@botodopo
He can't do martial arts training. The mental stuff he was still able to do even with it broken. He's doing that mind combat (I forget what it was called) that the old lady taught him. The one he got told about, then immediately did it on the first try and ticked off the dark haired girl.
@Tensei21
I don't think it uses the key center or channels. His entire body is basically a giant mass of spirit energy due to the insane medicinal pill they fed him back in the first series.