Peter Attia· MD
But when you then go put the bar on their back, as soon as the bar they don't have thoracic mobility, all the things that they're lacking start to change that that dramatically from just you think it's the same exercise cuz you're going straight up and down, but it's a very different exercise because now when your hands are up and again thoracic the extension is more required. They don't have that and the whole system gets thrown out of whack.