Special methodsthat are used to master the skill

of controlling the enemy

Stage II. Stability and unbalancing

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Stage II. Stability and unbalancing

At this stage of your training you’ll need to know the scientific bases and, first of all, basic principles and laws of mechanics. The knowledge of the theory is a lever that helps to raise the practice to a higher level.

Levers and forces

A lever is a solid object that has a pivot and that can rotate around this pivot thus forming a rotation axis; it’s an appliance that serves to convert a force. There are at least two forces with opposite moments that function in a lever.

Bony levers are the links of the body that are movably connected in the joints under applied forces, which can either keep their position or change it. They serve for communication of the movement and for working at some distance

When forces are applied to both sides of the lever pin (pivot), it’s called a double-arm lever, when the force is applied to one side – it’s a one-arm lever. The type of the lever may vary according to the type of muscles which are attached to different parts of the bony link. There are three types of lever: I – “scales”, II – “cart”, III – “crane” (fig. 1).

fig. 1

Every lever consists of the following elements:— Pivot (rotation axis, 0 point)— Points of force application (A and B)— Two forces at the minimum (f and F);— Lever arms (the distance between the pivot and the point of

force application AO and BO)— Arms of force (the minimal distance between the pivot and

the line of the force application – perpendicular dropped to the line – AO and OB).

The measure of the force application to the lever is its moment relative to the pivot – the rotation moment. The moment of the force is the product of the force and the arm of the force.

Mf = F · OBMf = F · AO

The moment of the force is a vector quantity. If the force is applied not in the plane which is perpendicular to the axis, then it’s necessary to define the component of the force which lies in this plane. It forms the moment of the force relative to the axis. Other components of the force don’t affect the moment of the force.

When the moments of the force which are opposite relative to

fig. 2

the axis are equal, the link either keeps its position, or continues to move with a constant speed (the moments of the force are in balance). If one of the moments of the force is bigger than the other, the link accelerates in the direction of its action.

The locomotor system contains all types of levers. The lever of type III is dominant; it’s a lever of speed, as muscles are attached near the joints generally.

Thus, the locomotor system in its nature is rather quick and deft, than strong. Moreover, all bony levers result in force losses because muscles are attached to the bones at an acute or a blunt angle.

In a hand-to-hand fight the operating force is applied to the opponent effort, the opposite force here is the effort of the opponent. For overcoming the opposite force it’s necessary either to increase the operating force, or to change the length of the arm, which takes part in the action.

As the force opportunities are often restricted, and as in the fight you may face a more powerful rival, the basic way of working with levers is the moving of the pivot. As a pivot you may use different parts of the body (both yours and of your opponent), as well as weapons and other objects.

Stability and balance

In the process of motor activity a human is influenced by static and dynamic forces, a combination of which can make him lose his balance. For example the objective of a fighter consists in ensuring his own stability by means of the right choice of stance,

distance estimation, usage of the most rational motor action in a given situation, or in making the opponent lose his balance.

That is the reason why when fighting, the principles of stability and balance are vital.

Stability is the ability of a fighter to steadily retain his balance without falling down if an opponent or environment exerts external forces on him.

To evaluate stability in terms of quality and quantity, different criteria, preferable for specific cases are applied. Those are:

— Stability angles;— Stability coefficients;— Maximum velocity of movement.

Balance is divided into static and dynamic.

Static balance of a human is the balance in case of absence of dynamical forces (centrifugal and inertial forces).

In static (slow) sway of the body, it falls in relation to a certain line, called the overturning line. Assessing the stability of a human as a solid body (fig. 3a), the overturning lines are а—b and е—f (in coronal plane) and а—f and b—е (in sagittal plane).

The distances between overturning lines (d, d1) determine the base of the body in the given plane.

The area аbеfа is the base of support.

The stability of a human depending on the scheme of the operating forces is assessed in one of the principal planes of

body – frontal or sagittal.

Thus, if there are no external forces, the stability is determined by the maximal sway angle of the body, angle of static balance.

This angle between the gravity (G) vector and the line, starting in the COM and crossing the upsetting line a-b (in fig. 3b it is projected in point O).

The angle of stability is determined with the help of the following geometrical construction:

tgα =0,5d/γцм,which can be rearranged to give:α = arctg (0,5d /γцм,),

where γCOM is the position of the center of mass of a human relative to the base of support.

fig 3

The larger the angle а, the higher the static stability of a human. Consequently, in order to increase the static stability, it is necessary to enlarge the base of support and lower the COM. For example in any fight those are the main characteristics of basic stance. (fig.4)

The choice of the stance involves ensuring not only initial static stability, but also the reaction on the change of external forces.

