"Strength Deficit" question

If an athlete’s static vertical jump and countermovement VJ are essentially equal (within 1%), should he concentrate on improving strength or explosiveness (with plyometrics)?

In researching this problem on the internet, I’ve come across two opposite points of view.

One (http://www.bodybuilding.com/fun/inmag22.htm) holds that with a difference between the jumps of < 20 % the correct course of action would be to concentrate on hypertrophy and thus improve strength. This article states that a difference of >20% indicates a need for olympic lifts, plyometrics and medicine ball work.

Other places, such as the t-mag forum, the thinking is just the opposite - < 20% difference between static and CMVJ indicates the need for plyos, oly lifts, etc.; > 20% suggests the need for increased strength.

The athlete in question is my son, mentioned in my previous post.

Age 16
Parallel squat - a little over 2 x body weight
Hang clean - 1.59 x BW
Static VJ - 27.75"/70.5cm
CMVJ - 28"/71cm

Obviously, elasticity is practically non-existant, so perhaps this suggests that the latter course (plyos) is the correct one?

It would be the latter IMO, and his lifts back that up. He has enough strnegth for now. He needs to work on his reactivity

Yes, definitely the 2nd. The reason for that mix-up in that article is because it was written using information taken from Supertraining. There was a mis-print in the book on that subject. that Siff later corrected.

Reactive strength always has more potential then pure explosive strength/Rate of force development. The example you give indicates large untapped reactive resources in that athlete.

Am I misreading the bodybuilding.com article? Here is a quote:

If the difference in the numbers is small (less than 20%), there will be a need to gear towards building hypertrophy (muscular size) using moderate weights with ample repetitions along with a concerted effort to improve starting strength.

Isn’t this correct? If the difference between the two jumps is small, there is little strength deficit and thus little need to work on explosiveness. It indicates that the athlete has about all the explosiveness he/she is going to get with the muscle strength at it’s current levels.

If the deficit is large, it indicates much untapped explosive potential.

Am I wrong about this?

from supertraining

Michael, from a post 1/8/03 Subject: Supertraining Erratum-Final Version!
Correct version:
In general, if the strength deficit is LARGE for a given muscle group, an
increase in speed strength may be produced by maximal or near maximal
neuromuscular stimulation(via weightlifting or plyometric methods). If the
strength deficit is SMALL, hypertrophy must be induced by submaximal
loading methods as commonly used in bodybuilding, following the maximal
efforts against heavy loads.

Corroborating evidence for this:
‘Dr. Gunter Tidow states in ‘New Studies in Athletics’ 93-110, 1990 that
strength deficit is the difference between isometric and eccentric maximal
strength. He points out that a small deficit implies a highly developed
neural activation and consequently only small ‘reserves’ are left, so that
hypertrophy must be the objective of this athlete. On the other hand, large
deficits necessitate improvement of one’s neural activation ability by
means of maximum strength methods.’

[To me it seems logical, especially in non-elite athletes, that if a small reserve would suggest that I’m not using the stretch reflex properly??? - DD]

For the throwing athlete, a test between a throw using the stretch reflex,
i.e., shot putt with the pulling back of the shot and subsequent throw
versus a throw from a ‘cocked’ static position with a hold from 3-5 seconds
(similar to a countermove vertical jump versus a vertical jump from squat
position with no countermove). A baseball player could be tested by a throw
with a ‘windup’ and prestretch with throwing from a static position
extended arm position with a hold of 3-5 seconds.

From the above statement, any muscle group could be tested for the strength
deficit by using a movement from a static or isometric start versus a
movement with a ‘prestretch’ or eccentric action as part of the total

The only problem would be what constitutes a small or large deficit-5, 10
or 25% ? Neither statement sets the bar for the quantification of amount


According to the published experts on this subject, Charlie’s statements are
correct. (In addition to Tidow, refer to Schmidtbleicher’s articles and Dr.
Zatsiorsky’s “Science & Practice Of Strength Training” text.) The smaller the
deficit, the greater the ability to activate one’s musculature, of which stretch reflexes are one component.

