Analysing the one-leg jump, part III: Quad dominance and weak quads – could they be related?

In the previous post we have covered how this complex combination of muscles, under the guidance of the Central Nervous System (CNS) is trying to do the job you have planned – in this case – a jump off one leg for a dunk.

And despite all this neuromuscular complexity, the entire process takes place in a fraction of a second – all these structures work together, communicate, give and receive feedback, coordinate themselves what to fire, how to fire, when to fire, when to relax, what to relax… sources of energy come into play, electrical currents come into play, neurotransmitters come into play… it’s really amazing when you think about how ALL these things coordinate themselves to do what we perceive as a “simple task”.

I’ve started with all this because I don’t think enough awareness and appreciation is given to this entire process. Becoming aware of this entire process means you start to figure out that a TON of things can go wrong, and despite all of this – it rarely happens. What a marvel of a thing the human body is, right?

OK, enough with this. Let’s pick up where we left off. We’ve discussed in the previous article how having tight hip flexors, that as a side effect inhibit the glutes from expressing themselves properly in the plant, can disguise itself as a quad weakness because the quad will get overloaded and the knee/tibia will translate forward (since the quad will try to do its best eccentrically to stop the knee from collapsing).

And since we’ve touched the quad part of the equation, let’s talk a bit about the quads. Now I’m going to warn you, again, that all the things I am writing here are not “necessarily” scientifically based FACTS. Instead, they are my interpretation of the process of the one-leg jump and more specifically – the amortization phase in the one leg jump – using logic and common-sense anatomical analysis in order to come up with hypothesizes (again, not scientifically proven facts) about what is going on. Therefore, I want you to keep in mind that I might be wrong, in which case I urge you, depending on the level of knowledge you have on the matter, to think about it, figure out if I make sense or not, and see if you come up with better explanations than what I will achieve. If you figure something out, or think that I am wrong somewhere (or everywhere) – I encourage you to comment on the subject and maybe together we can correct/establish a better understanding on this complex amortization phase.

Why would that be important? Well, the better we can understand the amortization phase, the better we can actually build a training program that will take all these things into account and manipulate the exercises/exercise selections/tempos/exercise successions/rest periods etc etc, basically all the parameters of training – in order to maximize your gains while at the same time increasing the safety of the training program/minimizing injury risk.

So basically, the better we understand the amortization phase, the better our training program can be constructed and the better both our results and safety concerns will become. THIS is the fundamental GOAL of this entire article series about the one leg jump.

OK, so let me start with a very controversial quad-related thing, that I have barely heard being discussed in the one leg jump (or in any athletic discussion at all, basically):

The VAST majority of trainers agree that being a quad dominant guy in athletics is a bad thing. It carries a number of disadvantages and injury risks. It promotes overuse injuries. It promotes bad mechanics. It does this and it does that. Well, OK, so common sense would say that in order to correct this you should train the posterior chain, get more glute dominant, try to improve the quad to hamstring strength ratio (very important for ACL health), basically get your posterior chain stronger so that the CNS will choose to use the hip extension more (that the glutes and hamstrings do) and limit the knee load/knee extension activities.

I mean, it makes sense, right? Well of course it does. But what to do with the quads?
Does having strong quads relatively to the posterior chain (hamstrings in this case as the antagonists of the quads) mean that you should ignore the quads, reduce quad strength training and increase hamstring strength training in order to improve the ratio? Should we go with low bar squats since they recruit the hamstrings more and involve the posterior chain more, while still being a squatting movement – instead of continuing with the high bar squat which is more quad dominant?

Again – this sounds like a good idea. But here’s something to think about: the quads and the hamstrings are opposed to each other – depending on the movement, one is the agonist (or PROtagonist) – the other is the ANTAgonist. One initiates a movement, the other acts as a break to prevent excessive extension/flexion of that particular joint.

For example, in the case of the quads/hamstring pair, when the quads fire to generate knee extension, the hamstrings have to be ready to fire at the end of the movement to prevent knee HYPERextension. So they work as a pair, and they, again, are being coordinated by the CNS in order to fire or relax the quads or, respectively, the hamstrings – to safely do the knee extension movement.

