Hi Mike,
The text only says,
“Strongly connecting your feet to the ground to increase your overall body flexibility and root. ” Module 1
But generally,
especially in bagua,
weight on the foot/feet of the substantial leg/legs should be evenly distributed on the entire sole of the foot
(doesn’t mean you flatten the arch–just no extra pressure on front or back or either side of the foot)
How to “sink” into the earth is a whole subject in and of itself. All 16 neigung come into play. As you encounter these elements apply them to your feet while executing the forward spinal stretch. Take your time.
When your weight shifts to the toes, make adjustments.
I’m no expert on this.
But yesterday I was practicing with a bagua master who also knew Feldenkrais and a physical therapist and they were skeptical of spinal exercises in general–especially rotating from the spinal stretch. I demo-ed the forward stretch and the rotations and their jaws dropped.
Tomorrow, I visit my chiropractor for realignment of a 20 degree spinal curvature to the left.
So I know I’m not doing this exercise perfectly.
On the other hand, my main teacher has severe sciolosis and has accomodated this and does very extreme postures with no problems.
The health and safety of the spine are paramount.