I have heard these exercises called a couple of different names (drop catch/relax catch) and to be quite honest, I think either one works. I am not quite sure who came up them, but I have seen them in being used by many successful coaches. For the sake of consistency, in this article I am going to refer to them as drop-catch exercises
What Are They?
Drop-catch exercises involve starting at the top of position of the movement, letting yourself relax and then catching your self at the bottom before exploding back up. I believe Cal Dietz and Joel Smith have written articles on how to perform these. Each person probably has their own specific method of teaching the movements, (some prefer to actively pull yourself to the bottom while some say just relax and fall) and I assume you can find their teachings at their respective websites. However, this article isn’t made to talk about the technique and form of the movement, but instead the principles behind the movement.
Below is an example of a drop catch performed by AFL
The Idea
The idea behind drop-catch movements is very similar to that of the depth jump. The movement utilizes high velocity loading as a stimulus for force production, instead of mass on the barbell. However, it is not just about the velocity, but it also has to do with rate of force development, neural mechanisms and physics.
Normal movements
Normal movements are done with some sort of eccentric portion that descends at a speed slower than the acceleration of gravity. The reduced falling speed is caused by muscular forces acting on the bar (eccentric forces). If there were no forces, then the bar would fall at the same rate of the acceleration of gravity (physics). Because these forces are developed, we can assume the body is in a pre-tensioned state (it is not completely relaxed). So, when you transition the movement from eccentric to concentric (downward to upward) the change in velocity is not a very large and the muscles are already “turned on”.
Drop catch
Physics
Unlike normal movements, drop catches utilize the velocity overload that gravity provides. When you “relax” you allow the barbell to fall at the acceleration rate of gravity. This means that there is no eccentric forces acting on the bar (bar falling at acceleration of gravity). So, when it comes to transitioning from downwards to upwards, the body has to produce a much larger change in velocity.
Physics and Neural
The relaxation part causes two things to happen. 1) As mentioned above, it increases the speed at which the bar falls. However, we know that the increase in falling velocity can only occur because there is not eccentric force acting on the barbell, which tells us there is no upward muscular force (breaking force) being produce. 2) If there is no upward muscular force being produced then we might be able to make the assumption that the muscle is not pre-tensed and the nervous system isn’t turned in the same way it is when the muscle is producing an eccentric force.
So, when we transition from the downward to the upward movement, we not only have to produce a large amount of force to produce a large change in velocity, but we also have to do it without having our muscles turned on. This theoretically requires a high level of neural output in a short period of time, to produce enough force to reverse this falling action (rate of force development). Like a light switch, we are turning it off, but then turning it back on just before its too late and we crash into the ground.
Conclusion
Understanding the “why” behind some of these movements can give you a better understanding of how they work and whether or not you want to put them into your training program. The concepts themselves can be applied to nearly exercise you see fit.