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Plyometrics FAQ

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Article 12450 of rec.sport.volleyball:
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From: charliex@ix.netcom.com (Charlie Bender)
Newsgroups: rec.sport.volleyball
Subject: Plyometrics and Strength Shoe FAQ (Long)
Date: 3 May 1995 17:57:30 GMT
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After one too many questions I have decided to put together a
plyometrics FAQ.  All information is for information purposes only.
Feel free to distribute, hell even charge money for it if you want,
just donít hold me responsible. Not that I have anything you could get
anyway.  Any comments please email me at CharlieX@ix.netcom.com

1) What are plyometrics?
2) Why should I care what they are?
3) What are good plyometric exercises for increasing vertical jump?
4) What are good plyometric exercises for increasing speed
5) Do strength shoes work?  Where do I get them? How much do they cost?
   Are there alternatives? Why are strength shoes included in a
   plyometrics FAQ
6) What is a good book on plyometrics and where can I get it.
7) Are plyometrics dangerous?
8) Random thoughts

1)  Q: What are plyometrics?

A: Plyometrics are any exercise where the muscle is contracted
eccentricly then immediately, concentricly.  In plain English, the
muscle is stretched (i.e. loaded)  before it is contracted.  A good
example is push-ups with a clap in-between each push-up.  Your muscle
(pectorals in this case) is elongated and loaded by the downward force
of your body, then immediately you must contract the muscle to push
yourself  back up.

2) Why do I care?

A:  Because plyometrics is one of the best ways if not the best way to
improve power.  To justify this answer lets first look at what is
power.  Power is similar to strength except you are adding the time
factor.  Therefore the relation of strength and speed is what we are
talking about when we talk about power.  A person who can perform a
specific resistance movement, such as jumping, bench press etc., the
fastest would be said to have more power in that movement.  So what we
are looking at is not just the contraction of the muscle, but how fast
will it contract.  It has been shown that a muscle will contract the
fastest when it has been loaded.  This is why you should be able to
jump higher if you crouch down then immediately jump up than if you
started in the crouch.  So if this is the best way to perform a
powerful movement lets practice these movements.  This practice is
called plyometrics and has been shown in study after study to decrease
the time it takes for the muscles to contract, resulting in more power.

3) Q: What are good plyometric exercises for increasing vertical jump?

A: There are an infinite number of plyometric exercises to increase
vertical leap but here are a few good ones.  

Two foot ankle hop (low intensity) - keeping your feet together and
remaining in one place hop up and down using only your ankles and
calves. Concentrate on getting as high as you can and exploding off the
ground as soon as you land.

Rim Jumps (medium intensity) - Stand under a basketball rim.  Jump up
touching the rim (or net or whatever) with alternate hands. 
Concentrate on getting as high as you can and exploding off the ground
as soon as you land.

Box to Box jumps - (high intensity)  Place two boxes that will support
your weight about 3 feet apart.  Standing on one box step (NOT JUMP)
off to the ground and immediately jump back up to the other box. Turn
around and repeat. Obviously the difficulty of this exercise is
increased as the height of the boxes are increased.  Once again
concentrate on getting as high as you can and exploding off the ground
as soon as you land (notice a pattern here?)

In all the above exercises you are using your body weight and gravity
to load the muscle before contraction.  The forces you generate are
much larger than could be safely accomplished using conventional
resistance (read weights) exercises.  It is true these forces only
exist for a brief amount of time, but they still stress the muscle
which is the point.

Also these exercises can be combined. For example try jumping off a box
before jumping up to the rim.

4) Q: What are good plyometric exercises for increasing speed

A: While all of the above exercises will also increase your speed (leg
speed), these are many others that just focus more on movement. Here
are some examples

Zig Zags ( medium intensity) run an elastic cord about a foot off the
ground.  While on one foot hop back and forth over the rope.  Repeat
with other foot.

Side to side ankle hops- Same as regular ankle hops (see above) but
instead of remaining in place you jump 2 to 3 feet side to side.

Sprints.  Yes sprints are plyometrics since the force of your body
coming down loads the hamstring.

5) Do strength shoes work?  Where do I get them? How much do they cost?
Are there alternatives? Why are strength shoes included in a
plyometrics FAQ

A: Yes  strength shoes do work, they make every step a plyometric
exercise for the calf. Since they only work the calf though you must do
regular plyometric exercised in them to work the other muscles.  They
do come with a excellent plyometric regime and a nice video.  For those
of you who donít know what a strength shoe is: It is a shoe with an
elevated sole, but the sole is only on the ball of the foot.  The calf
is allowed to hang free forcing it to be stretched ( thus loaded) on
every step.  Be aware that the calf plays a limited role in jumping and
acceleration, approximately 30%, so while strength shoes will help they
are no magic pill and are just a tool for a good plyometric regime. 
Strength shoes are available for about $140.00 at (800) 451-JUMP. You
can also get the strap on equivalent that turn any shoes into strength
shoes from Metapro at (415) 967-4787 for around $55.00

6) Q: What is a good book on plyometrics and where can I get it.

A: The best book on plyometrics is Jumping Into Plyometrics by Donald
A. Chu. It is $13.95 and available at Borders and Barns and Noble.  I
think you can also get it from Spike-Nashbar at (800) SPIKE-IT. The
ISBN number is 0-88011-433-6 . It has a great many exercises and good
tips about how to put together a program. Also each exercise is cross
referenced by what sport it helps. All in all a good book.

7) Q: Are plyometrics dangerous?

A: Since so many exercises could be considered plyometrics, of course
some of them are dangerous. Jump squats are a great example. This is
where you perform a regular squat (with weight) and actually jump at
the top of the motion coming off the ground 1-2 inches.  You perform
this exercise with about 1/3rd of your max. weight.  This is one of the
best exercises to increase your jumping ability.  Unfortunately it is
also a dangerous one. If you donít have great form, and you canít do at
least 50 reps of regular squats at the weight donít even think about
them. Also stay away if you have a bad back or knees.  On the other
hand the two foot ankle hop is very safe, and will offer good benefits.
 A good general test to see if you are ready for plyometrics is to
stand and jump up as high as you can.  Measure this height (chalk on
your fingertips and a clean wall is a good way to measure).  Then jump
off a 18 inch box and jump as high as you can.  If you canít reach as
high as you could on the ground you would be better off hitting the
weights and coming back later.

8) Random thoughts

While plyometric will increase your vertical jump, form has quite a bit
to do also.  Try to crouch to a point where your knees reach a 90
degree angle.  A good arm swing will easily add inches. By throwing
your arms up as you jump you are decreasing the weight that you have to
push off the ground and the inertia of your arms going up will help
pull the rest of your body up.  Also the faster you are moving before
the jump, the higher you can jump.  You can transfer this horizontal
speed to vertical speed with the proper form.  This is why high jumpers
get a running start to jump much higher than they could standing still.

Well here is my contribution to the net, feel free to make any comments
or suggestions (except grammar because I really donít care)    -Charlie

P.S. I have gotten some good sugestions so far that I will try to
incorporate when I have time

Jacques -