Hmm. Ok. I'm afraid you can count me as skeptical. I've been told "don't use strength" to move, and when things work really well they seem to have needed no effort, but humans can't move unless muscles contract. It may be a 'conditioned reflex' that we don't have to think about, it may be something that's well trained and can be done in a very "relaxed" manner, but movement can't happen without muscle contracting.
I've tried reading some of the IP info but I get confused because of my (long ago) biomechanics research background. I'm sure there's something in it, but I just don't get it.
I've also discussed with some of my sensei in the past "I'm trying not to use my strength." and have been met (by at least one shihan) with "You got it, use it, as long as your technique is good".
Discussing this sort of stuff with an Iwama-type godan today (he's teaching at a school nearby and I was doing classes on my sport - rowing) - and he said - yeah, right, what were the shihan doing when they were young - swing a sword 1000 times a day, then a jo 1000 (or 5000) times a day, and you're going to develop muscle.
Thanks for the reply Walter
One thing that interests me about IP practitioners is their attempts to put it in scientific terms, since in aikido it seems to be encoded in animism. But regardless of how it is explained, I would recommend that if you are able to find someone who can do it well, you should ask them if you can feel their arm while they lift a bokken.