The step-through is a knee prep exercise to help strengthen the muscles around the joint similarly to a Petersen or Poliquin step-up.
 
Stand with one foot on a low box or stack of plates and the other on the floor to the side and behind the upper foot.
 
Step forward, pushing up to the balls of the foot and trying to control the motion with the support leg to land gently. Reverse the motion to bring the foot backward to the starting position.
 
Purpose
The step-through is a knee prep exercise to help strengthen the muscles around the joint similarly to a Petersen or Poliquin step-up, that adds more motion and need for control.
 
Programming
This is a good preparatory exercise for use in a warm-up. 1-3 sets of 8-12 reps in each direction are appropriate.
 
Variations
Weight can be added with dumbbells or kettlebells.