Runner's Knee: Why Does My Knee Hurt When I Run?
Knee pain while running is one of the most common problems we see in runners.
Often referred to as runner's knee, the condition people are usually describing is patellofemoral pain: pain arising from the region around or behind the kneecap.
It commonly becomes noticeable during running, stairs, hills, squatting or after sitting with the knee bent for a long time.
The good news is that runner's knee rarely means that you need to stop running altogether.
In many cases, the most useful approach is to understand why the knee has become sensitive, temporarily adjust the amount of load going through it, and then build its capacity back up.
Our Running Physiotherapy service combines injury assessment, strength testing and running analysis to help determine what is relevant for the individual runner.
What Is Runner's Knee?
Runner's knee is not really a specific medical diagnosis.
The term is commonly used to describe patellofemoral pain, which produces pain around or behind the patella, or kneecap.
You may also have heard older terms such as:
- Patellofemoral pain syndrome or PFPS.
- Anterior knee pain.
- Patellofemoral syndrome.
- Chondromalacia patella.
These terms have sometimes been used interchangeably, but they do not all mean exactly the same thing.
Importantly, iliotibial band syndrome is a separate condition that more typically causes pain around the outside of the knee rather than around the kneecap.
What Does Patellofemoral Pain Feel Like?
The pain is usually felt around, underneath or behind the kneecap.
Common aggravating activities include:
- Running.
- Running downhill.
- Walking downstairs.
- Squatting.
- Lunging.
- Jumping.
- Sitting with the knee bent for prolonged periods.
Some runners notice discomfort only after a certain distance. Others find the knee becomes painful early in a run but settles as they warm up.
The behaviour of the pain can tell us quite a bit about how irritable the knee is and how much running it is currently able to tolerate.
Why Does Runner's Knee Develop?
There is rarely one single cause.
Patellofemoral pain often develops when the demands being placed through the knee have increased faster than the knee's current capacity to tolerate them.
A classic example is someone who has recently:
- Increased running distance.
- Added an extra running day.
- Started running faster.
- Added hills.
- Returned to running after time off.
- Started training for an event.
- Combined increased running with other gym or sporting loads.
The important factor is not necessarily that one of these activities is bad. It is the change in load relative to what the knee was previously prepared for.
Does Running Damage the Kneecap?
Generally, this is not a useful way to think about patellofemoral pain.
The knee is designed to accept load, and pain does not automatically mean that the cartilage underneath the kneecap is being worn away.
Patellofemoral pain can occur without significant structural damage, and structural changes on scans do not always correspond neatly with how much pain someone experiences.
This is one reason we generally focus more on symptoms, physical capacity and function than trying to identify one painful structure inside the joint.
You can read more about our broader approach to knee problems on our Knee Physiotherapy page.
Do I Need a Scan for Runner's Knee?
Usually not.
Patellofemoral pain can generally be diagnosed from the history and physical examination.
Imaging may be appropriate if there has been significant trauma, the symptoms do not fit the typical pattern, there is substantial swelling or locking, or another condition is suspected.
But an MRI is not routinely required simply because your knee hurts when running.
Do Weak Glutes Cause Runner's Knee?
This is another area where the answer is more nuanced than it once appeared.
People with patellofemoral pain can have reduced hip or quadriceps strength, and strengthening these areas is an important part of rehabilitation.
However, finding weakness after someone develops knee pain does not prove that the weakness originally caused the injury.
Our focus is therefore less about blaming one weak muscle and more about asking:
What physical qualities does this runner need to build so the knee can tolerate their running?
What Strength Should Runners Work On?
Exercise is one of the best-supported treatments for patellofemoral pain.
A rehabilitation program will commonly include exercises targeting the knee and may also include hip and calf strengthening depending on the runner.
That can involve:
- Quadriceps strength: Helping the knee tolerate repeated loading and knee flexion.
- Hip strength: Building capacity through the gluteal and surrounding hip muscles.
- Calf strength: Improving the lower leg's ability to absorb and generate force during running.
- Single-leg strength: Developing capacity in positions that more closely resemble running.
The exercises do not need to be pain-free at all times, but the amount of pain and the response over the following day should be considered when deciding how quickly to progress.
Do I Have to Stop Running?
Usually, no.
Complete rest is occasionally appropriate when symptoms are highly irritable, but in many runners the better option is to temporarily adjust training.
This might mean changing:
- Distance.
- Frequency.
- Running speed.
- Hills.
- Intervals.
- Consecutive running days.
For example, if pain appears every time you reach 8 km, repeatedly running 10 km and hoping it eventually disappears may not be the best strategy.
A temporary reduction might allow you to continue running while rehabilitation increases the amount of load the knee can tolerate.
How Much Pain Is Okay When Running?
There is no universal pain number that applies to every runner.
Mild discomfort during running can sometimes be acceptable if:
- The pain remains manageable.
- Your running pattern is not significantly altered.
