Plyometrics are a complex but rewarding part of athletic development. They’re complex because there a lot of nuances involved in doing them most effectively and efficiently, and the high forces involved should force you to emphasize optimal technique. However, once you put it all together and successfully implement them into your program, you can reap great rewards in the realm of power and rate of force development.
In my mind, plyometrics are a necessity in any athletic training program. The speed at which they are performed, allows an athlete to increase their rate of force development, ie. how quickly they develop and display power. It’s great to build strength in the weight room, but plyometrics will add the speed component to that and don’t require any equipment.
I hope you already checked out PART 1, as this will be a continuation on the foundation laid out there.
Next, we’re going to get into the more dynamic types of jumping: Counter movement jumps and reactive jumps.
COUNTER MOVEMENT AND THE STRETCH SHORTEN CYCLE
Once we’ve begun to develop strength in our athletes, they’re now better equipped to handle eccentric forces and utilize a stretch reflex. Strength is important to decelerate the eccentric force and also hold positioning, since that will dictate the direction of our jump. There’s no sense trying to create a powerful jump if we can’t aim it in the right direction.
If we’re going to aim for optimum performance (output), we’re definitely going to want to utilize elastic or kinetic energy. This is the next progression. A counter movement jump is a jump which utilizes a short stretch reflex before moving into the concentric portion of our jump. If you remember Part 1, imagine trying to connect your landing with a concentric jump, only without a pause in between. The most common example that comes to mind is a simple vertical jump test, like they utilize at the NFL combine each year. The athlete starts in a tall position, rapidly drops into a stretch reflex and rapidly moves into a concentric jump. If done properly, the result is a huge increase in output from our stationary jump.
There is a secret to these next two types of jumps though (counter movement and reactive). In order to effectively utilize a stretch reflex and generate these high forces, we need them to be done rapidly. In the case of the CMJ (counter movement jump), the amortization phase has to be rapid. This is the transition between eccentric and concentric phases of the jump. If the athlete is too weak and the amortization phase lengthens out too much, the jump will simply become a concentric contraction, which was mentioned in part 2.
Therefore, it’s absolutely crucial to coach and cue short amortization periods in a simple counter movement jumps
There is an example in the embedded video below.
REACTIVITY AND STIFFNESS
RSI paper http://journals.lww.com/nsca-scj/Abstract/2008/10000/The_Use_of_Contact_Time_and_the_Reactive_Strength.5.aspx
As important as it is to build up a base from our first Part, the real performance break throughs will come maximizing these types of jumps. Specifically, once you start to increase your RSI, you will see major performance breakthroughs!