You’re sitting with friends, and you reach for something next to you, when you hear a pop in your shoulder. There’s no pain, yet that popping sound has you concerned that something is wrong. Should you worry?

Popping or cracking sensations and sounds can occur just about anywhere in the body and, if they aren’t expected or commonplace for an individual, can be alarming. Scientists can’t agree on what it is exactly that causes all those strange noises, but one theory is that as tendons and ligaments tighten around or move over a joint, the result is snapping, popping or cracking. As for popping knuckles, one popular idea is that air bubbles within joint fluid escape, causing a popping sound, while another belief is that a vacuum is formed when the joint is adjusted, causing synovial fluid to rush into the space. It’s a different scenario with arthritic joints, which may creak and grind as a result of bone moving across bone.

Just because your body might make those strange sounds when you move, such noises and movements don’t necessarily mean bad news. However, any time those noises or movements are accompanied by pain or restriction of movement in the body part moved, it’s time to have it evaluated by a physician.