Effect of seat angle and lumbar support on seated buttock pressure

Abstract

The purpose of this study was to compare the effects of a lumbar support at two seat angles (0° and 10° of posterior tilt) on the area of highest buttock pressure. Twenty able-bodied subjects were seated on a pressure-sensing transducer incorporated into an adjustable chair (ischiobarograph). A video camera on the underside of the transducer detected changes in light levels in direct relation to pressure application. The camera output was processed by a microcomputer system that converted the signal into nine colors, each representing a distinct pressure interval in the range of 0 to more than 500 mm Hg. The microcomputer determined the area of each pressure interval before and after a 10-degree posterior tilt of the seat and lumbar support placement. The results demonstrated high test-retest reliability for each position (r = .95). A significant decrease in the six highest pressure intervals occurred when the lumbar support was used in both the upright and reclined positions (p