metal fatigue
Da achy weariness dat you feel after extended periods of "pumping iron".
Cool dude, speaking comfortingly to his gloomily-slumped weight-lifting buddy who is feeling inadequate and guilty for "running out of steam" sooner than he thought he should while working out at the gym: "Don't knock yourself around too hard, Pal --- even da great 'Ahhnold' would get metal fatigue from bench-pressing for too long at a time."