Saturday, 18 August 2012

What is quad dominance and does it actually exist?


WHAT IS QUAD DOMINANCE? DOES IT ACTUALLY EXIST?

Just an informal article guys and gals on a topic that was brought to my attention and thought I'd have a look into. As always your thoughts, opinions and questions are always welcome. 

Suggested definitions

“Defining an exercise as a being hip or quad dominant is determined by the joint at which the main action of the movement occurs and on which group of muscles are most active” Precision Nutrition
This website uses the example of a step-up exercise to demonstrate how altering the parameters will change the emphasis on certain muscle groups, making it supposedly hip or quad dominant.
For example, step-ups at a low step height will be more quad or ‘knee’ dominant, whereas raising the height of the step increases the activation of the glutes and hamstrings, making it more of a hip dominant exercise.


 
















Livestrong also define quad dominance as a category for movements rather than a condition i.e. exercises that involve more motion at the knee compared to other joints of the lower limb. The example they use is the squat.






These pictures show variations of the squat with the bar (or load) in different positions (front, high bar and low bar squat). The ‘elephant in the room’ here is the trunk angle variance, the front squat maintaining a fairly upright torso compared to the low bar squat where there’s  so much forward lean that the guy has almost folded in half.

Now full range of motion of the hip into flexion is supposed to be 120 degrees and at the knee about 140 degrees. If we’re talking about a ‘CrossFit squat’ in which the hip must go below parallel then by that definition hip flexion must be more than 90 degrees flexion.


In this picture hip and knee are both in full flexion so you could argue that neither joint is being overly emphasised by this exercise, performed to this depth.
You can tell Jim Wendler dislikes the term ‘quad dominance’ from this subtle description: “unless your quads hang over your kneecaps like an elephant’s testicles, you’re not quad dominant. You’re hamstring weak.” But what’s interesting, apart from comparing quads to an elephant’s balls, is that his example has nothing to do with a category of movements placing more emphasis on the quadriceps but rather an imbalance between agonist and antagonist muscle groups.

Still confused? The lack of consensus in terms of a clear definition for quad dominance makes the whole concept pretty ambiguous. So perhaps breaking down what’s going on with the use of another example can shed some light.
The quadriceps are primarily knee extensors. In a non-weight bearing position e.g. sitting on a chair and you straighten your knee, your quads work concentrically to overcome gravity and achieve this motion. Their action changes somewhat in function though, for example when you’re running the quads act eccentrically to decelerate knee flexion as you land on your lead leg.




NB: In the interest of keeping this fairly short I’m only going to be talking about the hip and knee flexors and extensors but there are a LOT of other muscles working during these activities.
If you perform a forward lunge the lead leg during the downward phase undergoes the most muscle activity. The body weight comes forward and the quads have a massive eccentric demand as the knee moves into flexion. Distally the hamstrings reciprocally shorten at the knee end while being eccentrically loaded at the hip end along with the glute max.






During the upward phase the knee drives into extension from the concentric contraction the quads while the hip is extended concentrically by the glute max and hamstrings. 
If you’re performing the classic 90/90 lunge in which your knee and hip are kept at 90 degrees then no one joint moves more than the other, so regardless if it’s a forward or reverse lunge, the above definition can’t call this a quad dominant exercise. But if you get up now and try a forward lunge chances are you’ll probably feel it working the quads in the lead leg a lot more than the hamstrings. But why is this? A reverse lunge for people with knee pain can be more comfortable due to less potential shear force from excessive anterior translation of the tibia and less eccentric demand on the quads putting stress through the patella tendon. You don’t have to ‘catch’ the weight of your body in a reverse lunge compared to a forward one and it’s a lot easier to maintain a vertical shin position.

But what if the angles were altered? A longer stride forward may eccentrically load the posterior chain more by decreasing the amount of knee flexion compared to hip flexion. The point of load on the foot can change the emphasis as well. Have a go at performing a forward lunge and moving the weight around your foot (heel, mid-foot, fore-foot etc) and you’ll feel certain muscles fire more than others.  
So in conclusion does quad dominance actually exist? It depends on which definition you use. If you’re talking about a category of movements that emphasise the quads then sure, that exists.  If you’re talking about an athlete with an agonist-antagonist muscle imbalance between quads and hamstrings I’d agree that this is quite a common condition. A lot of the athletes that I’ve treated have presented with this type of imbalance and it seems increasingly rare to find someone with over-active hamstrings and weak quads. Why is this? Perhaps for a lot of the population who spend several hours a day in a chair with the hip and knee flexed (quads and hip flexors in a shortened position) this can create long and weak hamstrings, altering the length-tension relationship. What do you need to do about it? If you were at my awesome mobility class last week we went over exercises to help increase glute and hamstring activation and this is the first port of call that I’d suggest.

Sources/References

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