Here are some facts about prolonged sitting posture:
1.Sitting with hip angle at 90 degrees increases
the load on the lumbar spine by as much as 40%
when compared to standing. Even slightly reclining
your chair can reduce the loads on the lumbar
spine by 45% when compared to sitting upright.
2. Standing is better than sitting when it comes
to minimizing loads on the lumbar spine. Sitting
in a slightly forward flexed position increases
the load on lumbar discs by as much as 85%!
3. A phenomenum called "creep" occurs when sitting
for prolonged periods of time. This is when spinal
ligaments stretch and take longer to recoil when
standing from a sitting position.
Here are some tips on improving your posture
1. Ensure you have 1"-2" of space between the
back of your knee and the edge of the seat. If
the distance is less than 1"-2" then you may be
slouching unncessarily. If the distance is greater
than 1"-2" then you maybe placing unncesrary pressure
under your thighs. Adjust your seat depth (if
available) if this is this the case.
2. Ensure your armrests are adjusted (both in
height and width) to properly support your forearms.
Proper forearm support can reduce the vertical
forces on the spine.
3. If you cannot stand, then change your posture
frequently when sitting. Use the recline feature
on your chair (if available) or even change the
seat angle (as most chairs do have this feature)
to "open up" your hips.