Hello there, These cracking and popping occurs due to the presence synovial fluid in the capsule of a synovial joint. synovial fluid present in your joints acts as a lubricant. The fluid contains the gases oxygen, nitrogen, and carbon dioxide. When you pop or crack a joint, you stretch the joint capsule. Gas is rapidly released, which forms bubbles. In order to crack the same knuckle again, you have to wait until the gases return to the synovial fluid. When you crack a joint, you are actually stretching the joint thus creating a neg pressure in the synovial joint. The process called cavitation occurs, which is formation of gas bubbles from liquid due to neg pressure. If more neg pressure is formed beyond that point, the bubble claps making a loud pop sound. Hence repeated cracking & popping is due to negative pressure in the joint more frequently.. and this may be due to a weak capsular strength...... If you hear joint pops and clicks with no associated pain in a joint, you don t need to worry, but you may want to begin some conditioning exercises to improve the overall integrity of the joint. Stronger muscles will take the weight off of the joint and help reduce the pressure on the articulating surfaces. If there is pain along with those joint noises, you may have signs of structural damage building in the joint. It would be wise to see a physician/physio/chiropractor for an appropriate diagnosis and treatment pain to help prevent further damage. wish you a good health .....