The efficiency of swimming propulsion is mainly determined by three characteristics of limb movements - direction, angle of attack and speed.
The direction of movement is characterized by a trajectory relative to water, which is usually called absolute. Its analysis is of paramount importance, since it is the influence of the limbs on the water that mainly determines the force driving the swimmer. The trajectory relative to the body of the swimmer is called relative, since it is assumed that the athlete, while performing a stroke, remains in place. Its analysis allows us to better understand the mechanics of the stroke. In Fig. Figure 1.10 shows the absolute trajectory of arm movements, typical of high-class swimmers. As we can see, regardless of the method of swimming, it is mainly characterized by horizontal and vertical directions of movements. In Fig. Figure 1.11 shows the backward movement necessary to push away the optimal amount of water (side view).
The angle of attack is formed by the inclination of the hand or foot relative to the direction of their movement. The dependence of the driving force on the angle of attack is shown in Fig. 1.12. As we can see, in the absence of such an angle, the driving force is minimal, since the hand almost does not move the water back and the force propelling the swimmer is very small. At an angle of 40° it is greater because the water flowing under the palm from the thumb to the little finger or, if we compare the hand with a propeller blade, from its leading edge to the rear, is subject to a significant force directed backwards. This angle of attack is close to optimal. At an angle of 70°, the palm is too flat a surface;
CHAPTER 1 BasicsTechniciansSwimming
Rice. 1.10
Trajectory of strokesMovements relativeWater when swimming in various ways: Breaststroke (a); on the back (b); butterfly (c); front crawl (g)
Rice. 1.11
Changing the angle of attack
In the final phase
Swimming stroke
Crawl on the chest
The effect of the leading edge of the blade changes, which leads to a decrease in the speed of movement of some molecules passing under the palm and the rebound of others. They collide with the molecules of the remaining layers and the resulting chain reaction causes significant turbulence. Moreover, these molecules are not able to sharply change the direction of movement in order to follow the contour of the “blade” from it. leading edge to trailing edge. As a result, only a small amount of water is pushed back. And it is completely ineffective to place the brush perpendicular to the direction of its movement. In this case, the blade effect disappears. The flat surface of the palm only pushes the flow of water in different directions. With a quick movement of the hand, an effect is created similar to pouring a bucket of water onto the wall. Some of the molecules bounce chaotically from the hand, and those “lagging behind” move in the opposite direction, producing a force that pushes the swimmer to the side, moving forward.
Opposite to the direction of movement.
Thus, the angle of attack should vary from 20° to 60° depending on the phase of the stroke. The irrationality of the angle of attack and direction of movement is indicated by a large number of bubbles, indicating turbulence and loss of driving force by the swimmer. Qualified swimmers create them in much smaller quantities. The formation of air bubbles around the hands as they enter the water when swimming front crawl, backstroke and butterfly is completely normal. However, if this happens during the pull-up phase, it indicates an irrational movement and, probably, an excessive angle of attack. Its arcuate trajectory helps ensure an effective angle of attack in each phase of the stroke.
Speed of movement. Councilman and Vasilyak (1982) revealed the acceleration of hand movement as the stroke is performed, and Schleihauf (1984) - its unevenness and dependence on the direction of its movement. Rice. Figure 1.13 illustrates the change in the speed of wrist movement during the stroke when swimming front crawl. As we can see, the speed of the left hand after it enters the water decreases and is 1.8 m-s-1 in the capture phase, increases to Zm’S-1 in the pulling phase, and up to 5 m-s-1 in the repulsion phase. In the final phase of the stroke, when the pressure on the water weakens somewhat, the speed of arm movement drops.
PART 1
TechniqueSportsSwimming
Rice. 1.12
The influence of the angle of attack on the direction of water movement
Rice.1.13
Dynamics of wrist speed when swimming front crawl
The speed of the right hand at the moment of grip is 1.8 m-s-1, in the pulling phase - about 4 m-s-1, during the transition to repulsion it decreases slightly - 3.4 m-s-1, and at its completion reaches 6 m-s-1. The dynamics of the speed of swimming almost coincides with the dynamics of the speed of movement of the hand, which, however, is also typical for other methods of swimming. The speed of arm movement decreases during each major change in direction of movement. There is probably an optimal relationship between hand speed and angle of attack in each
Do the stroke phase. There is no doubt that there is an optimum speed of hand movement in each phase of the stroke. When comparing Fig. 1.13 and 1.14, one can note the close relationship between the speed of movement of the hand and the traction force in various phases of the stroke.
Meaning of capture. Catch is the phase of the stroke in which the driving force begins to develop. It should not begin until the arm has moved about a third of the length of the stroke, and until a third of its total time has passed. In this case, vigorous effort should not be applied until the elbows are higher than the hands and the hands are facing back.
The main movements of the hands when performing a stroke are - to the sides, down, inward and upward (Table 1.1).
Hand movements to the sides. This movement begins the stroke when swimming breaststroke and butterfly (Fig. 1.15). It is not promoting, but preparatory to the capture. When swimming butterfly, immediately after the hands enter the water, and when swimming breaststroke, before moving them forward, the hands are spread to the sides along a curved path until the hands are wider than the shoulders in a position favorable for starting the grip. At the beginning of this movement, the palms are turned down, the angle of attack is close to 0°, until the hands take a position favorable for the development of the driving force. As it is performed, the palms turn outward and backward, and the speed of movement of the hands decreases.
Hand movement Down is typical for swimming crawl on the front and back (Fig. 1.16). It precedes and accompanies the catch and, like the lateral movement during breaststroke and butterfly, is not advancing. After entering the water, the hand moves down along a curved path. At the same time, the hands are bent, and as they approach the grip, they slightly unfold
CHAPTER 1
BasicsTechniciansSwimming
Rice. 1.14
Traction force dynamics
When performing a stroke
Eightfold
Olympic champion
Matthew Biondi
TABLE 1.1
BasicMovementsHand
AtExecutionGrebka
Rice. 1.15
Hand movements to the sides
When swimming breaststroke
And butterfly
Huddle outside. The grip begins no earlier than the elbows are higher than the hands, which usually occurs at a depth of 40 - 60 cm.
Hand movement inward Replaces the downward movement of the arms when swimming front crawl and backstroke and the movement to the sides when swimming breaststroke and butterfly. And when swimming in all ways except the backstroke, it is the first “promoting” movement. This movement begins in the catching phase and continues in the pulling phase.
(except for backstroke swimming). As it is performed, the hand moves down and inward, and then up and back until it is under the body in the area of the midline of the body. Moreover, individual deviations from this line are due to the characteristics of the technique, and these, in turn, are due to the morphofunctional characteristics of the swimmers. It should be noted, however, that although all qualified swimmers specializing in breaststroke have their hands crossing the midline of the body at the end of the movement in question, some athletes stop pressing the water when their hands are still at a considerable distance from each other, while others do not They do this right up to joining hands.
Hands moving up When swimming front crawl and butterfly, the arms move inward and ends when the hand reaches the thigh. In this case, the semicircular movement of the hand outward, upward and backward is accompanied by its rapid turn and the palm at the end point of the movement in question is turned back and outward (Fig. 1.17), the pressure of the hand on the water weakens. The speed of the hand during the transition from inward to upward movement decreases and then increases to a maximum. The existing idea that the arm quickly straightens at the elbow joint when moving upward is incorrect. It remains bent until the start of the swing, which ensures that the forearm participates in the production of the driving force. If the arm straightens too quickly, it does not push the water straight back. The upward movement of the arms when swimming butterfly is similar to the movement of the arms when swimming front crawl. And only some high-class swimmers, and only at the beginning of the stroke, fully straighten their arms at the elbow joints.
It should be noted that the effectiveness of the movement in question
PART 1
TechniqueSportsSwimming
Rice. 1.16
Downward movement of the arm when swimming crawl on the front (a) and on the back (b)
Rice.1.17
Water repulsion
When moving your hand up
During the stroke:
Side view, b - bottom view
Rice. 1.18
Promotion
When performing dolphin-
Figurative leg movement
Niya largely depends on the swimmer's ability to maintain a bent arm position in the final part. If this is successful, then the water is pushed back in the desired direction even with a not very rational position of the forearm. And this is especially true for butterfly. The most common mistake when moving the arms up is “pushing” the hands up and back into a bent position, in which they are perpendicular to the surface of the water. The angle of attack is such that the water is pushed upward rather than backward, which naturally reduces swimming speed. The movement of water back when moving the arms up is illustrated in Fig. 1.17. As the hand moves up and out along a diagonal path, it and the side of the hand from the little finger serve as the leading edge.
The ki are the propeller blades, and the fingertips and the side of the hand from the thumb are its trailing edge.
Rice. 1.17.6 illustrates the beginning of the movement under consideration. As you can see, the brush moves outward and backward, being rotated accordingly. In this case, the leading edge of the propeller blade is the side of the hand from the little finger, and the back edge is from the thumb. Water passing under the palm in the opposite direction is moved by the angular attack of the hand. In Fig. 1.17, and the final stage of the movement under consideration is shown. As you can see, the hand is facing back and slightly upward, which provides a great contribution to the development of the driving force of the forearm. The role of the leading edge of the propeller blade is played by the elbow, and the rear edge by the fingertips.
The meaning of leg movements. Many experts believed that when swimming front crawl, butterfly and breaststroke, the legs are practically not involved in the production of driving force. The main argument in this case was the direction of movement of the legs not back, but up and down, which supposedly only maintained the balance of the body in the water. At the same time, it is known that swimmers still move forward using only their legs, and high-class athletes quite quickly. And it is quite obvious that with the movement of the legs the swimmer moves the water backward in the same way as with the vertical movements of the arms. As can be seen in Fig. 1.18, although the feet move almost straight down when swimming butterfly, bending the knees and straightening the feet provides a hydrofoil effect. The function of its front edge is performed by the knee part, and the rear edge is performed by the forefoot. Bending the knees creates an angle of attack that allows the swimmer to move the water backwards. Similarly, the legs provide propulsion when swimming crawl.
CHAPTER 2 Hydrodynamics of driving force during swimming
2.1.Resistance. The swimmer's speed is the result of two forces. One of them is slowing down. This is the resistance caused by the water being pushed along the swimmer's body. There are three types of water resistance:
1) frontal or frontal resistance;
2) friction of the skin;
3) “tail retraction” or additional (“vortex” resistance).
Frontal resistance is created by water directly in front or in any part of the body.
Skin friction is caused by the resistance of water located directly next to the body.
Additional resistance, or “tail” retraction, is created by water that cannot fill the space behind the poorly streamlined parts of the body, and the swimmer has to drag some water along with him.
The amount of resistance that a liquid provides to the movement of a body immersed in it depends on the properties of the liquid (its viscosity and density), the size of the frontal cross-section of the body, the speed of movement of the body, the shape of the body and the smoothness of its surface. This dependence is expressed by the formula:
v 2
where F is the value of water resistance;
k is the coefficient of density and viscosity of the liquid;
S - frontal section of the body;
v - body speed
C is the streamlining coefficient, depending on the shape of the body and the smoothness of its surface.
When analyzing sports swimming techniques, the coefficient of density and viscosity can be ignored. The swimmer is in the same environment - water.
Dependence of water resistance on the shape of the body and the smoothness of its surface: The shape of the body has a great influence on the amount of water resistance. A body that has a streamlined shape experiences water resistance 25-30 times less than a body with the same frontal cross-section, but without a streamlined shape.
The shape of the back of the body affects the amount of resistance more than the shape of the front. This is explained by the fact that during swimming, an area of low pressure is created behind the swimmer. When the body moves forward, a void should form in the place where it was, which is immediately filled with water. An area of low pressure is created behind the body, which, as it were, “does not allow” it to move forward.
The swimmer's body must be given the most streamlined shape; minor changes in shape cause significant changes in the amount of resistance (Fig. 3).
The amount of water resistance is affected not only by the overall shape of the body, but also by how its surface is wetted by water. When flowing around a body with a well-wetted surface, the layer of water adjacent to the body seems to stick to it and is carried forward along with it. The next layer of water carries away the third, and so on.
The sebaceous glands secrete a certain amount of fat onto the surface of the skin, which makes it elastic and helps reduce skin friction.
Currently, high-class athletes use high-tech suits to reduce resistance.
2.2. Frontal cross-section of the body and its effect on the amount of resistance.
The frontal, or midsection, section of the body is the projection of the body onto a plane perpendicular to the direction of its movement.
The resistance changes in direct proportion to the change in the size of the frontal cross-section of the body. If the frontal cross-section increases three times, then the resistance will increase three times, if it decreases five times, then the resistance will decrease by the same amount.
In order to reduce harmful drag during swimming, the body must be positioned so that the frontal cross-section of those parts that are under water is as small as possible and so that during preparatory movements of the limbs the frontal cross-section is minimal. Working movements with the arms and legs should be performed by increasing the frontal section of the limbs to the maximum.
Increasing the resistance during working movements is beneficial - it increases the support on the water and the traction force.
The human body will have a minimum frontal surface if it moves in the direction of its longitudinal axis.
When swimming near the surface of the water, it is better to position the body with a small angle of attack so that the shoulder girdle is slightly higher than the pelvis. In this case, counter currents of water will create additional lifting force, improving the conditions for movement of the legs and making breathing easier.
The angle of attack depends on what method the swimmer uses, on the speed of swimming and on the individual characteristics of the swimmer.
Creating an angle of attack leads to a slight increase in the frontal cross-section and an increase in water resistance. However, with a positive angle of attack, a lifting force is generated, which helps keep the body closer to the surface of the water, in a “higher” position. As a result, if the angle of attack is not too large, the frontal cross-section practically does not increase. When the angle of attack is large, the ascent of the body to the surface of the water can no longer compensate for the increase in the frontal cross-section of the body, and the water resistance increases noticeably.
Therefore, an attempt to artificially assume a high position in the water does not bring success. Some swimmers lie higher in the water than others because they have better buoyancy and greater speed of movement. Many people raise their heads, trying to artificially take a high position in the water. However, in this case only the upper part of the body rises, and the lower part sinks. The movements of the arms and legs become less efficient: the swimmer has to expend a relatively large part of his effort to overcome the increasing resistance and keep his head raised above the water.
As the speed of progress increases, the resistance of the water increases only under the swimmer, and not above him. Therefore, when improving a swimmer’s style, one must strive to find an angle of attack that corresponds to the individual characteristics of a given athlete (within the limits specified when describing the swimming technique in one way or another).
To swim faster, an athlete needs to: 1) reduce resistance; 2) increase driving force; 3) use a combination of these two factors. This problem can be solved only by finding a rational technique. The biggest improvement in swimming technique in recent years has been the reduction of drag.
General physical training classes help develop the strength necessary to move quickly over a distance with the least amount of water resistance. As the swimmer gets tired, he applies less driving force and the streamlining of his body deteriorates.
When performing working movements, the rowing surfaces must be given a non-streamlined shape, and during preparatory movements over water - the most streamlined.
2.3. Forces that propel a swimmer forward: the forces that propel the swimmer forward are generated with the help of the arms and sometimes the legs, but mainly by capturing the water with the hands and pushing it back with the feet.
Traction force: An athlete moves in water due to the movements of the limbs, the work of which is provided by muscle forces. The swimmer makes the main progress through the use of his hands. When the hands move in the water, hydrodynamic reactive support forces F appear on their rowing surfaces, acting in the direction opposite to the movement of the hands. The horizontal component of the reactive support force, which propels the swimmer forward, is called the traction force (Fх), and the vertical component is called the lifting force (Fу). Force F, as well as the force of counter hydrodynamic resistance of the medium, depends on the speed of the rowing surface of the limb, its midsection, water density and streamlining coefficient. To create the greatest traction force, the swimmer performs an accelerated stroke and strives to increase the force of water pressure on the rowing surface. The greatest pressure will occur on the hand, since it has a large midsection, high speed and less streamlining (Fig. 4).
Hand movements. There are three variations of the arm stroke, with variations used in crawl or butterfly swimming. The speed of a swimmer's progress depends on the efficiency of the stroke. There are: 1) stroke with the elbow down; 2) straight arm stroke; 3) correct stroke.
The worst stroke is considered to be with the elbow down. It does not propel the swimmer forward enough because it pushes too little water back. This is how beginners usually swim.
A row with a straight arm is more effective than with a lowered elbow. The best stroke will be the one that minimizes the up and down components of the straight arm stroke. The movement begins as with a straight arm stroke, but the elbow is higher. During the stroke, it bends, and towards the end it almost straightens.
