Every truth has two sides; it is as well to look at both, before we commit ourselves to either.
-- Aesop

Definition of Terms
I find this subject so vital, so relevant, so critical to the health and welfare of all those who are moving or who want to move, that I cannot emphasize its importance enough. Once I had a grasp of this all-encompassing principle, I was surprised that these fundamentals of spinal function were not already included in current training systems of any kind. That said, I freely admit that the architectural miracle of the human spine and its support mechanisms are so complex with such a dense layering of structures and interacting elements, that the task of rendering its function to understandable principles for study and application is daunting indeed. The challenge lies in the attempt to find ways to express and work on aspects of SB without oversimplifying.

Simplification, although necessary, can be dangerously reductionist. To start with, the simplistic term “side” in Side-Bending leaves too much room for misinterpretation, allowing most of those who hear the word for the first time to think of a purely frontal plane, sideways inclination of the upper body. In any case, the Side-Bend we will appreciate and come to understand is an anterolateral compensation of the axial body (from the pelvis to the head) that includes slight counter-rotations of the neck, torso and lumbar/pelvis.

We can group Side-Bending phenomena into two kinds of lateral flexion: Static and Sequential. Static SB’s can be observed as postures that persist in situations where there is little or no movement forward. Sequential SB’s can be observed as transitory postures that offer credible support or generate and harness kinetic energy to the body as it locomotes through space.

The Static SB expresses itself in a muscle-efficient resting position, where major body blocks are countering each other to create balance. The sequential SB is actually an energy-efficient mobile compensation that offers a reasonable rage of motion while it safeguards the spine against excessive torsion, shear, compression and decompression.

Sequential SB, which includes the successive inclination, translation and counter-rotation of the three proximal motors, provides a pre- cise description of the subtle role the axial body plays in the act of locomotion. Functional, sequential SB allows for optimal use of available support elements by putting the masses of the proximal motors within support range. Because of the subtlety of the joint angles and the endless variations on them, sequential Side-Bending cannot be considered a “shape” or constant position, but rather a phenomenon of weight distribution.

The spinal relationships occurring during Standing Sphere lateral flexions include:
■ a flexion and external rotation in the weight-bearing hip

■ a swing of the anterior aspect of the lumbar spine away from the weight-bearing hip

■ a subsequent inclination and rotation of the anterior aspect of the thoracic spine towards the weight bearing hipp

■ the cervical spine will then incline towards the weight bearing hip as a whole, as well as rotate its anterior aspect away from the side of inclination 

■ the skull retains some degree of independence from the SB orientation, allowing further negotiation with the environment for more accurate assessments of subsequent responses.

Categories
Sequential Side-Bending mechanics can be subcategorized into priority support (PSB) or future support (FSB) lateral flexions.
In activity spheres one through four, PSB is a lateral flexion that is oriented towards an asymmetrical weight-bearing system. PSBs develop when the support elements stay the same over a period of time. The time period must be long enough to allow the SB to resolve, otherwise the spinal movements remain residual, non-defined, compensatory or undulatory motions.
Asymmetrical weight-bearing systems typically involve uneven uses of the Landing/Launching Pads or other supportive surfaces such as the foot of one side, the calf of the other, plus one hand or any other combination. When the activity uses the hands or forearms as complimentary to the support provided by the lower limbs, the PSB will most likely be dedicated to the weight-bearing arm. However, in the fifth activity sphere, or Climbing Sphere, the PSB generally drops away from the weight-bearing element.

Future Support Side-Bending (FSB) is observable when the weight is still decidedly on one side, but the SB is oriented towards the other side. FSB mostly occurs as a preemptive strategy for changing from one asymmetrical support system to another, or to prepare the body for landing from a jump. However, sometimes FSBs do not imply an immediate, impending shift of support, but offer energy-efficient and support-affirming solutions nonetheless.

PSBs and FSBs can be initiated or started by the movements of the three core masses: the pelvis-abdomen (M1), the torso-shoulder girdle (M2), or the head-neck (M3). Lateral flexions that are initiated by M2 or M3 often occur when weight is loaded directly to the pelvic area. Lateral flexions initiated by M1 most often occur when weight is loaded to upperbody or arm supports.

By augmenting movement in the mid-spine motion center (Tri2) and/or the hip-joint (Tri5*) flexion or extension, the SB can also be biased to one of the four quadrants: anterior left or right, or posterior left or right. The bias to one of these quadrants will allow access to various support elements and various combinations of those support elements.

