Who will talk about the main points and precautions of learning to swim?

1. Swimming skills 1. The structure and technical points of breaststroke technique (1) The swimmer is in a sliding posture and his body is close to horizontal. About 80% of the head is submerged in the water, the face is slightly forward, the arms are extended, and the palms face diagonally outward (2). Grab the water from about 7 to 9 inches underwater, paddle sideways with your hands, and then start exhaling. (3) There is no obvious flexion of the arm, continue to paddle outward, and the exhalation continues to increase. (4) When the swimmer's head starts to move slightly upwards, the elbow joint starts to flex and the upper arm starts to rotate. (5) When the arms reach the maximum width, the elbow flexion is about 1 10 degrees, and then the high elbow posture is obvious. (6) Keep your head up, and when the water comes out of your mouth, finally exhale. Hands began to move inward to complete the final push. (7) When the arm is ready to go backwards, start inhaling, and don't pull the elbow under the ribs. The knee joint begins to bend and the leg begins to return to motion. (8) Keep your mouth closed, inhale, bring your feet to your hips, keep your elbow extended, and keep your arms moving forward. (9) The leg return action continues. (10) The neck bends and the head continues to tilt downward. The instep flexes, the legs begin to move backwards, the water pushes and the arms return. (1 1) Push your feet back and start to come together. Then the swimmer holds his breath until the next stroke begins. (12) Arms are fully extended, hands are slightly below shoulder level, and kicking with both legs is nearly finished. When the swimmer finishes kicking, he concentrates on keeping his body in a straight line. He will keep this sliding posture for a short time, and then when he feels slower, another arm stroke cycle begins. 2. Structure and technical points of backstroke technique (1) The left hand enters the water directly above the shoulder, the tail finger enters the water first, and the right hand finishes the stroke and starts to do the backhand movement. (2) The momentum generated by the left hand in the second half of the backhand keeps the elbow and arm straight, sinks into the water, and makes them start to move upwards. When the right hand comes out of the water, the wrist joint bends. (3) When the left hand is paddling downward and outward, the elbow bends and the right leg begins to do diagonal paddling. (4) When the left hand is over the shoulder, elbow flexion reaches the maximum (90 degrees). Take back your hand and start to rotate, palms outward. (5) When the hand crosses the shoulder, the elbow joint of the stroke arm begins to stretch. At this time, the body leans to the maximum (40~50 degrees). (6) The left arm completes the stroke, the elbow joint is fully extended, and the palm is down, about six inches below the hip. (7) The right hand sinks into the water and is ready to receive water. (8) The right hand straightens the elbow joint to receive water. Kick the water down with your left leg and push it back with your right hand. Due to the rolling of the body, the left shoulder is raised. (10) The right arm starts to press the water downward, and the left leg continues to kick the water upward. (1 1) At the same time, the stroke of the right arm is completed, and the action of returning the hand of the left hand is almost completed. 3. freestyle technique 1. Action structure and technical points (1) Body posture In freestyle, the body is prone on the water in a streamlined shape, the muscles of the back and buttocks are kept properly tense, the head is kept stable when swimming, and the trunk rotates rhythmically around the longitudinal axis of the body by 35 ~ 45. (2) Leg movements Although the leg movements of freestyle have certain propulsion, they mainly play a role in balancing, keeping the body stable and coordinating the arms to do powerful paddling. It is required that the legs are naturally close together, the feet are slightly rotated inward, and the ankles are relaxed. With the hip joint as the axis, the thigh drives the calf and sole, and the legs are whipped alternately. The maximum range of motion of the two toes is about 30~40 cm, and the maximum flexion of the knee joint is about 160゜.(3) The arm movement freestyle is the main driving force for the arm movement to push the body forward. A cycle is divided into three inseparable stages: entering the water, holding the water, paddling, leaving the water and moving the arm in the air. 1. Entering the water: After the arm moves in the air, the hand will naturally relax and enter the water under control. The entry point of the hand is generally between the longitudinal axis of the body and the extension line of the shoulder joint. When entering the water, the fingers naturally straighten and come together, and the elbow joint is raised to the highest point through the internal rotation of the arm, and the palm and hand are inclined outward and downward, so that the fingers touch the water first, then the forearm, and finally the arm naturally enters the water. 2. Holding the water: After the arm enters the water, in the process of active downward insertion, the palm turns from oblique outside to oblique inside and back, and begins to bend the wrist and elbow, and the elbow is higher than the hand, so that it can quickly transition to a better stroke posture. After holding the water, the palm is close to the water, the elbow joint is bent to about 150゜, and the whole arm is ready to paddle like holding a big ball. 3. paddling: paddling is the main stage to exert the maximum propulsion, and its action process can be divided into two parts: pulling water and pushing water. Immediately after the water conservation stage, it enters the water pulling stage. At this time, keep raising the elbow and let the big arm rotate inward. At the same time, continue to bend your elbow, so that your hands can quickly catch up with the forward speed of your body, which can make the movement of water create a reasonable movement direction and call the way. At the same time, the main muscle groups can enter the water pushing action in good working condition, and pull the water to the vertical plane of the shoulder before entering the water pushing part. At this time, the elbow flexion is about 100゜. The big arm is keeping the posture of internal rotation, driving the forearm and pushing the water back hard. At the same time, make the shoulders move backwards and lengthen the effective stroke route. Pushing the water backwards has an acceleration process from bending the arm to extending the arm, and the palm is from the inside up and from the bottom up to the thigh. In the whole paddling process, the trajectory of the hand starts from the shoulder, then reaches the lower abdomen, and finally reaches the thigh, showing an S-shape. 