its interesting that this has come up at this time.
my own experiences:
have had pretty severe lower back pain for the last year and half to two years.
however when i do deads i find that this is theraputic (afterwards).
i have also found that if i purposely sleep on my stomach for even a short time that is also theraputic for me as in no pain for the early part of the next day.
recently i have been goig to an ART specialist, that is also a chiropracter and biomechanic here in the chicago area.
unfortunatly not too much success here. however he did tell me that my lower spine was acting like it was fused, so he got that back to working. but i do still have the same pain.
the pain is when i do anything that is using those lower back muscels, as in leaning over-forwards i.e. mopping a floor.
i have found that if i rotate my pelvis top rearward-bottom forward and tighten lower abs the pain abates considerably.
an xray was taken , showed nothing.
i also so use an inversion table and it seems to help somewhat.
i have recently started doing overhead squats and this same as deadlifts appears to be theraputic even during as well as afterwards.
best of luck to you, one other thing i am 45, and have led a relatively physical life.