Wednesday, 13 January 2016

The Stretch Shortening Cycle


In a previous post ‘Jump Height and the Dancer’ (http://performance-sports-therapy.blogspot.co.uk/2015/10/jump-height-and-dancer.html) I wrote about the use of plyometric training to enhance performance, prevent injury and rehabilitate athletes. Following on from this post, I am going to give you a little background information into the physiology behind it all.

I’m not one for writing massively long posts, and I know dancers aren’t one for reading them either. So here is a quick read on the stretch shortening cycle, what it is, and how it works.


source: Pinterest




The Stretch Shortening Cycle (SSC) is the body’s natural way to stretch, and so store energy. The benefit of this cycle comes by using it, in addition to your body’s own muscular strength. So, the more muscle, the bigger the stretch and the more elastic energy that can be stored.

Let’s take a look at how this works…

source: Google Images


The stretch shortening cycle involves two phases of muscular contraction

1.Eccentric phase – muscle lengthening under tension
2.Concentric phase – muscle shortening

The pre-stretch of the muscle causes it to be eccentrically lengthened. With this, tension is built in the muscle – similar to a rubber band when stretched. The longer the time the pre-stretch is held, the less tension is stored in the muscle. The shorter period of time for the pre-stretch, the larger the amount of tension.

This stored energy helps increase the strength of the following contraction.

The faster the muscle is stretched eccentrically, the greater the force will be on the following concentric contraction. For example, a quick plié into a Pas de Chat creates the tension necessary to create height off the floor.

Have a go yourself –

1. Take a rubber band or hairband and hold the band stretched for 5 seconds then release. Notice the small distance the band has travelled. Now, in one movement take the second band, pull back and release. You will note that this band travels a lot further. This is because the second band has not lost tension in the period it is held in, therefore it has a larger amount of tension.
2. The same principle applies when looking at a squat jump (SJ) in comparison to a countermovement jump (CMJ). Sit in a Squat jump and hold this squat position for 5 seconds. After 5 seconds, release and jump.

Next, perform a quick countermovement jump. You will notice
that when you performed a CMJ your jump height was greater.



I hope this brief article helps you to understand how the stretch shortening cycle works and how this can be applied to plyometric training which I shall look at in more detail in a future post.


-E
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1 comment

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