Plyometrics And Safety Part4

by Lyle McDonald

Guidelines for the (hopefully) safe and effective use of plyometrics (2):

Adequate preparation:
This may be one of the biggest places where people make mistake in
including plyometrics in their training. Number one, unless you are
a seriously competitive athlete, there is very little point in even thinking
about plyometric training, much less trying to incorporate them. Yes,
Jerry Robinson has written both a book and a two part article in Ironman
about their use for non-competitive athletes. However, the magazine
article was geared towards bodybuilders and suggested less than maximal
type plyometric activities.
If you are considering adding plyometrics, you should have an adequate
strength base behind you. Early Soviet writing suggested a squat strength
of minimum 2.5 times bodyweight to insure adequate tendon and
ligament strength as well as adequate musculature to help prevent
injury. However, the NSCA suggests a squat of at least 1.5 to 2.5
times bodyweight before any high intensity plyometrics are included.
I read the other night a post from Paul stating that this is a pretty big
margin and it is. However, I think the point is that a minimum of 1.5
times bodyweight squat is necessary before you even consider including
For upper body plyometrics, athletes greater than 115 kg (253lbs) should
have at least a bodyweight bench press and athletes less than 75kg (165 lbs)
should have at least a 1.5 times bodyweight bench.

Proper progression:
Another major mistake is trying to do too much too fast. For the same
reason that you should weight train for several months with sub-maximal
loads before doing anything of higher intensity, you should not begin
plyometric training at the highest level. You don't start running by doing
a marathon. You don't start gymnastics with double back flips. You should
always start easy and build up, peroid. Otherwise, you're just asking for
an injury. Before continuing, let me list the five general categories
of plyometric training.

1. Jumps: low intensity jumps (generally staying in the same place) with both
feet contacting the ground at once. Examples are a tuck jump repeated ten times
and a squat jump.

2. Hops: either a one footed or two footed jump which covers distance. An
example would be a double or single leg hop.
Frequently, hops are performed over various equipment like hurdles and
cones. This is another place where athletes can easily get hurt. Chu
described a case where a hurdle was placed backwards and an athlete
hit it while hopping. Since hurdles are made to tip over forward when hit (if
placed correctly), the hurdle didn't tip and the athlete tore their
ACL and sued the school. There are plyo-hurdles available which
collapse if hit but Chu recommends making your hurdles out of PVC pipe
that is not glued together so they will explode if hit.
Also, frequently, lateral hops are done over various equipment like
cones and stuff. One thing to avoid is jumping side to side over a
ball as you will easily twist an ankle if you land on top of it. Cones
may be used but make sure they will collapse if you land on top of them.
Hurdles and benches are probably a bad idea as hurdles will only tip
in one direction and a bench won't move at all if hit. Again, either
use the proper equipment or don't bother doing the movement at

3. Bounds: this is a moderate to high intensity type of jump alternating from
one foot to another usually measured for distance. It includes alternate
leg bounds or combination bounds (i.e. right leg, right leg, left leg; left
leg, left leg, right leg).

4. In-depth jumps or box jumps: this is the highest intensity plyometric
of all which is usually performed by stepping from a box of known
height, absorbing the impact of landing and exploding up as high as
possible. Alternately, jumping from one box to another or onto and
off of the same box is also done depending on the need of the sport.
For box jumps, the box height is one of the most important factors
in preventing or causing injuries. Recommended box heights are from
0.4 (15")to 1.1 (43") meters with 0.75-0.8 (~30-32") being average.
Large athletes (>100 kg or 220 lbs) shouldn't jump from higher
than 0.5 meters (20") or so. Six inch boxes may be used for total
beginners and rehab and Chu talks of a jumper that he got up to a 6' tower
although he says few athletes will even need a 42" box. (As a humorous
aside, Chu also describes a Soviet study which had the athletes drop off
a 3 meter tower, that's 9.9 feet, and try to explode up. The resarchers
had problems with getting the athletes to finish the study. Hmmm, I wonder
why? Maybe because they had jammed thier knees up into their chests).
But, what is the optimal height for maximal gains. At too low a
height, the overload may not be high enough. At too high, injury
will most likely result. Chu recommends measuring vertical jump
from standing and then measuring it again while box jumping. If
the athlete can replicate his or her vertical jump from a given
height box, raise the height. When they cannot, you are too high
and the athlete is spending too much time on the ground. The
athlete mentioned above continued to jump higher off a tower
6 feet high when Chu finally called it quits.
Also, please make sure that the box you're using has a sufficient
surface area and is stable, and has a non-slip surface on top.

5. Upper body: these are activities like medicine ball throws or
plyometric catch and push-ups (very high intensity). A clap
push up is another example.

But what type of progression should be followed within these
categories? Well, in keeping with the basic tenet of periodization,
you should begin with high volume, low-intensity work and
progress to low-volume, high-intensity work. So, the place to
start is with multiple sets of 10 or so of basic jumping. While
this probably won't elicit much of a training response, it will
help prepare the muscles and connective tissue for the higher
intensity work to come. Over 8-10 weeks, gradually increase the
intensity but lower the total volume (discussed below) and build up
to box jumping if necessary.

Obviously, shoes with adequate cushioning and ankle support should
be used.

