Flexibility and velocity of the normal and impaired lumbar spine.

Trunk mobility, as defined by trunk angle, has long been considered an acceptable means to evaluate the degree of impairment in patients with low back pain (LBP). However, biomechanically, there is reason to believe that patients with LBP may exhibit significant sensitivity to trunk velocity of motion as well as angular mobility factors. An experiment was performed to study the trunk action of patients with LBP and of a normal control group. A lumbar monitor was used to monitor both trunk angle range and trunk velocity. The results indicate significant differences between the two groups for both angle and velocity measures. However, the velocity measure revealed more dramatic difference between groups and was the only parameter that was capable of distinguishing between the particular experimental tasks for both LBP and normal groups. Thus, it is suggested that trunk velocity be used as a quantitative measure of low back disorder and that it be used as a means to monitor the rehabilitative progress of patients with LBP.