It is estimated that the prevalence of work-related back pain in the U.S., with at least one lost workday, is 4.6% (Guo et al., 1999). This suggests that nearly 1 in 20 employees is always afflicted with this disorder. Nationally, total indirect costs due to low back disorders (LBDs) are estimated at $40 billion to $60 billion (Cats-Baril, 1996). A variety of tools are available for assessing LBD risk. Many of these (e.g., static models, the NIOSH lifting equations) assume that motion is not a significant factor in injury causation or that all movements are slow and smooth. However, research (e.g., Bigos et al., 1986; Punnett et al., 1991) suggests that trunk movement plays an important role in LBD risk.