The iliotibial tendon runs down the outside of the thigh from the hip to the knee—more accurately, from the pelvic bone to the shinbone. And when it, or tissues surrounding where it joins the knee, become inflamed, it hurts. Conventional wisdom suggests the pain is frictional in origin. But more recent studies say the perceived motion of the iliotibial tendon at the knee is actually due to tension changes in the knee during flexion and extension. The pain is caused by an overuse injury, and may also possibly be associated with fat compression beneath the tendon tract.

Symptoms

Whatever the exact reason for the pain, it still hurts. You’ll feel it on the outside of the knee, in the general area of the bony bit (aka the lateral epicondyle of the femur). Pain generally begins during a run, may come on gradually or suddenly (as in you’ll think something is really wrong) and is often first noticed when running downhill. The good news is the pain generally goes away when you stop running and with rest. Although you may also feel additional pain when pressing on the knee over where it’s sore or while bending or straightening the knee. The iliotibial band may be tight, and you may experience pain while going up or down steps. Hip and thigh pain are not indicators of IT band syndrome. If pain comes from the front of your knee, it’s more likely that you have patellofemoral pain syndrome instead.

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Causes

Iliotibial band syndrome is an overuse injury. It is more common in women than men, and happens in both new and experienced runners. It can be brought on by muscle or structural imbalances—tilted pelvis, bowed legs, one leg longer than another—and weak hip muscles.

Your favorite run could also be to blame. Repeatedly running in the same direction on cambered or banked roads (as in always running against traffic with one leg downhill) or in the same direction on an indoor track may aggravate it. Hills are also to blame, either running too many or too many too soon without allowing muscles to adjust to the downhill load (the vertical drop of the Boston Marathon course is a perfect example). This causes stress because the IT band stabilizes the knee during downhill runs. Worn-out shoes or running too many miles may also be contributing factors.

Treatment

The goal with treatment is to reduce pain, strengthen and condition affected muscles, and return to running as soon as possible.

Rest, Ice, Compression, Elevation
Cut back or stop running for a couple days, especially running downhill. Ice the injured area for 10–20 minutes three to four times a day. Wear a compression sleeve to stimulate blood flow through the knee, and elevate it when you can. Swimming, pool running and rowing are all good options for maintaining fitness. No squats, though—they’ll aggravate the injury.

Visit your physical therapist
In addition to prescribing strengthening exercises, your physical therapist may be able to perform Active Release Treatments, acupuncture and e-stim, all of which may help with the pain and facilitate recovery.

Cryotherapy
This is showing promising results for helping with inflammation. It won’t cure you, but could help to temporarily alleviate symptoms.

Stretch and roll
Regularly stretching legs and rolling muscles will help to keep them pliable and less prone to injury. Here are three stretches to get you started:

 

Prevention

Even though iliotibial band syndrome is common, it isn’t inevitable. With thoughtful, measured training and a consistent strengthening and stretching routine, you should be able to tackle hills and your run from any direction.

Warm up
Walk and perform dynamic stretching and warm-up exercises before you begin your run, every time.

Stretch and roll
It works for prevention too. See above for specific iliotibial band stretches.

Get strong
Strengthening the legs, hips, knees and back will help to remedy muscle imbalances and make you less prone to injury. Here are 10 exercises to treat IT band syndrome.

Train for the terrain
If you are training for a race with a net elevation loss, you must condition the legs by incorporating downhill runs into your training plan. Likewise, if you want to run in the mountains, train by running in the mountains.

Switch up your runs
If you always run on the same side of the road, switch it up (as long as you can do so safely) or find a non-cambered path or sidewalk to build your miles.

Go shopping
Replace worn shoes as needed, usually every 300–500 miles, depending upon the shoes.

Take a break
If you begin to notice pain in the outside of your knee, reduce your mileage until the pain subsides.

More info

Watch this explanatory video from noted Boulder, Colo., physical therapist and running coach Douglas Wisoff: