Vertebral compression
Mechanical load on the lumbar spineWhen the body is seated, the lumbar vertebrae — the five bones forming the lower section of the spine — are subject to compressive load. In a neutral standing position, that load is distributed across the full length of the spine, the hip joints, and the legs. Seated, a greater proportion of it concentrates in the lumbar region.
Under sustained compression, the intervertebral discs — the cartilage pads that sit between each vertebra and function as shock absorbers — lose fluid gradually. This is a normal diurnal process that reverses overnight with rest. The problem arises with duration: a full working day of sustained seated load, repeated five days a week over months and years, does not allow complete overnight recovery. Intradiscal pressure remains elevated at the start of each working day, compounding incrementally over the working week.
Elevated intradiscal pressure restricts the movement of blood and fluid through the compressed tissue.