i never knew that either, i never understood til now that it got heavier as it was lifted, and now i get it, when its on ur chest the chains are still on the floor, adding no weight, but as your rep it, the chains come off the ground adding weight as you push, duh! Not sure why i never got that til now, i always thought what the fuck is the difference between that or adding more plates lol, and I'm an old head to and didn't know that shit!