Many workers in industrialized nations are now seated workers. More and more jobs involve doing tasks while sitting down. Back pain may be linked to seated postures. In particular, the flexed curve in the low back and static muscle load are two major risk factors for disc problems.

Studies estimate that about 100 million workdays are lost each year in the United States due to low back pain (LBP). This study reports the results of a back support that lowers the pressure on the spine. It helps keep the low back in the proper position during sitting.

The support is adjustable. The back part of the seat can be tilted down and the backrest adjusted. The seat height and depth can also be changed. Measurements of load, force, and pressure were taken with and without the support. The support was tested on office workers with no previous history of LBP.

The authors report that the new seating device shifts the weight off the sit-bones (called ischial tuberosities) onto the thighs. With the seat tilted down, muscle activity is lower--especially in the low back area.

The load on the low back is maximally reduced when support is given to the low back curve and when pressure is off the ischial tuberosities. Using this new seating concept may help prevent problems of LBP. For patients with limited motion, changing body position is still the only way to change pressure on the buttocks.

Mohsen Makhsous, PhD, et al. Sitting with Adjustable Ischial and Back Supports: Biomechanical Changes. In Spine. June 1, 2003. Vol. 28. No. 11. Pp. 1113-1122.