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Training Plyometrics, Part 2

Training 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, training 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 training 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.

 

Plyometrics build power

TRAINING PLYOMETRICS: 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.

 

TRAINING PLYOMETRICS: REACTIVITY AND STIFFNESS

When it comes to performance, we want to utilize as much elastic energy as possible. When I speak to groups I often use an example with two balls: a hard rubber ball and a softer foam ball.
If you drop both of these balls from the same height, what is the resulting rebound? The softer ball allows a ton of the kinetic energy to be absorbed and it rapidly loses height.
The hard rubber ball maintains a high degree of stiffness and maintains a higher rebound over multiple bounces, even with the same initial drop height. Our legs and our running strides are like the balls – if our legs can’t maintain a certain amount of stiffness, facilitated by strength, we will lose energy into the ground at high forces. The goal is not to lose energy into the ground but to have you rebound back off the ground. This is the easiest way to demonstrate reactive plyometrics.
 
When an athlete is moving at high speeds, like in sprinting, the resulting ground reaction forces are multiple times the force of their own bodyweight. The goal is to create maximum stiffness, minimize ground contact time and transfer as much force as possible. We call this the reactive strength index, the measurement of jump height/contact time. The higher the number the better. This means that we’re outputting more power in less time.
 
These reactive jumps are the types of movements we see in sport. Every hop, jump, cut, burst and fast reaction comes from a reactive plyometric.
 
 
 
In order to progress these drills, start with low forces (low jump height or slow speed entering ground contact) and aim to minimize contact times. This should be done both unilaterally and bilaterally.




Once your athletes show great control and effectiveness you can slowly add forces through more contacts, more height or faster speeds entering the contacts. Once an athlete becomes strong enough, these types of jumps don’t FEEL hard necessarily. However, don’t let your athlete be mistaken, reacting quickly at high forces is extremely hard on the nervous system and the performance drop off will still occur. Remember, increasing your Reactive Strength Index requires a focus on really cutting down the ground contact time.

 


 

RSI paper

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!

 

Remember,

It’s About Getting Better!

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