Lumbar spine fractures have received increased attention recently, with anterior wedge and compression burst fractures the most commonly reported in frontal vehicle crashes. The objectives of this study are to analyse the effect of seated posture in frontal crashes by using THUMS ver.4.02. Referring to the compressive studies of whole and isolated vertebral column under dynamic loading conditions (Stemper et al. 2015 and 2018), material properties of the vertebral bodies and intervertebral discs in THUMS ver.4.02 were modified. A similar response was observed in the modified THUMS with the PMHS component tests under compressive loading conditions. Spinal alignment in the seated posture can be broadly classified into kyphosis and S-shape. The stress on the vertebral body is higher when the spinal alignment of the occupant is kyphotic than when it is S-shaped. In order to reduce spinal injuries in frontal crashes, it is important to control the occupant’s posture (spinal alignment).