I dont quite follow the logic in your example, unless your mobile wall of flesh is swinging a building around.
I exaggerated a bit with the "two swings" part. I meant that the barbarian that is depicted in most RPG's is very unrealistic. With that amount of muscle you would not have any endurance to last in a fight. If you increase your endurance to last in a fight, you wouldn't have that amount of muscle.
Think about the extremely strong people you know with endurance. They don't look like roid-heads, they are more like hockey players.
Of course, we are in a fantasy world, so maybe physics are different?