38. What are Plyometrics?
Description
This article is from the Fitness FAQ, by Jeff Gleixner (glex@cray.com) with numerous contributions by others.
38. What are Plyometrics?
From: lylemcd@delphi.com
Well, plyometrics are basically a form of modified power train-
ing. However, generally speaking, only body weight is used due to
the high impact nature of this technique. Similar power train-
ing, plyometrics emphasizes speed of movement over anything else
(well, perhaps not safety). The goal is to "teach" your muscles
to respond quickly and powerfully. Also, some feel that
plyometrics may improve neural pathways and improve muscle fiber
recruitment over time. This makes it useful as well for athletes
who don't necessarily need power but desire improved strength
(i.e. power lifters and body-builders). So, what exactly is
plyometrics.
Well, before I get into the actual description of plyometrics and
how to incorporate them into a work out routine, let me bore you
with some physiology. Plyometrics relies on one of the basic
facts of muscular physiology: a pre-stretched muscle is capable
of generating more force. Basically, if two conditions are met
during the performance of plyometrics, greater force output can
be realized. The two conditions are this:
1. The muscle must be pre-stretched prior to the concentric
movement
2. This pre-stretch must occur immediately prior to the
concentric movement or nothing happens
Actually, you've probably all done this if you've even jumped.
Think about it, when you jump what do you do right before leaving
the ground? You take a slight prep by bending your legs so that
you can jump further or higher. Well, this prep movement satis-
fies the above two conditions. This is why high jumpers do a
quick knee flexion before jumping and basketball players do the
same thing, so that they can go higher easier. Ok, enough phy-
siology.
Although plyometrics can be used for essentially any muscle, it
is probably most frequently performed for the legs as most ath-
letes require the majority in their legs. Probably the most
basic plyometric exercise is depth jumps. Very basically, you
stand on top of a box, chair or table and jump to the ground off
of it. You should absorb some of the impact by bending your
knees (which fulfills requirement 1) and then immediately jump as
high as possible (which fulfills requirement 2). This can be
performed for several repetitions. As you can imagine, the limit
to plyometric exercises is really determined by one's imagina-
tion. Plyometric push-ups are very possible by exploding the
body off the floor, absorbing the impact with the hands, lowering
the body slightly and then exploding again in rapid succession.
Also, there are several books available which outline various
plyometric exercises for various muscles.
However, understand that there is a high injury potential as this
type of exercise is extremely high intensity. Generally, box
height on depth jumping should be kept between eight and sixteen
inches (1) to minimize risk potential. Also, due to it's high
intensity nature, plyometrics should probably only be performed
at limited times during the year (preferably during the power
phase if you are following periodization) and no more than once a
week to avoid injury. Also, due to the high stress that will be
felt on the connecting tissues (ligaments and tendons), at least
six months or more of basic weight training should be performed
before incorporating plyometrics into any routine.
For more information, please see "Explosive Power: Plyometrics
for Bodybuilders, martial artists and other athletes" available
from Health for Life (1-800-874-5339), "Jumping into Plyometrics"
by Donald A. Chu, PhD available from Human Kinetics (1-800-747-
4457).
For a catalog of previous posts send requests to
lylemcd@delphi.com along with questions/comments.
Lyle
References: 1. M.F. Bobbert et. al. "Drop Jumping II. The influ-
ence of dropping height on the biomechanics of drop jumping" Med.
Sci. Sports Exerc Vol 19(4), 322-346. 1987.
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