PERSONAL TRAINER INSTRUCTION :
The pistol squat is a single leg squat. The mechanics of a regular body squat are applied to the single leg. Slowly lower your body down in a controlled fashion with your weight on your heel. Extend the other leg forward through this process. As you lower, be sure to keep your knees behind your toes and to not allow your knees to dip inwards (valgus). Drive through your heel and consciously activate the gluteus maximus (buttocks) at the top of the repetition. Exhale as you stand up.
This exercise has many variations such as body weight or assisted with an exercise band.
Do not do this exercise if you have knee pain. This is an advanced exercise.