Runner's knee: what it is and the exercises that help

Patellofemoral pain — runner's knee — is a diffuse ache around or behind the kneecap. It is typically worse going downstairs, after sitting for a long time, and on downhill running. It is the single most common running complaint.

What it is not

It is generally not cartilage wearing away, the kneecap being out of place, or damage that gets worse the more you run. Those framings are common, frightening and mostly unhelpful.

The current understanding is closer to: the tissue around the joint has been asked to tolerate more load than it currently can, and has become sensitised. That is a capacity problem, and capacity is trainable.

What causes the flare

Usually a change in load:

• Mileage or intensity going up faster than adaptation
• A lot more downhill running than usual
• Coming back after time off at the old volume
• Sometimes a change in shoes or surface

Contributing factors that show up repeatedly: weak hip abductors and quadriceps, and a low cadence with a long overstride, which increases the braking force through the knee on each step.

What actually helps

Hip and quad strengthening has the best evidence — and hip work matters more than most people expect. When the glute medius cannot control pelvic drop, the knee absorbs the difference.

Practically:

• Squats, split squats and step-ups, loaded properly, in the 6–8 rep range
• Side-lying hip abduction and banded lateral walks
• Quad work — leg extensions or Spanish squats if the deep-knee positions hurt

Give it time. Meaningful strength change takes six to twelve weeks, and people abandon programmes at week three because nothing has changed yet.

Increase your cadence a little. Raising step rate by roughly 5–10% shortens your stride and reduces load at the knee. A metronome app or a playlist at the right tempo works. This often gives noticeable relief within a couple of runs, which makes it a useful bridge while the strength work catches up.

Do you have to stop running?

Usually not entirely. The working rule most physiotherapists use:

• Pain up to about 3/10 during a run is acceptable
• It should settle within 24 hours
• It should not be worse the next morning

If those hold, keep running at reduced volume, avoid downhills for a while, and let the strength work do its job. If they do not hold, reduce further.

Complete rest usually feels great and achieves nothing — the pain settles, capacity does not improve, and it returns on the first proper run back.

When to get it looked at

• Locking, catching, or the knee giving way
• Significant swelling
• Pain that is sharp and localised rather than diffuse
• No improvement after eight to twelve weeks of consistent work

Those are different problems and worth a proper assessment.

Where this fits

The strength material above is the same six-movement routine covered in more detail in strength training for runners. And if the flare followed a jump in mileage, how to come back after a break covers building more gradually.