Runner's Knee (Patellofemoral Pain): What the Research Says About Movement Patterns and Fixes

If you run long enough, you probably know someone with runner's knee, and there is a decent chance you have felt it yourself. Patellofemoral pain (PFP) is the clinical name for that dull ache around or behind the kneecap that flares on hills, stairs, long runs, and after sitting for a while. It shows up near the top of almost every survey of running injuries.[1][2]

This article walks through what PFP is, the movement patterns the research associates with it, and where the evidence points for runners and coaches. The honest headline: there is no single cause and no magic fix. But there are patterns worth understanding and levers worth pulling. If you want to see how your own stride moves, you can screen your stride with our free tool and read on with your own footage in mind.

What runner's knee actually is

The patellofemoral joint is where the kneecap (patella) glides in a groove on the front of the thigh bone (femur) every time you bend and straighten your knee. PFP is pain in and around that joint, usually without a single dramatic injury. It tends to build gradually and is often described as an overuse or load-tolerance problem: the tissue is being asked to handle more than it is currently prepared for.[2]

Two forces drive stress in this joint: how hard the quadriceps pull the kneecap into the groove, and the angle at which the kneecap tracks. Anything that increases the compressive load or shifts the tracking can raise the stress the cartilage behind the kneecap experiences. That is the lens researchers use when they study running mechanics and PFP.[3]

The movement patterns research links to PFP

Most of what we know comes from comparing runners who have PFP with runners who do not, plus a smaller number of studies that follow healthy runners over time. A recurring theme is that the knee is often the victim of what is happening above it, at the hip and pelvis.[3]

Hip adduction and internal rotation (dynamic valgus)

When the hip drops the thigh inward and rotates it in during stance, the knee tracks toward the midline. This inward collapse is often called dynamic knee valgus. Runners with PFP have shown greater hip adduction and altered hip rotation across running and single-leg tasks compared with pain-free runners.[5] In a prospective study that followed female runners over time, those who went on to develop PFP had exhibited greater hip adduction at baseline, which is one of the stronger signals we have that this pattern is not just a byproduct of pain.[4]

Contralateral pelvic drop

If the pelvis dips on the swing-leg side during stance, the stance-leg hip effectively adducts even more. Systematic review evidence links increased contralateral pelvic drop, hip adduction, and hip internal rotation to PFP in runners, though the certainty is moderate rather than definitive.[6] This is the same chain of mechanics implicated in other lateral hip and knee complaints, which is why it overlaps with IT band syndrome in runners.

Overstriding, low cadence, and trunk position

Landing with the foot well ahead of the body, often paired with a low step rate, tends to increase braking forces and knee flexion demands. An upright, extended trunk also shifts load toward the front of the knee. In a controlled study, adding forward trunk lean reduced peak patellofemoral joint stress, while running more upright increased it.[7] These are levers, not verdicts: your best trunk and stride are the ones your whole body tolerates.

Where the evidence points for fixing it

The encouraging part is that several of these patterns are modifiable, and interventions that target them tend to improve pain and function. No single intervention wins for everyone, so think in terms of stacking a few sensible bets.

Build hip and glute strength

Because hip control sits upstream of the knee, strengthening the hip abductors and external rotators is one of the most consistently supported directions. In a randomized controlled trial, isolated hip abductor and external rotator strengthening improved pain and function in women with PFP compared with no exercise.[10] Proximal work also complements knee-focused rehab rather than replacing it. If you are building a routine, our guide to glute medius exercises for runners is a practical starting point.

Nudge your cadence up

Taking slightly quicker, shorter steps reduces how far you overstride and lowers the load the knee absorbs per step. Modeling and lab work show that increasing step rate reduces patellofemoral joint forces.[8] In runners who already had PFP, a roughly 10% increase in step rate improved running kinematics and clinical outcomes at 4 weeks and 3 months.[9] A 5 to 10% bump is the usual starting range; see our running cadence guide for how to do it without forcing an unnatural gait.

Retrain the pattern, not just the part

Gait retraining aims to reduce the specific pattern a runner shows, whether that is hip adduction, pelvic drop, or overstriding. Reviews find that runners with PFP have altered biomechanics that targeted interventions can modify, alongside improvements in symptoms.[6] Cadence and stride changes are the most accessible form of this, which is why fixing overstriding overlaps so much with knee comfort. Our piece on how to fix overstriding covers the cues that tend to help.

Manage load like it matters, because it does

Even perfect mechanics will not save a knee from a training spike. PFP behaves like a load-tolerance problem, so sudden increases in weekly volume, hill work, or intensity are a common trigger.[2] Progress gradually, respect pain that lingers into the next day, and treat rest and easy days as part of the plan rather than a failure of it.

How to put this to work

Start by understanding your own stride rather than copying someone else's. Film a few strides from behind and from the side, or use the CritchPitch Run Lab tools to see whether your hips, pelvis, cadence, or foot strike show the patterns above. Then pick one or two levers, hip strength plus a small cadence change is a common, well-supported combination, and give them weeks, not days, to show up. Mechanics are worth studying, but they work best paired with patient, progressive loading.

Runners who developed patellofemoral pain had exhibited greater hip adduction than those who stayed healthy, pointing to the hip as a contributor rather than an innocent bystander.Paraphrased from Noehren, Hamill & Davis, 2013[^4]