Side posture adjusting (spinal manipulation) is thought by many to gap the Z joints, yet no measurable differences of the Z joints before and after spinal manipulation have ever been published. This study will evaluate gapping of the L3/L4, L4/L5, and L5/S1 Z joints by taking measurements directly from MRI scans of the Z joints before and during positioning for a side posture adjustment, and before and after side posture adjusting.