I must have done a shitty job describing this exercise since I’ve received numerous emails about the proper technique. So here’s further instruction:
The lunges should be performed static from a standing position. In other words, you should not be walking forward. You should step forward and lunge down (trunk vertical, touch the knee to the floor). From that position, push back to the starting (standing) position as hard/fast as you possibly can. Switch to the opposite leg and perform the same technique. Alternate legs until you perform 3 reps with each leg.
Hope this clears up any confusion.