I would contend that they are regular body mechanics from my short experience.
However regular people have not figured out how to do seemingly very simple things efficiently with those mechanics.
Once I saw and felt someone move very efficiently, transferring energy from the ground through a very focused point of contact, it makes sense. Nothing unusual or irregular about it. I am sure you could explain it all with physics if you took the time.
Problem is, at least with me, is that my mind, body, reactions, and proprioceptions all get in the way of that happening. Removing those things is what I am working on now, so I can do those regular body movements.
check out these two guys for some regular body movements that I also cannot do!