Re: Internal Power/Strength (IS/IP) in relation to non-human contact
In my opinion, there are most definitely different permutations and variations of so called 'internal strength/power', with varying levels of understanding and depth (completeness) in each martial art. But there are a lot of variables.
I believe there are some baseline principles to be used universally in most good effective martial arts (which Mike Sigman has already outlined), with different variations and permutations based on that particular art's fighting strategy and applications/techniques. A style's given strategy and techniques will determinute how those universal principles are used, and taking into account variables such as - how pure/deep was that art's transmission in the first place (how much did they originally get), how well have they preserved those teachings in transmission, etc. will determine to what degree and depth their level of understanding/completeness is.
I have in no way developed any skills to speak of, but I have heard on more than one occasion, from more than one source that this type of training is specifically for effective human to human martial interaction. ie. At the higher/more complete level, the training develops an efficient and unconventional way of moving that is so different and unexpected from normal human movement/interaction that others have a very difficult time dealing with the way you move.
While the training may give you peripheral or secondary benefits in manipulating and moving inanimate objects because you learn to more efficiently carry and transfer weight, and learn to power your movements from your lower body; it is really more effective in manipulating a live person (human body). A person expects you to move and react/respond in a certain way, and when you dont, it can be very jarring and difficult to deal with, so there are ways of developing your body to manipulate it in moving in very different ways. ("kuzushi") It is also effective with a live human because a human only has two legs so there are always two weak spots in a person's structure which can be exploited after this balance taking. A dog or a bear and a lot of other animals move on four legs, so their center of gravity is different and they are naturally more stable, more efficient at moving on four legs. I think it could work on some animals and possibly even primates but you have to consider a lot of variables, like a primate has a much stronger grip than a human does, proportionally much much stronger, etc.
so to sum it up, in my lowly beginner opinion, I think this type of training is a good healthy overall system for structuring the body but is specifically designed at effectively manipulating another live human person.