The adjustment, or manipulation as it's sometimes referred to, is the art of using force in a precise direction, applied to a joint that is fixated, "locked up", or not moving properly. The adjustment adds motion to the joint, helping the bones gradually return to a normal position and motion. The purpose of the safe and natural proccedure is improved spinal function, improved nervous system function, and improved health. Since the primary focus of care is to improve the nervous system function, Chiropractic can have a positive effect on many health conditions not normally thought of as "back" probelms (David Chapman-Smith).
When these vertebrae are out of place, it has an overall systemic effect from muscular to the central nervous system. Without proper alignment and flow of all nerves and systems in the body from the brain, we can't function at our peak.
An adjustment is often a pressure from the chiropractor utilizing the hands or an instrument to move a vertebrae back into place. This happens with a quick movement and is often without discomfort. You may hear a noise that sounds like you're cracking your knuckles referred to as joint cavitation. It is the release of gases such as oxygen and nitrogen from the joint.
Overall, adjustments are an excellent way to keep the body functioning at its highest level. When the body is in alignment, the body is able to respond and perform as it was designed to.
Under normal circumstances, adjustments shouldn't hurt. A few patients may experience a minor amount of temporary discomfort during or following the adjustment.