That's a fair question - and I think I'd keep it, for now within context of what Ikeda is showing and trying to get people to do? Is it the connection, joining, moveing the two-person single-unit? That's enough of a starter and if it then goes down the path of how to optimally condition the body to do that, great!
how's about using an example as a way to start the discussion?
uke stands in forward stand with fist out like so (hopefully the image shown)
nage stands in natural stand in front of uke with left palm rested against the front knuckles of the fist (i had seen Ikeda sensei did it with one finger and on the receiving end of such finger too). so, Ikeda sensei was nage. he would said three things (with accent): "connected", "unity", "change my inside". after a time, slowly, you can see uke posture shifted slowly toward his rear "third leg" (toward right rear) and lose his/her/it balance and staggered. and you will notice that Ikeda sensei body didn't move.
so, would that example be an ok starting point for the discussion?