To state that the execution of Form Five is unique within the American Kenpo system is to state the obvious, and not very helpful. That is the equivalent to saying Long Form Two, Long Form Three, Form Four, or any of the form's executions are unique within the system. But unlike the other forms, Form Five does indeed stand out. But what is more important than that specific observation is to understand why.
If one were to stop, take the time, and examine all of the prior forms, one might draw a large number of obvious conclusions about similarities between the forms. A lot of those similarities are probably also shared with Form Five. One of the more obscure observations that would probably be overlooked is to come to the conclusion that those previous forms concentrate the vast majority of their motions to only two (2) of the three (3) dimensions, depth and width; with the third dimension (height) mostly being the minor, not major dimension used in its overall execution.
Another way to state this observation is that all the previous forms used primarily Back-up Mass and Torque as their major Power Principles; and usually employed Gravitational Marriage as the minor Power Principle, to enhance the maneuver further. The real contender as an exception to this observation would be Short Form Two, which does specifically call out the use of Gravitational Marriage as the major power factor in its execution, but only briefly. And, although one might argue that the other forms do indeed use Gravitational Marriage as the primary Power Principle during execution, and this is without question true - but not nearly as often as Form Five.
To expand upon this observation a little further, it is important to understand that in these prior forms, the inclusion of Gravitational Marriage into the mix of Power Principles was most typically done (this is a general statement, to emphasize the point of the discussion) through the use of diagonals. Another way to think about this is that the strike's path of travel was either linear or circular in nature, using either primarily depth (Back-up Mass) or width (Torque), and only added height (Gravitational Marriage) as a way to help further enhance the effectiveness of the maneuver.
These enhancements were often done through some variation of settling (a vertical, not diagonal maneuver) and through purposeful angular adjustments. In other words, this is a fancy way of saying that instead of executing a straight punch perfectly parallel to the ground, its path of travel is instead adjusted to be slightly upward or downward (depending upon desired effect) in order to add some Gravitational Marriage to the maneuver mix. In short, a way of sneaking in extra power through the use of extra dimensions.
(As a side note: Body English is purposely being minimized as part of this overall discussion.)
This is where Form Five flips that prior narrative. While it still does use depth (Back-up) and width (Torque) as primary Power Principles judiciously throughout its execution, it also adds a large mix of maneuvers that use height (Gravitational Marriage) as its primary dimension.
This fact then exposes an answer to an important observation about Form Five: it is a form that has a large concentration on lower body maneuvers. And although not mentioned often, lower body maneuvering is an important theme of Form Five. But, why?
Because vertical motions are not only suited for upper body maneuvers, but work equally, if not better, for lower body maneuvers. This is due to our overall body structure, which emphasizes standing. From a physical perspective, the musculature of our legs is more developed for vertical motion and slightly less for horizontal movement (when standing). That is why we can move such large weights with our legs on a leg press, when compared with a bench press and the arms. Simply put, our legs are built for vertical power generation.
This factor, along with the definition of American Kenpo forms needing to show reverses and opposites, explains why Form Five is the form that expands upon this area of study further than all the previous forms.
And like the upper body maneuvers mentioned earlier, these lower body maneuvers not only take advantage of directly vertical maneuvers, but also often include diagonal angles to further enhance power generation. And also, like the horizontally oriented maneuvers, rely heavily upon the mass of the body and alignment in the proper execution of these vertical maneuvers. Another way to think about this is that vertical maneuvers are almost the same as horizontal maneuvers, just with the added benefit of gravity to aid in power generation.
The major difference between the two types of maneuvers (horizontal vs vertical) is that the body mechanics required to deliver these maneuvers correctly is different. Because of this, a new set of physical skills is required to master these new types of maneuvers. But in a general way, the overall goals and how to achieve them are the same. In other words, these motions share many of the same rules and principles, but there are definite differences in how they are applied.
(For more information into this subject, see the "Improving Execution" section of this guide.)
Combining the above factors with the other major themes of Form Five, such as: difficult transitions (aka out of position and hanging hands) and destabilizing the opponent (aka take-downs); one can appreciate how and why Form Five is different and somewhat unique in its execution from the previous forms. By expanding into areas of interest mostly not covered in the previous forms, Form Five pushes the practitioner into learning and mastering new physical skills and their associated conceptual frameworks. Skills and concepts that might otherwise be minimized and/or overlooked.
