If your lower back pops when doing sit-ups, crunches or other exercises, there's no need to be alarmed. It's quite common for joints to snap, pop, crackle and make all sorts of percussive sounds.
The back, neck, hips, knuckles and ankles tend to be the noisiest customers. There are a number of causes for this and most of them are nothing to worry about. However, if inflammation and pain go along with the popping or cracking, you should consult your health care practitioners.
When you flex your spine doing crunches, you open space between the vertebrae, causing pockets of gas to escape.
The Gas Escapes
Your joints are lubricated by a substance called synovial fluid that contains certain gases, including oxygen, nitrogen and carbon dioxide. When you flex your spine doing crunches, you open space between the vertebrae, causing pockets of gas to escape. A February 2013 article published by the Journal of Manipulative & Physiological Therapeutics confirmed that an audible pop occurring with spinal manipulation indicated an increase in spacing between joint surfaces. That rapid release of pressure is what causes the noise.
Joints,Tendons and Ligaments
Popping and cracking can also be caused by normal or abnormal movement of joints, tendons and ligaments. When a joint moves, the highly elastic tendon or ligament changes position, moving somewhat out of place and popping back into place.
It may make a sound as it snaps back into its original position. Another cause can be arthritis. In this case, the loss of smooth cartilage that normally buffers friction between joints can cause sounds because of the roughness of the joint surface. Popping caused by arthritis is typically accompanied by pain with movement.
Snapping Hip Syndrome
The popping sound you hear when doing crunches may seem like it's coming from your back, but your hip might actually be the real source of the sound. According to the American Physical Therapy Association, snapping hip syndrome occurs when a muscle, tendon or ligament rolls over a bony protrusion in the hip.
Snapping hip can occur in different areas of the hip. In the front of the hip, it involves the hip flexor muscle rolling over the front of the hip bone or the hip ligaments snapping over the thigh bone or the hip joint tissues.
At the side of the hip, it involves the iliotibial band, which runs along the lateral or outside aspect of the thigh, from the pelvis to the tibia, crossing both the hip and knee joints, sliding over the outer thigh bone. In the back, popping can be caused by the hamstring muscles rolling over the bottom of the hip bone.
Snapping hip often occurs when the hip muscles are overworked and become tight or inflamed. In some cases, snapping hip syndrome can cause problems with walking or rising from a chair. Physical therapy may be required to overcome the condition.
- Library of Congress: "What Causes the Noise When You Crack a Joint?"
- Journal of Manipulative Physiological Therapy: "Evaluating the Relationship Among Cavitation, Z Joint Gapping, and Spinal Manipulation: An Exploratory Case Series"
- American Physical Therapy Association: "Physical Therapist's Guide to Snapping Hip Syndrome"