Using Physics in Karate

Using Physics Equations to Improve my Karate Techniques

Chris Becker 6-25-2025

This paper is a result of a number of developments that I have experienced over the last several years. I am aging, and am constantly looking for strategies to maintain, or improve my technique. Strength, speed, flexibility, reaction time, and posture have all declined for me. Practicing karate, as you age, features a process of utilizing new and different strategies, in a seemingly futile attempt, to improve technique. Sparring becomes a unique challenge as natural abilities decline, and more time is required to execute defenses or attacks (and as the skill level of your opponents improves). As I attempt to overcome these challenges, I think about how my performance can be improved, and the scientist in my brain comes out, looking for an advantage. My thoughts include how physics manifests itself in my karate. This paper explores some of those concepts, in a limited scope.

As I proceed to explain my thoughts, let me share why you might be interested. I remember Leo Sensei, joking about making the karate you practice, “your own”. My initial interpretation of this comment revolved around a preference for techniques that was more comfortable, or played to an individual’s preference. As if making your style “your own” was a result of simple preference. Applying this concept takes on a very different dimension when one is compensating for diminished abilities. The adaptation or modification becomes much more important than just a comfortable preference; it becomes the essence of whether a technique will be effective, or not.

The discussion below begins with an assumption that one practices karate to the best of their abilities, every moment. That one’s speed or strength, at the time of training, is what it is, and represents the maximum ability in the moment. This assumption allows me to discuss how I attempt to maximize my abilities, whatever they are, each moment. Of course, if I can improve my ability level over the long term, I should be working on that, also. The following are some relationships in physics, applied to karate training.

Distance equals rate times time. (D=RT)

It is said that kumite is about timing and distancing. Interestingly, time and distance are related, mathematically. Timing usually refers to the opportune moment to execute a technique, so differs in concept from the time required to execute a technique, but I maintain that timing is also a manifestation of the time required to execute a technique. Distance is such an important concept, that it is related to time, is still worthy of discussion. If the rate (speed) I execute a defensive move or attack is “fixed”, depending on my ability in that moment, the things that are easily manipulated are distance, and therefore, time. How do I work to manipulate the variables of distance and time? That is the realm of technique.

Both offensively and defensively, stances can be altered to decrease distance, which reduces the time required to land an attack. I struggle to be fast enough to attack from a distance without an effective “setup”. The setup can allow me to decrease the time for the technique by decreasing the distance I have to cover. Kicks executed from the rear leg have to cover a longer distance, therefore, I find I am executing more kicks from the front leg. Also, to save time, I have been using cat stances a lot more, as this decreases the distance between my rear foot and my opponent. Cat stance also unweights my front foot, speeding up the execution of kicks from the front leg. Disguising my footwork to creep up on an opponent has become more important, again, to decrease distance, and the time required to execute a technique. This is often done with techniques involving my hands. All aspects of karate seem to be related, in some manner.

Summarizing, I focus on my stances, footwork, and have changed defensive and offensive combinations to better accommodate distance, and therefore, improve the speed of my techniques.

Force of impact = -1⁄2 MV^2 /S (M= mass, V=velocity, S=distance of deceleration)

Note: kinetic energy (KE) = 1⁄2 MV^2

Also, speed and velocity are not exactly the same thing, but I will interchange the terms in this passage, to simplify. I also will interchange the terms “force” and “power”. This equation embodies a saying that Whiteside Sensei used to say in class, “speed makes power”. This equation is the proof. The mass of the object accelerating towards the impact is seemingly constant, as we won’t be able to vary the mass of our fist or foot meaningfully. Something I like to remember is that we don’t just punch with our fist or arm, we punch with our whole body. The mass of the object we are striking with includes the mass of our body, if we connect our body to the fist we are punching with.

This is one reason why we drill on proper form, including the hip rotation, and body movement; it adds mass, which adds power to the impact. Even with the proper form, a less effective connection between the different parts of the body (ex. Arms to torso to hips to legs) can decrease the effective “mass” of the technique . This is one reason “kime” is such an important aspect of our training.

