As a broad definition, and for the context of this discourse, alignment can be thought of as properly positioning the body in such a way as to maximize the outcome one wishes to effect in relation to an action. And, bracing angle can be thought of as a method of checking whether specific alignments are properly oriented based on the path of directed energy that travels through the body in reaction to the point of contact with an external object.
Another very simple way to think about these definitions is that alignment is overall body positioning for getting the best results for the situation, and brace angle is a way to determine whether the alignments are effective or not; by maximizing one's ability to resist a directly opposing force with minimal stress to the effected body parts.
Regardless of how one thinks about alignment, the fact remains that it is an extremely important element when trying to maximize the execution of any motion. And, although alignment is most often discussed in the context of offensive maneuvers, it is equally important when referred to in a defensive context. Also, along with the discussion of alignment, bracing angle is a key method of understanding how to determine whether certain alignments are effectively obtained, through the ability to create an optimally stable posture with the body, given the specific scenario.
One thing to keep in mind is that this previous statement holds true even if the postural alignments and bracing angles are intended to be minimally resistant to the opposing force.
In other words, it doesn't matter if the intent of the maneuver is to be as solid as possible and resist further pressure, or as fluid as possible and yielding to further pressure. Regardless of intent, the stability of the overall structure is still just as important. Otherwise, the entire maneuver's effectiveness may be highly compromised both from an offensive and defensive standpoint.
Next, one must understand that the major elements of proper positioning are comprised of: foot, leg, hip, body, shoulders, arm, and hand. And, although these are the major elements; other, less critical, bodily elements also play a very important role in proper alignment. Some of these minor elements are: ankle, knee, spine, elbow, wrist, neck, and head. And, each of these elements combined together create the overall positioning and orientations in relation to directionality and point of reference.
Furthermore, it must also be understood that alignment is not limited to only forward directionality, and is not limited to just the neutral and forward bow stances - even though this is the most common direction and positioning used when discussing this subject. Along with this point, it must be stated that different directionality will almost always result in different positioning and orientation for achieving the appropriate alignment and creating the proper bracing angle.
Moreover, obtaining proper alignments and brace angles can be very subtle. Often, small degrees of variance from the right positioning and orientation can manifest as larger discrepancies in the creation of maximized outcomes.
In other words, it doesn't take much physical alteration to diminish a proper alignment into an improper alignment; which then effects the overall effectiveness of the result. So, one must be diligent and pay attention to seemingly small angle changes from what one determines to be optimal.
Most certainly, the most common example of this effect is having someone execute a straight, thrusting, vertical punch. The proper alignment would be to shift into a forward bow and create a straight line from foot, knee, elbow, hand in a front-to-back direction. From a bracing angle perspective, this alignment would be optimal for redirecting a reverse energy (from the front) through the body (e.g. hand, wrist, elbow, shoulder, body, spine, hip, knee, ankle, feet) to be redirected onto the ground, through the rear foot.
Using this as a base example, let's take a simple look at two (2) critical and obvious options that reduce optimal alignment: To start with, if the practitioner were to stay in a neutral bow, rather than shifting into a forward bow this stance change would dramatically change both alignment and brace angle. Secondly, if one were to not align the striking elbow directly in-line with the striking punch (a.k.a. create a chicken wing with the elbow), then it also becomes quickly apparent that the lack of proper alignments would again reduce the overall output potential of the punch, while also greatly reducing the overall bracing angle.
Obviously, the neutral bow, instead of the forward bow, is quickly recognized as an alignment problem. But the elbow misalignment is harder to pinpoint as a contributing factor. Yet, through experimentation, one can determine that even a small angle change to the elbow alignment can result in a compromised brace angle. Likewise, this is also true for each of the other unnamed elements that contribute to the make up this example alignment. Each is an important component to both alignment and brace angle.
This previous example demonstrates the most common scenario; but what about other angles of focus and attention points? Would this work the same? Do the concepts even still apply? For example, what if the opponent where positioned to the flank instead of in front? The short answer to these questions is: yes, but this is where our other stances and alternate alignments come in.
Showing an opposite example to the previous one, let's assume the opponent were at one's flank and the defender wanted to maximize the bracing angle / alignments for that positioning, in a defensive manner. How could that be accomplished? This specific situation is where a wide-kneel stance would be more beneficial than a close-kneel (or forward bow) stance. This is due to the fact that the wide-kneel positioning has more side-to-side (width) stability than the close-kneel (front-to-back stability).
Understanding these specific characteristics about the different stances provides one with the answer as to which stance would provide better bracing to the off angles. Alternatively, if the brace angle requirement was for the front or rear, it then becomes obvious that the close-kneel (or forward / reverse bow) stance would be the better choice.
Alternatively, this example can be manifested from an offensive perspective. Suppose one needed to strike an opponent at the flank effectively. Generally speaking, foot maneuvers to the front and rear with the arms extended to the flank would provide the required brace angle. But, not just any extension would be sufficient. For a physical (and visual) implementation of such a scenario, one can refer to the self-defense technique Destructive Kneel.
