What is it?
Iliotibial Band (ITB) Syndrome is one of the most common running injuries around. The pain is usually felt on the lateral side, or outside, or the knee. It becomes more painful when the knee is bending more, such as when one is running hills. Quite often though, the pain is never felt until one actually tries running, and sometimes is not felt until a few kilometers into the run. But what is it? Despite what it may feel like, it's not a problem with your knee. The ITB is a ligament that runs from the hip to the shins on the outside of your thigh, passing over the knee. The pain which is most commonly felt is the band rubbing against the bones in the knee. This results in inflammation in the area. The most common cause of ITB syndrome is increasing your mileage when you are not ready for it.

What should I do?
The first step should always be to back off on your training. Whether this means stop all together or reduce your mileage is up to you and the severity of the injury. When you back off on your mileage, you can always supplement your training with pool running, swimming, rowing, and activities like that. The important thing is to stop before it becomes chronic. If you are able to run with minimal pain, doing a complete and slow warm-up before your run could solve the problem. As far as stretching goes, there are some very effective ITB stretches out there.
The easiest is to cross the leg which is hurting behind the other leg, and then push your hips to the injured side. You should feel a pull along the outside of your leg. After runs, you should always ice the tender area to take the inflammation down. ITB can be treated like most other running injuries; with rest, ice, compression, and elevation.

Could it be my shoes?
Shoes are actually one of the first things to look at when you are experiencing ITB pain. If you are an overpronator, meaning your foot rolls in too much, you may need more support to align your knees correctly. The same goes for supinators, where the foot doesn't roll enough, there could be too much stability in a shoe pushing them further outwards and misaligning their knees. The best way to tell this is to come into the store and have one of us look at your feet and shoes. Beyond this, as a shoe breaks down, the stability and cushioning eventually break down and this is probably the leading cause of injuries like ITB syndrome.

Basically, ITB problems can be resolved very quickly if they are dealt with in time. Most runners, however, choose to continue running through the pain. This can make the problem chronic, and in this case it may never leave you. If the problem doesn't clear up with some rest and stretching, try seeing a sports-medicine doctor. They will usually be able to target the cause of the problem.