IT Band Syndrome: Why Your Outer Knee Hurts When Running

You are a couple of miles into a run, feeling good, when a sharp or burning pain appears on the outside of your knee. You slow down, it eases, and you assume it has gone. Then it comes back at almost exactly the same point on the next run. If that sounds familiar, you may be dealing with iliotibial band syndrome, usually shortened to ITBS.

It is one of the most common causes of knee pain in runners, and also one of the most misunderstood. Here is what is actually going on, and what tends to help.

What is the iliotibial band?

The iliotibial band (IT band) is a thick strip of connective tissue that runs down the outside of your thigh, from the hip to just below the knee. It connects into muscles at the hip, including the glutes and tensor fasciae latae, and helps to stabilise the hip and knee as you move.

Near the knee, the band passes over a bony prominence on the outer thigh bone. ITBS is the pain that develops in this area when the tissues around it become irritated.

Why does it hurt?

For years the explanation was that the band "rubs" back and forth over the bone like a rope. More recent thinking suggests it is less simple. The band is firmly attached and does not slide much. The current view is that it compresses a sensitive pad of fatty tissue beneath it, and that this tissue becomes irritated, particularly when the knee is bent at around 20 to 30 degrees, which is exactly where the knee sits just after your foot lands when running.

This matters because it explains why stretching and foam rolling, the usual first response, often provide only short-term relief. The issue is generally not a band that needs lengthening. It is a tissue that is being repeatedly loaded more than it can currently tolerate.

Common triggers

ITBS is usually a load problem rather than a single event. Typical contributors include:

• A sudden increase in training. More miles, more hills or more speed work than you have built up to, such as ramping up for a spring marathon.
• Repetitive downhill or cambered running. Running on the same side of a sloping path, or along a canal towpath, can change the loading on one knee.
• Weak hip muscles. If the glutes and hip stabilisers tire, the thigh can drift inwards and the knee can collapse in as you land, increasing strain on the outer knee.
• Limited recovery. Back-to-back hard sessions give irritated tissue little time to settle.
• Cycling, hiking and gym work. Heavy volume of any repetitive knee-bending activity can contribute.

It is rarely just one thing, which is why a proper assessment is more useful than a generic stretching routine.

What helps

The aim is to calm the irritation, then rebuild the capacity of the leg so it can cope with running again.

Adjust, don't necessarily stop. Pain that starts at the same point in a run is a useful signal. Reduce your distance to below that point, avoid downhill running and sloping surfaces for a while, and swap some runs for cycling, swimming or the cross-trainer if they are comfortable. Complete rest is rarely necessary and often makes the return harder.

Strengthen the hip and thigh. This is where most of the long-term benefit comes from. Side-lying leg raises, side planks, single-leg bridges, step-downs and single-leg squats work the glutes and quads in the way running demands. Aim for controlled, slow repetitions and stop short of pain. A tailored programme of strength and conditioning is usually more effective than a random list of exercises, because the right level of challenge depends on you.

Look at your running. Very short strides, a narrow step width or a long stride that lands well ahead of your body can all affect loading. Small changes to cadence, such as a few extra steps per minute, can reduce the load on the knee for some runners. A gait review can show whether this applies to you.

Build back gradually. Once walking and everyday activity are pain-free, return with shorter, flatter runs and increase in small steps. If you are training for an event, a structured marathon preparation plan can keep your build-up realistic while the knee settles.

When to get it checked

Most cases of ITBS improve with sensible load management and strengthening, but persistent pain deserves a proper look. It is worth being assessed if:

• the pain has lasted more than two to three weeks despite reducing your running
• it hurts when walking, on stairs or at rest
• the knee is swollen, locks, clicks painfully or feels unstable
• you are unsure whether the pain really is ITBS, as other problems such as meniscus irritation, patellofemoral pain or a lateral ligament issue can feel similar

A physiotherapist can examine your knee, hip and running pattern, rule out other causes and build a plan around your goals. That is the heart of good physiotherapy: identifying why your knee is overloaded, not just where it hurts.

Getting back to running comfortably

ITBS can be frustrating, but it generally responds well once the underlying cause is addressed. If outer knee pain keeps interrupting your runs, we are happy to help. You can book an assessment at our Vauxhall clinic, including through most major private health insurers such as Bupa, AXA and Vitality, and we will work out a sensible route back to running with you.