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.

True?
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..