That noise coming from your knees can be unnerving. But unless it is accompanied by pain, discomfort or swelling, there is no need to worry about it, said Dr. Michael Stuart, a professor of orthopedic surgery and co-director of sports medicine at the Mayo Clinic.

The crackling or popping sound you hear is known as crepitus. In some cases, it may be nothing more than bubbles of gas popping in your joints. It can also result from the cartilage in your knees losing their smoothness, causing bones and tissue to rub together noisily when you bend your legs.

“Crepitus is extremely common,” Dr. Stuart said. “Our joints make a lot of noise.”

Dr. Stuart said the most important questions are, first and foremost: Is there pain or swelling? And second, is the noise associated with locking of the knees? “If you have a meniscus tear, that can cause these mechanical symptoms like catching or locking,” he said.

“If there’s crunching or grinding when you perform a squat and it’s very painful, that may be associated with arthritis.” Any of those symptoms would be a good reason to see an orthopedic specialist. But the popping noise by itself, without pain or other symptoms, may be innocuous.

If the noise occurs during squatting exercises at the gym, it may be because you are going too low. A deep squat movement in which your hips go below your knees can put excessive stress on your joints.

“When you perform a full squat, you put almost eight times your body weight across your knee cap,” Dr. Stuart said. “And then when you add a barbell or load on top of that, it ends up being very, very high forces to the joints and tissues around the knee.”

You can still get the benefits of squatting by doing partial repetitions in which your knees do not bend more than 90 degrees. “You might want to stop at a right angle or less,” Dr. Stuart said. “That way, you can strength train effectively without joint overload.”