The arm is mobile in its joints - the shoulder, elbow, wrist joints, in the joints of the hand and fingers. This allows the working planes to be placed in the most favorable positions for creating traction force. Example: By bending the wrist in the first half of the stroke and extending it in the second, the swimmer keeps the palm in a position relatively perpendicular to the surface of the water, which allows the best use of water resistance for effective support. In addition, the optimal position of the hand at the exit from the water reduces the influence of the drowning force. The water pressure on the hand is about 70% of the total pressure throughout the entire hand. The hand is the main element of the mover, its main working plane.
To give the body a greater amount of movement, a sufficiently high impulse of force is needed. This means that it is necessary to choose a trajectory of movement of the propeller that would ensure prolonged contact of the working surface with water. It has the shape of a curve.
Movements of the arms and legs when swimming most often have a rotational and reciprocating nature. In this case, the direction of movement of the brush changes smoothly. The path traversed by the hand in water is 3 times longer than the path traversed by the elbow. The speed of movement of the hand at certain moments of the stroke exceeds 4 m per second.
The angle of attack of the hand during the stroke largely determines the effectiveness of the movement. Relative to the trajectory of its own movement, the hand is oriented during the stroke, usually at an acute angle.
If the hand is involved in creating continuous support on the water, then the function of the shoulder is to transmit the results of this contact with water to the swimmer’s body through a system of rigid links to the swimmer’s body in order to move it in a given direction. A rigid system is necessary for the rational transfer of force from one link to another. The system of supporting links can be shortened and lengthened, and change their relative position.
The first half of the stroke in all swimming methods should be performed with a high elbow position. A high position of the elbow and optimal rigidity of the hand are facilitated by a slight turn of the hand with the palm outward in the phase of entering the hand into the water and capturing the water.
Brush position. Five positions of the hand were studied: A - flat hand, fingers closed; B - the hand is flat, all fingers are closed except the thumb; G - flat hand, fingers open; D - the hand is cupped, all fingers are closed; E - the hand is flat, slightly bent, fingers closed.
The greatest resistance was observed in hand position A. In the other four positions, the resistance decreased according to the order in which they were listed. When the hand was in position D and E, both the frontal (frontal) and additional (vortex) resistance were significantly less.
Why shouldn't you keep your fingers open? With this position of the hand, more effort is expended. Fatigue sets in and the speed of progress drops, especially when swimming long distances.
However, we must not forget that even the best swimmers in the world have shortcomings in their stroke technique. The fact that an athlete, despite these shortcomings, achieves high results is explained by two reasons: 1) due to his exceptional characteristics, developed strength and general physical fitness; 2) the shortcomings are so insignificant that they do not affect the result.
2.4. Uniform advancement of the driving force. This principle can be called the principle of “continuous movement”. When moving the body forward, a uniform rather than wavy application of force will be more effective. Therefore, the front crawl is the fastest of the sports swimming methods.
The stroke technique should, if possible, ensure uniform movement of the body in the water. In other words, when swimming it is necessary to avoid various pauses. With a wave-like change in speed, most of the force that the swimmer could use to overcome the resistance of the water will be spent on overcoming the inertia of the body.
When swimming front and back crawl, the beginning of the stroke with one hand coincides with the completion of the stroke with the other. In this case, a more even and constant application of force is ensured. When swimming butterfly, the stroke begins immediately after the hands enter the water and any slipping at this moment slows down the progress.
When swimming breaststroke, after bringing your arms forward, it is useful to perform a small glide, which will allow you to better use the speed generated by the movements of your legs. Inertia will help the body take a more even position, resulting in less resistance. If the slide is too long, then the speed drops, the feet sink into the water and the swimmer again has to expend a lot of effort to acquire acceleration.
2.5. Newton's 3rd law and hand movements above water: Some coaches are indifferent to how the hand moves above the surface of the water, since the main phase of the stroke takes place under water. However, in three of the four swimming methods, preparatory movements of the arms (carriage) are performed above the surface and their mechanics affect the efficiency of the movements as a whole. An incorrect carry causes a disruption in the rhythm of arm movements, as a result of which the swimmer performs a stroke that is too fast or slow, forces it, or interrupts it with a pause.
Some of the most serious disadvantages of moving your arms above water include those that lead to an increase in frontal and additional resistance. If the movements of the arms over the water are performed in a wide stroke counterclockwise, then the hips or feet move in the opposite direction.
The muscles involved in carrying the arm are attached to the shoulder. By contracting, they shorten and do their job, causing the body to deviate from the longitudinal axis. This is especially noticeable when swimming with your hands (with a board or rubber rings between your legs). Performing a wide sweep, both when swimming on the back and when swimming in freestyle, causes the feet to move in the opposite direction.
When swimming on your back, it is best to carry out the stroke directly above your head - in this case, there is almost no lateral oscillation of the body. In the front crawl, this is achieved by reducing the radius of rotation of the arm by raising the elbow and bringing the hand as close to the body as possible.
When swimming butterfly, the movements of one hand are balanced by the same movements of the other hand.
When analyzing the technique of all swimming methods, it is necessary to refer to Newton’s 3rd law, formulated more than 250 years ago. In accordance with it, every action has a reaction equal in strength and opposite in direction. In other words, the reaction is directed in exactly the opposite direction and at an angle of 180 degrees. If a swimmer pushes the water directly downwards, counter forces push him straight up.
If an athlete is pushing back with 25 pounds of force on his hands (1 pound equals 453 g) and 5 pounds on his feet, then the total force propelling the swimmer is 30 pounds.
A number of authors believe that the force created during leg movements is ineffective; it requires a lot of energy. The question is, what is the role of leg movements when swimming front and back crawl? Research in recent years has shown that when swimming at high speed, advancement is created not only by arm movements, but also by leg movements (in sprinting).
Leg movements ensure the horizontal position of the swimmer's body, perform the function of balance, create traction forces, participate in the general coordination of the swimmer's movements, and support the rhythmic pattern of movements of all parts.
2.6. Principle of momentum transition: the amount of movement is quite easy to transfer from one part of the body to another. This effect is used in many movements that are performed in water and on land. The amount of movement that occurs during the “mill” with the arms at the start is completely transferred to the body and helps the swimmer to cover a greater distance after take-off.
The same can be observed during arm movements above the water when swimming front crawl, backstroke and butterfly. So, when swimming on your back, a certain amount of movement occurs during circular movements above the water. Immediately before the brush enters the water, the velocity vector is directed downward (point A). If at this moment the hand is sharply braked (point B), then part of the momentum will be transferred to the body. As a result, your shoulders and head will sink into the water. When watching athletes swim on their back, you may notice that some of them have their heads bobbing up and down as a result of ineffective arm technique. To avoid this, the hand must be immersed in water at a speed equal to the speed of its movement above the water.
2.7. Square rule: The resistance that a body experiences in water is approximately proportional to the square of the increase in its speed. For example, if an airplane traveling at 100 miles per hour experiences 1,000 pounds of drag, when the airspeed doubles (200 mph), it will experience 4 times as much drag. those. about 4000 lbs. The same law applies when a swimmer moves in water.
So, if a swimmer puts his hand into the water 2 times faster than before, then the resistance increases 4 times. Therefore, accelerated movements of the arms above the water not only disrupt the rhythm, but also, by increasing resistance, slow down the swimmer’s progress.
What should determine the speed of passage? The swimmer cannot plunge his hand into the water slowly in order to reduce drag. The speed of your hand moving above the water should match the speed of your stroke. Usually the carry is a little faster, but this is not noticeable. It is difficult to make a fast stroke with one hand over the water while the other makes a slower stroke. The correspondence between stroke speed and stroke speed is an important factor determining the rhythm of arm movements.
When a swimmer increases the speed of his arms in the water, then with the same stroke technique his propelling force increases 4 times. At the same time, from a physiological standpoint, any increase in the speed of muscle contractions is accompanied by a threefold increase in energy expenditure. In other words, when stroke speed doubles, energy expenditure increases eightfold. Thus, while the hand performing a fast stroke increases the advancement, energy expenditure and, accordingly, oxygen consumption increase much faster. This is why swimmers, who tend to move their arms frequently, get tired quickly. This also explains why athletes specializing in middle and long distance swimming must swim at a strictly defined and uniform rhythm.
There is a physical basis for speeds according to which a person cannot swim more than the length of his own body in a second. But it is not always the case. It is possible faster, but for this the athlete must not follow the wave that he himself creates, but plan on its crest. Vladimir Bure is one of the first who managed to “ride” the wave. In other words, he overtook not only time, but also himself. (Turetsky, 2002).
When swimming a distance with a certain result, a swimmer will spend less energy if he swims at a uniform speed.
Example:
A swimmer swims a distance of 100 m in 100 seconds. To overcome each meter of distance, he spends a certain amount of energy, which we denote by the letter E. Thus, he will spend E 100 = 100 E - one hundred conventional units of energy. Now suppose that the same swimmer swims 100 m in 100 seconds, moving unevenly: the first 60 m in 75 seconds, and the next 40 m in 25 seconds. The overall result will be the same - 100 seconds, but the energy consumption will be different. For the first 60 m, the swimmer will spend 0.8 2 x 60 = 38.4 conventional units of energy, i.e. less than when he swam in 60 seconds. For the last 40 m, the swimmer will spend 1.6 2 x 40 = 102.4 E (conventional units). The total energy consumption is 38.4 + 102.4 = 140.8 conventional units.
State University
Physical culture and sports
Swimming test
Topic: Technique and methodology for teaching breaststroke swimming techniques
Course 3, group No. 2
Moscow 2009
1 Swimmer’s body position in water 3
1.2 Hand movements 4
1.3 Coordination of movements 5
2 Breaststroke swimming technique 7
2.1 Leg movements 8
2.2 Hand movements 10
2.3 Body position and breathing 12
2.4 General coordination of movements 13
3 Methodology for teaching breaststroke swimming techniques 16
3.1 General requirements for swimming training methods 16
3.2 Exercises for learning breaststroke swimming techniques 19
3.3 Pedagogical model of breaststroke swimming technique 28
4. List of references used 31
^
1 General requirements for swimming technique
Biomechanical analysis of swimming technique, generalization of the experience of coaches and high-class athletes on technique make it possible to formulate requirements for swimming technique. Compliance with these requirements ensures rational technology. These requirements relate, first of all, to the position of the body in the water, rowing movements of the arms as the main source of driving forces, and coordination of movements.
^
Sports swimming technique
- this is a rational system of movements that allows the swimmer to best realize his motor capabilities and achieve high results in competitions. This concept includes the form, nature of movements, their internal structure (the natural relationship of movements). It includes, and the swimmer’s ability to feel well,
Be aware of and use all internal and external forces acting on the body to move forward.
^
1.1 Swimmer’s body position in the water
When swimming at competitive speed, an athlete's body should occupy a well-streamlined, elongated, relatively high and balanced position in the water with an optimal angle of attack. The technique of qualified athletes is characterized by minimal values of the angle of attack of the body (3-5°). The swimming technique that beginners master is characterized by slightly larger angles of attack (8-10°), which allows the body to be given a “planing” position, making it easier to perform preparatory movements with the arms and breathing. The position of the head and hips has a significant influence on the overall position of the swimmer's body in the water. During most of the full cycle of movements, the head is almost on the longitudinal axis of the body, the neck muscles are relaxed, the swimmer looks forward - down (when swimming on the chest) or up - back (when swimming on the back). In all methods, with the exception of back swimming, the head participates in auxiliary movements in rhythm with arm movements and breathing. For most of the full cycle of movement, the swimmer's hips should be positioned near the surface of the water. To do this, for example, when swimming crawl, the hips perform movements with a small swing, actively sending upward while striking the foot down. When swimming breaststroke, the hips at the end of the push back with the legs also reach the very surface of the water and maintain a well-streamlined position throughout the entire stroke with the arms. A serious mistake when swimming front crawl and dolphin is “hanging” the hips - lowering them too deeply and moving the legs not from the pelvis, but from the knees. The swimmer’s torso must be a fairly rigid structure (due to the optimal degree of tension in the abdominal and lower back muscles) so that the driving forces from the strokes with the arms and legs are directed without loss along the line of the swimmer’s forward movement. The rest of the muscles of the body, especially the back muscles,
Should be as relaxed as possible. Powerful muscle groups of the body serve as the basis for the swimmer’s motor mechanism. These muscles, on the one hand, ensure a streamlined and balanced body position, and on the other hand, they take an active part in all working movements of the legs and arms.
If in the swimming technique of beginners it is permissible, and in some cases even desirable, a stable, somewhat fixed position of the torso, then in the swimming technique of highly qualified athletes the torso should be actively involved in the rowing movements. When swimming crawl on the front and on the back, it rhythmically turns left and right relative to the longitudinal axis of the body (on average 30-35° in each direction). These rolls strengthen the hand stroke, help to perform it along the optimal trajectory, remove the hand from the water with minimal resistance and carry it over the water. When swimming front crawl, turning the body makes it possible to inhale with minimal tension in the neck muscles and maintain the position of the head almost on the longitudinal axis of the body during inhalation. The degree of body roll depends on the type of technique and individual characteristics
The athlete and the swimming pace. As the tempo of arm movements increases, the degree of roll decreases relative to the direction the swimmer moves forward. When swimming breaststroke and dolphin, the upper part of the athlete’s body performs active movements up and down along a gentle wave-like trajectory. These auxiliary movements of the torso are also aimed at increasing the efficiency of arm, leg and inhalation movements.
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1.2 Hand movements
Hands are the main mover when swimming sports. Even in breaststroke, where arm and leg movements create traction force approximately equally, the technique of arm movements has a greater influence on the overall coordination of movements, determines the tempo and rhythm of swimming, and is closely related to breathing. This means that arm movements are crucial for increasing swimming speed in this method as well. As noted above, the hand should be considered as one of the main elements of the mover, its main working plane. The main function of the hand during the stroke is to provide continuous support on the water. During the stroke, the hand should move continuously, at high speed relative to the water, along an optimal curved path, with optimal orientation relative to the direction of the swimmer’s forward movement. As already mentioned, the optimal orientation of the hand in the main part of the stroke is its position close to the front. During entry into the water and in the initial phase of the stroke, the hand should be oriented in such a way as to cut through the water with minimal resistance with the fingertips. After completing the stroke, it should take a position that provides minimal water resistance during the preparatory phase of the movements. When swimming front crawl, dolphin and backstroke, the hand at the very end of the stroke is turned with the palm inward (i.e., towards the thigh). In the first two ways
While swimming, she leaves the water with her little finger, and with her last finger, thumbs up. The arm begins the stroke completely (or almost completely) straightened at the elbow joint. The main part of the stroke should be performed with an optimal degree of flexion and extension of the arm in this joint. Specific values for the degree of flexion of the arm at the elbow joint are given below (when analyzing swimming techniques using separate methods). Note that in the swimming technique of junior athletes, the degree of flexion of the arm at the elbow joint is less pronounced than in highly qualified swimmers. The first half of the stroke in all swimming methods should be performed with the so-called high elbow position. This requirement includes: 1) advanced movement of the hand in relation to the elbow; 2) turning the elbow to the side (but not back or down); 3) slight inward rotation of the shoulder and forearm; 4) the optimal degree of arm rigidity in the elbow joint. The stroke technique with a high elbow position allows you to lean on the water with your hand and forearm at an effective angle, transferring the ground reaction forces to the shoulder and torso without loss.
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1.3 Coordination of movements
For a more productive analysis of technique and its improvement in the swimmer’s holistic system of movements, it is advisable to highlight the elements: phases of movements with arms and legs, generalized phases of the cycle. Generalized phases of the cycle include movements of all parts of the body. There are three such phases: preliminary, main, final. They flow together, conditioning each other and continuously repeating in a single flow of the swimmer’s movements.
The main phase is that part of the general cycle of movements in which the greatest amount of movement is acquired and a high intra-cycle speed is achieved. The beginning of this phase is the moment of significant acceleration of the main working movement of the arms - adduction and extension of the shoulder (determined by the change in the angular velocity of rotation of the shoulder), the end is the moment of a significant decrease in the speed of this movement. At this time, the athlete performs the most powerful part of the stroke, leaning on the water with his hand and forearm. All auxiliary movements and breathing in this phase of the cycle are strictly subordinated to the rhythm of the working movements of the arms. The main phase is performed by holding your breath or exhaling. By the beginning of the main phase, the swimmer’s body must be accelerated (have a relatively high intra-cycle speed), and the working planes of the arms must reach the optimal position for supporting the water. For example, the plane of the forearm should be inclined to the surface of the water at an angle of at least 45. The plane of the hand should be 50 - 60°, while the arm should be bent at the elbow joint at approximately half of its maximum working angle and have sufficient rigidity.
