Well, this just had to come at some point, I guess. Bret Contreras, whom I respect quite a lot, has succeeded in establishing himself as the “glute guy” and buttbuilding par excellance. He has identified people that have a hard time firing their glutes properly and he has grouped them as “quad dominant”. This is a concept that has been gaining some momentum along with Contreras’ fame and I think Quad Dominance deserves some attention, as the term is being misapplied.
It just so happens that this ties in with a pet peeve of mine. Or at least something that in my opinion should have had more attention in the pop science training literature as well as in the the sports science communities AND something I’ve been contemplating writing something about at some point. And that is about the way that loads going through the lower body are transmitted either through the posterior chain or the leg pressing chain (for a lack of a better name) and what implication this has for ergonomics, exercise execution, performance transfer and so on.
Most experienced resistance training trainees are familiar the concept of the Posterior Chain. The Posterior chain is the shit that gets sore from deadlifting, right? Hamstrings and erectors. Slightly more advanced trainees may be aware that squatting like a powerlifter, with your butt faaar out back, loads the posterior chain moreso than Olympic squats, where the hips are kept as far forward as possible. But if you’re not using the posterior chain for olympic squats, then what chain are you using? And why is this at all relevant?
What I’m going to make a case for is that when talking about lower body loading and exercise, at least when dealing with multipoint exercises, we should not talk about individual joints or muscles, but about movement chains, specifically the posterior chain vs. the leg pressing chain, for a lack of a better name. The reason that we can’t use the name “anterior chain” is that this name is already in use for another structure, i.e. the lumbar and hip flexors. Hence I normally use the “leg pressing chain”. This is just the term i myself use, but I think that it’ll make it easier to talk about training if more people had a name for this, e.g. Wikipedia says in it’s posterior chain entry that olympic squats are posterior chain exercises, which is obviously not right. This is not really a part of the scientific literature, and to a surprisingly small extent part of the pseudoscientific literature. Paul Chek, whom I’m otherwise not a big fan of, is using a similar way to describe this in his Primal Patterns system, separating the bilateral movement patterns into Bend (=posterior chain) and squat (=leg pressing chain).
Anatomical and biomechanical kinetic chains are not the same!
Before I move on, I’d like to make the point that multi-joint kinetic chains are not continuous anatomical structures. In the scientific and pseudoscience literature of anatomy and so-called “functional anatomy”, the term chains denote coherent anatomical structures through which forces are projected, i.e. if you pull in one end of the structure, you can measure a force in the other end. There is a substantial number of these chains (or trains) traversing the body, up and down, side to side, front to back and in any combination thereof. The existence of these chains and how they may be involved in motor control and posture is at the heart of schools of thought like Rolfing, Active Release and Myofascial Release. Please note that these anatomical chains may or may not be synonomous with movement chains. In the case of the posterior chain, this describes a structure that is both anatomical and biomechanical. In the case of the leg pressing chain, this structure is not anatomically continuous, but certainly mechanically.
The Posterior kinetic chain
The posterior kinetic chain or just posterior chain (PC) covers primarily the hamstrings, erectors and the traps and the articulations knee flexion, hip extension and extension of all spine segments. As you’ll note below, hip extension is also part of the lego pressing chain, but the posterior chain only drives hip extension, when the knee is extended. This is of course because most of the biceps femoris is biarticular (spanning two joints, rather than one). Thus, when the knee is flexed, the biarticular part of the biceps femoris is shifted to the left part of it’s force length curve and becomes insufficient. This is the reason that the bottom of power squats and (correctly executed) deadlifts feel so different. In this position, the knee is fairly flexed making the glutes more required, whereas when you just get 5-10 cm out of the hole, this shifts towards a cleaner PC movement.
The leg pressing kinetic chain
The leg pressing kinetic chain or just leg pressing chain (LPC) covers primarily the glutes and the quads and the articulations extend of the knee and of the hips. While both of these kinetic chains are related to hip extension, there is a very important difference between them. During posterior chain dominant movements, the hamstrings are the prime hip extenders, whereas during leg pressing chain-dominant movements, the glutes are the main hip extenders. This is because when the the knee are flexed, the biarticular (spanning two joints, in this case across the knee and the hip) part of the hamstring, which is the hip extender during posterior chain movements, becomes insufficient. All muscles display a bell-shaped force-length relationship, meaning that they have an optimal length for force produciton and at shorter and longer lengths, their capacity to produce force diminishes greatly. This is particularly true for the biarticular muscles across the hip and shoulder joints. Thus, when the knee is flexed, the hamstring is shortened to a degree, where it doesn’t work well. Therefore our motor systems use the glutes instead.
It really would have been a lot easier if we could call this the anterior chain, but this would be rather confusing as this is normally used to described the hip and lumber flexor anatomical structures.
Load distributions in weight bearing exercise
So in any multi-joint exercise where the hips are moved against a force vector, loads will be distributed through either the posterior chain or the leg pressing chain. If you’re squatting with your butt faaar out back, the majority of the load will go through the posterior chain and very little through the leg pressing chain, whereas if you execute a perfect olympic squat, the force distribution will be quite the opposite. However, in power squats the majority of the use of the leg pressing chain is in the bottom position. This is because this is where the knees are flexed and thus the glutes will be the dominant hip extensors. You’ll see a nice OL squat by weightlifting champion Ly Xiaojun. Notice how erect he is and how he seems to balance his body between the bar and his feet.
