Re: Kokyu explanation
Quick interjection from something I heard mentioned about how Abe Sensei teaches:
While the breath work is important, it isn't the breath itself, so much as the resulting "power".
Once you manifest it, it can be done while breathing in, breathing out, held breath etc.
I believe that's only once you manage to divorce the power generation from the actual act of breathing.
From that aspect Rupert, maybe the explanation is a little more complex than simply coordinating breath with movement? I.e. it's a training tool, not how it's actually performed.
Martial movement from a bujustu aspect, is much different when compared to the sports you mentioned, which have rythmic movement involved.
Martial movement occurs in an instant. From a practical standpoint I don't think there's time to actually coordinate the breath with the movement under duress, no matter how natural. But you can learn to automatically coordinate something else that is a result of the training w/ Kokyu. (Which like I said previously most likely can become divorced from the actual "breathing" process)