This problem is solved in the preliminary phase of the cycle, immediately preceding the main one. During the preliminary phase, the swimmer, through working movements of the arms and legs, imparts the necessary acceleration to his body, maintaining a well-streamlined position. The initial part of the arm stroke in this phase is always performed with a high elbow position and mainly due to the contraction of the muscles that flex the forearm and hand and rotate the arm inward (powerful extension and adduction of the shoulder is, as it were, reserved for the subsequent, main phase of the cycle).
Following the main one comes the final phase of the full cycle of movements. Here the task for the athlete is the following: maintaining a high speed of body movement forward (without allowing a significant drop in speed) and a relatively high position of the body, without allowing a noticeable lowering of the shoulder girdle), with minimal resistance, direct the arm (arms) and shoulder girdle along the optimal trajectory forward to capture water for the next stroke; stretch the muscles of the back and chest during this movement in order to use the energy of muscle stretching in the next, preliminary, phase of the cycle. The swimmer performs the final phase of the cycle through the final stroke movement with the hand and forearm of one hand (in freestyle on the front and back) or both hands (in dolphin) and part of the working movement with the legs (in all methods except breaststroke). By the end of the final phase of the full cycle, the athlete’s body should reach the most streamlined position. This will make it possible to again impart positive acceleration to the body in the next phase of the cycle with optimal expenditure of force. When analyzing the full cycle of movements, the swimmer’s boundary poses (instantaneous positions of the parts of his body) at the moment of phase change are also identified. Boundary poses serve as good guides when studying a technique (for example, from filmograms), visual pedagogical control over a technique, and its practical development.
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2 Breaststroke swimming technique
Currently, at the Olympics, the 100 and 200 m swimming distances are played out in this way for both men and women. Breaststroke is also used to swim one of the stages of the medley relay and medley swimming distances. This method has great practical value. So, they can travel long distances in clothes; in great excitement; you can transport various objects (holding them in your hands or pushing them in front of you); When swimming breaststroke, it is easy to navigate in the water. The competition rules quite strictly regulate breaststroke swimming techniques. The main points of the rules are as follows: 1) when swimming breaststroke, the swimmer lies on his chest, his shoulders are parallel to the surface of the water; 2) both hands perform movements simultaneously and symmetrically. During the stroke, they can move backward under the water or on its surface; They also stretch forward under water; 3) the legs perform movements simultaneously and symmetrically. When rowing with legs, the feet must be turned to the sides and move backward in arcs (dolphin-like movements of the legs up and down are not allowed); 4) during the distance, it is prohibited to immerse your head under water, with the exception of sliding after the start and turns.
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2.1 Leg movements
Leg movements are the most important part of breaststroke swimming technique. In modern versions of swimming techniques using this method, hand movements have acquired a decisive role. Movements of the legs, as well as the arms, play the role of the main mover of the swimmer. In their structure, the working movements of the legs when swimming breaststroke differ from the movements of the legs when swimming crawl on the front, on the back. In front crawl, back crawl and dolphin crawl, wave-like movements are performed, reminiscent of the movements of a dolphin's flexible tail; in breaststroke, there is an energetic repulsion from the water with relatively rigid supporting surfaces of the feet and legs.
Rice. 1. Technique of simultaneous movements of the legs when swimming breaststroke.
Leg movements in phases.
Repulsion- working phase of leg movements. By the time the push-off begins, the legs are bent at the hip joints to an angle of 115-140°, the shins are in a position perpendicular to the surface of the water (the angle of flexion in the knee joints is about 35-45°), the feet are turned with their toes to the sides, the knees are spread slightly more than width of the pelvis. During the push-off, the feet move in arcs outward - back, and then back - inward, the legs vigorously straighten and close together. This single united movement is performed powerfully and has an overwhelming, “explosive” character. During the push-off, the athlete strives to direct his hips up to the surface of the water, and his feet almost straight back, without lowering them deeply down. After the repulsion is completed, the thighs, legs and feet immediately relax and seem to float to the very surface of the water. There is a short pause in the movements of the legs, during which they maintain a well-streamlined position.
Pull-up- preparatory phase of leg movements. It begins by smoothly bending the legs at the knee joints. Relaxed shins and feet move close to the surface of the water, hips maintain a streamlined position and do not sink down. At the final moment of the pull-up (approximately in the last 0.1 s of the phase), the hips and shins are brought to the position of their greatest flexion in the hip and knee joints. Pull-ups are performed in a single smooth movement and with acceleration until the feet turn toes to the sides. The feet turn instantly, and the swimmer immediately starts pushing off.
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2.2 Hand movements
As mentioned above, when swimming breaststroke, the arms and legs are equally the movers. But the hands set the pace and rhythm, determine the overall coordination of movements and are closely related to breathing. Arm movements are critical in increasing your breaststroke speed. During the stroke, the swimmer's hands move along their trajectory at high speed, continuously resting on the water.
Rice. 2. Trajectory of hand movements
Technique of hand movements in phases.
^ Water capture runs smoothly. The swimmer sends his arms forward and slightly to the sides. The hands move at a depth of approximately 10-15 cm from the surface of the water and are turned with the palms down and slightly outward. The swimmer, with gradually increasing force, presses his palms onto the water, smoothly bending his hands at the wrist joints. The arms remain as if fixed at the elbow joints, the elbows are turned to the sides (but not down).
^ Main part The stroke begins with vigorous bending of the arms at the elbow joints and a supporting movement of the hands back. The hands move with acceleration along a rounded area, first outward and then inward, the elbows are held in a high position. The 2nd half of the stroke is the fastest and most powerful part of the considered phase of the movements. At this time, the working planes of the hands and forearms occupy a position favorable for support on the water (they are inclined to the surface of the water at an angle of about 60°), the hands continue to quickly move along a rounded trajectory back - inward, and then inward - forward. Following the hands, the elbows also move inward. Vigorously completing the stroke with his arms, the swimmer directs himself forward and slightly upward. Towards the end of the phase, the hands and elbows come together below, under the swimmer's chin.
^ Bringing your arms forward - preparatory phase of movements. The beginning of the pull-out continues a single rapid movement of the arms inward and forward during the end of the stroke. At this time, the hands are turned with palms slightly towards each other. The further path forward of the hands passes smoothly. The hands are turned palms down and almost touching. At the end of the recovery, the athlete again actively sends his arms forward, almost straightened at the elbow joints, in order to begin another capture of water with his hands.
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2.3 Body position and breathing
The swimmer's body should maintain a well-streamlined position throughout most of the full cycle of movements. When grabbing water with your hands, the angle of attack of the body is minimal (approximately 3°), the swimmer’s head is at ease facing forward - down. 
Rice. 3. Breaststroke swimming technique
While completing the arm stroke, the shoulder girdle rises above the surface of the water, the athlete moves his chin forward and inhales. In modern versions of the breaststroke swimming technique, the so-called late breath. It is performed after completing the arm stroke, when the hands and elbows of the bent arms are directed inward. The late inhalation technique helps keep the body in a well-streamlined position during the arm stroke with high elbows, allowing you to perform the stroke more powerfully.
At the moment of inhalation, the greatest angle of attack of the body is noted. For some swimmers it reaches 15-17°. This will not have a negative effect if the swimmer manages to re-align the body well before the start of working movements with his legs and arms. Having completed the inhalation, the swimmer lowers his face into the water and directs the shoulder girdle forward along with his arms.
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2.4 General coordination of movements
The overall coordination of movements should ensure the swimmer’s continuous movement forward with the highest average speed and optimal expenditure of force. It is not possible to achieve a uniform intra-cycle speed of advancement when swimming breaststroke and one should not strive for this. The structure of the movements of this method is such that differences in speed within a full cycle are inevitable even for highly qualified swimmers (reach 1.5 m/s). Maximum values of intra-cycle speed (exceeding
In highly qualified athletes, 2 m/s) are observed during arm strokes, minimal values (about 0.5 m/s) are observed during joint preparatory movements of the arms and legs and breathing. The task of rational coordination of movements is to increase the speed of body movement as much as possible during rowing movements and to lose it as little as possible during preparatory movements of the arms and legs. One of the common rational variants of the technique is sequential coordination of the movements of the arms and legs in the absence of pauses in the movements of the arms. In this variant, pushing off with the legs is immediately replaced by a stroke with the arms. The full cycle of movements consists of phases: 1 - preliminary (it, in turn, is divided into two subphases - A and B), II - main, III - final. The preliminary phase of the cycle includes the push-off with the legs and the initial part of the stroke with the arms. This is the acceleration phase. Its onset occurs at the moment of the lowest intra-cycle speed and the least streamlined position of the swimmer. During this phase, the athlete must bring the body into an elongated and well-streamlined position as quickly as possible, giving the body a relatively high speed of moving forward to the beginning of the main phase of the cycle.
Table
^ Phases of the cycle of arm movements when swimming breaststroke
| Phases | Preferred direction of movement of the hands | Signs of the beginning of the phase |
| ^ Working movements: Preliminary (water capture) | Forward-outward | Beginning of outward movement of the hands |
| Home: pull-up repulsion | Outward-backward-downward In-back-down | The beginning of the movement of the hands back Starting to move the hands in |
| Final (bringing hands near the chest) | Inward-forward | The beginning of the movement of the hands forward and upward |
| ^ Preparatory movements : Removal | Forward and up | Beginning of arm extension at the elbow joints |
In subphase A, energetic push-off with the legs is combined with sending the arms forward (they should take a streamlined position and, as it were, cut through the oncoming flow of water). An increase in intra-cycle speed is facilitated by the use of the POTENTIAL energy of the position of the swimmer's shoulder girdle and head, which, during inhalation (in the previous phase of movements) were at the highest point of their movement above the water. Sending the shoulder girdle and head after the hands should be done without delay, smoothly, in a forward direction and slightly downward. At this moment, the swimmer seems to be trying to catch up with his forehead to the forward bow wave.
In subphase B, the initial part of the arm stroke is performed (until the shoulder is actively involved in the stroke). Hand movements are performed with a high position of the elbows and a streamlined position of the body, which it manages to occupy by this moment: the legs are extended and relaxed, the pelvis and hips are at the very surface of the water, the angle of attack of the body is minimal. While maintaining a streamlined and dynamically balanced position of the body, the athlete strives to give it additional acceleration in the direction strictly forward, to bring the supporting planes of the hands and forearms into the optimal position for performing the next, main, phase of the cycle. By the end of the phase, the working plane of the hand and forearm should be tilted to the surface of the water at an angle of at least 45° with an angle of flexion of the arm at the elbow joint of about 135°.
The main phase of the cycle consists of the most powerful part of the arm stroke, performed through accelerated extension and adduction of the shoulders. The brushes move at high speed along a loop-shaped section of the trajectory, creating continuous support on the water. In the first half of the phase (movement outward - backward), they seem to slightly cover the flow with the outer edge of the palm, in the second (movement mainly inward) - with its inner edge.
In the 2nd half of the phase, the rowing movement of the arms is combined with an auxiliary movement of the shoulder girdle and head forward - slightly upward. This peculiar feature, both with the shoulder girdle and the head, strengthens the final part of the stroke with the arms, helps to direct the elbows inward (and then forward), and gives the shoulder girdle the necessary impulse for the subsequent forward-upward movement (for inhalation). Throughout the entire main phase of the cycle, the legs do not interfere with the arm stroke, continuing to maintain a well-streamlined position of the hips; a smooth pulling of the legs begins due to involuntary flexion of the relaxed shins at the knee joints. The phase begins at the moment when the elbows go down - inward to the frontal plane, conventionally drawn through the shoulder joints.
The final phase of the cycle includes sending the shoulder girdle and head to inhale with the beginning of moving the arms forward and pulling the legs to the starting position for pushing off with the completion of bringing the arms forward. In this phase, we can conditionally distinguish two parts - before the end of inhalation and after it. The first part (sending the shoulder girdle to inhale) is characterized by keeping the hips in a streamlined position, while the angle of flexion of the legs at the hip joints does not exceed 150 - 155°. The second part of the final phase of the cycle is characterized by a rapid (within 0.10 - 0.12 s) movement of the lower leg, feet and hips to the starting position for pushing off, i.e. to the position of greatest bending at the knees and
Hip joints.
The final phase of the cycle is unsupported, it is completely driven by preparatory movements of the arms and legs and inhalation. In addition, the athlete inevitably finds himself in the least streamlined position. However, he must strive, through smooth, fast, rational execution of movements with the arms, legs and breathing, to maintain the intra-cycle speed at the level necessary for moving forward, and to prevent a significant decrease in speed. The solution to this problem is facilitated by the optimal sending of the shoulder girdle and head forward, following the hands.
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3 Methods of teaching breaststroke swimming techniques
3.1 General requirements for teaching swimming methods
The study of sports swimming techniques is carried out in a strict methodological sequence.
The technique is studied separately in the following order: 1) body position, 2) breathing, 3) leg movements, 4) arm movements, 5) general coordination of movements. At the same time, the mastery of each element of the technique is carried out in gradually more complex conditions, which ultimately involve performing exercises in a horizontal, unsupported position, which is the swimmer’s working position.
Each element of swimming technique is studied in the following order:
familiarization with movement on land - carried out in general terms, without working out the details, since the conditions for performing the same movement on land and in water are different;
study of movements in water with a fixed support. When studying leg movements, use the side of the pool, the bottom or the shore of a reservoir as a support; hand movements are studied while standing on the bottom in chest-deep or waist-deep water;
study of movements in water with a movable support. When studying leg movements, swimming boards are widely used; hand movements are studied while walking slowly along the bottom or while lying on the water with support from a partner;
study of movements in water without support. All exercises in this group are performed while sliding or swimming.
moving the legs with breathing;
hand movements with breathing;
movements of the legs and arms with breathing;
swimming in full coordination.
At the stage of consolidating and improving swimming technique, the method of holistic performance of the technique takes on leading importance. Therefore, at each lesson, the ratio of swimming in full coordination and swimming in elements using movements of the arms and legs should be 1:1. Improving swimming technique is carried out with a mandatory change in the conditions for performing movements. For this purpose, the following swimming options are used:
alternately swimming long and short sections (for example, swimming along and across the pool);
swimming segments with the least number of strokes;
alternating swimming in easier and more difficult conditions at a given pace (for example, swimming through elements and in full coordination; swimming through elements with and without support; swimming with breath holding and in full coordination).
a variety of options for performing exercises, which allows you to maintain interest in classes, which is especially important in swimming;
ability to use various swimming techniques in changing conditions;
formation of individual swimming technique in accordance with body type and level of physical fitness.
Errors that occur when learning swimming techniques are divided into:
typical – the most common during initial training;
rough - distorting the basic structure of movements;
minor – reducing the effectiveness of movements, but not affecting other elements of the technique;
interconnected - arising from one another.
To prevent possible errors, you need to know the reasons for their occurrence. The main reasons are:
inconsistency of the educational task with the level of preparedness of students (violation of pedagogical principles of accessibility and consistency);
incorrect understanding by the practitioners of the form and nature of the movements performed;
incorrect starting positions when performing exercises.
1) systematic repetition of educational material;
2) use of introductory and preparatory exercises in classes;
3) changing the initial provisions and conditions for performing exercises;
4) students’ understanding of the reasons for their mistakes;
5) consistent correction of mistakes made (first gross, then minor).
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3.2 Exercises for learning breaststroke swimming techniques
The breaststroke technique does not place such stringent demands on mobility in the shoulder joints as in freestyle, but requires high mobility in the ankle (dorsal extension), knee and hip joints. For breaststroke swimmers, muscle strength is important not only in the shoulder girdle, but also in the lower extremities, which create effective forward movement.
^ General developmental, special and simulation exercises (Fig. 4).
Before starting a set of exercises, walking, jumping, bending, squats, and push-ups are performed.
I.p. – O.S. hands up. Squats.
I.p. – gray hair on the heels (toes pulled back). Bend back as low as possible; return to IP, resting your hands on the floor.
I.p. – emphasis lying on your hips. Bend over and grab your hands with your feet bent at the knees (toes turned outward to failure), roll from your hips to your stomach and back.
I.p. – half squat, hands resting on knees. Rotate your knees right and left.
I.p. – standing leaning forward, feet shoulder-width apart. Movements of the arms, as in breaststroke swimming.
