Knees caving in is a symptom, not a cause. Here is what to actually fix.
The squat is a movement everybody performs and few perform well. These five mistakes we see every day.
One: too much weight too soon. If technique falls apart on the last reps, the weight is too heavy — without exception.
Two: knees caving inward. This is usually not a knee problem but a glute strength or foot position problem. Try to 'screw' your feet into the floor without actually moving them.
Three: heels lifting. Almost always restricted ankle mobility. The mobility class addresses this directly.
Four: lower back rounding at the bottom. Only descend as far as you can hold a neutral position, then work on depth gradually.
Five: holding your breath through the whole rep. Take a breath at the top, hold it through the descent, exhale on the way up.
If you are not sure which of these applies to you, come to a Strength 101 class and we will go through your technique.