With the side-to-side plyo push-up, place one hand on a stable elevated surface and keep the other arm on the floor. As with the all plyo push-ups, the goal is to project yourself explosively. In this variation, you switch hand positions in mid-air. Keep your glutes and abs tight.
Absorb the impact with your elbows at about 90 degrees. Do not lower the chest all the way to the ground.
The Fortress believes there are four fundamental directions a weight must be pulled or lifted in order to build a kick-ass back. He calls it his Directional Back Training Principle and it has nothing to do with North and South.