Have you ever wondered how you can wake up in the middle of the night and know what position you are in without having to turn the light on to check? Before any movement takes place, the brain will “read” the present posture via the afferent (ingoing) nervous system. The constant information sent to the brain from nerve receptors around joints (ligaments, tendons and muscles) makes this possible. This is also why you can scratch your nose in the dark without poking yourself in the eye. The nerve receptors continuously feed the brain with necessary information regarding our position among many other things. If a muscle or even a small part of a muscle is dysfunctional it will sent the wrong message which will affect any movement and its stabilization. Joints out of their ideal alignment are not sending contented messages to the brain.
Imagine doing a standing biceps curl in the gym. Most people would understand that the arm muscles are working against the stabilizing forces of the shoulder-blade, which of course is correct, but it does not stop there. For the shoulder-blade to be stable the shoulder stabilizing muscles need a fixation point (Punctum Fixum). The first stabilization point is created by the diaphragm and the intra-abdominal pressure (IAP) which is created by its proper activation, but again it does not stop there either- the core is not hanging loose in the air. It all continues down to the point of physical support, which in this case is the floor. Taking that into account all joints, between the hand holding the bar and the foot support on the floor, will affect the stability of the movement. The more joints that are in a position of centration (ideal alignment) and properly stabilized the more isolated and therefore controlled will the biceps curl movement be. The execution and strength of a biceps curl is therefore dependent upon the proper alignment of all joints from the foot, ankle, knee, hip, pelvis, spine & torso (IAP), scapula, elbow and wrist. Of course the position of the neck will also affect this movement!
Do we want to send messages of stability and strength or of instability and weakness through our system when performing exercises? It all comes down to positioning and stabilization. Initially we have to be very particular with form and proper position, but after a short time these good habits become anchored in the nervous system and are more or less automatic. The correct patterns are all there from the beginning as we know from Developmental Kinesiology, they just have to be activated. Sometimes these faulty development patterns have resulted in altered structure that has permanently affected posture and joint development. These changes can of course not be trained away, but what we can do is to train the brain to use the body in the best way that it can. Joint function can still be vastly improved even if the structure is less than ideal.
Good centration of joints insufficient centration of joints
All joints have a position of ideal alignment for each movement. Developmental Kinesiology and Reflex Locomotion have given us a blue-print of these ideal positions. Joint centration is the position of greatest inter-osseous contact between the bones to allow for optimal load transfer and maximum muscle pull. In other words, joint centration is the ability to hold a joint in its ideal position, thereby allowing maximum loading with minimum strain.