In the other end of the spectrum, we have power squats, where considerable forward lean and backward transposition can be observed. At the very extreme, we see the kind of squat that Rippetoe recommends is about as posterior chain’ish as a squat can get. The way that he describes “hip drive” is rather controversial. Almost everyone else I’ve ever talked to about this, considers “hip drive” the intended forward push of the hips forwards when coming up from the squat. Using this hip drive forward visualisation supposedly improves the use of the leg pressing chain when squatting. In Rip’s version, he describes it as powering the hips back and up, putting the body into a position where the knees are extended and thus the posterior chain being the primary hip extensor
On a similar note, In a conventional (non-sumo) deadlift with a normal hip position, the load distribution will be quite similar to a power squat. It will primarily be a posterior chain movement, but with some leg pressing chain involvement at the bottom of the movement. The lower the hips are at the beginning of the movement, the more flexed knees and therefore more leg pressing chain involvement. This can be seen in the execution of a clean deadlift, i.e. a deadlift from the same starting position as the weightlifting clean:
CONSIDERATIONS FOR generic LIFTING TECHNIQUE, strength and performance transfer
What’s really interesting is that the learning curve for strength appears to be quite steep for the posterior chain, whereas it appears to be more gradual for the leg pressing chain, even though the limit strength appears to be fairly similar between them. Think about it, how easy is it to get to deadlift 200 kgs compared to OL squatting 200 kgs? In comparison, both the best raw OL squats and deadlifts are just a tad above 400 kgs. The argument I’m trying to make, is that humans are not inherently built for much bigger strength in the posterior chain, it’s just much easier to come by (for reasons unknown).
Probably due to our normal postural and physical activity environments, particularly the way we sit and work, the use of the leg pressing chain is harder to get at for most westerns than for the posterior chain. Because of this initial poorer function of the leg pressing chain AND the fact the the posterior chain pattern is initially more trainable, this easily leads to posterior chain dominance.
For this reason, my default prescription is always more leg pressing (OL squat, front squat, hack squat) work than posterior chain work, i.e. “squat two times for every pull”.
Considerations for strength sports and performance transfer
If an individual is much stronger in the posterior chain than, the leg pressing chain, they will tend to execute deadlifts with the hips as high as possible and furthermore to lift the hips as early as possible in the lift. Likewise, in squats, they will attempt to shoot their hips out back in order to keep the knees as extended as possible
While this may be okay for a powerlifter, because it is possible to perform very posterior chain dominant squats and deadlift and do very well, it is probably not of the same merit in other sports. Weightlifters, and by extension crossfitters, need to be as strong or stronger in the leg pressing chain than in the posterior chain, indicating that they should prioritise leg pressing chain strength vastly more than posterior chain strength. This also makes it particularly stupid that Crossfit.com officially associated with Rippetoe, because his exercise prescriptions will and would effectively fuck up olympic weightlifting movement patterns rapidly.
While tackling movements as seen in football, rugby or handball may require more posterior chain strength, jumping ability is usually more related to the leg pressing chain function. Therefore, different athletic activities may favor different strength distributions in the lower body.
Also, for aestethic purposes it should be noted that doing OL or front squats are practically the only real quad exercises that will really work. If you never learn to squat in a leg pressing dominant way (OL/front/hack squat), odds are that you will have a very, very hard time developing full muscular quads.
Considerations for injury prevention
Posterior chain exercises load the spine (especially the lower back) more and the knees less than leg pressing chain exercises. And there is no doubt that when exercising, loaded structures are at risk of getting injured, but there is not solid evidence favouring one over the over in terms of injury risk. However, if an individual develops massive posterior chain dominance, they will tend to get in positions where the spine is loaded to an unnecessary extent, i.e. when shooting up the hips too early in squats and deadlifts, causing a very bent over position. Even though the spine may be in good alignment, this will lead to increased compressive and shear forces in especially the lumbar spine. If alignment is lost in such a position because of fatigue or loss of stability, this puts them at increased risk of something bad happening. So while it is okay to do power squats over OL squats, I subjectively think that being too posterior chain dominant is a bad thing injury wise.
So even though I personally prescribe OL squats or front squats over power squats in order to keep a good balance between these two movement chains it should be noted that some people may just be stronger in the posterior chain or they may have trained in a posterior chain dominant way to an extent that their leg pressing chain strength will never catch up. In those cases, restoring leg pressing strength is done on a damage reduction scale ;o)
How does this relate to Quad dominance?
Well, most people that have a hard time firing the glutes, and by Bret Contreras’ definition “quad dominant”. They have a hard time firing the main hip extensor and so they must rely on something else, right? And that should be the knee, right? Instead of using that rationale and discussing this in terms of mechanical competence across individual joints, I suggest discussing it in terms of mechanical competence across biomechanical chains.
So what characterizes these gluteal amnesia individuals? I’ve taken the liberty of citing Stuart McGill’s description:
…From measuring groups of men with chronic back troubles during squatting types of tasks, it is clear that they try to accomplish this basic motion and motor pattern of hip extension emphasising the back extensors and the hamstrings, they appear to have forgotten how to use the gluteal complex….
While the exact definition can be argued, this pretty much sums it up
When instructed to do squat type movements, they will usually lift their heels significantly and keep their torso fully erect or if instructed to keep the heels in the ground, shoot their hips far out back, essentially changing the movement into a posterior chain pattern
When instructed to do deadlift type tasks, gluteal amnesiacs (?) will typically execute movements with fairly straight legs and rounded backs, again, just like McGill describes, causing the pattern to rely maximally on the hamstrings.
So, what I’m getting at is this: Most of the people that have shitty glute activation doesn’t compensate significantly at the level of the knee extensors, but at the level of the other hip extensor, the hamstrings and effectively display massive posterior chain dominance, rather than quad dominance.
Think about it, most people with gluteal amnesia have decent posterior chain strength for their trainings status. They can normally hoist decent weight in deadlift (although with horrible technique). On the contrary, if they should be quad dominant, they should perform well in something like a hack squat. Well, they don’t – at all. And they don’t normally do well in leg extensions either, further underscoring my point.