine, certainly supernatural: Glooscap of the Mi’kmaq and Cabrakan of the Maya are deities capable of tearing down mountains and diverting rivers. From east to west, from Hanuman to Thor, muscle-bound strongmen swagger through mythography as gods reshaping landscapes, slaughtering enemies, and holding up the sky. Their fury is legendary: they kill lions with their bare hands, slay monsters, and accomplish impossible labors that inspire terror but also admiration.

Over the past couple of centuries interest in male muscle development and fitness has peaked during times of economic precarity and conflict.…