Iliotibial band syndrome occurs when a tendon called the iliotibial band rubs against the hip or knee bones, causing it to become inflamed or swollen. The tendon runs from the top of your pelvic bone down to your knee on the outside of your leg. When it becomes overly tense, it grinds on your bones (tight).
The repetitive bending of the knee during physical activities such as running, cycling, swimming, and hiking is a common cause of iliotibial (IT) band syndrome. Fascia, or connective tissue, makes up the IT band. It is an elastic collection of fibers that extends from the hip to below the knee along the thigh.