Jumping surface:
This is another one of the major components of injury as well. In
general, a softer more giving surface is better, to a point. However,
this doesn't mean you should jump in a vat of jello. A wrestling mat
or gymnastics floor is probably ideal as is a well cushioned track
or grass field. Obviously, concrete, tile or hardwood floors are
not recommended. However, excessively thick surfaces may slow
the athlete down too much to be of any use (like a very thick gymnastics
mat) as they will increase the amortization phase too much.

For most athletes, jumping 2-3 times per week during the
off-season and 1-2 times per week in-season is plenty. Strict
jumpers (long, high, triple) may want to emphasize plyometric
training a bit more.
Don't forget that, as a high intensity training mode, plyometrics
will require several days between sessions and should be packaged
as such. There are many different ways to combine plyometrics
with weights, aerobics, etc but you must keep in mind that
overtraining (which can lead to injury) may occur if your workouts
are not packaged correctly in the week. For example, doing a plyometric
workout the day after a hard leg workout might not be the best
idea as the muscles are already slightly weakened and injury may

Volume is generally measure in terms of foot contacts per
workout. Obviously, a higher number of foot contacts will put more
stress on the body. Some recommended numbers are:
Beginner: 60-100 off-season of low to moderate intensity
100-150 pre-season of moderate to high-intensity
Depends on the sport in season of moderate intensity
Intermediate is 100-150 off-season and 150-300 pre-season
Advanced is 120-200 off-season and 150-400 pre-season
The numbers represent total foot contacts per workout. So, pre-season
you could do 3 sets of 10 of standing tuck jumps and 3 sets of 10
of squat jumps. These are only guidelines however. When starting,
you might start with just 30 jumps and then progress from there.
Since plyometrics relies primarily on the ATP-PC system, full recovery
between sets may take 2-3 minutes or more. And, as plyometrics is a type
of skill training, complete recovery should be allowed or injury may result.

As I talked about, the intensity of the training session has to do with
the type of jumps being used. However, I want to mention it again
within the context of volume and frequency. As most of you probably
know, volume, frequency, and intensity are all inter-related in any
activity. The higher the volume, the lower the intensity must be.
The higher the intensity, generally the lower the frequency. When
these three are not combined properly (like trying to do too high
a volume of frequency of high intensity stuff) overtraining and most
likely injury will result from any activity (not just plyometrics).
Unfortunately, the amount of volume, intensity, and frequency that
a particular athlete can handle is very individual so no strict
guidelines other than the couple I've mentioned exist. The
take home message is be careful in your progression. If you
raise the intensity of your jumping, by all means, lower the total
volume. Ditto for the other components.

When in the workout:
Plyometrics have a high skill component. Therefore, they should generally
be performed near the beginning of the workout when the athlete
is fresh. A general warmup (which may include some low intensity
plyometric activities like hops and jumps) should preceed adequate
stretching before the plyometric session. If they are performed
on the same day as weight training, they should probably preceed
the weights. An alternate method is to do lower body plyometrics
on the same day as upper body weights and vice-versa. However,
remember that recovery from plyometrics may take several days
if they are hih intensity and it may not be a good idea to follow
a heavy leg day with jump drills or vice versa.
The bottom line is that you can't condition the nervous system (which
is the basis of skill training) in a fatigued state. Not only can injury
result but improper skill acquisition may take place. And unlearning
an improper skill is probably just as hard (if not harder) as learning
a new skill.

These are some of the main guidelines for safe plyometric training. Let
me reiterate that following these guides by no means eliminates
the injury potential. However, many potential injuries can be avoided
by following these guidelines I think.

Let me say once again that I'm not recommending that anyone go
out and do plyometrics. I think they are safe and useful, others
disagree. That's fine. My purpose with this post was to print
some of the general recommendations (for what their worth)
regarding safety precautions to help minimize the injury
risk. I still don't feel that there's adequate scientific evidence
to say plyometrics are effective one way or another. Until that
evidence surfaces, all we have to go by is gut feeling.
My gut feeling is this: almost all sports are plyometric in
nature. If you really want to carry specificity to it's ultimate
extreme, then plyometric training should be an integral
part of your training. Again, others disagree. I don't doubt that you
can create a great athlete without plyometrics so perhaps the
injury potential does outweight the risk. However, some (like Greg
Shepard at "Bigger, Faster, Stronger") feel that without the power clean
and plyometrics you will never reach your athletic potential. I don't
know if I'd go that far.
If you want more info (and a little bit more detail on specific
exercises for specific sports) check out the suggested readings
below. I haven't read any of them but they seem to surface time
and time again.

Lyle McDonald

1. "Theories, concepts and methodologies of speed development as they
relate to sports performance" Dr. Donald Chu. Cassette from the
NSCA "Essentials of Strength Training and Conditioning Symposium"
2. "Essentials of Strength Training and Conditioning" Editor Thomas
Baechle. Human Kinetics 1994
(Yes, before the criticisms start coming, I know that both these sources
are from the NSCA. I think that many of the NSCA ideas are good. I think
that an equal number of them are probably wacked. These are my references
in any case.)

Suggested Readings:
1. "Jumping into Plyometrics" Donald Chu. available from Human Kinetics
for $13.95 and at some bookstores. There is also a companion video
demonstrating proper form for many of the common plyometric activities
available for $39.95. 1-800-747-4457.
2. "Explosive Power: Plyometrics for bodybuilders, martial artists,
and other athletes" by Jerry Robinson. Available from Health for
Life for $19.95. 1-800-874-5339.

source: newsgroup, posted 14 Oct 94

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