Mega Man’s arms are part energy weapon, so the gigantic forearms makes sense. But I got to thinking, why would Popeye have oversized forearms? So I grabbed a jar of salsa and squeezed (sorry, I didn’t have a can of spinach) and the muscle that was working the most was my forearm. In the cartoon, Popeye is known to be able to squeeze the spinach out of a can without opening if first. Even more impressive is that he can launch it out of the can at great speed and distance. So Popeye has huge forearms from squeezing cans of spinach.
Have I thought this through too much? I’m squeezing salsa jars, so maybe.