The variable S, distance of deceleration, is target specific, and is not the best variable to use to ensure a powerful impact. The target itself is not always a matter of choice, but a matter of what the most effective target is. The variable of velocity is most interesting. The force of impact is directly related to the velocity squared. I think this directly explains a very famous legend of karate: Bruce Lee’s one inch punch. The one inch punch was known for its power. Yet it did not feature a large amount of body mass behind it. Bruce Lee was not in a moving stance while executing it, although he did connect it to his whole body, he was not a very heavy person. The force of impact is proportional to the speed squared. Bruce Lee was known for being extremely fast. For example, since the equation is for velocity squared, a technique, executed at double the original speed, would have quadrupled the force of impact. Therefore, a freakishly fast execution of technique, would have an outsized force of impact.

Applied to my own practice, I look for opportunities to be faster, to increase the impact of my techniques. I work to be relaxing in between techniques, and remembering to not hold my breath. For kumite combinations, I strive to maintain a flow of motion. If I am already moving, I will try to harness that motion into the next technique, which should increase the force of impact. Decelerating and accelerating in the middle of a combination is getting harder to do, for me, anyway. Another method of increasing the speed of a technique is to harness the speed of one’s opponent. My speed may be limited, but if I can add the speed of my opponent by executing my technique with just the right timing, I can add to the overall force of my technique. I consider the timing to do this correctly to be “sen no sen”, as “sen sen no sen” timing allows a preemptive attack, before the opponent has initiated their attack (remember, go no sen is responding to an attack, for instance, a block and then a counter. Sen no sen is often described as a simultaneous block and counter. Sen sen no sen is a preemptive attack, usually just prior to an opponent initiating their attack). This strategy of harnessing the opponent’s speed to increase my force requires the opponent to be in motion, when my technique is executed.

In conclusion, since “speed makes power”, I focus on maximizing my speed through the use of good technique, and timing.

Pressure equals force over area P= F/A (P = pressure, F = force, A = the area the force is apple to)

We have a number of situations where we must apply pressure. I focus on pressure because I can increase the pressure applied by manipulating the variable of area, assuming the force variable is a direct correlation to strength, or speed. Force is not exactly a direct correlation to strength, but if a technique is correct, I consider the force to be at its maximum, or at least, not immediately improvable. The point is that by focusing on the area the force is applied to I can increase pressure without having to increase my strength or speed. Pressure is a component of a number of techniques we apply, most obviously, strikes, but it is also used in control moves, such as locks. The first two knuckles of a punch, the ball of the foot for a front kick, these are the most obvious examples where a focus on reducing the area of the impact will increase the pressure applied. As I depart from the most basic techniques, I find opportunities to minimize surface area to increase pressure.

For instance, backfist strikes with a slight rotation of the wrist to ensure knuckles impact, instead of the whole area of the back of the fist. Locks that include bars can be enhanced with a slight rotation of the wrist to ensure the narrowest part of the wrist applies pressure to the opponent. One choke included in “lock flow” allows me to rotate my hand to apply pressure with a projection on the edge of my hand, as opposed to the whole edge of the hand. Some blocks can be executed with the broad, or the narrow edge of the arm. This allows differentiation, with the narrow edge of the arm making a more effective strike, and the broad edge of the arm being used to be more gentle when training with a partner. The same principle applies, in reverse, when rotating the wrist to minimize contact when escaping a wrist grab. What I find elegant is that I can increase pressure with just a technique adjustment, independent of my strength or speed.

In summary, my martial arts practice is constantly evolving as I continue training. Main themes include how I work to shorten distances, increase speed, and increase pressure, to improve the effectiveness of my karate. The relationships described above are universal, they apply to all karateka, and therefore, are useful to anyone interested in improving their karate.

2020 Gasshuku Recap

USKL January 2020 Special Training

On January 30, 2020 the Defense Arts Center celebrated the New Year with its first ever Special Training since moving to its new location in Upland.

Sensei Tom Heyman, USKL Godan, led the class, sharing insights and anecdotes from his many years of participating in very intense special trainings organized within the Shotokan Karate of America (SKA) organization and led by their head instructor, Mr. Tsutomu Ohshima.

Twelve students were in attendance: Shihan Ty Aponte, Senseis Lynn Aponte and Leo Shortle, David Voiles, Christie Vella-Kramer, Don Marrolli, Jesús David Jerez Gomez, Shaw and Maya Siegel, Ti Tran, Alexander Vance, and Dr. Dave Michelson (yours truly).

