Have you experienced a nagging pain in the side of your knee? Are you someone who exercises regularly, but that pain seems to actually get worse with exercise? Well, today I am going to show you what might be causing that pain and why it hasn’t gone away yet. Let’s take a look at some relevant anatomy first. Iliotibial band syndrome is one of the most common causes of lateral knee (outside of your knee) pain in athletes, and is common in exercising adults as well. The iliotibial (IT) band is a long band of fibrous connective tissue that runs down the side of your leg from your hip to your knee. At the hip, the front outer hip muscle (tensor fascia latae), gluteus maximus, and gluteus medius muscles connect to the IT band. As the IT band runs down the side of your leg, part of your quad muscles (the vastus lateralis muscle) connects to it from the front of your thigh, while part of your hamstring (the biceps femoris muscle) connects to it from the back of your thigh. As the IT band reaches the outside of your knee, it connects to your kneecap (patella) and a part of your shin bone (tibia).