221 patients with low back pain were randomized to either (1) high-velocity, low-amplitude (HVLA) manipulation, (2) low velocity, variable-amplitude (LVVA) manipulation, or (3) sham therapy for the purpose of evaluating significant changes in postural sway and response to sudden load-bearing after active treatment. When measured between therapy sessions and over two weeks of allocated treatment, results demonstrated that although significant improvements in postural sway and load-bearing response were observed in all study groups, between-group analyses reported non-significant differences between active and sham therapies. Therefore, it was suggested that short-term spinal manipulation did not induce significant clinical changes in the specific outcomes measured.