Hearing a popping sound in any joint while running can indicate an injury. Joints can crack, however --- think cracking your knuckles --- without any damage to the surrounding tissues and bones. Popping noises may stem from natural joint movements or ligament injury. Assessing any accompanying signs or symptoms is important for diagnosis. Contact your doctor if a pop is accompanied by pain, swelling or joint instability.
Ankle Anatomy
A complex joint that withstands tremendous impact from running and jumping, your ankle is actually made of two separate joints, the Southern California Orthopedic Institute explains on its website: the subtalar and true ankle joint. Comprised of the shin bone, outer leg bone and talus bone, your true ankle joint moves your foot up and down. The subtalar joint is composed of the talus and heel bones, and promotes side-to-side foot movement. Each bone is surrounded by cartilage and has attaching ligaments to hold them in place. Major ankle ligaments include the anterior tibiofibular ligament, which connects your leg bones; the lateral collateral ligaments, which give your ankle lateral stability; and the deltoid ligaments, which hold the subtalar joint together.
Normal Body Movements
According to the Library of Congress, certain popping or cracking sounds accompany escaping gases and ligament movement. A non-harmful popping or cracking noise can occur when gases contained in synovial fluid ---- which lines your ankle joint --- are released during a specific movement. Oxygen, nitrogen and carbon dioxide are present in synovial fluid; stretching the joint capsule --- perhaps during a high-intensity sprint --- audibly releases these gases. Sounds are also emitted when ligaments and tendons move out of place over specific areas of bone. A snapping sound indicates the tissue returned to its original position.
Ankle Sprains
Ankle sprains are one of the most common sport-related injuries, particularly in sports that involve running, jumping and sudden starts or stops. High-intensity sprints place a great deal of force on ankle components, leaving your ankles vulnerable to sprains. Sprains differ from strains, according to MayoClinic.com; sprains are stretches or tears that happen to the ligaments in a joint, rather than the tendons or muscles. A popping sound is more likely to accompany a ligament sprain than a muscle or tendon injury.
Accompanying Signs and Symptoms
After hearing a popping sound while sprinting, discontinue exercise to assess your ankle joint. Pain, from mild to severe, can accompany a ligament sprain. This pain may only occur during a specific movement --- such as moving laterally or pointing your toes --- indicating localized damage. Immediately after the popping sound occurs, your joint may "give" or feel unstable. Swelling on one side or in several areas can also occur, and is a sign of tissue damage. Your ankle may exhibit bruising as well. Contact your doctor for further evaluation if any of these signs or symptoms occur.
