Spinal manipulation (SM) is used by clinicians for the treatment of several chronic pain conditions. The effectiveness of different spinal manipulations targeted at the lumbar spine in patients with low back pain is supported by an increasing number of high-quality randomized clinical trials1and systematic reviews. Although these techniques have shown some effectiveness in clinical practice, most of clinical studies solely investigated the effects of spinal manipulation on overall reports of pain and function and the underlying mechanisms by which manipulation produce clinical effects remain largely unknown.