Manual spinal manipulations performed by chiropractors target specific inflamed joint capsules of the spine by improving segmental vertebral mobility. Joints can be inflamed due to poor posture, scoliosis, arthritis, sports injuries, pregnancy and etc. A spinal manipulation increases pain tolerance by affecting primary afferent neurons from surrounding spinal tissues, the motor control system and pain processing. It leaves you feeling lighter, more flexible and feeling better. The "popping sound" is medically called "cavitation". It is harmless and is a result of a gas escaping from an adjusted joint, improving its mobility and reducing its irritation through normalizing the joint capsule's internal pressure.