What are plyometrics?

We have all heard the term “plyometric” before, but what really are plyometrics? I am sure if I asked you to list some, you could name a few, and may list some exercises that your high school coach told you are plyometrics but really are not. Jumping, sprinting, throwing, cutting, hopping, to name a few. But what really are plyometrics? 

The simple definition of a plyometric is a quick stretch immediately followed by a rapid contraction. This can be in any plane of motion, in nearly any joint of the body, and can have a number of different properties. The motion has to satisfy the above criteria in quick succession, meaning you cannot just have a quick stretch or rapid contraction by itself, but they have to be paired together. This is because there are three main phases of plyometrics and one phase is dependent on the other two.

The plyometric movement is built upon three main phases:

• Phase 1: Absorption (Eccentric Phase): This is the quick stretch phase. It occurs as the muscles and tendons rapidly lengthen and must respond to this sudden stretch.

• Phase 2: Amortization Phase: This is the critical, defining phase that makes a plyometric a true plyometric. It is the moment between the quick stretch and the rapid contraction. Without the immediate transition, the amortization phase is lost, and the movement is no longer plyometric.

• Phase 3: Propulsion (Concentric Phase): This is the rapid contraction phase. It involves a forceful and quick contraction of the muscles and the resulting recoil of the tendons.

  
  

The amortization phase is what helps to involve the tendon and its elastic properties, and not just rely on muscle. Think of your tendon as a rubber band - if you pull a rubber band apart quickly and let it go quickly, it snaps back to its resting position forcefully. If you hold a rubber band in the stretched position for a prolonged period and then let it go, it will not snap back as forcefully. This is similar to (not exactly like) how a tendon behaves and this is known as viscoelasticity. Viscoelasticity can be further defined as an object returning to its resting state after a force is acted upon it, while also being dependent upon the rate of the force applied.

A plyometric is so important because this movement involves the tendon and its ability to store and return elastic energy. The involvement of the tendon is known as the stretch-shortening cycle (SSC) and is what is responsible for fast movements being so much more explosive and powerful than movements that you take your time on. For example, from a standing position, squat down and hold that squat for three seconds. Without dipping back down, jump as high as you possibly can. Now start from a standing position, squat down to the same depth as quickly as you can and jump as high as possible.You will notice you jumped much higher on the second attempt. This difference illustrates the immense power generated by plyometrics and the SSC.

Stay tuned for further properties and types of plyometrics as well as how to train them.