The pause parallel back squat is a partial squat to strengthen the most mechanically weak position in the squat to help lifters move through their sticking points more easily and better control posture. Pausing at the parallel position magnifies the effects.
 
Back squat as usual but stop when the thighs are approximately horizontal—just look for the position you want to stop in least, and stop there. It may be slightly above or below horizontal. Ensure your position is exactly as it would be at that point in any other squat—don’t sit the hips back farther or shift to the heels to make it easier.
 
After 2-3 seconds to eliminate any stretch reflex, drive up directly from the pause position to standing without allowing your chest to lean forward or your weight to shift to the heels.
  Notes
This variation places more strain on the knees than full-depth squats for athletes with adequate mobility, so only use it if you have healthy knees and plan to take care of yourself.
 
Purpose
The pause parallel back squat forces the lifter to stop, support position and posture, and change directions at the most mechanically disadvantaged point in the movement, where the leverage is the worst. This will build strength in this position, which can help lifters improve their ability to drive through the sticking points of their cleans and squats.
 
Programming
There are a number of possibilities when it comes to programming the pause parallel back squat. Most common will be sets of 3-6 reps and using this variation as one of 2-3 or more squat sessions each week. It can also be used for back-off sets following sets of full-depth back squats.