In a standing position with your side to the support, bend one leg at the knee joint and, grabbing the foot from the inside, pull the shin and heel towards the buttock. Lower your leg and perform a breaststroke movement with it.
Rice. 4. An approximate set of exercises on land for breaststroke.
When lying on your chest, move your legs as if you were swimming breaststroke.
In a lying position, maximum flexion and arching of the torso.
I.p. – standing facing the gymnastics wall. Support your hands on the crossbar of the gymnastic wall at the beginning and in the middle of the “stroke”. During the exercise, strongly tense the muscles of the shoulder girdle and arms.
I.p. – standing at the gymnastics wall, leaning on it with your hands. Alternately swing your straight leg back and forth.
Movements of the arms, as in breaststroke, stretching the rubber shock absorbers.
"Start jump" up.
I.p. standing sideways to the wall, resting your hand on it. Bend one leg at the knee joint, move the shin to the side and grab the foot from the inside with the same hand; lower your leg and push it until it connects with the other - as when swimming breaststroke. Same with the other leg.
I.p. – sitting on the floor, supporting yourself with your hands behind you. Leg movements as in breaststroke: slowly pull your legs up, turning your knees to the sides and dragging your feet along the floor; turn your socks to the sides; push up, connect your legs and stretch them out on the floor. Pause, slowly and gently pull your legs towards you.
In a lying position on a bench, move your legs, as when swimming breaststroke, with the help of a partner (standing on the side of your legs). Pulling up the legs is done independently, but at the moment of spreading the toes to the sides, the partner takes the feet with his hands and helps to take the desired position before the push. Then, without releasing the swimmer’s legs, he helps him perform the movement correctly and connect his legs.
Rice. 5. Exercises to study leg movements
6. I.p. – sitting on the side of the pool, supporting yourself with your hands behind you. Breaststroke leg movements.
7. I.p. – standing sideways to the wall of the pool, holding the side with your hand. Bend your leg at the knee joint, move your shin to the side and grab your foot with the same hand. Lower your leg, performing an imitation movement with it, as when swimming breaststroke. Same with the other leg.
8. I.p. - lying on your chest near the side, holding onto it with your hands. Leg movements as in breaststroke.
^ Typical mistakes. Pelvic descent; spreading the knees too wide before kicking; the toes and shins do not turn to the sides before the push.
Methodical instructions. Do not spread your knees to the sides when pulling your legs more than shoulder width apart. Before pushing with your feet, stop, fixing the “toes to the sides” position. Do not begin pulling your legs after the push until they have floated to the surface. Push with your legs in a single continuous movement; after the push, maintain a long pause (time for “sliding”), tensing the buttocks and the muscles of the back of the thigh so as not to sink.
9. Swimming on your back using leg movements, holding the board with straight arms and pressing it to your stomach and hips.
10. Swimming on your back using leg movements, holding the board in your arms outstretched forward.
11. Swimming on the chest using leg movements with a board. After the push, be sure to pause, trying to slide as long as possible.
Exercises without support
12. Swimming on your back with breaststroke movements, hands at your hips.
13. Swimming on your chest, arms extended forward.
14. The same, using leg movements, arms along the body.
15. The same, but the arms are extended forward.
Typical mistakes. During the pause, my legs sink. Pull-ups and kicks are performed at the same speed. After the push, the legs do not connect together.
^ Methodical instructions. After pushing with your feet, tense the muscles of the buttocks and the back of the thigh so that your legs do not sink while sliding. Perform pull-ups slowly and gently. Spread your socks out to the sides quickly and vigorously. Push your legs strongly, but gently, until your legs close. When swimming on your back, your knees should not show out of the water.
^ Exercises to study the coordination of leg movements and breathing
To study leg movements in coordination with breathing, perform the previous set of exercises (from 1st to 11th), with an emphasis on breathing. Inhalation in breaststroke is performed while pulling the legs to the starting position, exhalation is performed simultaneously with pushing off with the legs.
You should pay attention to the coordination of leg movements and breathing when performing simulation exercises on land: inhalation and exhalation should be forced, so that the teacher can see and hear the duration of their performance by the student.
^ Exercises to study hand movements (Fig. 6)
Simulation exercises on land
16. I.p. Standing leaning forward, feet shoulder-width apart, arms extended forward. Simultaneous rowing movements with the arms, as in breaststroke swimming.
Exercises in water with a fixed support
17. I.p. – standing on the bottom, leaning forward, feet shoulder-width apart, arms extended forward; shoulders and chin lie on the water. Hand strokes (first with your head raised, then with your face in the water) while holding your breath.
Exercises in water with a movable support
18. Same as ex. 17, with movement along the bottom of the pool.
^ Typical mistakes. Excessively wide stroke; stopping the arms at the end of the stroke in the “elbows to the sides” position; no pause during the slide - at the moment when the arms are extended forward.
^ Methodical instructions. When performing a stroke, the angle between the hands should be no more than 90۫. Do not lift your shoulders and chin off the surface of the water. Pause in the “hands in front” position. At the end of the stroke, quickly “remove” your elbows - lower them down and press them to your body, then stretch your arms forward.
19. Slides with rowing movements of the arms while holding the breath.
20. Swimming using arm movements with a float between the legs (with the head held high); breathing is voluntary.
21. The same with holding your breath.
^ Exercises to study coordination of hand movements and breathing
To study hand movements in coordination with breathing, the previous set of exercises (from 12th to 17th) is performed with an emphasis on coordinating breathing with hand strokes. Inhalation in breaststroke is performed during the completion of the arm stroke ("late" inhalation), exhalation - while moving the arms forward and sliding.
Rice. 6. Exercises to study hand movements
Exercises for general coordination of movements(Fig. 7)
Simulation exercises on land
22. I.p. – o.s., arms extended upward. Perform a “stroke” with your hands and return your hands to the starting position; then perform a pull-up and push-off with one leg, simulating separate coordination of movements.
Rice. 7. Exercises for general coordination of movements
23. The same in coordination with breathing: inhalation is performed simultaneously with the beginning of the “stroke” with the arms, exhalation – while moving the arms forward and pushing the legs.
24. The same in full coordination. While spreading your arms to the sides, your leg begins to pull up, then you inhale; at the moment of moving your arms forward, you push off with your foot.
Exercises in water with a fixed support
25. Exercise in pairs. The first numbers hold the second ones by the side by the belt in a position on the chest. The second numbers perform movements in full coordination. Then the partners change places.
Exercises in water with a movable support
26. Breaststroke arm movements in coordination with breathing, moving along the bottom.
Exercises in water without support
27. Swimming in full coordination while holding your breath.
28. Swimming with separate coordination of movements (when the arms finish the stroke and stretch forward, the legs begin to pull and push); breathing through 1 – 2 cycles of movements.
29. Swimming with shortened arm strokes in coordination with breathing.
30. Swimming in full coordination (the legs are pulled up at the end of the stroke with the arms and a push is performed simultaneously with the arms moving forward and sliding), with voluntary breathing and exhalation into the water after 1-2 cycles of movements.
31. The same with the “late” exhalation.
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3.3 Pedagogical model of breaststroke swimming technique
The cycle of movements when swimming breaststroke is conventionally divided into four generalized phases.
First phase - kicking(start – extension of the legs at the knee joints). Basic actions: legs perform a kick, arms are extended and sent forward; the torso takes a horizontal position, the head is immersed in the water; breathing is held.
Target: increase the speed of forward movement, transferring the stroke from feet to hands.
^ Body position at the beginning of the phase : legs in the starting position for the strike, arms in front with palms down and slightly bent at the elbow joints, shoulder girdle above the pelvis at an angle of 4 - 6., head facing forward - down, face immersed in water.
^ Basic settings : 1) perform a sharp kick, fix the pelvis well and direct the force through the back to the arms; 2) complete the straightening of the arms and send them forward, the body in a streamlined position with the head between the arms; 3) do not lower your feet deeply during the impact; complete the stroke, relax your hips, shins and feet, direct your hips towards the surface of the water.
^ Second phase - arm stroke (beginning - completion of straightening the legs at the knee joints during the impact). Basic actions: the arms perform a stroke, the legs maintain a streamlined position, and the torso is almost horizontal; at the end of the phase, the head is raised facing forward.
Target: increase the speed of forward movement to the maximum due to the hand stroke.
^ Body position at the beginning of the phase : arms extended forward parallel to the surface of the water, hands turned palms down - outward, head between hands; legs relaxed and extended; the body is horizontal and well streamlined.
^ Basic settings : 1) perform a stroke with your hands along the optimal helical trajectory and with acceleration - capture the water; energetic and relatively long pull-up, fast and powerful push-off; monitor the rigid position and rational orientation of the planes of the hand and forearm; 2) until the end of the stroke, keep your head in a relaxed position with your face lowered into the water, at the final moment of repulsion, send the shoulder girdle and head up to inhale; 3) keep your legs relaxed; 4) due to a high-quality hand stroke, bring the body to a relatively high position; do not lower your pelvis; 5) at the end of pushing off with your hands, it is emphasized to complete the exhalation.
^ Third phase – bringing your arms near your chest and inhaling (start - movement of the hands forward - up). Basic actions: hands and forearms are brought together with a quick and sliding movement inward - forward - upward - hands under the chin, elbows near the chest; hands continue to go up - forward; inhalation begins; the legs bend smoothly at the knee joints.
Target: keep the speed of advancement as high as possible at a relatively high level due to inertial forces and rational support movement of the hands.
^ Body position at the beginning of the phase : arms are bent at the elbow joints and located below in front of the chest, hands slightly in front of the shoulder girdle and approximately shoulder width apart, palms facing back and slightly inward; head above water, face forward; legs in a streamlined position and slightly bent at the knee joints; The angle of attack of the body is expressed (12 - 15 .).
^ Basic settings : 1) simultaneously with a quick but smooth movement of the hands and forearms inward - forward - upward, inhale; 2) do not stop the movement of your hands, do not press your elbows towards your body; 3) continue moving the shoulder girdle and chin upward; 4) begin smooth bending of the relaxed legs at the knee joints; 5) maintain a streamlined position.
^ Fourth phase – raising the arms and bending the legs (beginning – extension of the arms at the elbow joints; ending – extension of the legs at the knee joints for a back kick). Basic steps: arms are brought forward, legs perform the main part of the pull-up - flexion at the hip and knee joints; the shoulder girdle and head move forward downwards, the position of the body is leveled, the head is again immersed in the water.
Target: Lose forward speed as little as possible.
^ Body position at the beginning of the phase : arms bent at the elbows, hands almost together under the chin, elbows near the chest; legs are slightly bent at the knee joints, feet and knees are approximately pelvis-width apart, hips are in a well-streamlined position; The angle of attack of the body is pronounced, the shoulder girdle and head are above the surface of the water, the swimmer looks forward.
^ Main stops : 1) finish inhaling and send your chin and shoulder girdle forward along with your arms; smoothly but quickly move your arms out, turning your hands with your palms down to the starting position for the next stroke; perform the final part of the stroke; perform the final part of the leg pull-up with acceleration; 2) bending the legs at the hip and knee joints and spreading the knees to the sides at the moment of completion of the phase, instantly spread the feet with the toes to the sides; 3) move forward with the shoulder girdle following the arms, aligning the body to the beginning of the kick; do not lower the pelvis.
- ^
Bibliography
Swimming. Textbook. Ed. N.Zh.Bulgakova
Health-improving, therapeutic and adaptive swimming. Tutorial. Ed. N.Zh.Bulgakova
Sports swimming technique. Educational and methodological manual. T.L.Mukhtarova
Sports swimming. James E. Councilmer
Sports swimming. Karl-Heinz Stichert
L.P.MAKARENKO
< СПОРТИВНОГО>
| The technique of sports swimming is understood as a system of movements that allows you to realize your motor abilities into high results. The concept covers the form, character, relationship of movements, as well as the swimmer’s ability to sense and use all the forces acting on his body to move forward. The concepts of “swimming technique”, “motor abilities”, “technical and tactical skill” are inseparable. The improvement of these aspects of sportsmanship is always carried out in unity. In the work of a youth sports school coach, priority should still be given to improving the technical skills of swimmers. Swimming technique is variable. It is constantly evolving. Examples include the changes that occur before our eyes in the breaststroke swimming technique with a short-term internal cyclic “diving”, the butterfly swimming technique with a relatively flat position of the shoulder girdle and elastic continuous movements of the legs, the freestyle swimming technique with a long power stroke, the technique of performing starts and turns with a long exit under water. Original elements of technology can be noted from our Honored Masters of Sports Alexander Popov, Denis Pankratov, and others, and from the new generation - Honored Master of Sports Roman Sludnov, international masters of sports Olga Bakaldina, Dmitry Komornikov, Anatoly Polyakov and others. Today, there are several variations of technique in each method of swimming. We find great variety in the individual manner of performing individual elements of technology. The origins of diversity are in the constant creative work of the coach and athlete to improve technique, taking into account: 1) the individual characteristics of the athlete, 2) the laws of biomechanics, 3) the rich experience of the domestic swimming school and new trends in the development of world swimming, 4) competition rules. The sports technique of a high-class swimmer is individual. The nature of an athlete’s movements depends on his talent, sports experience, physique, flexibility and strength, etc. and so on. But it would be a mistake not to see behind the individual characteristics of a swimmer’s movements the general patterns and characteristic features inherent in rational variants of the technique. Variability of movements and individual deviations are acceptable. But at the same time the boundaries of these deviations are specified. The boundaries narrow when it comes to the key elements of any technology option. For decades, coaches have experimented in search of answers to two basic questions: 1) how to reduce the hydrodynamic resistance to the swimmer's body as he moves forward at high speed and 20 how to increase the power and efficiency of the strokes that propel the swimmer forward. The most effective elements of movements and their coordination were identified and tested by time. Views on swimming technique were clarified, taking into account the laws of biomechanics. Thus, general requirements for rational swimming techniques gradually emerged. Let's consider these requirements. | ||
| Section 1 Fundamentals of rational sports swimming techniques | ||
| 1.1. Streamlined position of a swimmer's body in water. Body movements | ||
| The athlete’s body in water should occupy a streamlined, elongated, dynamically balanced and relatively high position with respect to the longitudinal axis with an optimal angle of attack. It must have optimal tension in the trunk muscles in order to have the basis for coordinating all the driving forces acting on the body during swimming. A rational swimming technique is characterized by active auxiliary movements of the body, performed with optimal amplitude and rhythm of movements of the arms and legs. When swimming front and back crawl, the body rhythmically turns left and right relative to the longitudinal axis of the body. These turns help strengthen the arm stroke by connecting large muscle groups of the back and chest to the working movements. Turns also help you make a long stroke, complete the stroke, and bring your arm forward over the water with minimal resistance. The work experience of the famous trainer G.G. is interesting. Turetsky with multiple Olympic short-distance freestyle swimming champion Alexander Popov over an element they call “shoulder girdle turn and torso turn.” When one hand enters the water and begins to grab, the other completes the stroke and leaves the water with the elbow up (see section 2 below for the first phase of the cycle in the pedagogical model of freestyle swimming technique). At this moment, the swimmer's torso begins to rotate relative to the longitudinal axis, providing an optimal dynamic position for movements with both arms. While the muscles of one arm contract, producing a powerful stroke, the muscles of the other arm relax and stretch, storing energy. A. Popov brings this element of technology to automaticity. G.G. Turetsky notes: “We call this element of technique the law of the kayak oar. It is based on simultaneous movements of both hands, as if a swimmer had a two-blade oar in his hands. The hands move so that when one of the waters comes out, its elbow rises high up; the elbow of the other hand is in this time is in front and below under water - the hand begins the stroke. If the shoulder girdle has sufficient flexibility, such a movement with a pronounced arm swing is not difficult to perform. The arm span and the turn of the shoulder girdle are individual characteristics. They are determined by height, the anatomical span of the arms, and the flexibility of the shoulder girdle and coordination of movements." G.G. Turetsky recommends several exercises for mastering this element of the technique: Exercise 1. Standing on land, leaning forward, holding a light kayak paddle (or gymnastic stick): imitate freestyle arm movements in coordination with turns of the shoulder girdle, torso and hip movements . Exercise 2. Swimming six-strike freestyle “for grip” with a pause in the starting position on the side, the lower arm is extended forward, the upper arm is at the hip. Six crawl kicks are performed, then - simultaneously - one hand comes out of the water and moves through the air with the elbow up (with acceleration at the moment of entering the water), the other makes a long stroke to the hip; at the same time, the torso (in strict accordance with the movements of both arms) turns to the other side. There is a pause in the movements of the arms, I perform six kicks with the legs, etc. Exercise 3. Swimming crawl with your head held high and dolphin-like movements with your legs. Promotes the development of coordination of movements of the shoulder girdle, pelvis and hips. (Alexander Popov calls the feeling of such coherence the feeling of “rock and roll.”) When swimming butterfly and breaststroke, the upper body moves up and down. The pelvis is also involved in these movements - but with a smaller amplitude. Rhythmic movements of the body increase the efficiency of movements of the arms, legs, breathing, and reduce counter resistance. In all swimming methods, movements of the body are associated with the execution of the so-called send. Its essence is the active movement of the shoulder girdle in the final phase of the cycle, which helps to direct the body parts along the optimal path forward, stretch the working muscles that are most important for the swimmer, in order to use the energy of elastic muscle stretching in the initial phase of the arm stroke. Optimal head position is the key to rational body posture. Throughout most of the cycle of movements, the head occupies a relaxed, comfortable position for the swimmer on the longitudinal axis of the body, the muscles of the neck and shoulder girdle are relaxed as much as possible. The position of the head with relaxed neck muscles reflexively reduces tension in the muscles of the shoulder girdle and back, promotes effective hand strokes, and does not create problems with inhalation. It helps to achieve a streamlined and dynamically balanced body position, when the head does not bury itself in the water, but, as it were, pulls the athlete forward. It is advisable that the coach identifies a specific point on the student’s head as a visual reference. Sometimes it is enough to simply rub your hand on a certain place on the crown, crown, forehead, or lightly pull the student’s hair in this place. Using the designated point, the athlete cuts through the water and feels it. In all swimming methods, the head performs small, sometimes barely noticeable movements during the cycle of swimming movements in the same rhythm with the strokes of the arms. The movements help to inhale, strengthen individual phases of the arm stroke, and direct the swimmer’s body along the optimal trajectory forward. Keeping your hips high near the surface of the water is another key to a well-streamlined and efficient body position. This requirement obliges, for example, when swimming front crawl and butterfly, to perform leg movements with a small swing, actively in both directions, with an energetic upward thrust of the hips and hyperextension of the legs at the knee joints at the moment of an overwhelming downward kick with the feet. When performing a back kick during breaststroke, the athlete also needs to direct the hips towards the surface of the water and keep them, along with the pelvis, in a high and streamlined position throughout the main part of the subsequent arm stroke. The optimal degree of tension in the trunk muscles (primarily the abdominal and lower back muscles) should provide a sufficiently rigid base onto which the forces from working movements of the arms and legs would be transmitted and directed without loss along the line of the swimmer’s forward movement. At the same time, the muscle groups of the body involved in working movements with the arms must have time to relax at those moments of the cycle when they do not bear the load. The muscle groups of the trunk serve as the basis of the motor mechanism. They are the largest and, for the most part, the strongest and most resilient. They carry out smooth, elastic movements and can exert quite a lot of force with little tension, which is why they don’t get tired so easily. The muscles lie deep, are attached to large surfaces of the supporting apparatus, and consist mainly of slow muscle fibers. The mode of operation of the trunk muscles is statokinetic - a mixture of tonic tension and dynamic contractions. Due to the significant volume of active mass of slow muscle fibers, these muscle groups during intense swimming prevent a rapid increase in lactate in the blood and thereby delay the onset of fatigue. Any program of special physical training for a swimmer on land that accompanies technical training must include sets of exercises aimed at thoroughly working out the muscles and ligaments of the torso and neck, shoulder girdle, and hips. An example of complexes is the well-known “25 golden exercises” by the American trainer R. Kifut. And also the no less famous “12 complexes of physical training for a swimmer on land” by Honored Trainer of the USSR I.M. Koshkin. In conclusion, here is the advice of coach V.B. Avdienko. He recommends starting work on correcting shortcomings in technique, increasing the efficiency of the stroke and improving the rational position of the swimmer’s body in the water by setting the correct position of the head. Then - sequentially - move to the shoulder girdle, torso, hips, legs, feet. At the same time, make sure that the named parts of the body participate in the best possible way in the creation of driving forces and that the movements of these same parts do not cause counter-resistance. | ||
