Energy comes in only two primary forms. Potential energy and kinetic energy. Potential energy is any stored form of energy. This can take many different forms, which we will discuss in a moment. Kinetic energy is the energy of motion. When something is moving it possesses kinetic energy. Examples of kinetic energy include a planet moving in orbit around a star, an electron moving about in an atom, and a fist traveling toward a face.
Energy is a constant. It is neither created nor destroyed. This is the Law of Conservation of Energy. The only thing you can do with energy is convert it to a different form. If you turn on an electrical motor the electrical energy supplying the motor is converted primarily into mechanical energy and heat (thermal energy). The chemical energy in the propane for a barbecue is converted primarily into thermal energy.
Potential energy refers to any form of stored or suspended energy. This energy may be stored in chemical, mechanical, gravitational, thermal, or nuclear form.
A common household battery is a good example of stored chemical energy. When the battery is connected to an electrical circuit a chemical reaction takes place between the metal anode and the chemical paste in the electrolyte portions of the battery. This chemical reaction produces electricity that is utilized by the electrical circuit.
Another common form of chemical energy is gasoline. When ignited it produces tremendous amounts of energy in the form of heat and expansive forces. This power can then be used to create mechanical, electrical, or heat energy.
The glucose (blood sugar) in your muscles is a form of potential energy. When your muscles move they convert this potential energy into kinetic energy and heat.
A metal spring is the most commonly cited means of storing mechanical energy. Much of the energy used to compress a spring is retained in the spring as potential energy. When the spring is no longer constrained in some manner it releases the stored energy and returns essentially to its original form.
Potential gravitational energy is created when you place a ball on a table. The only thing that keeps the ball from falling to the floor is the barrier created by the table. If that barrier is removed somehow (for example, the ball rolls to the edge of the table) then the potential energy will be released and kinetic energy (movement) will result.
Nuclear potential energy is the stored energy found within an atom. When an atom’s composition is changed by one of several different processes a sudden release of intense energy results. Fusion is the process by which highly unstable atoms lose one or more protons from the nucleus. Fission results when highly energetic atoms collide, forcing the two atoms to form a new and more complex atom. The new atom does not need all of the components from the original two atoms so these excess components are released with tremendous energy. This is the process by which the sun turns hydrogen atoms into helium. Stars are the only naturally occurring phenomenon that can create new elements from an existing set of elements. The byproduct of these collisions is tremendous thermal and light energy.
Kinetic energy is the energy something has when it is in motion. If you throw a football it has kinetic energy while it is flying through the air. When it strikes something (the ground or a receiver’s hands) it gives up some (or all) of the kinetic energy, which is converted to other forms of energy.
There are many types of kinetic energy which we will explore briefly.
Translational Kinetic Energy
This is the formal definition of the energy of motion. A car on the highway, an arrow in flight, and a book falling from a shelf all have translational kinetic energy. These objects are all in motion (relative to something else). As a martial artist most of the kinetic energy we think we experience is translational kinetic energy. But that is overlooking many other forms of energy.
Thermal energy is another form of translational kinetic energy. The heat held by an object is a measure of the rapid movement of the molecules in the structure. As an object is heated the individual molecules within it begin to move about more rapidly. Therefore thermal energy is normally classified as translational kinetic energy.
Rotational Kinetic Energy
This is the energy exhibited by something that is rotating or spinning. An electric motor typically exhibits this type of motion. A spinning kick also incorporates a component of this type of energy. Wheels, Nunchaku, and a rifle bullet also are examples of this form of kinetic energy.
Vibrational Kinetic Energy
This type of energy involves something that vibrates or exhibits some form of oscillation. Sound waves are good examples of this type of energy. So are electromagnetic waves (light, x-rays, radio waves, etc.). These waves travel through a medium (space and/or air) due to the propagation of their oscillations.
Energy in the Martial Arts
When you attempt to manipulate or control an opponent you might elect to place your forearm under the opponent’s humerus and then raise your heel off the floor to lift and compromise the opponent’s structure. This uses stored chemical energy in your muscles to produce the translational kinetic energy necessary to move the opponent. But in doing so you also produced another form of potential energy. Since your center of gravity has been moved upward by your raised heel you have created gravitational potential energy. You might elect to use this energy, which is a byproduct of your earlier energy expense, to initiate a subsequent manipulation or strike.
