The fact that the Treadwall exists means someone probably thought, “Hey, rocking climbing is hard, but what if I did it on a conveyor belt instead of a wall?” The Treadwall turns bouldering into a cardio workout that uses nearly every muscle in your body. We’re sore just watching people use the machine. But if the video makes you want to try it for yourself, your best bet is finding a climbing gym that already has one, because buying a Treadwall will set you back at least $9,000.