This material is a continuation of the article:Practical for Theory of Power
The beginning student may ask; “Where does one obtain the power to create the devastating results attributed to Taekwon-Do?”
This is how the “Theory of Power” began in the Taekwon-Do encyclopedia. The author of the theory is the creator of Taekwon-do gen. Choi. This theory is the basis on which Taekwon-Do was built and developed as a modern martial art. “Theory of Force” is studied by all practitioners of Taekwon-do, but…
- It does not give a specific answer to the question.
- It does not contain definitions.
- It contains formulas, concepts and laws that are true in themselves, but are not specific in the context of a strike in the martial arts.
- It contains examples that are principled and not particularly appropriate.
- It does not contain the “time of contact with the target” factor, which is essential…
Punches and blocks in Taekwon-Do are groups of techniques with hands and feet that can be performed as the main technique (in the air or) against a specific target (sparring with an opponent, breaking a board, training on a sack, etc.). Punches and blocks are performed with different trajectories and different impact/blocking surfaces of the arms or legs.
What Is Practical Impact Force in Martial Arts?
This answer is “visible” when performing a power test – breaking a board with a fist.
The essential thing here is why the board breaks?
The breakage is a consequence of plastic deformation of the board. This is a deformation (bending) beyond the elasticity zone (Figure 1) caused by the impact of the impact. The transfer of energy from the impact (fist) to the target (the board) is carried out by means of an impulse equal to the product of the mass and the speed of the fist!
Figure 1
Purely physically, the force of the impact is measured in Newtons. When striking a target, the shape of the pulse is not symmetrical – it increases sharply and falls relatively slowly and in waves. When we talk about impact force, we usually mean its maximum value in the process of impact (Figure 2).
Figure 2
Practice shows that a standard wooden board measuring 30x30x1.3 cm. breaks with deformation of more than 0.5 cm, as a result of contact (impact) and for this a transfer of kinetic energy above 64 J is required.
When performing a power test, depending on the level of the performer, assuming that the mass/weight of the fist (and part of the hand) is 7 kg , and the speed of impact varies from 7 to 14 m/s, kinetic energy is generated from 171 to 687 J, which is enough to break from 2 to 10 standard boards.
Therefore, the definition of punch in martial arts sounds like this:
A strike is a explosive movement directed against an object (enemy) with the aim of hitting on contact.
The execution of a blow consists of several successive phases:
- Preparatory – the body is preparing for execution (this includes correction of position, initial elements of a wave, backward motion, breathing, etc.
- Executive – the body and its individual parts accelerate towards the goal.
- The muscles of the body set in motion the body and/or its individual parts (arms and legs). Thus, kinetic energy is generated, which is proportional to the mass (of the striking limb) and to the square of the speed of movement.
- Depending on the technique, the movement is performed in a memorized sequence. A certain trajectory and direction are observed. To achieve maximum speed, a long and arcuate trajectory is suitable.
- Focus – the moment of contact with the target or the end point when performing against an imaginary opponent (in the air).
The essence of the striking technique is the generation by the performer of the maximum amount of kinetic energy and the optimal transfer of this energy to the target/opponent.
When performing a punch as the main technique, this energy is dissipated and absorbed by the body of the performer. When performing a strike against a certain target, the generated energy is transmitted to the target upon contact with it.
Figure 3 shows the energy transfer of a strong impact (F1) with a short impact on the target and a weak impact (F2) with a longer impact on the target, where the energy transferred to the target (the area of the figure) is less in the strong impact (red figure) than in the weak but sustained impact (blue figure).
Figure 3
This is where the influence of the missing factor in force theory is seen – the time of contact with the target. The area of the figure is the energy transferred to the target and it depends on the contact time. A practically weaker, but prolonged (therefore – powerful) blow can break more boards than a strong but short blow.
There are additional factors influencing the process of generating and transmitting energy to the target:
- Momentum is a vector quantity that has a direction and it must be perpendicular (Figure 4) to the target in order to transmit the maximum amount of deformation energy to the target.
Figure 4
- Hardness – it is clear that it does not matter whether the blow is with a bare fist or with a fist in a glove. Definitely, the glove deforms at the moment of contact and absorbs part of the energy of the impact. The same is true if the fist is not well formed and tight – some of the energy is absorbed by the “soft” fist and less energy is transmitted to the target.
- Contact with the target should take place when the fist is moving at maximum speed – then it has maximum kinetic energy and can give maximum impulse to the target.
- The total mass of the punch performer indirectly affects the force of the blow, as it helps the limb (fist) to accelerate to its maximum speed.
In practice, the force of impact in martial arts is not exactly a force in newtons, known from the physics textbook… due to the inaccurate translation in the Encyclopedia from Korean to English and subsequent translations from English to other languages. The appropriate term is power (an equivalent quantity from electrical engineering and one of the possible translations of the term power).
Logically, the question arises: What is the definition of a block, how is it performed and how does it differ from a strike?
To be continued…
