Actually, breaking your arm arm wrestling is not an uncommon injury. About 4 years ago I was arm wrestling (with another person, not a machine) and someone pushed me from behind. This caused a bad torque on my arm causing a spiral fracture. I needed surgery and many days in the hospital to recover from this. To this day I have a several screws and a metal rod in my arm. When I was in the hospital the doctors told me that actually breaking your upper arm is not an uncommon injury with arm wrestling. So I'm absolutely not surprised that this machine is causing injuries.