It took me a long time and a lot of study to reach the point of being able to perform the no-touch knockout. I have only done it once so far.
We had a new student in our dojo. He wasn't totally new, he had studied our style of karate under a different sensei when he was in his teens, but now he was in his mid-forties and coming back to training for the first time in decades.
He started attending classes and was enthusiastic about getting back in shape and re-learning all he had once known. And indeed, some of his techniques showed that he still had retained some knowledge and ability, he just needed to get the rust knocked off and he'd be fine.
One night after class, sensei told us to pair up and do some light kumite (sparring). No gear, just a teaching/learning environment, as we often do. Many of us are adults with jobs and we can't go to work the next day all busted up, so we emphasize the 'light' in 'light kumite'.
Since our new student had not done this before, I paired up with him, explained how it worked, and we both took up fighting stances. My plan was to not attack, but merely to defend, and to allow our new student to work his techniques, helping him by showing him holes in his defense, and so on.
Instead, our new student immediately charged me full power. He came at me like a freight train, throwing kicks, punches, everything. Really badly, I might add. It looked like he was having some sort of convulsion.
I stepped off the fight line and let him sail by me.
He hit the wall of the dojo, bounced off a bookcase, turned and hit a desk, and collapsed on the mat.
The noise was such that everyone in the dojo stopped and asked what I did to the poor guy, who was now motionless on the deck.
Some thought I had thrown a spinning back kick. Some thought they saw a backfist from me. Some thought I had employed a trip or a low kick to the legs.
I never laid a hand on the new student. I got out of the way and he demolished himself. I was horrified of course; had I known he was completely out of control and could not stop himself, I would have tried to catch him before he crashed, but I didn't and he did.
No-touch knockout folks. Am I not amazing?
FYI, it has taken him several months to get healed up, but he's still working out with us. A real trooper, he just needed to step it down a notch.