Pistol Squats: Understanding Squatting Mechanics
How to Pistol Squat Part 2:
In this segment Carl begins by reviewing proper squatting mechanics and positions for a normal two-legged squat. Carl explains the need to change orientation in order to engaging the posterior chain in order to stand up, and also emphasizes the need to drive the knees out in order to keep the shin vertical to avoid stress and shear on the knees while squatting. Finally, Carl progresses to the next drill which is to do step-ups onto a box.
Also check out Pistol Squat Progression Pt. 1.