Upper and Lower

You can read about upper and lower coordinating in tai chi.

Usually this refers to the body and the legs.

But you might also pay attention to the middle dantien coordinating with the lower dantien - the heart centre with the belly.

In my own practise with students I have found the heart centre to be the prime mover, not the lower dantien. It is more immediate and dynamic. The impulse comes from there and combines with the lower dantien accompanied by sinking and turning which in turn produces spirals. It doesn't mean to collapse the torso though. To me this actualises the imagery of the dragon body.

To move from the lower dantien alone seems to be too slow and leaves you stuck in the upper body.