Glutes, Quadriceps, Hamstrings
Calves, Core
Kneel on floor/mat. Barbell optional on back (use rack).
Sit back glutes towards heels.
Chest up, core braced.
Explosively drive hips forward/up.
Jump from knees to land on feet in squat position.
Stand up from squat.
Carefully return to kneeling.
Repeat.