Unless he has changed what he
Unless he has changed what he says in the last 2 years, Romanov's claim was the following:
By Falling, you allow gravity to convert your potential energy in to *forward* kinetic energy. You fall forward, thus converting gravity into forward motion. And, Romanov really does (or at least did) mean that you get this energy out of gravity for free.
Here is why it doesn't work.
Any potential energy from gravity is strictly vertical. If you hold an egg, say 1 meter above the ground, and let it fall. It drops, vertically. But, it doesn't go forward or backward.
The lean/fall in POSE is correct in that you have to lean at an angle that is matched to your speed. The faster you go, the more you have to lean forward. It is only a few degrees, even at a high speed, but even a few degrees is enough. It is correct, that the lean/fall will pull you forward. That means that you fall a bit with each step. Like the egg with each step you are falling a bit (say 2 cm). But--and this is the rub--you have to put exact the same amount of energy back in. If you don't then, with each step you are 2 cm closer to the ground.
(Note to Neil_D: when moving at a constant speed every runner, everywhere, and at all times, is centered over his or her center of gravity. When moving forward, the center of gravity moves just in front of the belly button, but the overall body MUST be in equalibrium, otherwise a wanted or unwanted acceleration is going to take place. The real POSE contribution here is getting rid of overstriding and heel striking.)
So, in reality, with each step, you push yourself back up those 2 cm, which means that you invest just as much energy as you "got for free" out of gravity. If you didn't do this, you would be on the ground very shortly. Or, another way to think about it, is you put energy into your forward movement with your legs, to keep the angle the same. In either case, you must put energy into it. Physics just doesn't allow a free lunch.
This pushing happens at the moment of your foot strike. It has nothing to do with the Pull. The Pull is a useful concept, because it teaches not to think about the foot strike, thereby letting your feet do their natural thing. But, that doesn't change the fact that the foot strike (and the consequent support mechanism of our entire body) must push us back up. Ideally, we wouldn't really fall at all, nor would we push back up. This would be eliminating all vertical movement, meaning that all of our energy is invested in going forward. No one really gets to this nirvana, but good technique gets us close.
That said: if you talk about matters of perception, the Fall might be a useful concept. It is perhaps a good way to feel the point where you are at your center of gravity (which is what I think Neil_D is saying). But, it is wrong physically. And Romanov said many times that he really believes that you are getting some "extra" energy out of gravity.
If my lay physical explanation doesn't convince you, then please talk to a real physicist, who might be better at explaning it.
Please note that I have a differentiated opinion of POSE and Romanov. I have no problem with saying he contributes good things in some places, but he is wrong on gravity. And please note that I am actually on Romanov's side here: I don't want to see him spoiling an otherwise useful technique with a theory on gravity that discredits him.
I am not going to further comment on what I called "Church of Romanov". I have already stated twice here what I think. It has been noticed by others. Let's just agree to disagree and call it a night.
Cheers
Paleo