If he’s talking about performing a higher vertical jump than he’s right. But if he’s talking about dropping from a greater height than he’s wrong. I think DB drastically over-emphasizes the need for isometric strength and it’s contribution to switching from eccentric to concentric.
talking about jumping 
ISOmetric leg strength is what allows you to brake the eccentric quicker
It has to become an isometric before you can reverse it.
That’s kinda the point of SSC training in the first place…a sustained isometric defeats the purpose of the SSC.
You’d be better training eccentric strength and the SSC directly instead of sustained isometrics.
ISOmetric leg strength is what allows you to brake the eccentric quicker
How can a muscle group perform isometricly and eccentricly at the same time?
Wouldn’t the inherent elastic properties (SSC) of the muscle groups contribute to a quick reversal?
Unless I’m holding a load against an immovable object (pins in a rack), wouldn’t their be subtle amounts of concentric and eccentric contractions and not truley isometric?
It has to become an isometric before you can reverse it.
There is no stopping of joint angles or interuption of movement when a person lands and quickly jumps again. A pause for a fraction of a second will decrease any plyometric effect however slightly.
Nearly every movement in humans incorporates the SSC. Are there isometric contractions (except subtle joint stabiliztions) on every movement or only when we jump off of boxes?
which is where altitude drops, depth jumps, jumpsquats, reactive dive bomb squats, band eccentric accelerated squats, power and fullsquat olys, and sprints come in
its not a vaccum, every bit of puzzle is in there. Even landing from jumps themseleves is bit of work as is.
But the ISO work is supportive
thomas im afraind your wrong when ever u change direction from a eccentric to a concentric no matter how fast you are no matter how good an athlete u are u have to stop ie. isometric. it is a small fraction of a second and the shorter that isometric stop is the more profecient and effecient you become in plyometric types of movements. think about a piston in a car it is going up and down extremly fast but b4 it changes direection it must stop for a nearly infintesimle period of time. If u dont believe me take a physics class and u will learn that all changes in direction are proceeded by a stop in motion.
I don’t consider a landing or dipping down as an eccentric as such, your basicly free falling down and resisting the movement with isometric type strength. Is there such a thing as eccentric strength at all? Your either pushing the load up or your resisting it. Resist it with enough force and it becomes static. Well that’s how I see it
I can see plenty of isometric situations myself in every movement - like me sitting on this chair right now
The SSC is what occurs in the transition between eccentric and concentric.
Yes, it becomes isometric, but in a different way than the isometrics we’re discussing here as training methods.
There’s a reason reactive strength is trained specifically.
Again, static isometrics won’t have any carryover to an SSC-dependent motion.
i never said that isometric training has a caryover even though i think u are mistaken and it does i only said that every change in direction is proceeded by a stop in motion which is by definition isometric.
PS wut is SSC
Remind me to ignore any further posts from you.
because why i asked a question about an acronym
SSC = Stretch Shortening Cycle
ahh see i know wut that is i just didnt recognized the acronym thx john
Got your panties in a bunch again?
Otherwise, great points by the way. You are a smart cranky lad 
"I’m not really sure if I agree with his statement (and one of the underlying premises of the article) that “all plyometric work consists of isometric work” (pg 1). I think eccentric rather than isometric may be a more appropriate way of saying this, especially concerning leg stiffness. The only point I really see any isometric conditions in plyometric activities is at the turn-around point of the motion from eccentric to concentric but this would still be quasi-isometric at best. As I understand things, the turn-around point from eccentric to concentric movement just happens to be the point (where ever the turn around point occurs) that the tension developed by the musculo-tendon unit exceeds the force being placed on the joint and wouldn’t really be isometric at all. Having said that, if we (or DB) are / is making this statement about only the contractile component (CC) of the muscle, it becomes far more (but still not completely) appropriate. This is because during certain parts of the plyometric activity, the CC may be functioning isometrically while the muscle-tendon unit itself is actually lengthening or shortening due to changes in the length of the elastic components of the muscle-tendon unit. I’m not sure and DB doesn’t really make clear if this is what he is referring to. "
There you have it. Isometrics, Eccentrics- all wrapped up in a neat little package. 
Force Absorption requires maximal strength so anything that improves muscular strength will improve this. Eccentrics, isometrics, whatever. One point I was trying to make on another thread related to this is that before you can benefit from SSC/plyometric work you have to be strong enough to absorb the forces.
The Sport Performance Research Centre in New Zealand aimed to determine what is the most important factor when looking to increase power-absorption. The investigated different inertial loads using power absorption and power production standards of measure. They had 54 test subjects on board, each of whom performed bench throws and miometric bench presses with 40% and 80% of their straight-weight 1RM. The bottom line; "Maximal strength was found to be the best single predictor of power absorption.
Isometrics only marginally improve maximal strength, though. Eccentric strength would have a far greater carryover for reactive ability.
before you can benefit from SSC/plyometric work you have to be strong enough to absorb the forces.
Kellyb, thats too broad a statement. I wouldn’t prescribe altitude jumps for a young athlete or one that hasn’t had much weight training experience, however low-level movements like jumping in place will work.
Also, an athlete that has had plenty of jumping experience like a basketball or volleyball player may be able to move right into higher level plyos like hurdle or box jumps. This sort of thing is done every day with no ill effects.
What was the training age of the subjects used in the study?
Isometrics only marginally improve maximal strength, though. Eccentric strength would have a far greater carryover for reactive ability.
Yes I agree. I should’ve added that there may be an isometric contraction but it’s still dependent on eccentric strength. A lot of the isometric stuff people are doing, like the yielding ISO’s for time, are really just slow eccentrics.
Kellyb, thats too broad a statement. I wouldn’t prescribe altitude jumps for a young athlete or one that hasn’t had much weight training experience, however low-level movements like jumping in place will work.
I’m not sure how old the subjects were in the studies but let me clarify. Even a low intensity movement which 99% of all athletes can do without any problem requires a certain level of strength but you’re right…match up the level of the drill with the ability of the athlete.
I believe that is why yeilding isometrics are preferred over the overcoming isometrics