There’s an isolation back (erector) exercise (altough you can design an ab exercise) where the shear force on the spine after the support (horizontally),say,the navel is negative and (MUCH, at least 2 times) lower.
(instead of “pressing” on the back of the spine, like the weight in a deadlift or hyper, it “presses” on the front of the spine, like in a sit-up or roll-out).
How would that affect the risk of spine injury?
Practically, you are doing isolation back flexion, only that the ROM in the (lower) lumbar spine is restricted.
Thanks, Vlad