There seem to be several interpretations of the word "mochimi".
The Naha Te interpretation seems to be that tightening the antagonist muscle somehow helps to generate additional force. I'm probably mistaken about that. The Shorin Ryu people seem to call this the loose, whipping "wigglyness" (for the lack of a better word).
Whatever mochimi is, it seems to be on the opposite end of the typical "snappiness". I'm totally confused. Is there one unifying concept of mochimi in Karate?