I am trying to figure this one out...
First, let's put a name to the "new phenomenon" - internal strength, correct? Fear of a name only increases fear of the thing itself, right? (sorry, a little Harry Potter humor there).
Second, the OP is using "feeling" as a emotional term, not a sense - so we are not talking about something you can "feel" using the sense of touch, correct? We are not talking about the instructional request to "feel" something because it is difficult to explain.
Third, we have this observation that a component of aikido has to be physically felt (touch sensory) in order for the body to process and internalize refined aiki.
Finally, we have a claim from the OP that the observation that "feeling" (sensory?) aiki is standard practice in his aikido. Through this statement the OP is also indirectly claiming he is applying internal strength training because the origin of the quote.
I do not know if I would describe internal strength as "new" or a "phenomenon". I believe the Japanese versions of strength training existed in early aikido and have been strained out. I know of many aikido people who are looking to re-invigorate aikido with these exercises and application. Hell, I am not even sure how much of the "internal strength" strength is Chinese compared to Japanese (as those guys teach it). I would not describe what I have felt (and classified as internal strength) as "feel" in an emotive sense - the stuff is quite tangible with a direct physical body reaction. I concede that you need to train your body to be acutely aware of your body state and subtle changes that affect your body state.
In the US, I know few aikido people who actually have strong aiki. Of those with whom I have personally worked, almost all have referred to a structural strengthening as a component of their understanding of aiki. I don't think any of them have claimed they had been doing the stuff all along. If fact, some of the people are simply saying, "I cannot explain this yet, but feel this..." I think we use the qualitative statement, "feel this" to describe a body reaction that we do not know well enough to coherently explain. It is a placeholder explanation that implies "I don't have the knowledge to concisely explain this, but I want to share this experience." Forgive my incredulity, but I think the OP has some strong claims that lack sufficient evidence to support the claim. I, for instance, have a million bucks. You don't have to believe me, but I do.
I think claim series has something to be desired; less if you read additional posts. I think we maybe need to clear up our statements, inferences and claims before continuing. Also, we need to apply the 70's kung fu master translation device to about half of these posts to translate the grand master pontifications. I echo a previous post - let's be clear and concise in our writing, or wait until we can better explain what it is we are expressing. I think this thread has some interesting posts, but some of the stuff is non-coherent.
Firstly I do not call it internal strength what I do. I call it Aikido but if you need a label then it would be spiritual perception or universal perception.
Secondly, I am using feel as a sense not an emotion.
Thirdly, body touch gives physical connection, spiritual perception (feeling) at that time should have already felt but that takes development.
I make no claim on AIKI in this thread, if I did it would not be the Aiki you refer to.
Allow me to echo something too. When I mention Aikido if you don't take it as my definition of then you are importing something which isn't there. If you think I refer to Aiki then once again the same as I do not use that term and do not use the term internal either.
I often use the term spiritual and often universal. I let 'external' Aikido be what it is and 'Internal' Aikido be what it is. Mine is neither.
The constructs put on external or 'resistive' Aikido are not the constructs of mine. The constructs put on I/S are not the constructs of mine.
If they are the only two 'types' of Aikido in your Aikido experience or what you can relate to then Mine is outside of your reasoning.
Sometimes it's the reader who has to just admit 'that's different' or even that they don't understand.
To me I say it's down to acceptance. People may read what I say, which is in plain English, and then attack it, belittle it, or even change it to something else, but in my view all this means is they can't accept it. They can't accept it means what it says.(apart from the normal different definitions we all have for things)
Those who can accept it don't have a problem with it. This doesn't mean they understand or even agree but acceptance leads to understanding and so they will, by accepting, reach an understanding. That understanding may be 'Idon't believe him' it may be 'that's interesting' it may be whatever but it will be an understanding rather than a reaction.
Acceptance is part of center and being centered. In life, in the dojo, everywhere. It's universal.