Although typically classified as AIS 1, whiplash injuries continue to represent a substantial societal problem with associated costs estimated at over $5 billion annually in the US. The primary objective of this study was to determine the effects of seatback and head restraint design parameters on occupant response in rear impact.

Rear impact sled tests were conducted using the Hybrid III mid-sized male (50M) dummy seated in a modified production seat, which allowed for the adjustment of recliner stiffness, seatback cushion stiffness, and head restraint height. Instrumentation provided measurements of neck forces and moments, head motion relative to the torso, seatback rotation, and head contact. An on-board digital video camera recorded dummy kinematics. Results from this study indicate that the risk of whiplash injury is not simply related to head restraint position, but is dependent on a combination of factors related to both head restraint and seatback design.