@patwerthman
My understanding is that flexion is okay but extension is not. Avoid extreme twisting of the spine, forward bends and rollups often used in yoga and pilates. Margaret Martin is a well-informed guide to safe movements. I think a few years ago the National Osteoporosis Foundation published one page guides to yoga and pilates.

Here is one link to Margaret Martin's information which is far more reliable than mine.
https://melioguide.com/osteoporosis-prevention/osteoporosis-exercise-contraindications/

@patwerthman, here is why my physical therapist also told me that I should not do any running or jumping:
Lumbar Spine BMD (L1-L4): T-Score: -4.0

Since everyone has different bone density, the advice that a physical therapist gives to me would probably be different than the advice that a physical therapist would give to you. I gave my physical therapist my DEXA Scan results at my first PT appointment.