A few years back, I was asked to participate as a subject in a research study that examined the differences in lumbar spine posture between standing and seated positions. This study was published in The Journal of Manipulative and Physiological Therapeutics and can be found here.
Lumbar lordosis (low back curvature) was measured via conventional x-ray and it was revealed that lumbar lordosis decreased by 43 degrees in the seated position. As such, it may seem reasonable to utilize an orthopaedic lumbar support to maintain the normal spinal curvature if seated for prolonged periods of time.
To the left are my x-rays that were included in the original publication...