Commonly adopted postures and their effect on the lumbar spine.

The activity of the erector spinae muscles and the changes in lumbar curvature were measured in 11 subjects in a range of commonly adopted postures to see if there were any consistent trends. Surface electrodes were used to measure back muscle activity and lumbar curvature was measured using electronic inclinometers. The results showed that many commonly adopted postures reduced the lumbar lordosis when compared with erect standing or sitting, even at the expense of increasing the back muscle activity.