NFL

Running shoes are kind of designed to pull/roll and have a bunch of different styles of soles, most of which are designed to absorb some sort of impact so they aren't supper stable. Adding 600 pounds or whatever probably flattens them out, but there are squat shoes that provide a flat/stable base with a slightly elevated heel so you're not relying on the side of your ankle to stabilize but just flat shoes are fine. The problem with running shoes is they're designed to move your feet which is the opposite of what you want in a squat.