Runner's knee is the most common running injury there is, and one of the most frustrating — because the pain is at the knee while the cause frequently isn't. Here's an honest overview. Runner's knee (patellofemoral pain syndrome) is pain around or behind the kneecap, usually from overload combined with poor control of how the leg moves — and hip weakness is often a bigger contributor than anything happening at the knee itself.
Important: this is general educational information, not medical advice. Knee pain has many possible causes. If yours is persistent, severe, involves swelling or instability, or followed an injury, see a doctor or physiotherapist for proper diagnosis.
What runner's knee actually is (the honest picture)
Runner's knee most often refers to patellofemoral pain syndrome (PFPS) — pain around, behind, or beneath the kneecap where it moves against the thigh bone. Typical presentation: a dull ache around the front of the knee, worse with running (especially downhill), going down stairs, squatting, or sitting for long periods with the knee bent (sometimes called the "theatre sign"). It's usually gradual in onset rather than traumatic. Note that IT band syndrome — pain on the outer side of the knee — is a different common running complaint, which is one reason self-diagnosis is unreliable.
Why the cause is often in your hips
Here's the insight that changes how people approach this: the knee is often where the symptoms appear, not where the problem originates. The knee is a relatively simple hinge with limited ability to control its own alignment — that control comes from above (the hip) and below (the foot and ankle). When the hip stabilisers, particularly the glute medius, are weak, the thigh rotates inward and the knee collapses toward the midline on each landing — repeated thousands of times per run. That's why treating the knee alone often produces temporary relief followed by return of symptoms, and why hip strengthening features so heavily in management.
Common contributing factors
Usually several combine rather than one single cause. Training load — rapid increases in mileage or intensity, the most common trigger. Hip and glute weakness, letting the knee track poorly. Quad weakness or imbalance, affecting how the kneecap moves. Overstriding and low cadence, increasing load through the knee on each step (see running cadence). Downhill running, which substantially increases the eccentric load on the knee. Foot and ankle mechanics, including limited ankle mobility. And worn footwear. Most of these are addressable, which is why outcomes are generally good with appropriate management.
The general management approach
Common principles, though specifics should come from a clinician. Modify load rather than stopping everything — reducing volume, avoiding downhill running and aggravating activities, while keeping moving; total rest tends not to solve the underlying issue. Maintain fitness with low-impact work like cycling or the rowing machine, within comfort. Strengthen the hips and quads — this is the cornerstone of most rehab approaches, and evidence generally supports hip-focused strengthening. Address mechanics where relevant, including cadence. Return to running gradually, which is where relapses commonly happen. Expect this to take weeks, and get a physiotherapist to sequence it properly.
Reducing your risk (prevention)
Prevention overlaps heavily with management. Increase mileage gradually — the 10% guidance in how to run longer. Strengthen your hips and glutes consistently, not just when something hurts — lateral band walks, single-leg work, and single leg deadlifts; the full set is in hip strengthening for runners. Build general leg strength including quads. Check your cadence if you're overstriding. Be cautious with downhill volume, which loads the knee heavily. And replace worn shoes. Runners who strength train consistently tend to have fewer of these problems.
When to see a professional
Get assessed if you have persistent pain (beyond a couple of weeks), pain that's worsening, swelling, the knee giving way or locking, pain following a specific injury or twist, or pain that limits daily activities. Also worth knowing: several different conditions cause anterior knee pain, and distinguishing patellofemoral pain from IT band syndrome, meniscal issues, or tendon problems isn't something to guess at from an article. Appropriate early assessment and a targeted strengthening programme generally produce good outcomes — considerably better than months of resting, resuming, and re-aggravating.
Quick answers
What is runner's knee?
Usually patellofemoral pain syndrome — pain around or behind the kneecap, typically gradual and worse with running, stairs, squatting, or prolonged sitting.
What causes runner's knee?
Usually a combination — training load increases, hip and quad weakness, poor knee tracking, overstriding, and downhill running.
Why do my hips matter for knee pain?
Weak hip stabilisers let the knee collapse inward on landing, so the knee absorbs poor alignment repeatedly.
Should I stop running?
Usually load modification rather than complete rest, but severity varies — get it assessed.
How long does it take to resolve?
Typically weeks with appropriate management; gradual return is essential to avoid relapse.
What exercises help?
Hip and glute strengthening plus quad work — ideally prescribed for your case.
When should I see a doctor?
Persistent, worsening, or swelling knee pain, giving way, locking, or pain after a specific injury.
The knee is where it hurts. The hip is often why. Which is exactly why resting the knee helps until you start running again.
Runner's knee is the most common running injury, and it usually reflects a combination of too much load and not enough control from the hips. Management means modifying load, strengthening the hips and quads, addressing mechanics, and returning gradually. Get it assessed properly rather than guessing — and build the hip strength that prevents it recurring.