In the martial arts all forms of energy lead to other forms of energy. As we mentioned earlier, energy is never created nor destroyed (this may not be true for some more extreme or theoretical forms of physics, but for every day considerations it holds true). You can only convert energy from one form to another. So whenever you use energy you should consider what other forms of energy are produced by that action. These other forms of energy may be of benefit or detriment to you in the future.
Whenever the chemical potential energy in your muscles is converted into translational kinetic energy (movement of a limb, for example) some portion of the chemical energy is also converted into thermal energy. In fact, less than half the energy is used for translational kinetic energy (the values may range from roughly 15% to 56%, with 25% being considered typical). The remaining energy is expended as thermal energy. So while you are busy throwing kicks and punches your body is generating massive amounts of heat. This is, in part, why we stress that you should be relaxed when fighting and only use those muscles necessary for an action. If you are grimacing, carrying tension in your shoulders, or dancing unnecessarily all you are accomplishing is producing excess heat your body must somehow eliminate. All of that will make you tired very quickly. Strive to become skilled at minimizing your movements and therefore your energy expenditures.
Your body utilizes a molecule called adenosine triphosphate (ATP) to produce chemical energy. We will discuss the muscular system in more detail in other topics, but for now you should understand that your body uses four different sources of energy when employing muscles. Fast response (Free ATP) energy lasts for only a few seconds (perhaps as little as two seconds). This process relies on existing ATP molecules stored in the muscles. Phosphocreatine can be used to rapidly create additional ATP that can fuel muscles for up to fifteen seconds. Glycolysis is the process of converting glycogen in the muscle fibers into ATP. It also produces lactic acid as a byproduct and can fuel muscle activity for up to thirty seconds. Finally, cellular respiration uses oxygen and fats to produce ATP. This is a less efficient system, but can rely on the vast stores of fats in the body to sustain long-term activities.
It should be noted that each power level beyond the initial Free ATP system results in a loss of power and efficiency. After fifty seconds or so you will see a rapid decline in the efficiency and power of movements. As a result Tensoku Ryu always strives to have a conflict come to a successful outcome within the first ten seconds or so (even less if possible). You will be less winded, hot, and far more effective if you can overcome an opponent in a very short period. This is a hallmark of Tensoku Ryu training.
We have previously discussed angular velocity. This allows us to observe that this is really an expression of the rotational kinetic energy of the object. The faster the object rotates the more rotational kinetic energy it will possess. This is not a linear increase. The rotational kinetic energy of a object increases with the square of its angular velocity. If the angular velocity is doubled, then the rotational kinetic energy increases by a factor of four. If the angular velocity is tripled, then the rotational kinetic energy increases by a factor of nine. This explains why we look for our rotating kicks, including kicks like Mawashi Geri and most spinning kicks to have a very rapid turning rate. This results in a far higher level of energy being delivered to the target.
Here is another example of using rotational kinetic energy. Suppose an opponent throws a right-left combination hand strike. As the opponent’s right hand is retracted you accelerate its return and impart a slight outward pressure on the arm. This induces added angular velocity to the return. This will cause an acceleration in the delivery of the left hand strike. Because of the added angular velocity the left strike will fall short of its target and will, in most cases, pass in front of you without contact. A beneficial byproduct in this scenario is that the energy in the left hand strike has increased dramatically due to the added rotational forces. When the strike reaches its full extension there will be much more energy than the opponent anticipated. This will certainly cause some instability in the opponent which you may be able to use to your advantage.
The dynamic and continual flow of energy is of great importance in the study of the martial arts. Having a fundamental understanding of energy and how energy is being used or re-purposed during a sequence of actions will provide you will greater understanding and increased opportunities during a conflict. Whenever you practice a skill, particularly when you are first learning it, consider how energy is being employed and what energy conversions are occurring as a result. This will afford you tremendous insights into dynamic movement that you will find quite useful in your studies of Tensoku Ryu and the martial arts in general.