When we talk about good ways to use the body here on AikiWeb, we often hear all kinds of different ideas. Some people (like me) say that the best ideas and examples come from modern athletics. Some people say that the human body can do things that most athletic trainers had no idea about. I would like to open up a discussion, and see if we can hash some of these things out so that we can better share our ideas about what is going on inside of the body.
Here is a diagram I made that shows a simple mechanical example of "alignment".
(Click to enlarge)
The "Unaligned support" diagram shows how downward force acts when someone is holding their arm out. Because the load (10kg weight) is at the end of the lever, the muscles located at the fulcrum (shoulder muscles) must work very hard to support the load. Next to this we see the "Aligned support" diagram, and what happens when we bring the load into "alignment" with our body. The lever arm gets shorter, thus making the muscles around the fulcrum, work much less. The Shorter we can make the lever length, the less force we will have at our fulcrum, if we make the lever length "0", then we will no longer have a fulcrum at all, this will give us perfect alignment. When this alignment is achieved the natural structure of the body bears the load, and no one particular group of muscles of over worked.
Because we have aligned the structure of our bodies with the load, we have less work to do at any one spot. This I believe is the basic idea of "ground path". However there is a price for this. We cannot align our bodies in every direction at once. We have to configure our bodies in the direction of the force, and line that up with the ground in order to do this. Because it requires special alignment between the load and the ground, we will naturally not have this alignment in all directions at once.
This is a simple idea of how alignment works. I know that in the "IP/IS/IT" community there are other ideas about how to solve this problem. One of the ideas is, I believe, is based on "pressure". I would like to talk about these ideas, and create different models to show how the ideas work.