As a side note – the same happens if you want to punch harder. You can be a great bench presser, you can have beast triceps – but if you are in that situation – the limiting factor might be, of all things – the biceps. If the CNS recognizes the fact that the biceps are too weak to stop the elbow from being hyperextended by the triceps, then your punching power will suffer. In that situation, extra biceps work could help you punch harder, despite the fact that the biceps has no bussiness doing any kind of elbow extension.

But going back to our quad/hamstring pair – here’s the thing – when a protagonist fires, the antagonist must relax. This is always the case. When your quad fires to extend your knee, the hamstring must relax in order to allow the quad to exert the power that it has. Obviously, the better the balance in between them in this pair, the better (and safer) the knee extension will occur.

Now remember, we said that if you’re quad dominant you want to get stronger in the posterior chain in order to balance things out and to relieve some of this quad dominance. The problem with all that is this: if you are quad dominant and you have weak quads, you will have another problem: this would mean that, most likely, your posterior chain is weaker than the quads, and the quads are already weak. This makes you weak OVERALL.

The problem with being weak overall and being quad dominant, a feature that is more predominant in the female population – is that – going back to our quad/hamstring pair – stabilizing the plant for a one-leg jump will require a HIGHER percentage of the motor neurons in your quad to FIRE, since the quad is weak and can’t stabilize the plant unless it’s being heavily recruited. Otherwise, you will have the knee collapsing. This high quad recruitment that is happening for an overall weak person will mean that a similarly high percentage of the hamstring must be shut down (relaxed) in order for the quad to do its job.

When that happens, the quad will act eccentrically generating an anterior tibial translation shear force, while the hamstring – which was supposed to counter that by pulling on the tibia backwards, generating a posterior tibial translation shear force – will be shut down.

What does this result into?

Remember this?

Raptor knee collapse picture
This is how knee collapse looks like

The knee goes forward and the ACL is put under tremendous strain.

See how we came back to the same knee collapse, but due to totally different reasons? In this particular case, being both quad dominant and weak overall is the reason the knee collapse has happened.

Well, OK, but what if you were to have STRONG quads, and you were to have the same ratio of quad-to-hamstring eccentric-to-concentric strength? Basically the same as in the weak, quad dominant guy example, but in this case we would have a strong, quad dominant guy.

Again – it’s a bit counterintuitive. In this situation you might think that since we have stronger quads – then we’re at an even BIGGER risk of injury or knee collapse since the quads can generate more power and therefore either the ACL is being subjected to more power, and therefore has a “better” chance to get injured, or the CNS will tend to utilize the quads more since they are stronger than in the weak example.

But, surprisingly, at least according to this hypothesis – having a strong quad would mean that a LESSER percentage of motor neurons would need to fire in order to stabilize the plant and prevent the knee from collapsing, because, being a stronger quad, that lesser percentage would be enough to do the job. If the quad is being recruited LESS because it’s stronger and can do the job, then the hamstring needs to relax LESS. And if the hamstring relaxes less, and therefore is more available to protect the knee, then the quad/hamstring pair can actually work BETTER in a quad dominant, strong guy. This is without even mentioning that the muscles can take a ton of stress out of the non contractile elements of the leg whenever they are stronger (which should be obvious but I’m pointing it out nonetheless).

Now, again, this is just a hypothesis and something to think about. Don’t take all this as fact – think about it and see if it makes sense. If it does, then make it a priority to get stronger and make it a priority to find a way to keep this quad-to-hamstring ratio very balanced. It will not only give you a much safer position to be in, no matter the athletic movement you’re going to make, but also put you in the position to properly move and properly allow the RIGHT muscles to fire at the right time.

Doing this, and keeping an open mind and being aware of what is going on will maximize both your progress in the gym, and increasing strength (because of better mechanics and balance) – and your actual performance on the field.

In the next article I will try to discuss a bit about the glutes and hamstrings, and identifying dominance or CNS preference of using them for the hip extension task.

Meanwhile, if you agree or disagree with this article – please comment, I appreciate input!

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