Today, we’ll simply scratch the surface of the concept of differentiating between a stability/motor control issue or a mobility issue during an athlete’s assessment.
At PUSH we take pride in how well we conduct our initial assessments; we are thorough and particular on the process that we use with our athletes.
Knowing what tests to do is easy, knowing what to do with that information obtained from those tests is a different story and what separates us. Having the proper knowledge base to be able to understand the data we receive and an ability to apply the correct course of action helps our athletes to perform at their highest potential.
Stability/motor control or mobility?
An aspect of the system we use is being able to discern if the root cause of dysfunctional movement is involved with a stability/motor control issue or a mobility issue.
Having this capability in your tool box as a coach demands a certain level of understanding of how the central nervous system affects our muscular system.
Let’s start by defining some key concepts within this approach.
Looking at the interrelationship of mobile and stable segments we must consider that any joint that has a fundamental movement in one particular plane of motion is a stable joint and one that does not have one particular plane of motion is a mobile one. 
Mobility is defined as “the quality or state of being mobile or movable.” If a joint has poor mobility it is important to address this first to create an environment for optimal motor control to occur.
Stability is defined as “the quality, state, or degree of being stable: such as the strength to stand or endure, the property of a body that causes it when disturbed from a condition of equilibrium or steady motion to develop forces or moments that restore the original condition.”
Having the awareness of what regions are responsible for mobility or stability builds the foundation for the ability to incorporate the correct exercises within the program. For example, if the ankle lacks proper mobility it will in turn affect the foot and knee’s ability to stabilize.
Motor control, the necessary input, sufficiently processed, with an acceptable output.  Motor control is the concept that helps our CNS and muscular system work in tandem to help our body increase our movement capabilities.
Our CNS helps learn how to embrace movements from outside imposed demands from basic to complex and specialized. Our movements are conveyed as ‘patterns’ which are regulated by the CNS. 
“Poor movement can exist anywhere in the body. Poor movement patterns exist only in the brain.”
Unfortunately, our body tends to forfeit quality over quantity of movement, inducing a certain amount of compensation from other regions within a threshold. Once that threshold is broken, the movement becomes a dysfunctional one.
Let’s break it down further.
A mobility dysfunction is a decrease or limit in full range of motion.
If the finding is the same when done actively and passively, it is most likely to be mobility dysfunction. A stability/motor control dysfunction is present when the required mobility is met but the output is unacceptable based on the imposed input.
To detect further, you may have to change postural demands with either passive or active tests, in prone/supine or vertical positions.
For example, looking at hamstring mobility you can perform a passive leg raise and then have the athlete perform an active leg raise. If the range of motion is the same in both tests it is potentially a mobility dysfunction; if they are different, it is potentially a stability/motor control dysfunction issue.
There is more to be examined and discussed within this approach. It can become complex when dealing with a wide range of athletes.
The body has a way of being able to appear as a functional unit, but in a sneaky way. The CNS works to make our movement patterns able to handle volume compromising our motor control. Seeking these out helps us to truly understand how the athlete functions and what deficiencies we must address first before we can progress them in their strength training.
There will be more discussion on this topic in the future, so, stay tuned for fresh information on how to get the most out of your initial assessment and understand your body.
Looking to read more on specifics to watch for in an initial assessment? Click here.
- SFMA Instructors. Selective Functional Movement Assessment: Level 1 Version 25.6. 1st ed., vol. Ver 26, FMS, 2019.
- Merriam-Webster. “Dictionary By.” The Merriam-Webster.Com Dictionary, 2021, www.merriam-webster.com.