Hitting with the heels by going back up, and all this by immobilizing the opponent by a hit to the vital point of the foot the Eiyo. Not only does the human body have little resistance to attacks coming from the bottom but on top of that, the attack came from the legs, which possess three times the strength of the arms. Regardless of strength no regular human could take that. The jirai-satsu’s goal isn’t to fracture the jaw. It’s a technique that’s used to provide shock to the neck and the brain. The brain first tips towards the front. Then it’s the cervical veins that get jolted. No external injury, just a temporary sensation of confusion then the pain disappears. The victim usually doesn’t notice the effect.