What is the “pop” or audible sound?
Answer: The pop sound occurs when a joint has been moved past its normal physiological active range of motion. When this happens, there is a release of nitrous oxide gas, which causes the “popping” sound. It normally takes about 15-20 minutes for the gas to get back inside the joint, so a second popping sound will not be achievable until that time has passed. Healthy joints usually do not have the audible sound. Of note, the audible sound has been shown to have no bearing on the efficacy of the manipulation.