I really just see it as general conditioning right now. Some things have a pole shaking feel to me more than others. For instance, post hole diggers and from this past weekend, swinging a pick axe for hours on end. Definintely different, but similar in some ways. Other things seem to provide different conditioning. Throwing 60lb bags of top soil and gravel on my shoulders and moving them from place to place. You quickly feel how the shoulders can raise/tense to support that load and how the lower back, hips/kua, etc start to tense up and kick in when fatigue sets in. When you relax all that stuff out of the way and just let it pass through you, it's stupidly easy to do and takes very little muscle as we commonly think about it. One of the most interesting things to me was the sensation in the feet and the stability that resulted from keeping that pressure in one part of the foot vs. another. One part I felt extremely stable and connected to the ground and the other my feet felt loose, unstable and disconnected from the rest of me. That particular feeling in the feet is something that I've been thinking about a lot when I train in general, so it stood out to me.
Jason, how do you deal with the physical compaction of the spine with those drop loads on your shoulders? Or does the act of passing through to the ground, actually involves extension of body alignment such that it naturally averts the compaction the spine?