When you lift weights your muscles break down and release proteins into your bloodstream. I've heard that if you do things like 1000 bench presses with just the bar then you can get so much muscle breakdown that the protein can actually cause liver damage. If that is true then that is something I would worry about when using this device. You are basically circumventing your body's defense mechanism to prevent that from happening. If I were a coach I'd probably have the athletes do some bloodwork to make sure this wasn't a problem, especially for college kids who are likely to be drinking and such in addition.