Maybe it would clear up some of the arguments if someone could define what Internal Power is exactly.
You get the distinct impression that it's something very esoteric, like "The Force". Then sometimes it's described as more of a physical thing, having to do with obscure muscular development. Erick's description in post #58 seems most plausible from my sophomore point of view.
"Hands on" experience with "it" is hard to come by in Central Illinois so in the meantime, how about a little intellectual reinforcement?
What is it and how does it work?
I'm going to be nice, and sum it up real quick, nice n' dirty, just the way girls at the 109 in Tokyo like it
The subject can be roughly split into two subject Ki/Kokyu or Qi/Jin, although they're intertwined
(roughly speaking) Kokyu power = Jin power (Always differentiated from overt muscular power)
This is, for lack of a better term, a "weight" path that you direct out of the ground. (Ki soceity refers to it as weight underside).
It is a skill where you can direct the weight of the lower body, through the hands (and this is oh so general, no one shoot me please), without actually committing the weight of your body.
In other words, when you use "Jin" or "Kokyu" skill on someone and push them, if they were to suddenly remove themselves, you wouldn't fall over, in fact you wouldn't move at all.
This is achieved through something called 6 directional forces, where you basically create 6 opposing tensions within the body, keeping yourself in equilibrium at all times. There's another two, for a grand total of 8, but we won't get into that.
(I'd lay good money on the fact that this is what Ueshiba meant when he referred to Ki of Heaven Ki of Earth etc)
In short this "weight" path can be "willed" by the mind (nothing freaky, the body simply reorganizes itself to create a path to a different outlet, be it the hand, shoulder, top of the head etc)
But Kokyu power can be largely affected by leg strength, hence all the emphasis on training the legs in the beginning, not to mention the middle.
Ki = Qi/Prana etc
This encompasses several different uses of the body to train the same thing.
The character for Ki/Qi originally refers to Air, or pressure.
Hence the relation to breathing.
If you do breathing in a certain way, and are taught "what" to focus on, you condition a bunch of tissue under your body, the latest theory to all of this is that its the fascia, but who really knows.
Mike S. already posted a brief descrip of basic exercises and how-to's in the Baseline skillset thread.
This nexus of tissue runs all through the body, connecting the organs as well as limbs etc, and runs thickest through the torso (hence the focus in a lot of arts on conditioning the middle).
If you condition this tissue to a substantial degree, torquing it can produce a significant amount of power which is separate from muscular power. Control over a certain part of the middle, as well as the illial psoas is critical. (Why do you think Tai Chi guys look fat
Ueshiba had a substantial middle for his size as well)
Imagine a human shaped balloon filled with air. Twist the extremities, and you'll get a torquing effect that builds up in the body. Now release it, and you get power that is generated without "winding" the muscles necessarily. (Shioda doesn't use this torquing windup, but he uses something similar, it's dead obvious in a couple of his vids, same goes to Ueshiba)
Training the tissue/Qi is achieved by stretching (think shaolin, yogic exercises), breathing (everyone's favorite past time of navel contemplation) etc. But really any exercise should be a practice of the Kokyu Skill and conditioning of the Ki.
Combine it with your ability to "will a weight path" from your legs, along with control of the "Qi" in your body, which is trained through air pressure, stretching in various poses etc, and you get a potent combination of generating power which lasts much longer than sheer muscular power.
Ok, now someone post the quick n' dirty on some wiki so no one has to go looking through posts again.
And shoot me if I missed anything, that should be information overload as it is.