Apparently, a person standing with his legs straight preserving vertical position of the spine can move his center of mass only downwards.

A person, who squats bending his knees preserving the vertical position of the spine, has an additional advantage. He is able to Рис. 4

move his center of mass upwards as well as downwards. This ability, insignificant as it may seem at first, has high importance for perfecting response to the actions of the opponent.

The angle of static stability changes in the process of locomotive action. For example, if the fighter, without changing the base of support, bends one leg, simultaneously straightening the other (fig.5), his COM shifts by e.

The angle а is determined by the formula а= arctg [(0,5d ± e)/ γcom].

Plus-minus sign in the formula means that the angle а decreases relative to the overturning line a-b (point O), and increases relative to the line e-f (point O1). Thus, stability can be controlled.

However, generally the gravity (O) is not the only force that influences a sportsman, in the principal planes external forces (the opponent’s and environmental influence) are involved.

The loss of stability in sagittal plane due to small supporting base d1 is the most probable, meaning the most dangerous.

Loss of balance

There are numerous ways to make your opponent lose his balance.

The balance of the body is stable as long as the projection of the COM (point C in fig.6) is within the base of support abefa.

Keeping it there is possible by means of manoeuvring (stepping left and right and back and forth), i.e. changing configurations and shifting the base of support.

Thus, the main objective of making the opponent lose his balance comes down to shifting his COM out of the bounds of the base of support.

In order to illustrate the situation, a variation breaking the balance of the opponent is the creation of overturning moment.

Let the gravity G form stability moment Mst = Ga relative to overturning line ab (point O1 in fig.7).

The overturning moment M1 sufficient for breaking it, can be formed by the force of minor quantity P1, applied to relatively large arm c. However, in this case there is a necessity to fix the overturning line (otherwise the opponent easily defends himself by stepping aside and shifting the overturning line).

The applied force P2 directed not only sidewards but also

fig. 5

downwards, creates an overturning moment М2 = Р2b on the arm b.

Squatting not only adds mass (applying additional inertial force F=ma), but also makes the opponent unable to defend himself (by stepping aside and shifting the overturning line).

It is possible simultaneously to change the direction of the attack by relocating it from the frontal plane XOY to the sagittal plane YOZ by shifting the point of applied force P2 out of the plane at the side of the back overturning line. It abruptly cuts the support base, and the loss of balance is inevitable.

fig. 6

Biomechanical aspects of stability

Any position of a biological body is an oscillation process. The general center of gravity (GCG) of the body in static stability experiences oscillations in the range of 2-3 cm due to blood and lymph circulation, breath, muscular trepidation etc. of the biological body. This process is controllable. A human can change the stability of his body by varying the following stability factors:

1. The area of the base of support. This is the area limited by maximum points of support. It includes the active area of base of support that appears after the body contacted the base of support, and the passive one.

In practice the latter one is more changeable (e.g. by setting feet shoulder-wide). The bigger the general area of the base of support, the more stable the body. The optimal area of base of

fig 7

support in hand to hand combat is in the posture when feet are set shoulder-wide.

2. The height of the GCG point position. The lower the GCG of the body, the more stable it is.

3. The gravity line position. The gravity line is the perpendicular dropped from the GCG on the base of support. The position and direction of gravity line permits assessment of the stability of the body in different directions (in two-dimensional image it is back-forth direction). If the gravity line passes through the center of the base of support, the degree of body stability is the same in all directions; if it is shifted to one side, in this direction the degree of stability is lower.

4. The value of stability angles. The stability angle is the angle between the gravity line and the line connecting the GCG with the edge of the base of support.

The stability angle is a dynamical factor of stability. It includes three previous static factors. If one of the previous static factors changes, it will be mirrored by the stability angles. The meaning of this angle is as follows.If the body is rotated at this angle, it returns to its initial position. If it is rotated at the angle exceeding the stability angle, it loses its balance and changes the position. The stability angles of the body in case of two-dimensional image characterize the balance in front- and backward directions. The larger the stability angles, the more stable the body in this direction.

5. The body stability coefficient characterizes the body's ability to maintain balance in case of a force being applied. The ability to control the body stability coefficient (change the stability moment by changing the pose) is the aim of hand to hand combat trainees. In terms of biomechanics, in hand to hand combat the purposes are as follows: maintaining and using one’s own balance, breaking the opponent’s balance and usage of his loss of balance. The conscious appliance of laws of mechanics when analyzing movements of a human is ultimately aimed at search of ways to refine movements.

