This article reports a prospective, randomized, multicentered study documenting changes in the intensity and location of low-back and referred pain to repeated end-range lumbar flexion and extension movements performed first while standing and then while recumbent during a single clinical patient evaluation. Significant and rapid changes in central and distal pain intensity and location of peripheral pain resulted from the performance of these movements. For the mean in both protocols, regardless of the order of spinal movements, end-range extension significantly decreased central and distal pain intensity and centralized referred pain. Flexion spinal movements, however, significantly increased mean central and distal pain intensity and peripheralized the pain. Forty percent of individual subjects had a clear preference for extension and 7% a clear preference for flexion.