How to Fix Knees Caving In on Squats (Knee Valgus)

Knee valgus is when your knees track inward, toward each other, instead of staying in line with your toes. It usually shows up during the drive out of the bottom of a squat, and it often gets worse as the weight climbs or as you fatigue.

A small, brief inward movement under a max effort isn't always a problem. A consistent collapse on most reps is the pattern worth fixing.

The usual suspects are weak or under-active glutes and hip external rotators, limited ankle mobility (which lets the arch and knee cave), and simple motor control — your body hasn't learned to hold the position under load.

Loading too heavy too soon is a multiplier: when a weight is beyond what your positioning can handle, the knees cave as a compensation.

Valgus puts shear stress on the knee and leaks force you could be using to stand the weight up. Over time, a hard, repeated collapse is associated with higher knee-injury risk.

It can also reveal a left/right imbalance — one knee caving more than the other is a sign one side is doing more of the work.

"Knees out" or "spread the floor" — actively push your knees out so they track over your toes.

Grip the floor with a tripod foot (big toe, little toe, heel) so the arch doesn't collapse.

Brace your core before you descend, and control the way down instead of dropping.

Banded squats: loop a mini-band just above your knees and push out against it for a few sets — it teaches the "knees out" pattern fast.

Goblet squats with a deliberate knees-out cue, tempo squats (3-second descent), and glute work like clamshells and hip abductions.

If ankle mobility is the limiter, add ankle mobility drills or briefly elevate your heels to groove the pattern while you build range.

Film yourself from the front. Watch whether your knees stay stacked over your toes through the whole rep, and whether one side caves more than the other.

This is exactly what FormLens measures automatically — it tracks knee angle and flags left/right asymmetry on every rep, so you can see the fix happening instead of guessing.