Erick Mead

Riddle me this. If I tie a weight on a rope and hit somebody with it -- does it have any muscle to exert effort? I can hit you with my fist the same way, driven by the motion of my center, without muscular effort for the arms. With practice you can use the arms in the same manner in less obvious but instinctively directed ways also. Funetori undo, tekubi furi and seated kokyu dosa are training in the ways in which this is done

His shoulder is not under any appreciable load, because uke's push has been dissipated into his own instability.

Look at uke's stance. He pushes the first time with his front shikaku (the direction of his push) away from O Sensie, and O Sensei plainly is entering, extending out -- projecting uke's balance perpendiculalry (juji) to the point of kuzushi where his push resolves to zero balance to push from. Clever uke realizes this stance is not working and so reverses it, leaving the open shikaku toward O Sensie, who nolonger is extending -- he now simply draws uke's balance into that shikaku toward him, instead. Obviously, it requires fine senitivitiy and instinctive adjustment to be able keep uke so precisely at the null points -- but HOW it is done is no mystery -- you can see it, and it requires no mysterious strength -- but it does require much hard training.

That is called a "moment" -- a potential rotation of the structure resisted by the physical elements of structure being torqued (or sprung, in a sense) against the ground, in this case, hence the pressure -- although the moments can also be resisted by elements of the structure straining against each other, like tensile muscles compressing bones.

In essence, what Mike is doing is resolving the imbalance of forces created by the push in his own body with resistance at the ground, (countering an in-plane moment with another in-plane moment (the path they travel to get there is not really that relevant)

Conversely, O Sensei is resolving the imbalance of forces in the jo trick within his opponent's balance structure, not wihtin his shoulder or body. He destroys his opponent's ability to make the "ground path" that Mike talks about -- and which is necessary to generate the push. But O Sensei does not do it by countering moment with in-plane moment -- like a beam shear moment resists bending moment . He does it by countering moment with an out of plane rotation, which alters the entire framework of uke's force problem -- rug-snatching, essentially.

That's becasue it actually is --there are places to act that do not require more effort than moving yourself, and radically destroy the foundation on which uke's effort is generated.