| 1.2. Arm stroke is the main source of driving forces | ||
| Hands are the main mover when swimming sports. Even in breaststroke, where arms and legs participate approximately equally in the creation of driving forces, the technique of arm movements is closely related to breathing, general coordination of movements, tempo and rhythm of swimming. Close attention is constantly paid to this element of swimming. The hand and forearm are the main elements of the mover, its main working planes. Their main function during the stroke is to create continuous support on the water. When analyzing the stroke, movements of the hand and forearm are assessed first. During the stroke, the brush must move continuously, at high speed relative to the water with which it interacts. The trajectory of the hand must be optimal in length and shape, the orientation of the hand relative to the direction of the swimmer’s forward movement must remain rational at all times. A position close to a plane perpendicular to the direction the swimmer is moving forward is most effective for the hand and forearm in the main part of the stroke. In the initial phase of the stroke, the planes of the hand and forearm are inclined to the surface of the water at an acute angle. At this time, they work as a carrier and guide plane. They support the front part of the body in a relatively high and well-streamlined position and promote forward movement at a high internal cyclic speed due to the currently available driving forces, helping to keep the body on the longitudinal axis and in a streamlined position. During a stroke, as a rule, the hand interacts with an obliquely directed flow of water, as if covering it with the palm. Motor-gifted swimmers experimentally find the optimal position of the hand relative to the stroke line, which allows them to: 1) maintain prolonged contact of the working plane of the hand with a relatively large mass of water during the stroke; 2) perform the movement in a steady flow and thereby better feel the stroke and more accurately control it; 3) perform the stroke at high speed. If the function of the hand and forearm is to create support in the water, then the function of the shoulder and shoulder girdle is to directly move the swimmer’s body forward relative to this support. The shoulder is the main lever of the rowing mechanism. The muscles of the shoulder, shoulder girdle and torso serve as the main elements of a swimmer's motor. The magnitude of acceleration of the swimmer’s body during hand strokes depends on the power of their contraction. The hand begins the stroke straightened. She must perform the main part of the stroke with an optimal degree of flexion and extension in the elbow joint. The coach and athlete experimentally select the degree of flexion and extension of the arm at the elbow joint. This element of technology must: 1) give the working links of the hand a rational shape and the necessary rigidity when supporting the water; 2) quickly move the hand into a position favorable for applying forces to the support and maintain this position over the largest possible portion of the stroke; 3) ensure a rational trajectory of the hand in shape, length and direction; 4) help to ensure that the muscle traction forces match the ground reaction forces that occur on the hand and forearm (by bending and extending the arm, the swimmer reduces or increases the lever arm with which these forces are balanced). The “high” position of the elbow at the beginning of the stroke allows you to bring the “hand - forearm” plane into a position favorable for support on the water. The essence of the technique element is the advanced movement of the hand in relation to the elbow. When swimming crawl, butterfly, breaststroke, the stroke begins with the movement of the hand and forearm forward - outward - downward with the arm bent at the elbow joint. At the same time, the shoulder turns slightly inward, the elbow turns to the side (but not back - down!) and is held above the hand. This allows you to lean on the water at an effective angle and give your hand the necessary rigidity. A similar advanced movement of the hand in relation to the elbow (with an optimal degree of arm rigidity in the elbow and wrist joints) is also characteristic of backstroke swimming. | ||
| 1.3. Working movements with legs | ||
| The working phase of the leg movements is called the kick. The main supporting links during impact are the foot and lower leg; they provide approximately 95% of the ground reaction forces. For example, when swimming crawl, about 64% of useful resistance forces arise on the dorsum of the foot during a downward kick, about 32% of similar forces arise on the lower leg, mainly on its distal half; on the thigh, practically no useful ground reaction forces arise. The legs have good capabilities for creating driving forces. The muscle groups involved in working movements with the legs are much stronger than the muscles that carry out rowing movements with the arms. The foot and lower leg have an advantage over the hand and forearm in terms of supporting surface area. In all methods, except breaststroke, the legs work like a wave propulsion, which allows the foot to effectively interact with the flow even at high speed. In this case, the feet should rest well on the water and push off from it in the forward direction, and the hips should perform continuous and elastic movements. Don't let your hips fall! Don't drop your hips and feet too deep! With a moderate range of motion of the hips and their rational position, the counter resistance of the water when swimming with the help of the legs can be minimized. Taking this into account, swimmers, if necessary, use in all swimming methods, except breaststroke, long exits under water after the start and turns using movements with only their legs, taking the most streamlined position with arms extended forward. Yet, when swimming with full coordination, the legs create less thrust than the arms, with the exception of breaststroke. Therefore, the coordination of leg movements in all methods is subordinated to arm movements and breathing. In addition to creating propelling forces, leg movements should: 1) strengthen individual phases of arm movements; 2) smooth out cyclic speed fluctuations; 3) compensate for the negative effect of some transverse and vertical forces that arise during movements of the arms and torso; 4) help maintain a balanced, streamlined and relatively high body position. | ||
| 1.4. Coordination of movements | ||
| Rational coordination of movements is the most subtle element of technique, clearly reflecting the individual characteristics of the swimmer. The main points of coordinating the movements of the arms, legs, torso and breathing are described below in pedagogical models of the technique of specific swimming methods. But essentially, coordinating movements into a single whole is an area of creative work for a coach and an athlete. This is the formation of a swimmer’s individual style. Rhythm, tempo and step length The effectiveness of cyclic locomotion is based on the rhythm of movements. Maintaining its constancy or, conversely, its changes affect primarily the speed of swimming. Rational rhythm is closely related to the optimal competitive pace of a given swimmer. Speed control is achieved by changing the rhythm, tempo and step length. Pace and rhythm are extremely individual and conservative indicators for the mastered version of the technique, the achieved level of preparedness, and the stage of age development of the swimmer. However, as practice shows, we can also talk about the optimal values of the competitive pace and stride length of highly qualified swimmers. A guideline for work in this direction can be the average pace and stride length of the finalists of the 1996 Olympic Games at distances of 100 and 200 m in various swimming methods, given in the appendix. An example of a productive approach to the formation of a swimmer’s individual technique is the experience of coach G.G. Turetsky with Olympic champion Alexander Popov. “Rhythm, grace and naturalness of movements...” - this is how G.G. Turetsky comments on his student’s swimming technique. The coach and student consider the optimal rhythm of movements to be the main factor in stable progress along the distance. To train rhythm, A. Popov performs exercises in which he alternates fast swimming with a minimum number of strokes and an optimal competitive rhythm and “super-slow” swimming maintaining the same rhythm. They control the rhythm through breathing - the respiratory cycle combines the elements of movements into a single whole. “At optimal swimming speed,” notes G.G. Turetsky, “one gets the impression that Alexander is simply walking along the path: he moves forward so naturally, overcoming resistance.” Anyone who has seen the technique of this swimmer will agree with the above words. At the highest level of technical mastery, A. Popov has mastered a rhythm of movements in which he best uses the forces of muscle traction, inertia, and elastic stretching of muscles and ligaments to move forward. Note that from a biomechanical point of view, the swimmer’s body and its working parts represent a system in which one part of the mechanical energy is dissipated (for example, spent on overcoming the resistance of the aquatic environment), and the other is stored and used during subsequent movements. There are three ways to conserve mechanical energy during a swimmer’s movements: 1) converting the kinetic energy of movement into the energy of elastic deformation of muscles and tendons and further using this energy to increase the power of the stroke; 2) the transition of mechanical energy of movement from one link to another (for example, when a hand enters the water after it is carried through the air, part of the inertial forces applied to the hand is realized in the forward movement of the swimmer’s body - i.e. pulls it forward; the other part - converted into elastic stretching energy of the working muscles of the back and shoulder girdle); 3) the transition of the kinetic energy of movement into the potential energy of the high position of the body parts and vice versa.) A. Popov’s swimming technique is a good illustration of the most rational use of mechanical energy created during rowing movements. G.G. Turetsky and A. Popov call their approach to improving swimming technique the “principle of three R.” - rhythm, rotation of the shoulder girdle, relaxation. The rhythm of movements has just been discussed; the rotation of the shoulder girdle and the rotation of the torso have been discussed in section 1.1. A few words about relaxation and competitive pace. If the swimming skill is brought to automaticity, the athlete has the opportunity to relax even at high swimming speed. “Relaxation is the key to perfection,” notes G.G. Turetsky, “it helps reduce the amount of energy expended when swimming. The best way to achieve the combination of the three named elements of technique (the three “Rs”) is to work on a competitive pace, swim with a high speed, using the right technique, and compete more." To form a competitive pace, the athlete is asked to swim a series of segments strictly at the pace of the competitive distance, but at a speed adequate to the current state of his readiness (if during the exercise the stride length decreases slightly, this does not cause concern for G.G. Turetsky). Mastery in controlling the pace and rhythm of movements over a distance is acquired in competition starts. At competitions, a swimmer’s ability to regulate muscle efforts and achieve high swimming speeds with optimal expenditure of force is also developed. On this occasion G. G. Turetsky will note: “When we talk about swimming technique, we must not forget that this concept includes not only biomechanical parameters (stroke frequency, stroke length, etc.), but also the body’s reactions (heart rate, lactate level etc.) and, of course, the result in competitions and courses. The swimmer needs to develop a balance between effort and technique - then he will be able to develop the desired pace and the required intensity..." | ||
| 1.5. Control of swimming technique | ||
| In the 1970-80s, a method for analyzing and monitoring a swimmer’s technical training based on models of swimming technique was developed in our country and proved to be highly effective in practice. The technique was widely used in the work of both coaches of national teams of the country and coaches of youth sports schools. Nowadays, when high-quality video cameras and VCRs have become widespread, this technique is receiving a second wind. The essence of the technique comes down to the following. The coach makes above-water or underwater video recording of the student’s sports technique during training or competition. Analyzes the technique by cycle phases, comparing the student’s movements with the requirements of the pedagogical model of the technique, and draws conclusions. Taking into account the conclusions, he makes the necessary adjustments to the process of sports training, selects the necessary technical exercises, discusses the problem with the student and introduces new methodological guidelines and visual guidelines. It is more convenient to analyze and control equipment if you use special cards to record the results of the analysis. An approximate form of the cards is given in the appendix. The cards can be photocopied and used in everyday work. The effectiveness of work increases if students also keep similar analysis cards. | ||
| 1.6. Unity of technical, tactical and functional aspects of preparedness | ||
The efficiency of the technology (high level of swimming speed), its reliability and efficiency are determined by a number of factors. This:
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| FREESTYLE SWIMMING TECHNIQUE | ||
| The cycle of movements when swimming crawl is divided into two half-cycles, each of which consists of three phases. In terms of their formal composition, the phases of the first and second half-cycles are identical. However, in the movement technique of a real athlete, individual elements of the first half-cycle may differ from the formally identical elements of the second half-cycle. Therefore, individual swimming technique is analyzed within the boundaries of a full cycle of movements, combining six phases (three phases of the first half-cycle and three phases of the second half-cycle). In some cases, 2-3 cycles of movements, united by a common rhythm and one full cycle of breathing, can act as a complete system of movements for a swimmer.) The half-cycle consists of the following phases: 1 - capture with exit; 2 - pull-up with carry; 3 - repulsion with capture. Scheme of rational breathing: First half-cycle: 1st phase - beginning of inhalation; Phase 2 - end of inhalation; Phase 3 - holding your breath; Second half-cycle: 1st phase - breath holding; Phase 2 - beginning of exhalation; Phase 3 - end of exhalation. Let's look at the six-stroke freestyle swimming technique. | ||
| 1st phase - capture with exit | ||
Beginning - the elbow of the left hand comes out of the water. Basic actions: the right hand actively completes the capture of water, leaning on the water with the hand and forearm with a high elbow position; the left one comes out of the water with the elbow up and relaxes; the left leg performs a downward kick with the foot; in a cycle with inhalation to the left side, inhalation begins. Goal: transfer the stroke from one hand to the other, reducing the forward speed as little as possible. Body position at the beginning of the phase: The athlete’s body is elongated and streamlined, the head is on the longitudinal axis of the body, facing forward and down (in the cycle with inhalation to the left side, the head is turned to the left). The right arm is extended forward and fixed in its joints for support on the water, the elbow is slightly higher than the hand, the hand is at the width of the shoulder of the same name and forms a single supporting plane with the forearm; the left arm is bent at the elbow, the elbow is on the surface of the water and directed upward, the hand is turned with the palm back. The swimmer's legs are spread: the left one is at the top in the starting position for the kick (the leg is slightly bent at the knee, the foot is at the surface of the water), the right one is straightened at the knee and is at the bottom. Basic settings: 1) send the shoulder of the right hand forward with the elbow and perform an active capture of the water with the hand and forearm of this hand, strictly coordinating it with the simultaneous: a) exit of the left hand from the water with the elbow up; b) an energetic downward kick with the foot of the left foot; 2) control the simultaneous nature of sending the elbow of the left hand up and sending the elbow of the right hand forward; 3) avoid stopping the elbow of your left hand above the water and freely direct it (and behind it the forearm and hand) up and forward; 4) perform a downward kick with the left foot energetically, actively directing the thigh of this leg towards the surface of the water; during an impact, maintain a stable and optimally fixed position of the pelvis; 5) maintain a streamlined and balanced body position. In a half-cycle with inhalation, inhalation is performed in this phase. In our example, the inhalation will be performed in the second half-cycle. |
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| Phase 2 - pull-up with carry | ||
The beginning is the exit of the left hand from the water. Basic actions: the right hand performs the first half of the stroke, the left hand carries it over the water; the right leg performs a downward kick with the foot. Goal: speed up the body's movement forward. Body position at the beginning of the phase: the athlete’s body is well streamlined (the body is slightly arched and horizontal), the swimmer looks forward and slightly downward under the water. The left arm is behind, bent at the elbow and relaxed, the hand is at the level of the hip joint, the elbow is above the hand. The shoulder and elbow of the right hand are directed forward, the arm is slightly bent at the elbow (140-160°), the hand-forearm plane is oriented to the surface of the water at an angle of about 30°. The swimmer's legs are spread: the right leg is slightly bent at the knee and is ready to kick down with the foot. Basic settings: 1) perform the first half of the stroke with your right hand - pulling - in the same rhythm with the active movement of the other hand above the water; 2) during the right stroke, give it the necessary rigidity; perform the pull-up with a high and fixed position of the elbow (with advanced movement of the hand in relation to the elbow) and active connection of the shoulder and torso muscles to the stroke; 3) perform the pull-up gently, but with acceleration; 4) coordinate the acceleration of pulling up with the right hand with the simultaneous acceleration of carrying the left over the water; 5) move above the water with your arm bent at the elbow, keep your elbow high, relax your forearm and hand, do not specifically turn your hand outward; 6) emphasize the leading importance of the right hand in relation to the left; 7) coordinate arm movements with rotation of the body relative to the longitudinal axis (refrain from rotating the pelvis); maintain a streamlined and balanced body position; 8) perform a kick with your right foot, keeping your thigh at the surface of the water. |
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| Phase 3 - repulsion with grab | ||
The beginning is the passage of the right hand during the stroke under the tear joint; ending: the appearance of the elbow of this arm at the end of the stroke on the surface of the water. Basic actions: the right hand performs the second half of the stroke - pushing off; the left one enters the water, is sent forward and begins to actively capture the water; the left foot performs a downward kick; the body maintains a horizontal position. Goal: achieve maximum promotion speed Body position at the beginning of the phase: the athlete’s torso is strictly on the longitudinal axis, the face is turned forward and down. The right arm is bent at the elbow (90-110°) and moves to the second half of the stroke; the hand and forearm are oriented almost perpendicular to the surface of the water. The left arm is also bent at the elbow, touches the water with the hand and begins to dive into the water. Basic settings: 1) energetically complete the stroke with the right hand, coordinating it with a downward kick; 2) perform the kick with a stable and optimally rigidly fixed pelvis, finish the kick by the time the elbow of the right hand comes out of the water; 3) simultaneously with the kick, send the left arm (and the shoulder girdle of this arm) forward as far as possible to grab the water; firmly fix the hand and forearm to support the water, maintain a high elbow position (do not lower the shoulder and elbow deeply); 4) avoid rotation of the body; take the most streamlined pose. The first half-cycle is completed. The second half-cycle also includes 1, 2 and 3 phases. Formally, they are a mirror repetition of similar phases of the first half-cycle. So, for example, if in phase 1 of the first half-cycle the right hand began to grab (the left hand came out of the water), then in a similar phase of the second half-cycle the left hand began to grab (the right hand came out of the water), etc. |
TECHNIQUE OF PERFORMING THE START WHEN SWIMMING CRAWLINE.
