Then, a couple of days ago I found this YoutTube of Okamoto's (Roppokai). It is in Japanese, and I do not speak Japanese, but the commentator appears to be stating the exact physical principles my example of "the hammer" was referring to at 4:20. The hammer strikes when you sequencially relax your muscle, have correct posture, and uke (or a nail or a large rock) is positioned well.
Without getting into the technical argument, the video is not by the Roppokai. Takaoka Hideo is a martial arts researcher who has published a lot of books in Japan on these kind of subjects. I've read one of them, and wasn't that impressed, although it was
fully buzzword compliant.