Intervertebral discs are biologic tissues which (despite what much popular writing would imply) adapt to imposed stress much like muscles, albeit on a slower time scale. Classically, combining flexion+rotation is generally considered to place the discs under the most mechanical stress. Please note that mechanical stress simply means “load at length”.
Much like a muscle, applying mechanical stress to the discs can be therapeutic, provided it is provided at the right intensity and volume. If we apply excessive stress to a muscle, it may tear. If we progressively apply stress to a muscle but monitor symptoms/response, the muscle can get much, much stronger.
An individual with very irritable back pain may be aggravated by any of the exercises you posted. However, as their symptoms improve, reintroducing such exercises may be an appropriate tool to restore or otherwise “normalise” their trunk. Similarly, an individual without back pain may be able to tolerate such exercises to a high level, and including them may serve to increase their discs’ tolerance to mechanical stress over time. In contrast, if an otherwise healthly individual were to go too gung-ho such exercises, they may aggravate their discs/lower backs. As is the case with medicine, the magic is in the dose.
If we had to place the three exercises you proposed on a continuum from “least mechanical stress” to “most mechanical stress” (again, remembering mechanical stress is good at the appropriate dosage), then they would be ordered as:
Supine hip twists: no load bearing through discs
Broomstick twists: bearing weight of upper body through discs
Rotational kettlebell swing: bearing weight of upper body + kettlebell, with additional stress imposed due to the flexion/extension involved in the KB swing motion
In terms of creating a “smooth” progression, I would propose adding a loaded barbell twist as an intermediary betwen the broomstick twist and the rotational kettlebell swing. This is because it involves bearing the weight of the upper body, plus additional load without adding the additional flexion/extension stressor.
Absolutely! Back pain presentations can be absolutely mixed bags, and N=1 approach seems to be best with symptom relievers.
I believe you’ll tend to find the individuals who get relief from flexion+rotation are likely the ones with a fairly high level of muscle guarding around the spine, but I could certainly be wrong.
