The Joint by Joint concept of movement

The joint by joint approach to the body is attributed to Gray Cook and Mike Boyle. It is a systematic way of looking at the body as it moves and how the joints act and react in a relative way to each other. Our movement behavior and the adaptions that are created are very much a response to the laws of physics. These primary forces are gravity, ground reaction force (Newton's 3rd Law - Action-Reaction), and momentum. The standard kinesiological approach to looking at the body cannot explain many of the overuse injuries that occur because it analyses movement outside of the laws of physics. That model simply looks at muscle attachment points and describes the role of the muscles as bringing these two points together. This is concentric muscle function. However, the main role of the muscular system is to control the effects of physics on the body. This is primarily done first by elongating or maintaining tension in response to potential change. This is eccentric muscle function.

The joint by joint theory looks at the body as a series of mobile joints stacked on a series of stable segments. While this may seem to be an oversimplification, it is really just a model to look at the relative relationship of a skeletal structure with an overlying muscular system which is encased in a fascial net. The terms mobile and stable are also relative and dynamic.

Mobility - What is a joint system capable of performing without external influence

Stability - Ability of a joint system to maintain position in the presence of change

Given these definitions, the next step is to consider the concept of proprioception. From the definitions above we can see that mobility and stability are co-dependent. Mobility has to come first. A joint system cannot stabilize unless it knows it has to. That is proprioception. Often proprioception is considered maintaining balance but actually it is the ability to sense change. In order for proprioception to function optimally, all joints must have full mobility so the mechanoreceptors can tell the brain this joint can go from here to there before we can stabilize naturally and reflexively. This is the concept commonly referred to as joint centration. Stability has to come second. Stable does not mean lack of movement. It is the ability of a joint system to maintain position in the presence of change.

In it's simplest form, the joint by joint concept starts at the ankle and works up to the glenohumeral joint. The rationale is that you need to look at the primary need of the joint in relation to motion and the other joints of the body. There is another concept to consider thai is the directional susceptibility of movement. The body will move in the path of least resistance. The point of the concept is that if you have a painful joint, look at the joints above and below the joint. A practical example is the knee. It is primarily a hinge joint and so moves mainly in the sagital plane but needs dynamic stability in the frontal and transverse planes. The joint below, the ankle, and the joint above, the hip, are classified as mobile joints. If either of these two joints give up their mobility, the relative rotation of the tibia and femur is disrupted which can cause abnormal torque over time and excessive movement in the planes of motion that have very little. The result can be degenerative damage to the joint. Surgery may fix the joint, but if the movement mechanics are not addressed, there is no reason to believe the person is not at risk for further complications.

The takeaway is this. If mobile joints give up their mobility, they become more stable. Usually this shows up as stiffness. At worse, it causes degenerative changes in the joint. It is a natural adaption of the body trying to move the best it can. Proprioception is lost because the joint has lost it's end range capacity. If stable joints lose their stability, they become more mobile. This is compensatory relative flexibility. This will show up as dislocations, muscle strains, and disc herniations. No matter how much you try to train them to stabilize, they will give it up because motion dictates it. That is why mobility has to come first, then stability, then strength. The key is that as soon as you provide more mobility to the system, you have to reflexively stabilize it.