What knee collapse is
Knee collapse is when your knee drifts in toward the middle as your foot takes your weight.
From the front or behind, the knee falls inside the line between your hip and your foot.
Why it matters
A knee that drifts in sends some of each push sideways instead of forward.
It often goes with hip drop, so the two are worth working on together.
How to work on it
Aim to keep each knee travelling straight, over your second toe, as you land.
Single-leg work off the treadmill helps the leg hold its line.
One drill to try
- Do slow single-leg squats in front of a mirror, knee over your second toe.
- Hold the bottom for a breath, then stand tall.
- Run a minute easy and feel each knee track straight.
How to film it so Llyr can read it
Stand your phone in front of or behind the treadmill at about hip height, a few steps back, with your whole body in the frame.
Keep the stand well clear of the belt. Run steady for at least thirty seconds.
Already have a clip? You can import a video you filmed earlier instead. Read the full filming guide.
What you see in Llyr
When a knee drifts inward as you land, step after step, Llyr names it Knee caving and shows it on a still from your own video.
The cue to take into your next run is Knees over toes.
Llyr is a second set of eyes, not a coach. Check each correction on the replay, and if your coach sees it differently, go with your coach.