Preferred position and associated forces for lower back supports in vehicle and office seating environments

The definition of seated postural comfort depends on several factors and varies from person to person. The contour of a seat can influence the posture achieved by an individual. This study focuses on the normal, vertical shear and lateral shear forces exerted on 3 differently designed lower back supports by subjects from 3 anthropometric groups in vehicle and office seating environments. Ten mid-sized males, 4 tall males and 4 short females were tested over a 2 hour period each to gather data that were statistically analyzed by comparing the effects of each lower back support pad individually as well as by comparing the results achieved by the 3 anthropometric groups.

Results from this research indicated that subjects exerted normal forces onto the lower back support pads in a manner that maintained a relatively constant pressure irrespective of pad size. Vertical shear forces exerted on the back supports depended on the position of the pad and not on the sitter's anthropometric weight. The pad with the longest length was positioned significantly lower than the shorter length pad. All pads apexes were positioned below the subjects' third lumbar vertebrae locations.

Data from this research provides an insight into the preferred levels of lower back support and position independent of a seat contour. Further, these data will be useful in obtaining the appropriate ranges of support in seats with active lower back supports.