My experience: clients who came from the doctor with instructions that they must not load the spine with flexion and rotation, had problems with the discs in the lumbar spine and were forbidden to exercise in extension. The lesson is beautifully put together, but unusable for a person with problems with the vertebrae.
This was perfect for my sore back today. Challenging without aggravating my lower back which doesnt love flexion when sacro- ileitis is flaring. This is why I LOVE pilates. :)