Let's look at the technique of starting with a grab when swimming crawl. After the starting signal, the athlete’s actions are conditionally divided into phases:
push-off with arm swing (jump)
entrance to the water
gliding underwater with active leg movements
reaching the surface
Initial position.
The swimmer's legs are bent at the knee joints (angle 135-150 degrees), feet shoulder-width apart, toes grip the edge of the bedside table in front between the feet (or on the side of them). The head is lowered, breathing is held. In this position, the swimmer's knees are above the front edge of the table, the shoulder girdle and head are slightly forward. The weight is transferred to the front of the feet, the swimmer is ready to immediately begin the starting actions.
Basic settings:
maintain stability by supporting yourself with your hands;
carefully wait for the starting signal, controlling the parts of the body (hands, knees, etc.) that will be the first to begin movements.
Push-off with arm swing (jump)
Start - start signal.
Basic actions: the athlete, pressing his hands on the edge of the bedside table, throws the body out of balance, pushes off with his legs and swings his arms and sends his head, torso and arms forward and up.
Target: Perform a powerful jump as quickly as possible and send your body flying forward and upward along the optimal trajectory.
Basic settings:
pressing with your hands on the edge of the bedside table, perform a quick shallow squat so that your legs begin to push off at an angle in the knee joints of about 80-90 degrees
instantly begin to straighten the body at the hip, knee and ankle joints, pushing off the bedside table with maximum force and sharply sending the pelvis and shoulder girdle forward and upward
simultaneously swing your arms with acceleration in the same direction, increasing the speed of movement of the shoulder girdle; By the time your feet lift off the bedside table, have time to move your hands further than the vertical, conventionally drawn through the shoulder joint
at the same time, following your hands, send your head with your chin forward, and then lower it face down between your hands
complete the push-off with active extension of the legs at the ankle joints; complete full body straightening by this point
avoid bending the body and keep it optimally rigid.
Start: taking your feet off the bedside table
Basic actions: the body stretches, tenses and flies along a rational trajectory; hands are directed forward, the head takes a position between the hands; then the body turns forward and down with its arms, at the end of the flight it bends slightly at the hip joints, the arms are extended to the point of intended entry into the water.
Body position at the beginning of the phase: the torso and legs are straightened and the longitudinal axis of the body is directed forward and upward at an angle of 20-30 degrees to the horizon; straight arms are extended forward, with them and the longitudinal axis of the body equal to 40-80 degrees; head between hands.
Basic settings:
following the swing of your arms, energetically direct your pelvis upward;
extend your arms, point your hands as far as possible to the imaginary entry point into the water; hold your head between your hands;
during the flight, turn your body and take a pose to enter the water at an acute angle and, as it were, at one point;
Raise your legs slightly as your hands touch the surface of the water.
Entering the water
Start: immersing brushes in water.
Basic actions: sequentially and as if into one hole: arms, head, torso, thighs, legs, feet. The swimmer, maintaining a streamlined position, regulates the depth of immersion (due to the horizontal direction of stretching the hands and deflecting the torso in the chest) and glides under water.
Target: enter the oda with minimal resistance and minimal loss of momentum (speed).
Body position at the beginning of the phase: arms and torso at an angle of 30-40 degrees to the surface of the water; the head is squeezed between the hands, the legs are slightly bent at the hip joints and stretched, the tah maintains a high position.
Basic settings:
Stretch your arms forward, hold them together and optimally tense, directing your body during entry as if to one point and at an optimal angle
raise your legs and keep them tightly closed
avoid deep immersion due to deflection of the torso and rational direction of stretching the arms
keep your hands together and rigidly, stretch your arms forward as far as possible, covering your head and torso with them from the oncoming flow of water.
Sliding underwater with active leg movements
Start: immersion of feet in water.
Basic actions: the swimmer performs elastic dolphin-like (or rabbit-like) movements with his legs, maintaining a high gliding speed under water.
Target: slide forward at maximum speed.
Basic settings:
keep your arms extended forward, optimally tense and with your hands tightly connected (one hand over the other), adjusting the direction and depth of sliding under water and covering your head and torso with your hands from the oncoming flow
maintain a high speed of progress under water using active dolphin-like movements with kicks; at the end of the slide, switch to crawl movements with your legs
adjust the depth of the slide so that at the end of the slide, due to the first hand crawl stroke, you can reach the surface to advance along the distance.
Exit to the surface
Start: first hand stroke (in our example, see position 6-a-right hand)
Basic actions: the first stroke is performed with the freestyle hand, the other remains extended forward and cuts the oncoming flow of water, the legs perform continuous crawl movements, the swimmer’s head and shoulder girdle come to the surface, the athlete looks forward and down under the water, breathing is held.
Target: reach the surface at high speed due to rowing movements performed in the rhythm of a six-beat crawl.
Body position at the beginning of the phase (position 6-a) 6 The swimmer’s body is located towards the surface of the water at a slight angle of attack: the shoulder girdle is slightly higher than the pelvis, the head is raised facing forward and down. arms stretched forward to failure; legs in the starting position before kicking down with the left leg on the first hand stroke (as in our example) or the right leg on the first left hand stroke.
Basic settings:
perform a powerful and, if possible, longer stroke with one hand (with an emphasis on the end of the push-off stroke)
send the other arm forward to failure along with the shoulder girdle of this arm; maintain rigidity in all joints of the outstretched arm (avoid falling down the shoulder girdle and elbow!)
raise your head and shoulder girdle a little to reach the surface through the first half of the stroke
continue energetic leg movements in the rhythm of the six-beat crawl (regardless of the version of the technique that will be used further on the distance)
complete the hand stroke together with a sharp kick
refrain from turning your head early to inhale (at sprint distances it is recommended to refrain from inhaling in the first cycle of swimming movements on the surface)
immediately after the elbow of the rowing arm comes out of the water, begin the stroke with the other hand.
According to coaches Gennady Turetsky (Russia), Ernest Maglisho and Mark Schubert (USA), there are several significant points in performing the start:
the center of gravity of the swimmer’s body is above the front edge of the starting block; the leg muscles are tense in order to instantly jump into the jump at the start signal
the swimmer concentrates attention on the parts of the body that will move first (for example, on the hands resting their fingers on the edge of the bedside table), and not on when the start signal sounds
at a signal, the hips push the athlete's body forward with the force and speed of a rifle trigger
at the moment of lifting the legs from the bedside table, the torso is extended in a line at the smallest angle to the surface of the water
the swimmer’s body enters the water in a streamlined position through the same small hole formed by the hands and head tightly brought together; the legs should also be tightly connected and extended
when immersed, the hands change position from arched to horizontal, which provides the effect of vigorously pushing (shooting) the body forward
in water, the body remains tense and streamlined and moves along a trajectory similar to a torpedo
It is advisable for the hand of one hand to be above the hand of the other (the stronger hand, which will be the first to start the stroke), and the thumb of the hand on top to lock the edge of the hand of the lower hand during diving and sliding under water
reaching the surface due to rowing movements is carried out at the lowest possible angle of attack.
TECHNIQUES FOR TURNING WHEN SWIMMING CRAWLINE
Let's consider a turn with rotation without touching the wall with your hand when swimming crawl (freestyle).
The swimmer’s actions during a turn are conventionally divided into phases: entering the rotation, rotation, repulsion, sliding under water with active movements of the legs, reaching the surface. Swimming up to the backboard with the freestyle, the athlete orients himself and about two meters before the backboard begins to enter the rotation. He completes the stroke with one hand (and leaves it at the hip), immediately picks up the high speed of movement towards the backboard with the last stroke of the other hand and (at the same time as performing the second half of the last stroke) begins to rotate.
ROTATION
Start- sudden immersion of the head under water.
Basic steps: simultaneously with the downward kick(s) and the completion of the arm stroke, the head sharply goes under the water, the swimmer vigorously bends the body at the hip joints, bringing the chin closer to the knees, and performs a forward-downward rotation (relative to the transverse axis) with a screw movement (relative to the longitudinal axis ); the legs are thrown towards the wall over the top and bent at the knees; hands help rotation, breathing is held.
Target: Rotate in the shortest possible time and place your feet on the backboard in the optimal position for pushing off.
Body position at the beginning of the phase: the body is positioned horizontally at the surface of the water, arms along the body, the body is slightly turned towards the upcoming rotation, the head is face down in the water.
Basic steps:
1) begin a sharp dive of the head (diving) at the moment of performing the last arm stroke and kick (legs);
2) quickly perform a rotation (simultaneously with a screw movement of the body), bending the body as much as possible at the hip joints and trying to touch the knees with the forehead;
3) avoid deep immersion of the shoulder girdle; assist rotation with hand movements;
4) maintaining a high speed of movement of the pelvis towards the shield, throw your legs (bending them at the knees) through the air with your feet on the shield;
5) simultaneously with the end of the rotation, complete the screw movement of the body in such a way that by the time the feet are placed on the backboard, you are in a position on your side;
6) accurately and simultaneously place both feet of the legs bent at the knees on the shield (the angle of flexion at the knees is about 90°) at a depth convenient for subsequent repulsion (approximately 30-40 cm);
7) have time to point your arms forward by the time your feet touch the shield, leaving your head between your hands.
REPULSION
Basic steps: immediately after the feet touch the wall of the pool, a push-off is performed; arms stretch forward, head hides between hands; the torso begins to rotate relative to the longitudinal axis to assume a position on the chest; the swimmer assumes a horizontal and streamlined position.
Target: perform a push-off with maximum force and direct the body forward in a streamlined position and at the optimal depth (the depth is selected taking into account the option of sliding under water).
Body position at the beginning of the phase: legs bent at the knees at an angle of about 90°; feet touch the rotary shield; torso - in a position on its side; The arms are slightly bent at the elbows, extended forward, the hands are connected, the head is between the hands.
Basic steps:
1) perform a small quick squat at the moment the legs touch the shield (in order to use the elastic properties of the muscles at the beginning of repulsion), and immediately - a sharp strong repulsion from the shield with the legs;
2) complete the leg movements with an explosive push-off with the feet and achieve maximum push-off speed;
3) rigidly secure the back and pelvis to transmit pushing forces through the joints of the legs to the torso (avoid rotation of the pelvis and bending of the spine during repulsion!);
4) fully extend your arms forward, hold your head between your hands, ensure a horizontal and streamlined position for everything
Sliding underwater with active working movements of the legs
Start: moment of separation of the legs from the rotary shield.
Basic steps: the swimmer's body, remaining elongated and streamlined, completes the turn into a chest position and glides under water; to maintain a high gliding speed, the swimmer performs several dolphin-like movements (position 4-6), then switches to freestyle leg movements (position 4-c).
Target: cover the intended distance underwater at the highest speed (without violating the rules of the competition).
Body position at the beginning of the phase: the body is elongated and streamlined, the head is hidden from the oncoming flow of water between the arms extended forward, the hands are tightly connected.
Basic steps:
1) keep your arms extended forward, optimally tense and with your hands tightly connected; cover your head and torso with your hands from the oncoming flow of water;
2) with active dolphin-like kicks to maintain a high speed of sliding under water; at the end of the slide, switch to crawl movements with your legs;
3) adjust the depth of the slide so that at the end of the slide, with the first hand stroke, you can reach the surface to advance the crawl along the distance at the optimal competitive pace and rhythm.
Start: first hand stroke.
Basic steps: the first crawl stroke is performed with the hand, the other remains extended forward and cuts the oncoming flow of water, the legs perform continuous crawl movements, the swimmer’s head and shoulder girdle come to the surface of the water, the athlete looks forward and down under the water, breathing is held.
Target: reach the surface at high speed using rowing movements performed in the rhythm of a six-beat crawl.
Body position at the beginning of the phase. The swimmer's body is positioned towards the surface of the water at a slight angle of attack: the shoulder girdle is slightly higher than the pelvis, the head is raised facing forward and down. The arms are extended forward to the full; legs in the starting position for kicking with the left leg on the first stroke with the right hand or with the right leg on the first stroke with the left hand.