If one were to examine the proper alignments of the arms on the first double strike section of Destructive Kneel, one would discover that: a) the arms are not overly extended (to allow for anchored elbow), b) the elbow of the closest hand would be anchored below (height) the striking hand, but on the same side-to-side (width) plane and in-line with the body (depth), and c) that the furthest hand would have the elbow to the same relative height as the striking hand - also on the same side-to-side (width) plane and in-line with the body (depth).
An observation about the above example is that it uses the primary power principle of back-up mass through the use of a foot maneuver (e.g. push-drag) to generate power. But this same arm positioning would also hold true if the major power principle were torque (e.g. rotation) instead.
A note about the above example: an element of gravitational marriage (e.g. vertical back-up mass) can be used to further enhance the strikes through the bending and unbending of the knees during execution of the maneuver (either back-up mass or torque version). This additional body manipulation (and many more like it) are commonly referred to as Body English. And, Body English is just another one of the factors in maximizing outcomes.
Secondarily, this note rightfully implies that bending and unbending of the knees is not just for changing height, but can also be used extensively in enhancing offensive maneuvers, both circular and linear - adding yet more enhancement (than just alignment) to the movements.
Up to this point in this discussion, the concern has been focused on the entire body (a.k.a. a macro level). But alignment and brace angles are also extremely important for individual areas of the body (a.k.a. at a micro level).
For a third example, consider a two-finger slice. There is a very specific way that a finger slice should be executed to be considered proper. An outward finger slice should be executed with the palm pointing downward, and conversely, an inward finger slice should be executed with the palm pointing upward. Why? This has to do with both the physical construction of the fingers, the musculature of the arm and wrist, along with the number of fingers being used.
In this specific example, one finger is considered the active finger (e.g. the middle finger) and the other finger is considered the bracing finger (e.g. the index finger). This is because the longer finger is the middle finger and if the shorter finger was used as the active finger, then the longer finger would make contact, regardless of intention; and this would potentially compromise the overall bracing angles of the maneuver.
Furthermore, a single finger is not used because there is typically not enough strength naturally built into any individual finger to take the pressure from the side safely and without potential of injury to the weapon itself. This is due to the fact that fingers are naturally designed to take directly applied pressures, not lateral pressures; and therefore, risk a possibility of breaking, if something does not go according to one's plans. Thus, a bracing finger is added to the strike to ensure proper stability of the entire weapon (e.g. the fingers and hand) during execution.
But there is another part of this example that is often overlooked - the alignment element. If one were to consider the musculature of the arm and wrist, one would quickly determine that an outward, palm up movement is not as sound an outward, palm down movement - and the converse is true for the reverse direction (e.g. inward). This is due to the natural physical design (e.g. the bones and musculature) of the arms and wrists.
We, as martial artists, are trained to use the most sound and effective alignments to produce a maximum outcome on the intended target. Through analysis of this weapon formation and experimentation with the intended maneuver, the alignment of palm down for outward motion and palm up for inward motion are typically deemed to be the proper orientation overall for this maneuver; where the opposite orientation is typically determined to be less optimal.
True, this secondary alignment option is possible to execute, and without doubt, may be used to produce an effect; it just isn't as sound a physical alignment, and will not produce the maximal results as its counter-part. Because of this analysis outcome, we refrain from using the less optimal alignment as our primary choice and would only engage the secondary option in very special circumstances.
This previous statement implies another refrain that Kenpoists like to quote: "there are two (2) reasons why we do things: because we want to and because we have to."
In this current example (but this also holds true for all scenarios), we would use the more optimal option because we want to; but would resort to the less optimal option if we had to. And, this mindset holds true for this entire discussion. We always try to achieve optimal alignments and brace angles, but sometimes we are forced into situations where this is not possible. And, that is an undeniable and acceptable reality.
In other words, train for the best, but prepare for (and take into consideration) the worst. But we do not do the opposite because we will respond how we train. And, if we train less optimally, we will naturally respond that way. And, one reason why we train is to produce better results, not less optimal results.
Needless to say, that these are not the only examples that may be given. There is a plethora of examples that could be illustrated. But, this discussion cannot, and is not intended to, provide them all. Instead, the provided examples are important for demonstrating the implementation of the concepts of alignment and bracing angle. But, the more important point of the examples is that they provide the reader with a more visual, physical, and concrete way to better comprehend the presented concepts.
Additionally, it is hoped that the reader uses these few examples as a base to take the time to develop the ability to determine which alignments and bracing angles are best for any given scenario on their own.
In other words, the reader is encouraged to use this discourse as a springboard for further exploration into the concept of alignment and brace angles and how important they are to proper execution of any maneuver.
Finally, these concepts are subtle, yet key elements that are often glanced over and/or not given enough attention in one's training. It is hoped that this discussion exposes just how invaluable alignments are to maximizing one's natural abilities through the proper use of the body. And, through the exploration of this subject, one's mind is open to other facets of their martial arts journey that would otherwise be neglected, overlooked, or remain unexamined.
For more information on the concept of Body English refer to "EPAKS Guide to Long Form Two - Appendix-C - Body English".