In my last blog I explained what actually happens when your back cracks.  Now you may be saying to yourself, if all that happens when I crack my back is that gas bubbles are popping in the joint, then why do I feel better? The answer is not related to the release of gas bubbles popping but is instead related to the stretching apart of the joint.  When two bones are pulled away from each other, the tissues connecting the bones (joint capsule) are stretched.  These tissues have receptors in them that respond to stretch.  These receptors send signals to the spinal cord and brain to provide information regarding the position and condition of the joint.  If, however, the receptors are stretched maximally (which is necessary to produce popping in a joint) they will trigger a reflex to inhibit the muscles surrounding the joint.  This reflex is designed to protect the body.  If the body is receiving a stimulus that it perceives as excessive, the muscles are encouraged to relax in order to prevent catastrophic tearing and ripping.  To summarize, when you crack a joint it causes relaxation of the muscles adjacent to that particular joint.  This makes you feel better. If you're experiencing muscle spasms, cracking your back and causing muscular relaxation will certainly reduce pain.  Also, wherever a muscle crosses a joint (most of the muscles of the back cross numerous joints.) It will cause compression at that joint.  This compression can lead to pain at the joint, nerve or disk. Once again, if the muscles are made to relax, this will alleviate the problem.