When an athlete can’t hit depth on their squat, the same advice is often trotted out to them
“it’s a hip mobility issue, work on that” or maybe “it’s an ankle or thoracic spine mobility issue”
But what if its none of these? what if it’s a stability issue?
If you are someone with generally crappy squat mechanics, can’t hit depth, excessive spinal tilt, knees not tracking over toes, etc. First off you need to ascertain if your mobile enough. To do this get into a quadruped position, from here rock back as far as you can maintaining your spine angle. If your able to bend at the knee, so the hip crease is back past the knee, congratulations you have passed and it’s not a mobility issue. If you fail, hammer the mobility work on the hips, ankles and thoracic spine, as the advice above.
Next, is it a stability issue? Grab a resistance band, dumbbell, squat rack or even doorframe at arms length as a counter weight and squat down. If your mechanics magically clean up and you hit depth (this will happen for many of you, believe me) then you have a stability issue. Pound your anterior core with with planks, rollouts, weighted carries, chops lifts etc and regular squat will start to look as pretty as the counterweighted one in no time.
Lastly, if you can get yourself into a nice, deep squat position using a squat rack or door frame as a counterweight but you can’t stand yourself back up then you have a major strength issue. Get yourself to the leg press machine and go to town. Do some planks to boost your anterior core stability whilst your over there too.