The purpose of this study was to compare the preferred low-back motion of normal subjects and low-back-pain patients. Each subject performed a maximum isometric flexion trial followed by repeated flexion and extension against a relative resistance set at 50% of the recorded maximum flexion isometric torque. The subjects were instructed to move at their own pace through their preferred movement range until either exhaustion or for 120s. The results showed that the groups differed significantly in their preferred motion characteristics, although the performances were equally consistent.