What Is Plyometrics?
By: Vincent Belviso, CSAC, SCS
What is Plyometrics?
Hear the word around a crossfit circle, it probably means you will be “jumping around all nimbly bimbly like” until you feel like your heart is going to explode…or until you misjudge that one fatal step and skin your knees.
But, what if I told you the concept of plyometrics (plyo) applies to much more than box jumps alone?
Plyo can be performed in both upper and lower extremity movements in exercise and in sport. A basketball player soaring through the air to posterize some poor defender en route to a rim rocking dunk can easily be seen as plyometric; but, a pitcher (or any baseball player) making a throw is also utilizing the same concept, only being demonstrated by a different muscle grouping during a different movement pattern. In the weight room, plyometrics are not just those agonizing box jumps- the concept is also being utilized during explosive squats, olympic lifts, and even the bench press.
A plyometric movement is one in which a Stretch Shortening Cycle (SSC) occurs within a muscle by using a lengthening movement (eccentric) and is quickly followed by a shortening movement (concentric). The easiest comparison is that of flicking a rubber band: place a rubber band between two fingers, create little to no tension in the band and remove your fingers. The rubber band will harmlessly fall to the ground. However, pull one of your fingers back, lengthening the band and quickly letting go, the band will first shorten and then propel itself across the room in accordance with the amount of built up tension prior to the release.
Thus, plyometrics is split into three phases:
The eccentric pre-stretch phase is the muscle during the lengthening stage. If you have performed a box jump, before you go to take off you more than likely (at least, you should be) bending at the waste, sitting back into your hips and priming your glutes and hamstrings for take-off.
That moment pre-jump when you no longer are lowering or sitting your hips back any further, but just before you drive your feet as hard as you can into the ground to initiate the jump, that split second of isometric action is referred to as the amortization phase.
Technically speaking, it is the time delay between overcoming the negative work (the pre-stretch) of the initial lengthening phase (the muscle getting longer) to generate the force production (pushing your feet into the floor during jumping) and accelerating into muscular contraction (shortening phase, BLAST OFF!).
The shorter this phase is, the more effective and powerful the preceding movement will be. Like our rubber band, or slingshot, stretching and holding is far less effective than, say, stretching it and releasing very quickly. Energy is being stored in the form of elastic momentum within the working muscle group during the pre-stretch leading to the “stretch reflex.”
Think about hitting the bottom of a really heavy squat and feeling your hamstrings bounce you out of your terminal position- stretch reflex! However, if you reach end range of motion and hesitate (or purposely delay like in paused reps), that bounce is no longer there. This amortization phase has been removed because that stored elastic energy is wasted as heat and the stretch reflex was not activated. As a result, the following concentric contraction will not be as effective. An experienced lifter knows the timing of activating and utilizing the stretch reflex can be the difference between hitting that new PR or turning your spotter into a lifeguard.
The final phase, the concentric, or shortening, phase can also be referred to as “resultant power production performance” phase… or not, because that is a mouthful. This is take off-- actually leaving the ground during the jump, or utilization of the stretch reflex out of the bottom of the squat or bench press to return the weight forcefully back to the top.
This is how jump performance can improve from repeatedly practicing proper jump technique. It is why a coach might program you to drop a few pounds in your olympic or compound lifts and tell you to move the weight faster. Efficiency is key: efficiency in the desired movement pattern, efficiency in barbell path, efficiency in utilizing the stretch reflex. Efficiency= better power production and efficient power production over time = more strength.
Blending the three aforementioned phases to perform a plyometric movement is used to enhance a muscle’s power performance. The rapid deceleration to acceleration produces an explosive reaction that increases both speed and power during athletic activities.
So if you want to develop speed, or power, utilizing plyometrics is a valuable tool in your toolbox.
Vincent can be reached at firstname.lastname@example.org
Check out his Instagram: vibes_training
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