Your knee’s structure is complex, and it’s responsible for supporting the weight of your body. These two factors make this joint the most commonly injured—in fact, between 5 and 6 million people each year seek treatment for knee injuries. One of these injuries is known as iliotibial band syndrome, or ITBS.

The iliotibial band is a strip of connective tissue known as a ligament that stretches from the outside of your hip all the way down to your tibia, or shinbone. Certain sports and activities—long-distance running, or sports requiring a lot of running, such as soccer and basketball—can tighten this band to the point that it rubs against your thighbone as you move your leg. This causes irritation that can lead to sharp pain and tenderness on the front or outer side of your knee, but doesn’t generally cause swelling. You might also feel a clicking sensation when you move your knee.

ITBS can occur when you increase your running or biking mileage too quickly, or if you perform exercises such as hill running or weight-lifting with poor form, putting undue strain on your knee joint. The degradation of your running shoes can also irritate the knee, as can weakness of the hip muscles that help you move from side to side. You may initially only feel pain while running, and this discomfort may temporarily disappear when you take a break from training. But eventually, the condition can worsen, making simply walking a very painful task.

That’s why if you have think you may have ITBS, you should see a doctor or sports medicine specialist. He or she will likely have you ice the knee, decrease your activity level and perform stretches to boost flexibility in the area. You may also need to see a physical therapist to heal the knee. If all else fails, surgery may be necessary, but more conservative treatments generally do the trick. If you’re determined to keep up your physical fitness while you’re resting, lower impact activities may be an option, such as running in a shallow pool or using an elliptical exercise machine.

To prevent a recurrence of ITBS, make sure you keep your hip muscles strong and that you stretch in the way your physical therapist or sports medicine specialist instructed you to. Also, always increase your mileage slowly to make sure your knee is up to the task.