Lateral Explosive Step-Up
Stand alongside a box or other sturdy platform. Put your inside foot on the box's surface, your foot and knee pointed straight ahead. With your arms in a running position, explode up, driving your box-planted foot down, like you're trying to break through the box, and launch yourself into the air. At the top of the movement, your outside knee should now be raised, with your inside leg straight (just the opposite of how they were positioned at the start of the movement). Make sure to switch your arms, too, just like you were running.