Had an argument with a few guys at the gym today. I told them that loading a barbell with 100 on each side instead of 2 45s and a 10 causes more pressure on your spine. This example is in reference to someone performing a low bar squat in which the bar has contact points across the entire back. My theory is that because the mass density is bigger closer to the spine. The load distribution will be different than that of a loaded bar with lighter plates.