One more intermediate conclusion of the information set forth is the necessity to use the principle of minimum power inputs in hand to hand combats. The essence of it is that a mentally sane living creature organizes its motor activity in such a way that the power input is minimal. Unnecessary, unproductive muscle contractions and tensions are to be avoided, and the use of unnecessary and unproductive motions is to be cut down. Further development of the principle is the use of energy recuperation, i.e. :

- Opting for the least power consuming proportion of force and speed;

- Using energy, coursing from one link of body to another (for example whipping motion of a shin using the energy, accumulated by hip swing);

- Using strain energy, accumulated in muscles during the previous phases of motor action.

The same principle implies the necessity of usage in hand to hand combat such resources as levers, inertia, accumulated by an opponent, and torque in order to control and defeat the opponent. The usage of these elements makes it possible to substantially cut down the energy inputs of the fighter in hand to hand combat. It is advisory to perform the following optimum motion switching (shifts):

- Changing of intensity of muscular work (e.g. the speed of movement);

- Changing in motor action of strength and speed (e.g. step length and frequency);

- Shifting from one way of performing motor action to another (e.g. offensive and defensive alternating actions of legs and arms).

By attracting the attention of the reader to the aforementioned points we want to emphasize the importance of the theoretical basis of hand to hand combat and the necessity of understanding the practical deductions out of it.

The basics of muscle biomechanics

It is known that muscles are controlled by the Central Nervous System. Biomechanics studies the changes in state and position of muscles influenced by nerves, i.e. the connection between linear movement of muscle endings (kinematics of movement) and exertion developed by it (dynamics of movement). The mechanics of muscular contraction consists in the connection of exertion in it and its deformation.

In order to fully describe the biomechanical properties of muscles, the following principles are used:

Rigidity – the quality of resistance to the forces applied. It manifests itself as elasticity and quasirigidity;

Relaxation – the lowering of exertion (tension) in time;

Durability – manifests itself as tensile strength;

When analyzing mechanical properties of the human body and its elements the influence of sinews is frequently neglected. They are considered as absolutely nonstretching flexible parts of muscles, while they are able to cushion and rigidly dampen abrupt jolts.The strength of sinews is twice as high as one of the muscles. Sinews of the human body generally tear in places of their connection to muscles.

Strength, speed and efficiency of movements depend on the degree to which a human uses the biomechanical properties of his locomotive system. Strength and speed could be increased by using elastic force, efficiency – by the recuperation of mechanical energy and decrease of it waste on dispersion.

The biomechanical properties of muscles have a key influence on it. It is widely known that the result of a jump upwards from a squatting position after a pause will be lower, than the one of an immediate one, as in the second case, the force of previously stretched muscles resiliency is used. The recuperation of resiliency force is believed to be the main reason for high efficiency of a running human or jumping kangaroo.

In muscular and tendinous structures a substantial quantity of resiliency force can be accumulated. However, the accumulated resiliency is not always used to the full extent. The degree of its usage is dependent on the conditions of movement performance, in particular, the time span between stretching and contraction of a muscle. In hand to hand combat it is necessary to use this energy in the right way.

Apart from that, it is necessary to know that as the speed of active muscle contraction increases, the quantity of its ultimate stress decreases and vice-versa, meaning that to deliver the fastest possible (abrupt) kick or hit, before performing the strike it is necessary to relax the part of the body that delivers the strike.

In the training process it is to be taken into consideration that the mechanical strength of sinews and ligaments increases comparatively slowly. A forced development of speed and strength properties can cause inconsistency between the increased speed and strength abilities of the muscular apparatus and insufficient strength of sinews and ligaments, which can lead to injuries.

That is why during training it is necessary to pay attention to strengthening the tendinous-ligamentary apparatus. It is attained by extensive training at low intensity. It is advisable for the movements to be performed with the widest range possible for the joint and also in all directions.

Test questions and tasks

1. What are the basic elements of any lever?

2. What are the bony levers in the human body for?

3. What is the basic way of working with levers?

4. The combination of what forces influencing the human body in the process of motor activity can unbalance a person?

5. What are the basic criteria for the quality and quantity estimation of stability?

6. In what planes is the stability of a person regarded, depending on the scheme of the operating forces?

7. What should be done to increase the static stability?

8. What is the purpose of unbalancing?

9. What are the main factors of stability?

10. What is the principle of minimum of energy wasting and why is the use of this principle necessary for effective self-defense?

11. What are the basic principles of optimal movement changes?

12. Why is it important to pay attention to the strengthening of the tendon-ligament apparatus?

13. Master the practical performance of basic special preparation exercises dealing with unbalancing of an opponent while keeping the stability and geometry of your own stance.