Category: Applied Functional Science

Have you ever played the game “Would You Rather?”

The game, played at a party or in simple conversation, is meant to make you think. It is also meant to learn more about you as a person (or learn more about the person you are asking the questions to). Sometimes the would-you-rather questions can be both on the positive side (choosing between two seemingly good things), sometimes on the negative side (choosing between two seemingly bad things), and sometimes on a creative side (choosing between two neutral things).

Let’s play …

Would you rather have a joint that has mobility or stability?

Yes, this certainly makes one think. Would you rather have a joint that can move and be flexible or would you rather have a joint that can be strong and control movement? The seemingly “copout” answer of “Both!” is the best way to answer this question, in our humble opinion.

In fact, not only do you want a joint to be both mobile and stabile, but you would certainly want a joint that is mobile and stabile in all three planes of motion! Why? Because all joints move in three planes of motion.

In this blog entry, we take a deep dive into the Functional Movement Spectrum. Specifically, we focus on Mobility and Stability, 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 Mobility and Stability: Combined (functional) vs. Segregated (non-functional).

The power of the Analysis Movements in 3DMAPS® (3D Movement and Performance System) is the complementary assessment of mobility and stability. Using the same global movements (driven by the legs, arms, and head), the individual’s available motion at all the joints, as well as control of the motion can be determined. As mentioned above, the descriptors for the ends of the spectrum are combined (functional) and segregated (non-functional).

At Gray Institute®, the functional combination of mobility and stability is referred to (and coined by Gray Institute®) as Mo-Stability. Effective and efficient function (the most ability) requires both mobility and stability (mostability). Analyzing mobility and stability using the same actions allows for the observation and comparison between the quantity and quality of local joint motion combined into global, full-body movements.

Very frequently, an individual joint motion is not contributing to a global body movement. Sometimes the motion is restricted. This would be evident during the 3DMAPS® Mobility Analysis. If the joint motion is available during mobility, but is not being used when the movement is tweaked for stability, it would suggest that control of that joint motion is lacking. During function, mobility and stability are combined.Stability of movement is not measured by the lack of motion, but rather the ability to control as much motion in each of the three planes as possible. (Learn more and get certified by clicking on

In the discipline of motor control, there is a debate about posture versus movement. Are there separate systems for posture and movement? Are posture and movement just different requirements of a single system? Posture refers to the position of the body, as well as ability to maintain and adjust that posture in response to the physical forces of gravity, ground reaction force, mass, and momentum. Movement is the combined joint motions of the intended task imposed upon the body’s posture. Some researchers favor the segregation of posture and movement. However, more logical arguments can be made for the combination of posture and movement. Similarly, for mobility and stability, combination is more logical (and functional) than segregation. Probably the most powerful argument is that the muscles can’t be segregated into different mobility and stability muscles any more than they can be separated into posture and movement muscles. All muscles are involved in both!

Recently, some in the movement industry have promoted a mobility / stability segregation with regard to joints. The body is proposed as an alternating sequence of mobile and stable joints. For example, the knee is considered a stable joint between the foot and hip (both mobile joints). This may have gained some credence because the knee has limited motion in the frontal plane. In the sagittal plane, the knee has a great amount of motion. So is it a stable joint or a mobile joint? YES! Each motion at all joints requires both mobility and stability. Even a small amount of motion in the frontal plane at the knee will facilitate motion at the hip and throughout the Chain Reaction® of a global movement. If a motion (mobility) is important to function, then control of that motion (stability) is essential. Combined mobility-stability (“mostability”) at each joint is a hallmark of function, and therefore our analysis and training movements must emphasize combination instead of segregation.

Principled Strategies: Load to Explode
Functional Movement Spectrum Series: Mobility & Stability – Vlog Part 1

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