Knees Caving In During Squats (Knee Valgus): Causes and Fixes

Your knees track inward toward each other as you drive out of the bottom, usually worse on heavier sets or the last few reps.

Why it happens

Weak or under-recruited glute medius, which is what holds the femur in external rotation under load.
Stance too narrow or toes pointed too straight ahead, leaving no room for the knees to track over the feet.
Simply loading more weight than your current stabilizers can control - valgus that only appears above 85% is a strength problem, not a mechanics problem.
Ankle mobility restriction forcing compensation further up the chain.

How to fix it

Cue "spread the floor"

Think about pushing the floor apart with your feet rather than pushing down. This fires the external rotators without you having to think about your knees at all.

Widen your stance slightly and turn your toes out 15-30 degrees

Then track your knees directly over your second and third toe. Most caving is a stance-width problem masquerading as a strength problem.

Add banded lateral walks and single-leg work

Two or three sessions a week. Glute medius responds fast, usually within three to four weeks.

Drop to a weight where it disappears entirely, then build back

Grooving the pattern under control beats grinding reps that reinforce the fault.

Worth knowing: Sharp knee pain, or caving that shows up even with bodyweight, is worth a physio visit rather than a cue.

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Knees Caving In During Squats (Knee Valgus): Causes and Fixes

Why it happens

How to fix it

Not sure if you are actually doing this?

Other back squat faults