Some of these physical skills include sweeps, stomps, buckles, specialized kicks, and combining and coordinating lower and upper body maneuvers in a variety of new ways. This last item brings in a design that is important to note about Form Five. It starts out with the lower and upper body working in tandem by leveraging the concept of directional harmony (e.g. going in complimentary directions to maximize effect). But as the form progresses, it purposely switches the lower and upper body coordination to employing the concept of opposing forces (e.g. going in opposing directions to maximize effect). Opposite, but equally important concepts.
It is at this point, that it must be strongly noted that these new areas of study have to be learned, practiced, and mastered, in order to correctly and effectively execute the form. Just like the other forms of the system, practice DOES NOT make perfect. Perfect practice makes perfect. And, an experienced and informed practitioner can very quickly discern between a form that is being performed properly and effectively from one that is ineffective and improperly executed. Crucial elements such as improper weight transfers and mis-alignments become very obvious, once one understands their proper implementation.
So, the practitioner is encouraged to not just "go through the motions" of the form's execution. Or even, just trying to execute the form as hard as possible. But rather, take the time to understand the proper body mechanics; the rules and principles of motion, for maximizing the maneuvers of this form. As stated, this form incorporates new body mechanics and therefore new physical and mental proficiencies that must be absorbed and studied in order to master them. Not taking the time to understand and correct for the subtleties of these new skills will most definitely result in a Form Five that does not rise to the effectiveness of its design. And, this will be blatantly obvious to the informed observer.
With all of the above being explained, there is still one more controversial point about Form Five that needs to be explored. This point can be presented as follows: all of the Long Forms of American Kenpo have at least one (1) isolation sequence contained within their execution; except for Form Five - why?
It can be noted that short forms do not contain isolation sequences and long forms do, that is one of their distinguishing differences (e.g. opposites). And therefore, Form Five does not express the opposite by not containing one.
But first, for those that do not fully comprehend what an isolation sequence is, it is important to give a definition. An isolation sequence can be defined as: the purposeful isolation of the lower body from the upper body to highlight specific maneuvers for any combination of the following reasons: 1) to demonstrate new information: 2) to fill in missing information: 3) to demonstrate a preview of things to come.
Another way to look at this definition is that these maneuvers basically are short-hand maneuvers that are calling out important information that would otherwise be missing. Or, from yet another perspective, brain teasers for the practitioner. Maneuvers designed specifically to make the practitioner think about what is being demonstrated within the sequence - e.g. why are these maneuvers part of the form.
Given that explanation, one can easily mentally or physically move through the forms and see that each of the Long Forms contain at least one (1) area of the form where the practitioner is demonstrating maneuvers in this manner. Everyone except Form Five. To be more precise, each form has at least one (1) point where the practitioner is standing in a horse stance (immobile) and executing maneuvers with the upper body extremities.
It is important to notice both the definition and what was just said, because this is where the controversial point comes into play. What is the opposite of what was just described above? That would be: having the upper body being immobile and the lower body executing maneuvers. And, if one where to execute Form Five they would find multiple sections of the form where these types of maneuvers are indeed taking place.
For example, the transition between sides of Back Breaker, portions of Hopping Crane, and the end of Falling Falcon. And although these sections are commonly referred to as: "three on line", these maneuver sequences could just as easily be called out as isolation sequences. And, where better to place such lower body isolation sequences, than in Form Five, the form with lower body usage as one of its themes. This is the general argument for defining these maneuvers as isolation sequences.
What makes this a controversial issue is that some high ranking practitioners reject this observation and explanation. And, SGM Parker is no longer around to give a definitive answer. This leaves the practitioner open do decide whether they will include this point as part of their reservoir of knowledge about the forms, or not. Or, even express this as a potential explanation, or not.
And finally, what makes this guide different from other similar works is that its purpose is to express this subject to the reader in a non-biased way, and let the reader come to their own conclusions. It is important to expose the reader to this information because it rises to historical relevance - regardless of whether everyone universally agrees upon the point presented. Enough practitioners accept the premise, and therefore, the argument should be presented and not dismissed without consideration.