Introduction: The use of back support is one of the common methods aimed to prevent low back pain. The purpose of the present study was to investigate the effect of wearing a lumbosacral support on lumbar spine velocity and torque in six directions during combined trunk motion.

  Materials and Methods : In this interventional study, 30 young healthy men were selected simply from convenient samples. They were asked to stand in Isostation B200 system and perform three-dimensional trunk motion against a resistance of 50% of maximal voluntary contraction torque while wearing or not wearing a lumbosacral support. Under each condition of test, five successive motions of trunk were performed in downward direction (as flexion, right lateral flexion, and right rotation) and upward direction (as extension, left lateral flexion, and left rotation), and the variables of average velocity and average torque were recorded during motion.

  Results : With the use of a lumbosacral support, average velocity was significantly increased in flexion (P=0.015) and extension (P=0.005), but no significant changes were found in other directions (P>0/05). Back support decreased average torque of right rotation significantly (P=0.006), but did not significantly changed this variable in other directions (P>0/05).

  Conclusion : Wearing a lumbosacral support can increase velocity in sagittal plane. Decreased rotation torque of trunk, as a result of using a back support, may reduce the twisting forces on lumbar spine joints.