The class began with Sensei Heyman explaining the meaning of Special Trainings or gasshuku (合宿: lodging together). The theme for our class was the concept of misogi (禊), a Japanese Shinto purification ritual in which participants traditionally stand under an ice-cold waterfall. As Sensei explained,

“Special trainings are an opportunity for us to push ourselves more than we do in our normal practice; to dig down deep into our subconscious parts and find out that we are much stronger than we thought.  In our daily lives, we manipulate our environment to match our spoiled, lazy mentality. In special trainings, we put ourselves into hardship, a difficult environment, and our mentality must rise to the occasion. The practice is to ideally push ourselves from top to bottom, first moment to last moment, without any weak thoughts, moments of feeling sorry for ourselves, or 'cruising'. We hone and polish ourselves, our mentality, and our spirit like the multitudinous folding and pounding out of impurities used in the making of a samurai sword. In this way, we face ourselves honestly and strictly, rid ourselves of our weak parts, and try to find our ideal technique, ideal breathing, and ideal mentality.”

After a brief warm-up with calisthenics and stretching, the real fun began. The students stood in a circle and performed 150 squats concentrating on good form and a steady rhythm. Each student took turns counting as Sensei occasionally encouraged us to slow down, stay focused, and “tighten your mind”. My own legs felt like Jell-O at this point, so I was felt lucky that Sensei went “easy” on us and gave us a rest and water break.

The next exercise was done in the dark so that we would be freed of distractions and more able to concentrate on just our own actions. Sensei said he wanted to share the experience of a midnight training in nature, far from city lights. Even with the lights in the training space turned off, there was a bit of light coming from the front office, and our eyes adjusted. As the exercise continued, Sensei closed the door to that room, leaving us in near pitch black. We were lined up along one edge of the mat and went forward and back performing oitsuki (追い突き: lunge punch or chasing jab), with each student counting. Sensei urged us to try to make each punch better than the last and to imagine ourselves breaking through an opponent’s guard, pushing ourselves into and through them with total alignment of our fists, foreheads, hips, and knees. He reminded us to breathe naturally through each punch without holding our breath and to use this opportunity to practice the true meaning of kiai (気会い: energy/spirit harmony). He asked us try to join our mental, physical, and spiritual forces into one focused action with ferocious power. In all we did 560 punches.

For the next exercise, we performed the kata Tekki Shodan 14 times, with each student giving the commands to start (hajime: 始め), stop (yame: やめ), and relax (yasume: 休め). Sensei encouraged us to start out using a deep stance and to push ourselves to deepen our stance each time through. He told us that prior special trainings would often end with the students performing this kata 100 times - and that by the 50th he would kiai on every move. He told us that the current president of the black belt association has done Tekki Shodan more than 100,000 times and that it shows in his technical brilliance. He also said he would sometimes move around the training space to push younger students to train harder and that he very much appreciated being called “an animal” by them afterwards. Since he knew this to be the last exercise of the training, he said, his intention was always to finish with nothing left in reserve, having put all of his energy into his training and left on the field. He and others would often lose their voices from the intensity and number of their kiais. Toward the end of our shorter version of this exercise, Sensei had us add kiais to our every move. This was when my brain started to shut down, but the rest of the students hung in and finished strong.

Finally we lined up and did ki breathing. Sensei asked us to breathe in as deeply and slowly as possible and to then breathe out as fully and slowly as possible, with our mouths wide open. Sensei encouraged us to imagine drawing breath into and filling our centers, our tanden (dantian in Mandarin Chinese), a point a few inches below the belly button but also deep inside. He reminded us that tanden (丹田) means red (fire) rice paddy (source of food, energy, and life). It is also called the elixir-of-life field or sea of energy. He asked that we imagine our exhalation to be like a tightly focused beam of our energy, traveling forward for at least 100 miles, maybe going all the way around the earth to hit the back of our heads. Sensei shared that at his peak he could breathe once per minute, inhaling for 30 seconds, then exhaling for 30 seconds. As we settled into our practice of this we were probably reaching 20-30 seconds per breath. Sensei clicked two wooden sticks together to synchronize our breaths.

We closed the class, exhausted but refreshed, using our mokuso (黙想: meditation) to visualize the goals we hope to pursue in this new year for ourselves, our loved ones, our dojo, and our community.

We took a few class photos and said our goodbyes for the night, as Sensei Heyman warned us, with a smile, that we might be even more tired than we realized and that special training was not truly over until we had all gotten home safely.