You should be able to jump much higher with a countermovement, if you can’t then your reactivity needs work! :slight_smile:

I still don’t think this is a good test, because there are 2 different things at work here. Neural effeciency and reactivity.
Perhaps a better method would be jumping with 50% of your bodyweight, then speed strength would be better measured vs just how good your stretch reflex is with a dip vs no dip.

ding ding

quoting Chris Korfist

We know that the equation for power is Power = Force x Acceleration. So, some move a light weight very fast while others move a very heavy weight. Either can be beneficial for power development. However, both Bosco and Verhoshansky agree that too much of max weight can actually slow you down because an athlete will begin to recruit slow twitch muscles (more on this later). So, how do you know when to stay light or to use maximum weight? Bosco deals with this problem in his book Strength Assessment with the Bosco Test. Bosco describes a series of tests to determine an individual’s optimum path to power development. One of the tests that I have used is the squat jump test. An athlete measures his squat jump. Remember, hands on hips and hold the bottom position for a couple of seconds to remove momentum. Then, the athlete performs a squat jump with a barbell loaded with his bodyweight and measures the jump. If the athlete has a jump of 50 cm and a loaded Squat Jump of 20cm, divide 20 by 50 and multiply by 100 to give you a percentage. In this case it will be 40% which is the optimal percentage for a sprinter type athlete. If the number is lower, your explosive strength dominates and you need to do more max strength lifts. If the number is higher, do more explosive lifts. When an athlete reaches his goal, then he can balance his program. I have found that most of my athletes are over 40%. So we spend our workouts moving the bar fast with light weights.

Thank you, CoolColJ, MikeH and KellyB.

We attempted to perform the Bosco test this evening. What we ended up with is pretty much an estimate because our only means of measuring the jumps was 'ol pops crouching on the floor with a steel tape while junior was hopping with a loaded barbell over pop’s head. Great entertainment for my wife!

His static jump with the BW barbell is in the neighborhood of 35%-38% of his unloaded static jump with hands on hips. In fact, it may be closer to 30%. So, according to this test he needs to improve his lower body maximum strength, though it isn’t too far out of balance with his explosive strength.

The other test seems to indicate that he would also benefit from attempting to improve his elasticity.

I was just noticing in the “Peak When It Counts” book by Freeman that the Italians called the other test (CMVJ minus static VJ) the index of elasticity , though I haven’t run across this term elsewhere.

Thank you for your help/input guys. He plans to continue trying to improve lower body strength and improve his SSC through sprinting and plyometrics.

I was just noticing in the “Peak When It Counts” book by Freeman that the Italians called the other test (CMVJ minus static VJ) the index of elasticity , though I haven’t run across this term elsewhere.

Yes it is better to call that the elastic defict test rather than the strength deficit or explosive strength deficit. That is cause for confusion on the interpretation of it. In order for it to be a test of strength deficit or explosive strength deficit you have to be able to determine Fmm (maximum force capable under any condition) or maximal isometric force. In the static vs countermovement jump test there is no measurement of Fmm or max isometric force, but only of explosive strength and elastic strength, thus saying that if the 2 jumps were close one should work on hypertrophy is the wrong interpretation, although if it were truly measuring strength deficit that would be the correct interpretation.

kcat: You can do the Bosco test with CMJ and squat jump. You do CMJ and SJ with just body weight, and then then the 100% jumps as CMJ and as SJ. SJ measures explosiveness, but not SSC ability.

I recommend getting enough spotters so you can catch the bar when he jumps. Coming down with a bar loaded with body weight is NOT a great exercise for the spine, especially for a younger athlete. This is may be tough to do without an olympic bar, but you really need a strong person on each side of the bar and they catch the bar after the jump so the athlete is not catching the bar himself as he lands.

Thanks for your response. Can you define “reactivity” for me? Is that the same as hypertrophy?

Nope! :stuck_out_tongue:

It’s the ability to utilise the potential energy of the stretch reflex maximally, or the elastic properties of the tendons etc, ie bounce.

It’s like stretching a rubber band and letting it go. You can either have a loose responce or a more short, sharp and snappy. There is usually a relationship with eccentric strength.

I was backwards - thanks for the help!

or you could use dumbells and drop the at the top :slight_smile:
Just have to make sure you don’t sure your arms on the unweighted jump