*The main motion centers in the skeleton are categorized in the AS reference system according to their independent ROM. Those that have 30 degrees or more ROM around three axes are termed triaxial (Tri), those that have 30 or more degrees around two axes are termed biaxial (Bi), and those that have only a single axis option are called monoaxial (Mo). Please see the Classification chapter and Motion Center Descriptions chapter of the Axis Sylllabus Reader for a full list and overview of the motion centers.

A Triaxial Reality
As has been mentioned earlier, it is very likely that extreme monoplane and single axis motions of the spine will cause a loss of joint alignment. Therefore, all descriptions of lateral flexions must include minor torsions and inclinations. The appropriate range or degree of these secondary and tertiary rotations must mostly be discovered through an individualized process. Experimentation seems essential to the affirmation of healthy, personal motion parameters. The research of these parameters will very likely be constant, because age, health, weather, relative flexibility and strength are all constantly shifting variables. The assessment of an educated outside eye is important, but must be enhanced through dedicated personal study. An impediment to the objective study of SB is that functional postural habits need to be established before the phenomenon can be observed at all. Functional posture is defined by the alignment of the synovial joint surfaces, and a balanced use of the musculature; but these are only words on paper or screen. To truly understand the reality of how the SB feels and works for you is to enter into constant research and dialogue with your spine.

Tensegrity
The Tensegrity Principle is an integral aspect of appropriate Side-Bending
“Tensegrity” is a composite of the words tensional and integrity. The term was coined by the famous architect and engineer Buckminster Fuller to describe the balance of more rigid and more elastic elements (i.e. bones, fascia) that allow for efficient load-bearing and dynamic suspension in organic structures.

Sequential Side-Bending Subdivisions

priority/future support - initiated by M1, M2, or M3 right/left anterior quadrant right/left posterior quadrant

Recent advances in the understanding of fascia and its importance for posture make the concept that our skeleton is our fundament obsolete, allowing us instead to percieve the skeleton as a suggestive guidline, but also help us to understand its relative fragility. Most injuries among training athletes occur in the joints, indicating that an appropriate understanding of the limitations indicated by the skeleton is a first-line defense of our health.

It is easy to observe, that in static and dynamic situations alike, if we put our weight first through a moderately angled skeleton, we establish tensegrity, augmenting the body's weight-bearing capacity with the collaboration of surrounding myo-fasical systems, allowing to use our strength more efficiently and making the task of moving more pleasurable.

More specifically, practically speaking, this means: put all available articulating points together and keep as much of the available surfaces of these articulating points in contact as possible at all times. This means that for each of the spinal segments (two vertebrae), both of the vertebral joints, the disc, and the vertebral bodies will be brought together in an even fashion when we are landing from a step or jump.

Anatomical Clues

The axial skeleton (skull, spine, pelvis) has the characteristics of a “unit”, given the interdependence and strict functional influence the various pieces have on each other, as well as the progressive changes of angle in the joint facings throughout this system. The only exception to this rule of progressive angle changes is the abrupt shift from the frontal to the sagittal plane in the joint orientations of the 12th thoracic vertebra. There is a clear and obvious division of the axial and appendicular systems at the hip and shoulder joints, where range of motion is largely independent. Of course the disposition of the axial skeleton will have an influence on the support value and freedom of the peripheral elements through weight distribution, momentum and the successful collaboration or competition of solicited muscle chains, which is where the utility of the Side-Bending principle becomes apparent. The most important fact for our discussion of locomotion is the motoric value of the axial body, for not only does the spine assist us in taking advantage of the offer of support, it serves to generate energy to drive the arms and legs as well as providing an energy conduit for forces arriving from the periphery. The muscular systems can now be employed in a more diversified role, not only through voluntary contraction, but also through elastic recoil and reflexive contractions, as well as representing potential energy because of their sheer mass and location.

The main muscle groups located in the trunk of the body that support lateral flexions by order of proximity to the spine are:

1st Layer Stabilizers
■    multifidi and rotatores
■    intertransversarii and levitor
■    costals and intercostals

2nd Layer Stabilizers
■    transverse abdominis
■    psoas
■    scalenes
■    occipital group
■    diaphragm

3rd Layer Stabilizers
■    spinal erectors
■    latissimus dorsi
■    external/internal obliques
■    quadratus lumborum
■    serratus anterior
■    serratus inferior

4th Layer Stabilizers
■    trapezius
■    pectoralis major and minor
■    rectus abdominis

