I still can't figure out what it means specifically. Everything Carsten said and everything Dan hinted at suggests to me:
elbow power is just another name for the basics of internal strength.
And if true-- we still seem to have different people using the same term to mean non-related things.
On this note, I really agree. It sounds more like the use of a parking brake when doing stop-and-go up a hill in a manual transmission than a continual engine engagement. I've watched a lot of Shioda videos and I just don't see him doing that back leg thing. Hey Lee, did you get my email reply to you? Check your spam filter..
I would say it is not a basic. There are many things to learn about it but that doesn't make it a basic. The basics for me are centre, one point,Ki extension, centre line, koshi, hara and kokyu. Then comes the natural pathways of energy and thus harmonious motion. That's enough to get on with for the first ten years at least.