Basic steps:
1) perform a powerful and, if possible, longer stroke with one hand (with an emphasis on the end of the stroke - pushing off);
2) send the other arm forward to failure along with the shoulder girdle of this arm; maintain rigidity in all joints of the outstretched arm (avoid falling down the shoulder girdle and elbow!);
3) slightly raise the head and shoulder girdle to reach the surface through the first half of the stroke;
4) continue energetic movements of the legs in the rhythm of the six-beat freestyle (regardless of the version of the technique that will be used further on the distance);
5) complete the hand stroke together with a sharp kick;
6) refrain from turning your head early to inhale (at sprint distances it is recommended to refrain from inhaling in the first cycle of swimming movements on the surface);
7) immediately after the elbow of the rowing arm comes out of the water, begin the stroke with the other hand.
Maintain the maximum possible speed in the last 5 m before the turning shield;
Use the minimum radius of rotation (head close to knees);
Do not twist your feet when pushing away from the shield;
Give the body a streamlined position when sliding after repulsion under water;
When sliding, it is under the wave moving along the surface onto the rotating shield (following the swimmer);
When reaching the surface of the water, give your body the smallest angle of attack.
Start- extension of the legs at the knee joints.
Basic actions: the legs perform a kick (push-off), the arms are extended and sent forward, after the arms the head (face down forward) and shoulder girdle are immersed in the water, the body takes a horizontal and most streamlined position under water, breathing is held.
Target: begin to accelerate the body (increase the intra-cycle speed) by kicking and simultaneously sending the arms, head and shoulder girdle forward to begin the arm stroke.
The legs are in the starting position for the impact (the shins are perpendicular to the surface of the water, the knees are slightly wider than the pelvis, the feet are at the level of the buttocks and the toes are turned outward, the hip flexion angle is about 140°); the back is straight, the shoulder girdle is slightly higher than the pelvis (the angle of attack of the body is from 5-6 to 10-12°), the arms are in front with palms down and slightly bent at the elbow joints, the head is facing forward and down and partially immersed in the water.
Basic settings:
1) while holding your breath, perform a sharp and powerful kick in arcs back-outwards and back inwards, optimally fixing the pelvis and straight back; make sure that the blow from the very beginning has an explosive, overwhelming character;
2) during the strike, send your arms forward, stretching them to the limit and stretching the muscles of the shoulder girdle and torso; remove your head between your hands and give your body the most streamlined position under water (do not dive deep!);
3) ensure that the maximum impact force falls on a horizontal and well-fixed position of the body;
4) during the impact, point the pelvis forward, hips up (avoid deep immersion of the feet at the end of the impact!);
5) after completing the strike, immediately relax the leg muscles and point your legs towards the surface of the water.
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Start- completion of leg extension at the knee joints.
Basic actions: the arms perform the stroke, the torso and legs maintain a well-streamlined and horizontal position; at the end of the stroke, the head turns to face forward, the shoulder girdle and head rise to the surface of the water; exhalation begins.
Target: increase the speed of progress to the maximum.
Body position at the beginning of the phase: arms extended forward parallel to the surface of the water, hands palms down outward and almost touching, head between hands; legs relaxed and extended at the surface of the water; the body is in a well-streamlined and horizontal position under water.
Basic settings:
1) perform a powerful arm stroke with acceleration at the end, an optimal degree of bending of the arms at the elbow joints, a rational position for support on the water and a relatively rigid position of the hands and forearms (maintain a high position of the elbows!);
2) until the end of the stroke with your hands, keep your hips in a relaxed and streamlined position, your head lowered face down into the water (refrain from early raising your head face forward for inhalation and early pulling of your legs);
3) align the end of the stroke with exiting the water and simultaneously sending the head and shoulder girdle to slide forward and upward to inhale (make sure that the pelvis and hips do not sink deep down during this movement!);
4) start exhaling into the water first calmly, then - at the very end of the stroke - emphasized through the mouth and nose.
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Start- movement of the hands and elbows inward and forward.
Basic actions: the hands and forearms are brought together with a quick sliding movement inward and slightly upward - the hands are in front under the chin, the elbows are near the chest; the swimmer leans on the water with his hands, shoulder girdle and head up and forward (to the highest point of his trajectory above the surface of the water) and at the end of the phase begins to inhale; the legs involuntarily and smoothly bend at the knee joints, the hips maintain a well-streamlined position.
Target: maintain the forward speed at the highest possible level through the use of inertial forces and support movements of the hands and forearms.
Body position at the beginning of the phase: the arms are bent at the elbow joints, the elbows are approximately at the line of the shoulder girdle, the hands are below and slightly in front of the line of the shoulder girdle with the palms back (the hand and forearm are relatively rigidly fixed and form a single supporting plane); head turned to face forward; legs closed, relaxed and at the surface of the water; body at a minimum angle of attack to the surface of the water.
Basic settings:
1) perform a quick and energetic movement of the hands and forearms inward forward, continuing to rest your hands on the water and lifting the shoulder girdle and head up to inhale;
2) while bringing your hands together, rotate your hands and forearms inward and slightly upward, clasp your hands together, as if covering your elbows and shoulders with them from the oncoming flow of water (while bringing your hands together, do not press your elbows to your chest, do not stop the movement of your hands!);
3) while continuing to move your chin and shoulder girdle forward, inhale quickly (do not stop moving your chin forward and do not hang up while inhaling!);
4) begin to smoothly bend the relaxed legs at the knee joints, maintaining a high and streamlined position of the hips;
5) refrain from excessively extending the shoulder girdle upward, leading to an increase in the angle of attack of the body (the angle of attack should not exceed 12-15°).
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Start- extension of the arms at the elbow joints.
Basic actions: hands are moved forward under water or on the surface of the water with minimal counter resistance; the legs perform the main part of the pull-up - flexion at the hip and knee joints; the head and shoulder girdle follow forward and slightly downward after the arms, leveling the position of the body and reducing its angle of attack; The head begins to plunge face first into the water.
Target: Lose forward momentum as little as possible and complete preparation for effectively performing the breaststroke kick in a new cycle of movements.
Body position at the beginning of the phase: arms bent at the elbow joints, elbows near the chest, hands together and under the chin in front of the elbows (as if covering them and the shoulders from the oncoming flow); legs slightly bent at the knee joints, knees approximately hip-width apart, heels of the feet near the surface of the water, hips in a well-streamlined position; the shoulder girdle and head are near the surface of the water (the angle of attack of the body can reach 12-15°), the swimmer looks forward.
Basic settings:
1) finish inhaling and hold your breath;
2) smoothly but quickly move your arms forward with minimal resistance, energetically send your head and shoulder girdle after them; towards the end of the withdrawal, turn your hands palms down;
3) combine the extension of the arms with simultaneous bending of the legs at the knee and hip joints and bring the legs and feet to the starting position for the impact (perpendicular to the surface of the water);
4) pull up the legs with acceleration until the feet instantly turn with their toes outward; at the same moment, vigorously spread your knees to the width necessary to begin kicking backwards;
5) continue to move forward and slightly downward following the arms, leveling the torso, fixing a straight back and slightly raising the pelvis to the beginning of the kick back.
The cycle of movements is completed. The athlete finds himself again in the position of the beginning of phase 1 of the next cycle of movements
FEATURES OF START TECHNIQUE WHEN SWIMMING BUTTERFLY AND BREATH STROKE
When swimming butterfly and breaststroke, a catch start is also used. But the technique of its implementation has some differences in comparison with the technique of the just discussed start for crawl swimmers. Differences are observed in the actions of the swimmer while sliding underwater and reaching the surface. In addition, in butterfly and breaststroke swims, athletes sometimes use a start with a steeper entry into the water, which provides them with a deeper glide under water.
Jump and flight. Entering the water.
From the starting position, the athlete performs a starting jump. At the moment the legs lift off the bedside table, the body is extended, the arms are straightened and are in front of the shoulder girdle and head, the angle of departure is approximately 30 degrees.
At an angle of approximately 30-40 degrees to the surface of the water (entry angle), the swimmer’s arms and torso are immersed in the water, the swimmer strives to dive into a pipe with the smallest possible diameter (with the smallest possible area of the disturbed water surface), then he bends and adjusts the depth diving by changing the direction of extending the hands, raising or lowering the head and - turns into horizontal sliding under water, avoiding too deep immersion.
Gliding underwater while swimming butterfly
Basic actions: the swimmer's elongated body glides underwater; goal: move at high speed underwater.
Basic settings:
Keep your arms extended forward as far as possible, optimally tense and with your hands tightly connected; cover your head and torso with your hands from the oncoming flow of water; create as little resistance to sliding forward as possible
At the moment your legs are completely immersed in the water, perform a single dolphin kick (to give additional acceleration to the body); while sliding, promptly begin continuous and elastic dolphin-like movements with your legs (with moderate amplitude) to maintain a high speed of advancement
Slide at the optimal depth, perform leg movements so that your feet do not break the surface of the water
By slightly raising and lowering the head and outstretched arms, adjust the sliding depth
At the end of the slide, approach the surface of the water to such an extent that the first butterfly stroke with your hands can bring your head and shoulder girdle to the surface; calculate so that the first hand stroke can begin at the moment of the end of the last sweeping downward kick with the legs.
Reaching the surface when swimming butterfly
Start: The first hand stroke is butterfly.
Basic actions: immediately after kicking down, the swimmer performs a long stroke with his arms and carries his arms forward through the air (coordinating the movements of the arms with the movements of the legs in the rhythm of the so-called two-beat fused coordination) and brings the head and shoulder girdle to the surface of the water.
Target: pick up the high gliding speed with working arm movements with minimal resistance, bring the front part of the body to the surface of the water to continue butterfly swimming along the distance at the optimal competitive pace and rhythm.
Body position at the beginning of the phase: the body is elongated and streamlined, the head is hidden from the oncoming flow of water between the arms extended forward to the limit, the hands are tightly connected, the legs are in the starting position for kicking with the feet down.
Basic settings:
Perform a sweeping movement with your feet down and immediately begin a long butterfly stroke with your arms.
Start rowing with your hands with active movement of the hands and forearms to the sides and down (grabbing water); maintain a high position of the elbows in relation to the hands
Perform the first arm stroke with the fullest range of motion, combine the second half of the arm stroke (push-off) with an accentuated downward kick.
Using the first stroke with your hands, bring the shoulder girdle completely to the surface of the water and ensure that at the end of the stroke you can freely carry your hands above the water forward along the longest possible trajectory
At the end of the stroke, raise your head with your hands, face forward (or turn it face to the side) to inhale and point your chin forward along the surface of the water; (at sprint distances it is recommended to refrain from inhaling after the first arm stroke in the first cycle of movements)
n1.doc
Rice. 1.5
Correct (1)
and incorrect (2)
body position
when swimming
on the back(s),
breaststroke (b)
and butterfly (c)
The current force does not allow the swimmer to maintain the body position at which the resistance is least. When swimming front and back crawl, turns of the body to the right and left are inevitable, and when swimming butterfly and breaststroke, wave-like movements up and down (Fig. 1.5). High technical skill of a swimmer requires a streamlined body position that at the same time promotes the effective development of driving force. In practice, this comes down to movements of the legs that are deep enough for effective advancement, but do not greatly increase resistance, and turns of the body that are sufficient to develop significant driving force, but do not lead to “wobble.” Rice. 1.4-1.6 illustrate the inappropriateness of the opposite option. The body position of an athlete swimming on her back is very unfortunate (Fig. 1.5, a). Her head is
Too high and hips too low. And an athlete swimming on his back has a more advantageous body position. The head is located almost horizontally and only slightly bent at the neck, and the legs are at a depth that allows for effective movements. Rice. 1.6 illustrates the fact that “wobble” when swimming backstroke is caused by too wide or narrow entry of the hand into the water. Rotations of the torso relative to its longitudinal axis are inevitable, since when performing a stroke with one hand, the other carries out a carry and the torso turns from side to side, following the movement of the arms. Naturally, these turns should not be too sharp, so as not to lead to “falling over” on the side. At the same time, an attempt to limit them would lead to shocks of the body with rowing movements from side to side and strong “wagging”. The question of the optimal
13
PART 1
Sports swimming technique
Rice. 1.6
Impact on value
excessive resistance
body movements to the sides
when swimming crawl
on the back (bottom view)
The body position when swimming breaststroke is not so clear. Proponents of the “wave” and flat styles have not yet completed the debate about which of them is associated with less shape resistance. With the wave, despite the wave-like movements, it is probably still less, since the hips are pulled up with almost no flexion at the hip joints (it is the pulling of the legs in breaststroke that causes the greatest braking) and not against the flow of water, as happens with the flat style.
The wave-like movements of an athlete swimming butterfly (Fig. 1.5, c) are sufficient to provide an effective driving force and are not so great as to greatly increase the resistance. An athlete swimming butterfly, on the contrary, plunges her head and legs too deep. At the moment her hands enter the water, her torso and hips form almost a right angle, thereby creating excessive resistance.
The analysis of the dependence of resistance on swimming speed is mainly theoretical, since the athlete will not reduce speed to reduce resistance. However, the fact that the greatest economic benefit of evenly covering distances is largely due to overcoming less average resistance also has a certain practical significance. Please remember
Due to the resistance caused by the shape of the body and its orientation (position) in the water, the athlete also overcomes shock wave (also called frontal or frontal) and friction resistance or, in other words, friction resistance.
Shock wave resistance caused by frontal frontal waves and is mainly determined by the swimmer's body position, swimming speed and, to a certain extent, the quality of the pool. Such frontal waves are created by the swimmer's head and torso as they move forward, sideways and up and down, as well as by arm movements when swimming in any way and by pulling up the legs when swimming breaststroke. The torso, arms and legs are “pushed” forward, compacting the water molecules in the oncoming flow and thereby increasing the pressure of the water in front of it and, accordingly, the resistance to movement. An athlete swimming crawl literally “drives” his hands into the water, thereby creating a large shock wave resistance. “Pushing” the back of the hand when entering the water also increases it. And only their entry with the edge of the palm reduces the area they occupy and, accordingly, the resistance encountered.
Frictional resistance. As a result of friction between skin and water, water molecules are retained on the surface of the skin, which, colliding with other molecules in front of them, chaotically rebound and, “interfering” with neighboring flows, increase their turbulence and thereby create additional resistance to movement. The frictional resistance created in this case is mainly determined by the area of the body, the roughness of its surface and the speed of movement. Naturally, less friction is created near smoother skin.
For almost forty years, swimmers have achieved more than
14
CHAPTER 1 Basic Swimming Techniques
High performers have their hair shaved off before competition. And the debate continues about what actually provides this well-known effect - whether it is simply an increase in self-confidence due to belief in the effectiveness of shaving, an increased sense of water in irritated skin, or a decrease in resistance. And if all these factors are combined, then which one is the most important? Meanwhile, there is reason to assert that, if not to a decisive extent, then to a large extent, the third of those listed. They were, in particular, given by the results of the research of Sharp and Costill (1989). At an interval of 9 days, a group of qualified swimmers before and after shaving were measured for their stride and lactate concentration while covering a distance at a given pace, oxygen consumption while swimming “tethered” at maximum intensity, and the length of the slide after pushing off from the side of the pool. The average step and lactate concentrations were 207 cm and 8.48 mmol-L~ 1 and 236 cm and 6.48 mmol-l - ! after shaving, which indicates a significant increase in the efficiency of work and* the efficiency of movements. The sliding length has also increased significantly. The only thing that has not changed is the energy cost of work when swimming “tethered” and, accordingly, with negligible frictional resistance. There is no doubt that the improvement in shaving results is mainly due to a decrease in frictional resistance.
1.2. FORCES THAT ENSURE THE PROGRESS OF A SWAMMAN
The question of what law underlies human advancement in water has not been resolved to this day and is quite controversial. Many people believe that the theorem
Bernoulli, according to which advancement is ensured by the difference in pressure on the back of the hand and the palm that creates a lifting force. This difference, combined with the pressure acting on the arm, creates a net force that propels the swimmer, in other words, the traction force. The approval of this point of view was greatly facilitated by the studies of Brown and Councilman (1971), who concluded that the stroke is not performed strictly backward, but also diagonally. However, there is no less reason to assert that the basis of a swimmer’s progress is Newton’s third law: an action always corresponds to an equal and opposite reaction. In relation to the phenomenon under consideration, the law can be expressed by the following formula: the acceleration that a swimmer gives to his body is proportional to the force with which he pushes away the water. Moreover, the fact that the traction force is predominantly provided by pushing the water back, and not by its accelerated flow at the back of the arm, confirms the significant difference in this force with different bending of the arm at the elbow joint during the stroke. Otherwise, its degree would not be as significant as it actually is.
