At the risk not being politically correct (yet blatantly honest), muscles are dumb!
What muscles do, however, is anything but dumb. In fact, muscles are amazing in that they lengthen and shorten in all three planes of motion.
Back to the “dumb” comment, though … muscles are dumb in the fact that they react subconsciously to the movement in order to control the movement. To think that we need to consciously get these things to turn-on is not the best strategy. Perhaps the best strategy is facilitating the proper motion at the joints to allow the muscles to then react properly, in all three planes, for the task at hand.
In this blog entry, we take a deep dive into the Functional Movement Spectrum. Specifically, we focus on Muscles, which is included as a principle / truth in the Biological Sciences. In “The Introduction” to this Functional Movement Spectrum Series, we identified the following descriptors for Proprioceptors: Reactors (functional) vs. Actors (non-functional).
With regard to muscle function, the descriptor terms above – Reactor (functional) and Actor (non-functional) – the difference may not be apparent until we take the perspective of an individual muscle. Dr. Gary Gray calls this “intransformalizing,” which is best defined as “becoming the body part.”
The Actor perspective was born out of anatomical dissection. It was reinforced by electrical stimulation, and even the isolated muscle paralysis that occurs in Polio. Dissection of cadavers on a table allowed muscles to be pulled, and observation of what movement occurred at the primary joint. The advent of electrical stimulation using direct current via the muscle electrolytes reinforced this Actor perspective. The Polio epidemic drove a need for isolated muscle testing without any substitution from other muscles with similar functions. This Actor perspective has at its foundation that concentric (shortening) muscle contractions create movement (act on the bones). This perspective considers muscles in isolation. This fosters training and rehabilitation programs that promote conscious activation of a muscle with minimal or no contribution from other muscles. We might call this the “isolationist” approach.
The Reactor perspective considers all of the forces that influence muscle contraction. This perspective considers the body as whole, the task to be executed, and the context of the body within the physical environment. The body is a connected series of bone segments. At Gray Institute®, this is a Principle of human movement called Chain Reaction®. One moving part affects all the others. The force generated by one muscle affects forces in other muscles. Very often a muscle is being lengthened in one plane or at one joint while it is shortening in one plane or another joint. At Gray Institute®, we call this “econcentric” muscle function. One muscle’s contraction is combined with all the others creating muscle synergies. Different muscles can be combined to do the same task. The same muscles can be combined to do different tasks. We might call this the “integrationist” approach.
The Reactor perspective considers the intended task to be of primary importance in determining how the muscles React together. The individual joint motions of the intended task, occurring simultaneously, cause the muscles to React to the global movement of the body during functional activities. Throwing a baseball pitch to the catcher is a very different task from throwing a football to a receiver. In fact, throwing different pitches are different tasks requiring different motions and subsequently different Reactive muscle synergies. Hitting the different pitches requires different Reactive synergies to put the bat on the ball.
To understand the context-dependency of reactive muscle function, let’s use the example of writing your name. Once you have been through elementary school, this is a very automated task with specific muscle synergies. However, if you were asked to get up from your desk and write your name on the white board, the context of this task changes drastically. You would be standing rather than sitting, creating much greater use of your lower extremity muscles. Your position relative to the writing surface has changed 90 degrees. Instead of using your fingers and wrist muscles primarily with your forearm supported, you would use a lot of shoulder and elbow motion. Even though the letters would look very similar, the size of each letter would be much larger when writing on the board. The context changes the joint motions, producing a different Chain Reaction®, and requiring a different combination of muscles.
So which perspective is functional? If as you read this, you have intransformailized and become a muscle, then you can easily recognize the answer. Do you contract in isolation to produce a specific joint motion, or rather with other muscles during motion of multiple joints? Do you consciously contract, or react to what is happening around you without thinking? Are you affected by gravity, ground reaction force, mass, and momentum? Does joint motion in three planes, as part of a functional movement, force you to react to control and reverse that motion in order to accomplish a task? The answer becomes obvious.