If you’ve been around coaching/fitness/performance for some time you’ll have seen multitudes of buzzwords come and go, everything from ‘functional’, ‘CNS fatigue’, ‘neuroplasticity’ and more. Often these terms are used to create authority via confusion, with no real understanding of the meaning of the term, nor it’s real-world application.
Movement Variaiblity is just one in a long-line of those things - so what is it?
Defining Movement Variability
“Movement varaibility is the normal variation that occurs in motor performance across multiple repetitions of a task” - Stergiou & Decker
Essentially, as we perform repeated movements, their execution will be slightly different each time, after all, we are not robots programmed with systemised motor patterns. We are dynamic organisms, living in a dynamic environment and NEED to have the ability to improvise and adapt to the changing demands placed upon us.
The concept of Rigidity vs Chaos from Faust’s work on hemispheric integration sits very well here in explaining the continuum principle that underpins a need for variability:
Rigidity <———> Variability <———> Chaos
In terms of movement, too much rigidity could be taken literally as too much muscle tone that leads to restrictions and potential injuries. On the other end of the continuum ‘Chaos’ could be defined by excess amounts of range, with little neurological control over that range - hypermobility for example.
What I love about this model is that it doesn’t JUST apply to movement but to neurology, heart rate, chaos theory, politics, the microbiome, financial markets, metabolism, ecological systems and more.
Take the example of soldiers marching on a bridge, if they are marching 100% in unison the impact of each step creates huge amounts of mechanical resonance - enough to bring the bridge, and soldiers, crashing down. Which is why they will typically break step when marching over a bridge - variability is needed.
WHAT IF WE LOSE MOVEMENT VARIABILITY?
Loss of movement variability is commonplace and can be driven by a range of factors:
neurologically perceived threat
soft tissue restrictions
poor training design/execution
lifestyle factors (sleep, nutrition, hydration etc)
deliberate loss of varaibility for specific purposes
An easy example to make is that of the elite level powerlifter. With the majority of their sport and training taking part in the sagittal plane, they will typically lose variability (movement options) in the frontal and transverse planes. In much the same way as building a drag racer that can accelerate to 300+ mph in a straight line, this comes at the expense of being able to change direction.
“Specificity ALWAYS has a cost” - Kyle Dobbs
This loss of movement varaibility (whether deliberate or consequential) is often referred to as an extended or sagittalised state. This state creates a loss of ability in the frontal and transverse planes which if deliberate CAN lead to increased performance in the short term, in many cases however, it is not deliberate and leads to loss of performance.
STRESS & EXTENSION
Under chronic stress or perceived threat we can be driven into an extended state though upregulation of contractile muscle-spindle activity again leading to loss of movement options in the frontal and transverse planes.
This extended state can be intepreted as a proxy for autonomic balance and has wide-reaching systemic implications on immune and hormonal function, joint centration, the ability to generate power efficiently, ability to assimilate nutritients from food, blood sugar regulation and the ability to perform in any arena.
If the individual is constantly extended this time under tension makes it a habit and joint centration is changed. As the joint can’t get into optimal postion because of the systemic extension, they have to ‘fake’ joint centration through compensatory strategies to generate (suboptimal) power and performance.
Extension isn’t always a bad thing though, in the examples below, capitalising on sagittalism allows greater control over an opponent by creating a loss of movement variability:
CAN WE HAVE TOO MUCH MOVEMENT VARIABILITY?
Put simply - no.
One of the great things about us being a dynamic organism in a dynamic environment is that we are able to train and adapt to increases in variability. If, for example, someone has a loss of movement in thoracic rotation which is addressed through an intervention to open up more range of motion, this could be termed as a temporary state of ‘too much’ variability.
I look at it as two primary facets of the organism:
In the example above the increased thoracic rotation range leaves too much variability, as they have no neurological control of that new level of musuloskeletal variability.
The neurological system needs to grow and adapt too, once the musculoskeletal system has new space we need to send new ‘input’ (afferent feedback) from that range to the neurological system. The more time we can spend in the new range, with varied stimuli the more the neurological system can adapt.
“Where neurological control and muscloskeletal variability are mis-matched, performance suffers, resilience is reduced and injury occurs”
TOP-DOWN OR BOTTOM-UP APPROACH?
In the example of a client who has a loss of internal rotation in the shoulder, attacking this solely with a sleeper stretch (bottoms up approach) suggests we think the joint has autonomy to become tight.
But it’s important to ask, what created the restriction/stiffness? If we were to sedate or knock out that same client, would the lack of IR remain?
Whilst there can be other factors at work, this stiffness is typically coming from top-down, so it’s important to address the brain as a potential cause of movement restriction through neuromuscular inhibition.
In general principle:
The amount of variability you have = amount of permission brain gives you to move
The more threat/danger that the brain perceives = less variability
Less variability = higher injury risk, espcially in a sports or dynamic setting
If you have or create mobility by brute force WITHOUT neural ‘permission’, it can LOOK like variability to an outsider, which is why it’s important to use simple observable, repeatable test to assess for variability.
ASSESSING MOVEMENT VARIABILITY
Modified Obers Test
Shoulder Horizontal Abduction
Each of these tests give me information about the client’s axial skeleton, their ability to achieve joint centration, an approximation of the position of the diaphragm, information on what phase of respiration they may be in, their infrapubic angle, ribcage position and how much extension they are in. All of which gives me a starting point to try and train for improved variability.
TRAINING FOR IMPROVED MOVEMENT VARIABILITY
As I mentioned earlier in this article, ALL adaptation comes at a cost. Increased movement varaibility in some instances may NOT be desired as it comes at the expense of specialisation.
In the case of extended individuals, looking to train glutes, hamstrings and abs to get them OUT of extension and give them more control over the sagittal plane is my starting point. I’d then look to create stability and good sensory awareness of the frontal plane, before then training that plane.
Sagittal Plane Competency + Frontal Plane Stability = Better Chance of Success in Transverse Plane
It’s also important to note that variability is driven by perception, so whilst physical training interventions have their place, it’s also important to address other neurological factors, which is why you’ll notice many of the tools below relate to creation of a parasympathetic shift:
Recovery modalities & cooldowns
Fight extension, glutes, hamstrings, abs
Progressive muscle relaxation
Variety in training modalities/exercise selection
Fill your toolbox with as many tools as you can. There will come a time where it is most appropriate to pull out a specific tool. That tool may have come from strength and conditioning, it may have come from neurology, or it may have come from physical therapy. Avoid barriers between them, learn them, recognize they are specific tools for specific purposes, and execute them with as much skill as you can.
- Dr Stuart McGill
Interested in learning more about variability and it’s implication on coaching for performance, to get clients out of pain and more? Click here to check out our coach mentorship program