Training for Centrification?

Image courtesy of eorthopod.com

One thing that I have been seeing on other blogs and websites and hearing from various people is that there are certain exercises or parts of their programs that train specifically for the centrification of joints.  To me, this statement falls somewhere between puzzling and just downright misleading, but let's explore it a little.

First, what is centrification?  Paraphrasing the RTS manual, centrification is the "recruitment of all of your muscles around a specific joint in such a way that the axis remains relatively fixed in the same position as the you move throughout a given range of motion" (RTS Science 1).  For example, when looking at the motion of humeral abduction, there appears to be an axis running anterior to posterior through the gleno-humeral joint as you move throughout the range.  There are other axes of motion to consider due to the scapulo-humeral rhythm that ideally occurs throughout humeral abduction, but for the sake of simplicity, I will just look at the gleno-humeral joint in this example.

So during the motion of humeral abduction, you have the six divisions of the deltoids, supraspinatus, and the superior fibers of the infraspinatus all concentrically contracting at some point in the range to help abduct the humerus.  Additionally, there are some muscles that are directly opposing this motion that your brain will have generate tension in varying amounts depending on the position of the humerus.  From the brain's perspective, the goal of this "some muscles generating tension some muscles generating not as much tension" scenario is to hold the joint together as efficiently as possible while still allowing for that motion to occur.  This, in turn, may lead to this relatively fixed axis.  Once again, I'm not taking into consideration everything that has to go with the scapula and the muscles that control its position in this example to keep it a little simpler.

I say relatively fixed axis because depending on the shapes of the contact surfaces of the bones and how they articulate with each other in addition to the tension-generating capabilities of the muscles at any given point in the range, the actual position of the axis may have to shift in order to allow for the most efficient movement to occur that is least detrimental to the joint.  A great example of this can be found in the knee.

So, what centrification seems to boil down to is the ability of the brain to command some muscles to pull harder and some muscles to pull not as hard in order to allow efficient motion to occur while minimizing the degradation of the joint.

I could go into the topics of force couples and co-contraction here, as well as bring up multiple other points about centrification, but I want to get back to the question at hand of whether centrification can actually be trained for in these exercise programs, as is being claimed.

In part, the centrification of a joint is dependent on the ability of the muscles controlling that joint to generate tension, but what is also important is the recruitment of certain muscles to generate tension at specific points throughout the motion in addition to how much tension they are required to generate.  Too much of one, not enough of another, or lag time between when that tension is needed and when it is generated can all lead to unfavorable joint mechanics and degradation of that joint.

While most exercises can certainly provide a stimulus that results in greater tension generation, the orchestration* of "some muscles generate this much tension right now, some muscles generate that much tension right now" seems to fall outside of the ability of most traditional forms of exercise.  In fact, the only form of exercise that I have experienced that appears to provide an opportunity for improved orchestration* is MAT.

It is certainly feasible that most exercise and programs that claim to improve centrification are able to build a bigger engine, but the question that remains is are they improving the ability of the driver to control the vehicle--steering**, accelerating, and braking appropriately.
Your body.  Your training.

*"orchestration" is an RTS term presented throughout the different course manuals as well as during the course lectures.
**"steering" is a term presented in the RTS Science 1 manual when describing the muscles' role in centrification.
The ideas found in this post were first presented to me during the RTS courses.

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