Runners Knee - What is it and what causes it?

Training for a race? There is nothing worse than that gradual pain that starts in your knee and just won't go away! When you are increasing your milage or intensity to prepare for races or if you are just getting into running, 'Runners knee' can be really frustrating.

Injuries are like this are particularly common for people getting started with running as their bodies aren't used to the repetitive jarring and specific motion involved with running.


A sound diagnosis and management plan can catch these types of injuries early and prevent it from getting worse.


If not identified early, you try a standard rest/self diagnose/go again method, I can assure you that your frustrations will be long lived!

Runner's knee:

An umbrella term given to conditions affecting the knee as a result of running. It's most commonly used to describe Patellofemoral Pain Syndrome (PFPS).

PFPS refers to the condition where pain is present around or behind the kneecap, believed to be caused from altered positioning/alignment of the patella (kneecap) on the femur (thigh bone). You may feel like the pain gets worse later in your runs.

The most likely symptom associated with PFPS is pain under or around the patella bone at the front of the knee which is aggravated by activities that increase the load or pressure on the patellofemoral joint - Squatting, lunging, stairs, walking/running, especially downhill.

It is also usually aggravated by long periods of sitting, maybe at work or watching a movie on the couch at home. Hence why is can sometimes be referred to as movie-goers knee.

Possible causes for Runners knee:

Muscle weakness:

Without giving an essay here, the key muscles a runner needs to have good strength in to avoid this injury are the gluteals and the quadriceps. If weak, it effects the biomechanics (see below) and the control when we load the leg in our running motion and can be the underlying fault for why the knee becomes painful. See the treatment information for Runners knee for details about how to improve your glutei/quad strength.

Training errors:

The most common cause for new or returning runners is doing. too much, too often without enough rest time. It may be increasing your training distance too quickly, increasing the intensity too quickly, or doing your sessions too close together not allowing your body to recover enough. Whichever reason, the knee isn't happy because your muscles are getting tired and there is added pressure at the fronton your knee that leads to pain.

To prevent this happening the simply solution is a graduated loading program for you training.

Biomechanics or movement control:

The two main points to look at here are the control of the knee when it comes under load and the timing of the contractions by the most important muscle groups, the glutei and the quads.

If there is control issues we generally see when the runner does a single leg squat their hip rotates and their knee moves inwards towards the other knee. Generally as a result of muscle weakness which gets even worse as the key muscles get fatigued.

The contraction of the muscles in also important to maintain effective control of the knee when is comes under load to prevent the above.

The other biomechanics point to touch on is the foot and ankle. This can effect the knee in the same way the hip does in the act that if there is a positional change, such as increased pronation, this can lead to the knee deviating inwards towards the other knee and causing pain at the kneecap. Identifying where needs addressing normally requires a trained professional eye, so seek help early if possible.

Poor flexibility:

Due to the fact the knee cap is essentially 'floating', all the soft tissue connections play a large role it how it moves. When specific soft tissue structures, such as the quads and the iliotibial band are tight/stiff it can result in increased pressure through the patellofemoral joint. If you are running (repetitively loading) a joint with more pressure than its used to then it is likely to become irritated and painful.

The hamstrings and calfs also help to control the knee so don't forget to check/manage these too.

Please note these are the main causes of Runners knee, but like every injury, each person is different so we always recommend consulting a physiotherapist to get a proper assessment and to help with how you need to manage your injury.

Check out the 'Runners knee - How we treat it' article to find out the best research based management techniques for getting back out running after your knee injury.

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