The Box squat is used to strength the hamstrings, quads and glutes as well as starting strength in the squat with some transfer to the first pull of the deadlift. Unlike the squat (without a box) that is used to help strengthen recover in the clean and snatch. For our purposes the  box squat is used to develop strength “coming out of the hole”, especially when an Athlete looses momentum at the bottom of the clean and snatch.

Box height: at parallel
Stance: wide
Bar: high bar squat, drive traps into bar
Core: Expand your abdomen, not your chest. This will help keep your midline/spine tight when stopping gone the box
Eccentric Phase: With heels touching the box tilt hips and sit directly on your heels. Keep head and chest high, midline tight
Static/Relaxed Phase: Starts when your glutes hit the box. You should sit down completely on the box and roll back. This does not mean rocking, bouncing or touch and go.
Concentric Phase: Ascend from the box in an explosive manner. Yea moves first followed by glutes and hips. Forcefully flex the hips, glutes, hamstrings, abs and midline.