LOW-BACK LOAD IN 2 CAR DRIVER SEATS

Low back pain is a significant health problem for professional drivers . Therefore it is important to design a car driver seat with less load to reduce low back pain. The purpose of this study is to compare the low back load in a long-term driving experiment between two different types of driver seats (the new seat and the standard seat). The new se at has the following characteristics vs. the standard seat: (1) a lumb ar support, (2) side supports, (3) seat is firmer at the ischial tuber osity region, but it is softer at the femoral region, (4) a head rest which is adjustable sagittally, and (5) a rubber mat under the seat. S ixty male subjects, who commuted 5 times/week for about 50 min/trip wi th the standard seat and complained of low back pain in driving, were selected from a group of 1600 subjects. The existing seat in their per sonal vehicles was replaced with the new seat for 30 subjects. For 6 m onths, 30 used the new seat, and the other 30 used the standard seat. Before, and 3 and 6 months after the start of the study, the low back load was estimated by lumbar examination and subjective evaluation of low back pain. At the second examination, the subjective evaluation si gnificantly improved for the new seat (vs, the standard seat). At the third examination, the kinetic pain score in bending backward and the Lasegue test significantly improved for the new seat(vs. the standard seat). It is suggested that the low back load of the new seat was less than the standard seat. The factors of the lumbar support, the side s upports, the firmer seat at the ischial tuberosity region, the adjusta ble head rest and the rubber mat all contributed to a reduction in low back load.