Re: Using ki-skills for "aiki" in Daito-Ryu
I also have not said that fascial contraction is the only factor, just that I think it's likely a big piece of a complex system. I'll lay out the case as I see it, and everyone can be their own judge.
When we're talking about the *scientific basis* for the internal movement---at least in regard to basic, martial usage---I think it comes down to one simple question: How does one stabilize the body?
In other words, what bio-mechanic is being used to hold/move the body? We all know that force is transferred through the skeleton, but how is the skeleton held in place? It's fine to say that we "use our intent", but intent doesn't hold the bones in place. There has to be some sort of bio-mechanical process at work in the body.
I've only come across a few plausible answers (excluding the idea of mystical force):
1. "Internal" and "external" use the same biomechanics, the difference is just a matter of technique.
That is, "internal" skill is just a sophisticated use of gravity, momentum, angles of force, and timing. You can believe that if you want, but it leaves a lot of stuff unexplained. Like the pseudo-spiritual sensations experienced by internal practicioners, or why most long-term martial artists (20-30+ years) never seem to be able to match the ability of the "greats" likes Ueshiba, as well as a variety of "ki tricks" (like the jo trick).
2. Internal movement is simply an unusually efficient arrangement of normal musculature, facilitated by various mental images.
This is plausible, no doubt about it. But I have some doubts---if normal musculature is still being used, why don't we see the same amount of muscle development in top internal practitioners as we do in ring fighters, particularly in the arms?
The problem I have is that muscle is a local mover. Using normal muscle, complex movements are achieved by creating long chains of individual movements. But a chain is only as strong as it's weakest link. It's fine if internal practitioners have strong legs (as many do), but if your leg muscles are out of proportion with your arms, the arms will collapse under the strain of strong leg movement, and won't be able to transfer all the force. (Yet the top internal practitioners don't seem to have a problem with that.)
3. Internal movement depends on a hyper-development of postural muscles.
This is an explanation that's been around for a while, but has a bunch of holes. I wouldn't be surprised if internal movement exercises postural muscles, but by themselves they can't explain all the ki-related phenomenon. There's also not a strong distinction between postural and "normal" muscles, so this theory doesn't really even explain how "internal" movement is different from "external" movement.
4. Fascial Tensegrity
Lastly there's the fascial tensegrity theory that I've been talking about. The tensegrity idea explains how it might be possible to have "relaxed" or "muscle-less" strength. Also, unlike muscle which is local, the fascial system is global, which provides an easy explanation for "whole-body" movements (like how I can generate movement in my arms by activating my legs).
As you look more at it, the fascia/tensegrity theory also provides plausible explains for a lot (but not necessarily all) of the ki-related phenomenon. But for the moment that's a separate issue from explaining the stability question I posed earlier.