SACH-SAWCH

This we know, walk too slow and we need more vertical support as we are not flying anymore. Side sway increases with going slow in order to get center of mass more 'supported' on the stance side rather than shoot forward between the average of the two sides as inertia allows.

As kinetic energy is put into the swinging leg to then draw that energy back from it, a prosthetic leg made too light becomes a NERF leg. A prosthesis too light to cooperate in a chain of energy transfers? A prosthesis needs to swing with inertial normality and be tuned as a metronome when in stance to match the opposite intact stance or swinging leg. Absent that, the intact side will instead mimic the abnormal for cyclic symmetry which allows energy passing. Lots of volunteers helped us to see that. Where weight is distributed in the prosthetic matters as that sets the natural speed of the metronome and pendulums.