it is b.t.w.,
but,
`cause hips are are supporting the spinal cord ,
I may clear it from judo and karate "veteran" position, :
common westerners >hips problems< not seen in asians are result different sitting positions taken from the earliest age.
Sitting on your as while in kneeling position, or better - sittin` on the arse while heels are on the same level,
slightly changing hips joints formation/shape,
so
we, as the chairsitting fox, can develop problems later in the life, from too much high mavashigeri...
lack of the high quality teacher/s/, and mistakes on the way are also very common, but it`s another story.