Studies of lumbar intradiscal pressure (IDP) in standing and upright sitting have mostly reported higher pressures in sitting. From my student carrier I have known that sitting transmits 11 times more pressure than standing (on central spinal pillar).
It is assumed clinically that flexion of the lumbar spine in sitting relative to standing, caused higher IDP, disc degeneration or rupture, and low back pain. IDP indicates axial compressive load upon a non-degenerate disc, but provides little or no indication of shear, axial rotation or bending.
Claus A et al found that IDP is often similar in standing and sitting. Current studies indicate that IDP in sitting is unlikely to pose a threat to non-degenerate discs, and sitting is no worse than standing for disc degeneration or low back pain incidence.
If sitting is a greater threat for development of low back pain than standing, the mechanism is unlikely to be raised IDP.