Although it is next to impossible to predict the firing order of the above-mentioned muscle groups in dynamic situations, I have read suggestions from the scientific community that the muscles nearest the spine (i.e. multifidi, rotatores, scaleni) are the first. These muscles are irrigated with blood and then are innervated or contract before the command to move has even been formulated in the brain, or about .11 milliseconds before the brain has conceived of and sent the command. Newer sources describing the course of information through the nervous system indicate that this flow can be enhanced through the development of new sensory tools, but also disrupted or rerouted through habit-forming training. The Rolphing community has done electrode testing that demonstrates this fact. Rolphers have also noted that over-trained “global”, or more externalized, larger muscles often cause skeletal misalignment. I take this to mean that these muscle groups take precedence over the stabilizers when they are trained to do so in an isolated fashion, or when they are maintained in constant contraction when the body is moving. In line with this growing notion that conditioning regimes might present some dangers to appropriate function, Paul Chek, the sports and biomechanics expert, has written several enlightening articles on the secondary role of the rectus abdominis (considered one of the global muscles). He reminds us that the nerves leave the CNS from its spinal housing and spread out from the back to the front, a strong indication of an inbuilt chain of command that recruits the spinal stabilizers before the rectus abdominis. A researcher associated with the Chek Institute wrote in one of his responses to a query on my part about muscle mechanics: “ ...many athletes get hurt because they are working out on machines which train their muscles in single-plane movements.” My correspondent stated that monoplane repetitions essentially “detrain the nervous system”, so that it no longer recognizes the coordination chains involved in real life dynamic situations.
The relevance of these observations is that spinal mechanisms respond to or even drive coordinated weight distribution and the establishment of optimal support systems as we move, and depend less on the strength of individual or global muscle groups.

Applications
In my observation, SB has some relatively constant phenomena. If you are standing or crouching over a single foot or lower leg landing pad, or sitting on your buttox or thigh for an extended period (ap- proximately a second or longer), we can call this support element a Priority Support (PS). The SB will be best deployed when dedicated to that support, therefore dubbed a Priority Support Side Bend (PSB). If you are using a hand as a support for an extended period, the SB will be dedicated to this support element, even if the weight is shared with a support element on the leg of the opposite side.*

* see Landing/Launching Pads in the AS Classification chapter

Try the following ramp pattern to understand what I mean:
■    Standing on two feet, take a step forward on the left foot (ILP1 -L) and allow the PSB to develop for that foot.

■    Keeping the PSB, continue to deepen the flexion at the standing hip, bringing your torso down until your left hand touches the floor.

■    Put weight first in your left hand, then start to transition to your right (SLP1 -L, SLP1 -R).

■    You still have some of your weight on ILP1 -L, but you will now feel how the weight of your pelvis drives the inversion of the SB, confiding the weight of your torso to SLP1.

■    The new PSB brings the right buttock (ILP1 C-R) closer to the floor, putting it within optimal reception range.
In a normal walk, the receptive leg gets the Side-Bend. But before the weight is transferred to the other foot, the SB starts to invert, beginning with the pelvis.

This is the same pattern that is extrapolated for most jumping. In the case of a medium-to-large jump, SB inversion is often complete before the weight has left the receptive foot. When the shifts of weight from one support element to the other are quick, the SB’s blend into each other and become what we can call oscillations or resonance.

PSB’s move most of the weight of the body to the priority support element. This principle reverses in the case of a jump, where the SB for the landing leg or hand develops even as the launching foot or hand is still loaded. “Future Support Side-Bending” or FSB, is the Axis Syllabus term for this class of lateral flexion phenomena. I have found some exceptions to this rule (ten of them so far) so let us consider the data cautiously and continue our research.
Arguably the most effective way to determine if the degrees of rotation are correct is to see if the weight of the body is centered over the most supportive part of the priority support element. For standing situations, the AS proposes a specific area of the foot where weight is distributed from and shock returns to. This theoretical weight distribution center is located at the nexus of the last cuneiform, the os cuboideum and the back end of the 3rd and 4th metatarsals, termed “Meta-Center” for short. We are fairly certain at this time that the weight of the body moves forward through the third toe from the Meta-Center in most dynamic Sphere 3 and Sphere 4 situations.
The place to focus the weight in the hand is located around the back end of the 4th and 5th metacarpals. In activity spheres 1 and 2, the trunk is approaching the transverse plane, and appropriate SB will become more obvious as a partial release and counter-rotation of the motoric masses of pelvis-abdomen (Motor 1) and torso-shoulder girdle (Motor 2), in other words, torsion becomes the most obvious clue to the correct SB in the first two spheres of activity.