Bumper plates vs iron plates
So today at the gym a guy told me that lifting a barbell loaded with, let's say, 200kg of iron plates is actually harder than lifting a barbell loaded with 200kg of bumper plates.
I immediately thought it was bullshit, but then another guy who had overheard the conversation stepped in and confirmed what was being said. The reasoning behind this is that bumper plates are bigger, so the weight on each side of the barbell is applying a larger lever arm on the bar which will make it bend more than that same weight of iron plates. I studied a fair amount of physics and that made sense. So with bumpers, the bar will bend more easily, but why would it be easier to lift a bar that bends more ?. For the deadlift, I think that the bar will have bended a fair amount before it leaves the floor, so one might actually start the pull from a more mechanically advantageous position. For the other lifts, I can't think of a single reason why it would be easier to lift a bar that is bending than a bar that is straight.