The dangers of sitting
Changing from a standing to a sitting position makes the top of the pelvis rotate backwards. This flattens the natural lumbar curve of the spine, causing an increased uneven pressure on the intervertebral discs. On leaning forwards, or slouching (80° angle) the spine describes a ‘C’ shape, further increasing lumbar disc pressure (+190%) and extra strain is placed on the back muscles. Commonly we are not aware of this pressure on the spine. The discs become dehydrated, muscles stiffen and tighten with less oxygen flow, and they can then cramp.
How posture controls disc pressure
The secret of varying and reducing disc pressure while sitting is to change your position frequently or, even better, use a floating tilt chair that allows for constant change.
Encourage the spine to lengthen into its neutral ‘balanced’ position, as when standing. By sitting upright and leaning slightly backwards (100° angle) the top of the pelvis rotates forwards allowing the spine to hold its natural ‘S’ shape. There is a better balance in the spinal column, with the head centrally positioned over the spinal column, and less activity is required from the supporting musculature. Weight is more evenly distributed across the intervertebral discs.