With a diagonal movement of the arms, the swimmer pushes the water back. As we see from Fig. 1.7, the hand is located at an angle, the thumb is located higher than the rest, and this is what mainly ensures that the water is pushed back. A force directed backwards causes, according to Newton's third law, an equal and opposing force, which propels the swimmer.
Thus, both Bernoulli's theorem and Newton's law explain a swimmer's progress, but Newton's law appears to play a more significant role.
15
PART 1 Sports swimming technique
Rice. 1.7
Moving water backwards with a diagonal movement of the hand
Rice. 1.8
Promotion principle
using a propeller
Rice. 1.9
Similarities between
swimmers' wrist movements
and rotation of the blades
propeller
Progress during swimming is well illustrated by the principle of operation of a boat engine propeller (Fig. 1.8). Although the propeller blades rotate in a circular path, their curved shape ensures that when water passes from the leading edges to the rear, it moves backward and the boat moves forward. In Fig. 1.9 clearly shows how similar the movements of the swimmer’s hands and the rotation of the propeller blades are: in the initial part of the stroke, or, in other words, when pulling up, the hand moves inward, up and back (Fig. 1.9, a), and in the final, or phase repulsion - outward, upward and backward (Fig. 1.9, b).
The curvilinearity of the trajectory of the hands is associated with providing greater traction force when pushing away slowly moving water. Having accelerated the movement of some of its layers, the hand moves to layers that have not yet been disturbed, etc. This trajectory of movements ensures greater efficiency of the stroke and by increasing its length.
1.3. GENERAL CHARACTERISTICS OF MOVEMENTS ENSURING THE PROGRESS OF A SWAMMAN
The efficiency of swimming propulsion is mainly determined by three characteristics of limb movements - direction, angle of attack and speed.
The direction of movement is characterized by a trajectory relative to water, which is usually called absolute. Its analysis is of paramount importance, since it is the influence of the limbs on the water that mainly determines the force driving the swimmer. The trajectory relative to the body of the swimmer is called relative, since it is assumed that the athlete, while performing a stroke, remains in place. Its analysis allows us to better understand the mechanics of the stroke. In Fig. Figure 1.10 shows the absolute trajectory of arm movements, typical of high-class swimmers. As we can see, regardless of the method of swimming, it is mainly characterized by horizontal and vertical directions of movements. In Fig. Figure 1.11 shows the backward movement necessary to push away the optimal amount of water (side view).
The angle of attack is formed by the inclination of the hand or foot relative to the direction of their movement. The dependence of the driving force on the angle of attack is shown in Fig. 1.12. As we can see, in the absence of such an angle, the driving force is minimal, since the hand almost does not move the water back and the force propelling the swimmer is very small. At an angle of 40° it is greater because the water flowing under the palm from the thumb to the little finger or, if we compare the hand with a propeller blade, from its leading edge to the rear, is subject to a significant force directed backwards. This angle of attack is close to optimal. At an angle of 70°, the palm is too flat a surface;
16
CHAPTER 1 Basic Swimming Techniques
Rice. 1.10
Trajectory of strokesmovements relativewater when swimmingdifferent ways: breaststroke (a); on the back (b); butterfly (c); front crawl (g)
Rice. 1.11
Changing the angle of attack
in the final phase
swimming stroke
front crawl
The effect of the leading edge of the blade changes, which leads to a decrease in the speed of movement of some molecules passing under the palm and the rebound of others. They collide with the molecules of the remaining layers and the resulting chain reaction causes significant turbulence. Moreover, these molecules are not able to sharply change the direction of movement in order to follow the contour of the “blade” from it. leading edge to trailing edge. As a result, only a small amount of water is pushed back. And it is completely ineffective to place the brush perpendicular to the direction of its movement. In this case, the blade effect disappears. The flat surface of the palm only pushes the flow of water in different directions. With a quick movement of the hand, an effect is created similar to pouring a bucket of water onto the wall. Some of the molecules bounce chaotically from the hand, and those “lagging behind” move in the opposite direction, producing a force that pushes the swimmer to the side, moving forward.
Opposite to the direction of movement.
Thus, the angle of attack should vary from 20° to 60° depending on the phase of the stroke. The irrationality of the angle of attack and direction of movement is indicated by a large number of bubbles, indicating turbulence and loss of driving force by the swimmer. Qualified swimmers create them in much smaller quantities. The formation of air bubbles around the hands as they enter the water when swimming front crawl, backstroke and butterfly is completely normal. However, if this happens during the pull-up phase, it indicates an irrational movement and, probably, an excessive angle of attack. Its arcuate trajectory helps ensure an effective angle of attack in each phase of the stroke.
Speed of movement. Councilman and Vasilyak (1982) revealed the acceleration of hand movement as the stroke is performed, and Schleihauf (1984) - its unevenness and dependence on the direction of its movement. Rice. Figure 1.13 illustrates the change in the speed of wrist movement during the stroke when swimming front crawl. As you can see, the speed of the left hand after it enters the water decreases and is 1.8 m-s -1 in the capture phase, increases to 3m"S -1 in the pulling phase, and up to 5 m-s -1 in the repulsion phase. In the final phase of the stroke, when the pressure on the water weakens somewhat, the speed of arm movement decreases.
17
PART 1
Sports swimming technique
Rice. 1.12
The influence of the angle of attack on the direction of water movement
Rice. 1.13
Dynamics of wrist speed when swimming front crawl
The speed of the right hand at the moment of grip is 1.8 m-s -1 , in the pulling phase - about 4 m-s -1 , during the transition to repulsion it decreases slightly - 3.4 m-s -1 , and at its completion it reaches b m-s -1 . The dynamics of the speed of swimming almost coincides with the dynamics of the speed of movement of the hand, which, however, is also typical for other methods of swimming. The speed of arm movement decreases during each major change in direction of movement. There is probably an optimal relationship between hand speed and angle of attack in each
Do the stroke phase. There is no doubt that there is an optimum speed of hand movement in each phase of the stroke. When comparing Fig. 1.13 and 1.14, one can note the close relationship between the speed of movement of the hand and the traction force in various phases of the stroke.
Meaning of capture. Catch is the phase of the stroke in which the driving force begins to develop. It should not begin until the arm has moved about a third of the length of the stroke, and until a third of its total time has passed. In this case, vigorous effort should not be applied until the elbows are higher than the hands and the hands are facing back.
The main movements of the hands when performing a stroke are - to the sides, down, inward and upward (Table 1.1).
Hand movements to the sides. This movement begins the stroke when swimming breaststroke and butterfly (Fig. 1.15). It is not promoting, but preparatory to the capture. When swimming butterfly, immediately after the hands enter the water, and when swimming breaststroke, before moving them forward, the hands are spread to the sides along a curved path until the hands are wider than the shoulders in a position favorable for starting the grip. At the beginning of this movement, the palms are turned down, the angle of attack is close to 0°, until the hands take a position favorable for the development of the driving force. As it is performed, the palms turn outward and backward, and the speed of movement of the hands decreases.
Hand movement down is typical for swimming crawl on the front and back (Fig. 1.16). It precedes and accompanies the catch and, like the lateral movement during breaststroke and butterfly, is not advancing. After entering the water, the hand moves down along a curved path. At the same time, the hands are bent, and as they approach the grip, they slightly unfold
18
CHAPTER 1
Basics of swimming technique
Rice. 1.14
Traction force dynamics
when performing a stroke
eightfold
Olympic champion
Matthew Biondi
TABLE 1.1
Basic hand movements
when performing a stroke
Rice. 1.15
Hand movements to the sides
when swimming breaststroke
and butterfly
| Direction | Way | Phase |
| movement | swimming | stroke |
| To the sides | Breaststroke, butterfly | Capture |
| Down | Crawl on the chest, on the back | Capture |
| Inside | All | Pull up |
| ways | gagging |
|
| Up | Crawl | Ottal- |
| chest, butterfly | nodding |
Huddle outside. The grip begins no earlier than the elbows are higher than the hands, which usually occurs at a depth of 40 - 60 cm.
Hand movement inward replaces the downward movement of the arms when swimming front crawl and backstroke and the movement to the sides when swimming breaststroke and butterfly. And when swimming in all ways except the backstroke, it is the first “promoting” movement. This movement begins in the catching phase and continues in the pulling phase.
(except for backstroke swimming). As it is performed, the hand moves down and inward, and then up and back until it is under the body in the area of the midline of the body. Moreover, individual deviations from this line are due to the characteristics of the technique, and these, in turn, are due to the morphofunctional characteristics of the swimmers. It should be noted, however, that although all qualified swimmers specializing in breaststroke have their hands crossing the midline of the body at the end of the movement in question, some athletes stop pressing the water when their hands are still at a considerable distance from each other, while others do not They do this right up to joining hands.
Hands moving up when swimming front crawl and butterfly, it is replaced by an inward movement of the arms and ends when the hand reaches the thigh. In this case, the semicircular movement of the hand outward, upward and backward is accompanied by its rapid turn and the palm at the end point of the movement in question is turned back and outward (Fig. 1.17), the pressure of the hand on the water weakens. The speed of the hand during the transition from inward to upward movement decreases and then increases to a maximum. The existing idea that the arm quickly straightens at the elbow joint when moving upward is incorrect. It remains bent until the start of the swing, which ensures that the forearm participates in the production of the driving force. If the arm straightens too quickly, it does not push the water straight back. The upward movement of the arms when swimming butterfly is similar to the movement of the arms when swimming front crawl. And only some high-class swimmers, and only at the beginning of the stroke, fully straighten their arms at the elbow joints.
It should be noted that the effectiveness of the movement in question
PART 1
Sports swimming technique
Rice. 1.16
Downward movement of the arm when swimming crawl on the front (a) and on the back (b)
Rice. 1.17
Water repulsion
when moving your hand up
during the stroke:
Side view, b - bottom view
Rice. 1.18
Promotion
when performing dolphin-
figurative leg movement
Niya largely depends on the swimmer's ability to maintain a bent arm position in the final part. If this is successful, then the water is pushed back in the desired direction even with a not very rational position of the forearm. And this is especially true for butterfly. The most common mistake when moving the arms up is “pushing” the hands up and back into a bent position, in which they are perpendicular to the surface of the water. The angle of attack is such that the water is pushed upward rather than backward, which naturally reduces swimming speed. The movement of water back when moving the arms up is illustrated in Fig. 1.17. As the hand moves up and out along a diagonal path, it and the side of the hand from the little finger serve as the leading edge.
The ki are the propeller blades, and the fingertips and the side of the hand from the thumb are its trailing edge.
Rice. 1.17.6 illustrates the beginning of the movement under consideration. As you can see, the brush moves outward and backward, being rotated accordingly. In this case, the leading edge of the propeller blade is the side of the hand from the little finger, and the back edge is from the thumb. Water passing under the palm in the opposite direction is moved by the angular attack of the hand. In Fig. 1.17, and the final stage of the movement under consideration is shown. As you can see, the hand is facing back and slightly upward, which provides a great contribution to the development of the driving force of the forearm. The role of the leading edge of the propeller blade is played by the elbow, and the rear edge by the fingertips.
The meaning of leg movements. Many experts believed that when swimming front crawl, butterfly and breaststroke, the legs are practically not involved in the production of driving force. The main argument in this case was the direction of movement of the legs not back, but up and down, which supposedly only maintained the balance of the body in the water. At the same time, it is known that swimmers still move forward using only their legs, and high-class athletes quite quickly. And it is quite obvious that with the movement of the legs the swimmer moves the water backward in the same way as with the vertical movements of the arms. As can be seen in Fig. 1.18, although the feet move almost straight down when swimming butterfly, bending the knees and straightening the feet provides a hydrofoil effect. The function of its front edge is performed by the knee part, and the rear edge is performed by the forefoot. Bending the knees creates an angle of attack that allows the swimmer to move the water backwards. Similarly, the legs provide propulsion when swimming crawl.
20
CHAPTER 2 Hydrodynamics of driving force during swimming
Hydrodynamics
driving force
when swimming
The properties of a moving fluid differ significantly from the properties of a fluid at rest, therefore, as soon as the hand and water begin to move relative to each other, hydrodynamic resistance arises - a force that ensures the movement of an object in the fluid. Analysis of stroke mechanics has usually been done without taking into account such drag and the resulting flow reactions.
When analyzing a stroke, you can take the principles of hydrodynamics as a basis. This makes it possible to: understand the essence of the driving force and understand the features of the impact on water when rowing with different trajectories; analyze the driving force by relating the flow reactions to the characteristics of the stroke mechanics by assessing the size and shape of the vortices, as well as the location of their origin; analyze the conditions for providing the greatest driving force.
Like any liquid, under the influence of force, water changes its shape, which is manifested in flow and changes in its elasticity, which, in turn, is due to viscosity. Flow and elasticity are characteristics of moving water that any qualified swimmer can evaluate fairly objectively.
The streamline (streamline), indicating the direction and speed of the flow, is defined as a curve that is always tangent to the flow. Therefore, the liquid cannot cross
Roll a current line, it only flows along it. The speed of fluid movement is higher where the streamlines are closer to each other, and lower where the distance between them is greater.
If the streamlines retain the same shape, we can talk about flow uniformity. It is much easier to analyze the structure of a uniform flow than an uneven flow.
The flow around a submerged object can be represented on a diagram by streamlines. If the fluid velocity at a given point depends not only on its position, but also on time, the streamlines are constantly changing. The totality of all streamlines at one time or another forms a momentary flow structure, which can be represented by streamlines showing the direction of flow at various points. From the countless number of streamlines, five to ten lines are usually chosen to divide the flow into several "channels", each of which carries the same amount of water in an equal amount of time. Reducing the width helps to increase the flow speed. The structure of the flow determines not only its direction, but also the speed at any point in the water flow (Fig. 2.1), and knowing it, specialists in the field of hydroaerodynamics can also determine the pressure force within the boundaries of the flow.
Back in the 18th century. Euler and Bernoulli founded the school of classical hydrodynamics to study the motion
21
PART 1
Sports swimming technique
Rice. 2.1
The structure of the flow around the wing indicating the direction and speed of the flow; smaller spacing between streamlines shows areas of highest velocity
Rice. 2.2
Classical hydrodynamic model of the flow structure of an “ideally” flowing medium without taking into account the viscosity of the liquid; The figure illustrates the structure of the flow around a cylindrical obstacle
Rice. 2.3
Turbulent flowbehind submerged bodies: cylindrical shape (a); streamlined shape (b); the boundary layers of the “slow” fluid are shaded
Living in a hypothetical “ideal” liquid. However, the lines on the diagrams of the flow structure of such a liquid are correct, constant (Fig. 2.2) and do not explain the phenomena in which the role of viscosity is important. Without arrows indicating the direction of flow, it would be impossible to determine it due to the absolute symmetry of the flow and pressure structures. In addition, according to the theory of an ideal fluid, it slides behind the body without “sticking” to it and without forming a boundary layer. The symmetry of the flow structure and the absence of a layer of “retaining” fluid in this ideal inviscid fluid means that there is no drag force acting on the cylinder.
Due to the relatively low viscosity of water and air, at least compared to liquids such as oil, the ideal fluid theory could be accepted in some cases, but not in analysis
The structures of their flow past a solid object when their viscosity cannot be neglected (Fig. 2.3).
Thin lines in Fig. 2.3 reflect the average flow trajectories. There is also a boundary layer of "slow" fluid around the front half of the cylinder (shaded), in which the fluid elements stick to the object, which increases the viscosity and slows down the movement of their "neighbors". On the other hand, the moving “neighbors” act in a downward direction on the “adhesive” elements, which, in turn, impart to its body in the form of surface resistance.
Water cannot accelerate indefinitely precisely because of its viscosity (internal friction), in the absence of which the flow speed in rivers would reach hundreds of kilometers per hour, which would have quite disastrous consequences. A swimmer is able to "grab" water only because the viscosity of the water promotes a separation of the flow, and this leads to a difference in pressure around the hand. Under certain conditions, this pressure differential provides the resistance that produces the driving force (Councilman, 1982). However, viscosity not only helps the swimmer move forward, but also creates shape resistance that impedes his progress, as a result of which the liquid elements in contact with it “stick” to the body. Those adjacent to them move relative to these elements, which “turns on” resistance forces opposing the movement and causing friction.
Most viscous deformation occurs within the boundary layer - a relatively thin zone immediately adjacent to the surface of a body that moves in an aqueous environment. The boundary layer, which consists of a number of very thin layers, always has a velocity gradient;
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