"Stand facing a wall. Reach out with both hands, palm outboard, thumb down, find the place to stand where you can touch the fingertips to the wall at the limit of extension. Stand up straight at maximum reach. Now just turn your hands palm up. Your fingertips are now 3-4 inches from the wall still fully extended -- but shorter."
I must have a different build, cause no matter how I do this, my fingers are still touching the wall. And yes, I did it fully extended. Weird huh.
If that happened -- then you let your center shift toward the wall. In other words you committed your weight to the wall, and when you altered the extension, your weight followed. if you punched in this mode kuzushi
would not be far behind.
Which suggests that you likely did not notice that your weight shifted, since the three inches is well within the normal balance "orbit" and it can shift without your head position changing. That tells me that you may be primarily relying on your vestibular and visual cues for determining your own position more than your proprioceptive sensors in the structure of the body.
We do furitama
regularly, but for a long while I had little explanation of why, exactly. After much puzzling out, however, I have concluded that it accomplishes two things. One, it attunes you to the nature of resonance in the body (yours and theirs) and two, it dials up greater sensitivity to changes in position of the structure as whole, in ways that allow you to sense changes in the opponents structure in the same way you sens them in your own (essentially, through changes in the resonance signal(which certain structural sense organs are very sensitive to, and for good reason).
This is the way I can tell a student when doing kokyu tanden ho
when exactly I have compromised him at the wrist, the elbow the shoulder, the spine, and his center before much of anything has even moved. I can feel the limit of that extension into him in exactly the same way I feel the position of extension of a backscratcher as I reach to scratch my back, and before making contact.
When I extend into him the limit of that extension is sensible to me, because something stops at the current limit of my extension, and when I perform a further slight change of the potential for rotation, in our connection, I go around that and on to the next junction inward. This is true in both tension and compression.
I like the resonance theory. Kinda ubscribes to what Systema's wave power is like.
Like the "rubber" pencil trick -- your eye senses the shifting center of rotations, in a rigid or relatively static medium. Waves only move a water particle locally, in a vertical circle. In a lever, shear is automatically created and wants to move the fulcrum perpendicularly out of the line of the lever arm (gyroscopic precession occurs for the same reason). In curling a handweight held at arms length, your muscles have to stablilize the elbow holding it upward or else the shear would force that center of rotation downward.
That's what this stuff is, forgetting about leverage entirely and just shifting the centers of rotations (and more subtly -- potential rotations or moment) around the body using shear.