All men are the same physically speaking. They have been that way since the species was a hunter-gatherer culture. Two arms, two legs, flesh and bone. We have physical limits that can be pushed vis-a-vis training, and for some due to being gifted in some areas physically, but those limits cannot be eliminated. And for those who seem to worship the past, in our day, we have better food, better medical care, and better knowledge on making the body stronger and resilient than ever in history. An athlete today is far stronger, faster and agile than an athlete from the 1700s. No matter how much some want the ancients to know more, be stronger and nearly god-like in their powers, the truth is that they were just men. Men, who I will add, would not only be astounded at the performance capabilities of modern men, but who would have readily embraced modern muscle building, nutrition, and medical practices.

Moreover, we all tend to fight very conservatively when the stakes are life and death. At such times we tend to use methods with a high success rate rather than take a gamble. Lose a match and you shrug and go home sulking. And in a few days, your pride has recovered (and likely several reasons why things did not go your way have become evident). Lose a fight on the battlefield, or the street and the results are different. There is a good chance you may not live to repair your pride or at best, never be physically whole again. That last is the world where Karate was born.

First there was the street fight, not the sport. And the founders of karate lived in a competitive world where challengers to their skills and abilities were common. And a loss might mean a loss of livelihood at best, or a life altering injury at worst. Their nature was the same as ours, and when victory became the most important matter, they used methods that would guarantee success regardless of how they looked.

Interestingly enough, those methods are memorialized in the kata. And it is in this area that this article focuses. We can filter all technique in a kata through these two primary filters:

1). Urgent need for the technique to succeed
2). Realistic human physical performance limits

And in order to really learn and be able to apply in combat, our filters must be honed to that end, and not to the preservation of myths, or unrealistic traditions. For example, a very basic Karate kata, Pinan 5, or Heian 5. There are two movements there that I want to use as example. And I am picking on this particular kata because it is one of the basic ones, and found in every karate derivative from original Tae Kwon Do (pre-sport) to Okinawan, to Japanese.

The first move is at the last section of the kata. Movements number 13 through 14...depending on how you count it. The karateka raised his arm high, and then jumps. The traditional (mythological) explanation of the movement is that the fighter is facing an adversary with a staff or a sword. The fighter raises his hand high to create a target for the swordsman. When the ostensibly retarded swordsman swings at the hand, the fighter pulls it down. The frustrated swordsman now swings at the fighter's feet, where upon the fighter leaps into the air to avoid the sword swing. Let's look at this through our filters -

1). Urgent need for the technique to succeed -
2). Realistic human physical performance limits -

I have studied some sword, and in a past life I had occasion to actually fight a bad guy that had a knife in his hand - admittedly not a sword, but as close as we will likely get in modern industrialized worlds (not intentionally, I was not informed of his knife at the time). Based on the urgent need to succeed to stay alive, I doubt anyone is going to go up against a knife, much less a sword, unless the swordsman is drunk or blind...and even then it is a bad idea. I am sure we could find a highly skilled Kendoka with a live blade that would be available to test the technique in question. So the traditional "mythological" explanation doesn't hold water. And the acceptance of realistic performance limits tells us that unarmed facing a large blade, anyone with a brain in his skull will either quit that fight or arm themselves in some manner.

More realistic explanation?

Rather than the jump, the method is a manner to build power and drive in the lower body and legs. Even in more modern times the vertical jump is used to measure an athlete's potential. In an era of no protein supplements, barbell training or other similar aspects, how do we teach students to drive with the hips and legs? Teach them to jump of course. So the real application is not some Last Samurai fantasy, rather it involves a very simple shoulder throw followed by a couple of ground and pound finishers. Physically the same and fitting within the need for success and the limits of human performance.
The point is this - don't take any of your training on faith, nor accept a method's mythology at face value.  Test and filter everything, and if it smells like bullshit, whether in the martial arts world or the gun world...don't step in it.