Biomechanical measurements of back shape and interface pressures in unsupported sitting.

The paper describes the use of two non-invasive techniques to provide simultaneous measurements of interface pressures and back shape in the seated posture. A modified wheelchair was used to provide adjustments of various seating parameters. The effects of varying seat angulation with four normal subjects are reported. The lumbar lordosis, evident in the standing position, was absent in the sitting position. The changing of seat base angulation affected the balance between the main areas of seating support. For example, forward inclination of the seat reduced pr posterior thigh.