Why Your Knees Cave In When You Squat (It's Not a Knee Problem)
You're squatting, someone tells you your knees are caving in, and you think about pushing them out. It works for a rep or two. Then they drift back in again.
If this sounds familiar, the fix isn't more cueing. The problem isn't your knees at all.
The Knee Is Just Following Orders
When your knees cave inward during a squat — a movement pattern called knee valgus — the instinct is to treat it as a knee problem. Cue the knees out, tape the knees, strengthen around the knees. But the knee isn't making a decision here. It's going where the hip is allowing it to go.
The femur — your thigh bone — connects the hip to the knee. During a squat, the glute medius is responsible for controlling the position of the femur. It's the muscle that keeps your hip stable as you load through it and prevents the knee from collapsing inward. When the glute med is weak or not firing efficiently, it can't do that job. The femur rotates inward, and the knee follows it down into valgus.
Every time.
Why Cueing Doesn't Fix It
Telling someone to push their knees out works in the short term because it forces a conscious override of what the hip is allowing to happen automatically. But the moment attention shifts elsewhere — heavier load, more fatigue, faster pace — the pattern comes back. You haven't fixed the underlying weakness, you've just created a temporary workaround.
This is also why people can spend months working on their squat technique without lasting improvement in knee tracking. Technique work addresses what you're doing. It doesn't address why you're doing it.
It Shows Up Everywhere, Not Just the Squat
Knee valgus driven by glute med weakness isn't limited to the weight room. It shows up during running — particularly at higher speeds or as fatigue sets in during longer efforts — during cutting and jumping movements in sport, and during single leg activities like lunges and step-ups where the demand on hip stability is even higher.
This is why knee valgus is such a common thread in anterior knee pain, IT band syndrome, and patellofemoral issues across active populations. The knee takes the load that the hip wasn't controlling.
What Actually Needs to Be Addressed
The fix has two components — and both matter.
First, the glute med needs to be loaded and trained specifically. Generic glute work like hip thrusts tends to bias the glute max. Targeting the glute medius requires exercises that load hip abduction and single leg stability — banded clamshells, lateral band walks, single leg deadlifts, and lateral step-ups done with intention and control.
Second, the movement pattern itself needs to be retrained once the strength is there. If someone has been squatting in valgus for years, the nervous system has grooved that pattern deeply. Strength work alone may not be enough to change it automatically — the pattern needs to be practiced correctly, with enough volume and attention that it becomes the new default.
In some cases there are also soft tissue restrictions at the hip — in the glute med itself, the TFL, or the lateral hip capsule — that are limiting how well the muscle can fire and control the femur. When that's the case, manual treatment targeting those restrictions can significantly accelerate how quickly the pattern changes.
The Bottom Line
If your knees cave in when you squat, someone telling you to push them out is the right cue but the wrong solution. The knee is doing what the hip is allowing it to do. Fix the hip stability, fix the squat — and fix it for good this time.
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Dr. Brian Trautman is a chiropractor, certified athletic trainer, and strength and conditioning specialist at Optimal Health & Performance in Cincinnati, OH. He specializes in movement-based care for athletes, runners, and active adults.
