The purpose of this randomized, double-blinded, placebo-controlled, parallel trial was to compare high-velocity low-amplitude spinal manipulation with chemical treatment. In this case, the chemical treatment was diclofenac, a nonsteroidal anti-inflammatory. The trial also included comparison with placebo. Considering the staggering impact of low back pain, the authors of this trial felt there were too few studies comparing spinal manipulation to nonsteroidal anti-inflammatory drugs or placebo. They aimed to test patient satisfaction and function, time off from work, and rescue medication, specifically.