Here's a video clip that Salahuddin Muhammad Sensei produced a year ago, exploring one way that aiki is used to intercept and control an opponent's body on contact, using downward compression on his spine, through to his center of mass. "Hakkei" is the direct Japanese translation of Chinese "fajin" -- the expulsion or expression of force.
https://www.youtube.com/watch?v=R-uvXO4LYvU
