Rupert Atkinson wrote:
I think what you are saying is tilt the hips up (sacrum underneath), which goes against what some others have been saying. I also think that the hips should tilt up. To me, down is wrong. In this respect, many arts are the same (even though they are often not aware of it).
I think that if you're using normal strength, you have various options. If you're going to use kokyu power, though, your only real choice is to relax the lower back and allow the buttocks to drop as a result of the relaxation. Kokyu power doesn't go well through stiff joints or too-bent joints ... and a stiff lower back is a stiff joint. Deliberately tucking or holding the hips in an artificial position is not relaxation and that seems to be the main point to consider, IMO.