Just in aikido alone, you have Ueshiba point blank demonstrating Funakogi Undo with Terry Dobson and talking about how you need to cultivate the body. That's only one nod to many, many Asian texts where people "in the know" gave a nod by relating the root strength of martial arts to one's internal conditioning and prowess via the idea of "cultivation" and adhering to the laws/connections between heaven and earth.
The notion that internal strength just "happens" because it's in nature is only espoused by those that don't actually have any abilities in this area. Internal power in the martial arts landscape references very specific things around manners in which the body is conditioned through physical training of the bones, connective tissues, etc. through poses, postures, gravity drills, breath drills, etc. .. different styles have (or had) different means and emphasis on aspects of this but they all related towards the same fundamental weird and different types of strength that martial arts training was supposed to confer.
Internal strength is a term I am not familiar within the renown texts and CMA I have spoke to, though I have talked about it in the context by which others have defined, and that was in error. Strength and power are not the same or interchangeable as I thought In my correction, power is he ability to do something or act in a particular way, esp. as a faculty or quality : the power of concentration. I am referring to the term of internal power within the documented definitions by texts of masters both past and present. Again the analogy of the steam of a boiling water pot moving the pot lid, and not like the strength used to lift the lid. I understand how I might be confusing and offering this delineation to avoid any confusion.
Also, my opinions and views as I stated are the result of my research and contacts in understanding in relation to CMA. My career is not in teaching CMA or Aikido. I am not a professional teacher nor do I wish to gain recognition of any sort or have an vested interest in such recognition in either CMA or Aikido. It is my hobby, it is my past time. I enjoy sharing ideas and information.
With that said, I hope that provides readers with where I am coming from and my purpose for posting as a means of sharing information I have found and understand with others.