Chiropractic Manipulative Therapy/Spinal Manipulation or "adjustment" refers to gentle pressure or a high-velocity low-amplitude thrust to help restore function and motion to a joint that has become restricted. The manipulation also stimulates the nervous system to help reduce pain and relax local musculature. The noise that can be heard with an adjustment is that of release of nitrogen gas from a joint capsule. It has been researched and documented that motion is restored following an adjustment but no bones are moved for this to happen. There have been many studies that have proven its effectiveness, safety, and high levels of patient satisfaction. As a result, in 1994 the U.S. Agency for Health Care Policy and Research published this technique as a gold standard for low back pain. Since then more research has been done on neck pain, headaches, carpal tunnel syndrome, infantile colic and rehabilitation, all supporting the role of Chiropractic and its manipulative procedures.