This one’s great for developing that necessary power for transitioning out of the eccentric (negative) portion of the lift and into an explosive concentric. Set-up is such that you have some support that bottoms out just above your chest (in this case, the safety arms of a squat rack. You might hafta get creative on this one in a public gym, but it’s not overly complex). Starting at the bottom of the lift, explode into the concentric lift. Control the eccentric back down to the bottom and repeat.