Super Stiffness

Last weekend was spent at the “Running Medicine” Conference at UVA.  Lots to talk about from that conference in future newsletters…

Sometimes there are novel ideas that seem sort of trendy, but I think exercise is generally moving toward much more of a “functional training” rather than sitting on weight machines that don’t engage the whole body.  This newsletter today is along that same idea: “super stiffness.” I’m sure that by now, the world has heard (ad nauseam) the importance of training THE CORE. Unfortunately, this often equates to a million sit ups or crunches. My hope is that this article will give a different perspective on how to train the elusive “core”.

So what the heck is “super stiffness” anyway? First of all, I know some of you too well and I can hear you giggling already. Super stiffness is not what you think!

In many athletic endeavors such as running, jumping, swinging a golf club etc, there is a very rapid contraction in the muscles instantaneously before an action is carried out. In other words, we pre-load tension into the muscle so that it stays “stiff.” In this case, the word “stiff” doesn’t mean a lack of flexibility – rather, your ability to generate muscle tension to brace, or “stiffen” the muscle.

“Super stiffness” is a term coined by the arguably the world leader in spinal biomechanics – Dr. Stuart McGill. He has over 200 scientific papers published (and I was lucky to have him as my biomechanics professor in undergrad). According to Dr. McGill, his research team has studied many athletes with fairly sophisticated equipment and measured commonalities. They found that it’s not strength that separates the great ones – it’s their ability to quickly contract and relax muscles.

“These great athletes optimize mobility in some parts of their body with this great, rapid stiffness in other parts and not only was performance greatly enhanced, but the risk of injury was reduced as well.”

This concept can be applied to many areas of the body, and maybe I will expand on this in a future newsletter, but for now I just want to talk about the core. According to McGill, power is rarely generated through the spine or the core, but rather through the hips and shoulders. The job of the core is to stop movement, not produce it.  In other words, in most athletic (and even many non-athletic) moves, the power is generated in the hips and shoulders and then transferred through the core. If the core does not stiffen, the power that was generated by the shoulders and hips is lost.

That being said, it is a big mistake to train the core with a lot of movement, such as sit-ups or back extensions. Instead, it would be better to train the abdominal wall and spine in the way they are supposed to function – to stiffen and stabilize rather than create movement. For example, instead of doing exercises like side bends, do a suitcase carry. This unilateral loading of the torso during walking requires the core to stiffen and stabilize during the gait cycle. Instead of doing sit ups and crunches, do“stir the pot”. And instead of doing Russian twists (not a lot of stability here!) do chops and lifts (this last one is done by Gray Cook, PT – one of the most knowledgeable people when it comes to functional movement).  In all of these exercises, the core is not moving (i.e. it’s “stabilizing” – which is the point of “core stability”)

McGill speaks about the certain areas generating power and other areas creating stiffness. If a strong part of the body overdrives a weaker part, you get an “Energy Leak.” For example, if you are jumping off one foot, the power generation comes from the hip and gets transmitted through the core to the shoulders. Your core has to be solid like a rock (i.e. “stiff”) in order for the energy to be transmitted. If the core was not stiff, there would be a loss of the energy transmission. He says, “You can’t push a rope, but you can push a stone.”

   Dr. McGill goes on to say “that’s why the great jumpers train their core stiffness. They don’t do exercises like heel raises which wouldn’t do a darned thing”

   I really have just scratched the surface of this topic, but I’ll wrap it up here. Below, I have put some video’s of “real world” examples of runners with a lack of core stiffness. You can clearly see why not only is this an injury risk, but also a significant “energy leak” that reduces performance. The force produced from the hips is clearly not being transmitted through the body, but instead, dampened by the lack of core stiffness.


instability in the sagittal plane.mpg
instability in the sagittal plane.mpg
instability in the frontal plane.mpg
instability in the frontal plane.mpg

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