- The pain does not progressively increase throughout the run.
- Symptoms settle reasonably quickly afterwards.
- Your knee is not clearly worse the following day.
Increasing pain, limping, significant swelling or a progressively worsening response after each run suggests that the current loading strategy probably needs to change.
Can Changing Running Cadence Help?
For some runners, yes.
Increasing step rate slightly can reduce the amount of load experienced at the patellofemoral joint during each stride.
This is where the old advice to “increase your cadence by 10%” came from.
But 10% is not a magic number and cadence does not need to be changed for every runner with knee pain.
Running retraining is most useful when there is a clear reason for making the change and when the change actually improves symptoms or loading.
For some runners this might mean a small increase in cadence. For another runner, a different change may be more appropriate. Others may not need their running technique altered at all.
This is one reason we use running analysis as part of our Running Physiotherapy assessment rather than prescribing the same gait change to everyone.
What About Footwear?
A new pair of shoes is rarely the complete solution to runner's knee.
However, footwear can influence comfort and running mechanics, and a sudden change in shoe type combined with a change in training may sometimes be relevant.
There is no single type of running shoe that prevents patellofemoral pain in everybody.
Comfort, previous experience in the shoe and how the runner responds to it are generally more useful considerations than trying to prescribe one universally “correct” shoe.
Do Foot Orthotics Help Runner's Knee?
They can help some people, particularly in the short term.
Current best-practice recommendations suggest prefabricated foot orthoses may be useful where a simple trial produces an immediate improvement in symptoms during a relevant task.
They are generally considered a supporting intervention rather than the main treatment.
In other words, an orthotic can sometimes make exercise and running more comfortable while the broader rehabilitation program builds capacity.
Does Knee Taping Help?
Taping can reduce symptoms for some people with patellofemoral pain.
Again, the effect tends to be individual.
If taping allows you to complete your strengthening exercises or stay active with less pain, it can be a useful short-term tool.
It does not mean your kneecap needs to be permanently held in a particular position.
What About Massage, Dry Needling and Foam Rolling?
These may make some runners feel more comfortable in the short term, but they are not the main treatment for patellofemoral pain.
Massage, dry needling or foam rolling does not replace the need to consider running load and build the physical capacity of the lower limb.
If you enjoy these approaches and they help manage symptoms, they can sometimes sit alongside rehabilitation rather than becoming the rehabilitation itself.
Does Running Technique Matter?
Potentially, but there is no one running pattern that causes runner's knee.
Running mechanics vary considerably between healthy runners.
Rather than labelling movements as simply good or bad, we are more interested in whether a particular running pattern appears to be contributing to symptoms for that individual.
Running analysis can consider factors such as:
- Cadence.
- Stride length.
- Foot strike position.
- Knee movement.
- Hip and pelvic control.
- Trunk position.
- Running speed.
The important part is then combining what we see with strength testing, training history and the runner's symptoms.
How Do We Assess Runner's Knee?
At RHP Physiotherapy, we take a broader view than simply looking at the kneecap.
An assessment may include:
- Your recent and longer-term running load.
- Changes in distance, frequency, speed or terrain.
- Knee movement and tolerance to loaded knee flexion.
- Quadriceps strength.
- Hip strength.
- Calf strength.
- Single-leg tasks.
- Running technique where relevant.
- Your goals and upcoming events.
The aim is not to find every tiny asymmetry.
It is to identify the factors that actually matter for your knee and your running.
How Long Does Runner's Knee Take to Improve?
There is no fixed timeline.
Some runners improve quickly once their training load is adjusted and rehabilitation begins. Others have experienced symptoms for months or years and require a more gradual progression.
One important point is that patellofemoral pain can persist if it is repeatedly aggravated without any meaningful change in training or rehabilitation.
Improvement generally comes from finding the right balance between:
- Keeping active.
- Temporarily reducing provocative load where required.
- Building knee and lower-limb strength.
- Gradually restoring running volume and intensity.
- Using supporting strategies when they genuinely help.
Can You Keep Running With Runner's Knee?
In many cases, absolutely.
The goal of rehabilitation is not simply to remove running until the pain disappears.
Running is something your knee needs to become capable of doing again, so an appropriate amount of running can often remain part of the rehabilitation process.
The challenge is finding the amount your knee can currently tolerate and then gradually increasing that capacity.
If knee pain is interfering with your training, our Running Physiotherapy, Knee Physiotherapy and Sports Physiotherapy services can help assess the problem and develop a plan that keeps your running goals in mind.
Research Informing This Article
- Neal BS, Lack SD, Bartholomew C, Morrissey D. Best practice guide for patellofemoral pain based on synthesis of a systematic review, the patient voice and expert clinical reasoning. British Journal of Sports Medicine. 2024.
- Willy RW, Hoglund LT, Barton CJ, et al. Patellofemoral Pain: Clinical Practice Guidelines. Journal of Orthopaedic & Sports Physical Therapy.