4. Out of the water: At the end of the stroke, the palm turns to the thigh, the little finger is up when coming out of the water, the arm is relaxed, and the elbow is slightly bent. Driven by the upper arm, the elbow is pulled outward, the forearm and hand come out of the water, and the palm turns to the upper back. The water movement must be rapid and non-stop, and at the same time, it should be gentle and relaxed. 5. Move your arm in the air: When the water comes out, move your arm in the air immediately, and don't stop. When moving the arm, the elbow is higher than the hand. 6. Coordination of arms: There are three kinds of crossing positions of double-arm stroke in freestyle: front crossing, middle crossing and back crossing. The front cross means that when one arm enters the water, the other arm has swung forward to the front of the shoulder and formed about 30 "with the plane. The front cross helps beginners master freestyle movements and breathing. The middle crossing means that when one arm enters the water, the other arm is in the internal stroke stage, forming 90 "with the horizontal plane. Back crossing means that when one arm enters the water, the other arm strokes below the abdomen, and the hand is about 150゜. (4) Arms, legs and breathing and coordination techniques In freestyle, one breath is usually taken during the stroke of each arm. Take inhaling to the right as an example: after the right hand enters the water, the nose and mouth begin to exhale slowly. Pull your right arm under your shoulders and turn your head to the right to increase the expiratory volume. At the end of the right arm push, exhale forcefully. When the right arm comes out of the water, open your mouth and inhale until the first half of the arm moves in the air and begins to turn around and restore. Then, until the arm enters the water, there is a short process of holding your breath and turning your face forward and down. When the head is stable, the right arm enters the water, and then the next process of slowly exhaling begins. The breathing in freestyle is in harmony with the arms and legs. Beginners generally use the method of 6: 2: 1, that is, breathing once, paddling twice and hitting six times. This coordination method is easy to keep balance and master freestyle techniques harmoniously. Second, the exercise method (1) leg exercise 1. Land imitation exercise (1): Sit by the pool or on the ground, hold your hands up, straighten your legs, turn your legs inward so that your toes are facing each other, separate your heels into a figure of eight, relax your legs, take your hips as the axis, and your thighs drive your calves up and down alternately. (2) Draw water on your stomach: kneel on a stool and draw water alternately with your legs up and down. The requirements are the same as above. 2. Practice in the water (1) Prone slapper: Hold the tank with your hands, or hold its abdomen with your partner, take a horizontal posture, straighten your legs, and do straight or bent legs to fetch water. (2) Draw water on your back: Lie on your back, hold the basin in your hand, or hold his back with the help of your partner, so that your legs can draw water alternately, and be careful not to expose your knees to the water. (3) Water skiing: Hold your breath while practicing, keep your arms straight and close together, and put your head between your arms. (4) Help the board to draw water: When practicing, straighten your arms and relax the board. When your shoulders are immersed in water, don't press the plate hard with your hands and breathe naturally. (2) Exercise of coordination between arms and breathing 1. Imitation exercise on land (1), with your feet open, your upper body leaning forward, and doing imitation exercise of arm paddling. (2) Practice as above, combined with breathing coordination. 2. Underwater exercise (1): Stand in the water, lean forward with your upper body, immerse your shoulders in the water, do arm strokes, walk while doing it, and turn your head to breathe. (2) Hold your breath and cooperate with your arms after sliding. (3) Legs with paddles, do double-arm paddling after pedaling and sliding, combined with turning and breathing. (3) Coordinated exercises of arms, legs and breathing. (1) Standing in the water, the upper body leans forward to coordinate the action of paddling arm and breathing, paddling forward with force, then pedaling off the bottom of the pool, and paddling with both legs forms complete coordination. (2) Push, slide and float for 5~ 10 meters, and do freestyle arm paddling and breathing exercises. Thirdly, the practice suggests that freestyle technique does not have the intermittent stage like breaststroke, and it must turn its head sideways when breathing, so beginners often appear busy and nervous. Pay attention to the coordination of movements and the relaxation of movements. 4. Technical structure and technical points of butterfly stroke (1) At the beginning of backstroke, hands are shoulder-width into the water, feet are flexed, ready to hit the ball, and the head leans forward slightly. When returning the hand, the momentum generated by the arm makes the hands sink, and with the help of muscle strength, the arm makes diagonal strokes. Kick, go. (2) After kicking, continue paddling. The reaction of kicking under the leg makes the hips rise to control the water surface. Start raising your head. (3) Pull the arm downward and backward to reach the maximum width and raise the elbow joint. The legs complete the first kick. (4) The hand passes directly below the body, approaching 90-degree contact. (5) When the hand passes under the shoulder, the elbow begins to approach the body. My legs began to accumulate water. The swimmer's neck began to bend and his head sank slightly into the water. (6) Lift your arm off the water and start to return your hand. Grab your legs, straighten your knees and lower your head, it's easier to fight back. (7) Swing your hands over your shoulders, palms down and elbows fully extended. Feet began to flex. (8) Submerge your hands into the water and stroke your thighs downward at the same time. The knee curvature is increased. Feet close to the water. (9) During the first stage of paddling, the lower leg paddling is nearly completed. The swimmer holds his breath in the previous cycle and exhales at the same time as the stroke begins. The rotation of the upper arm causes the position of the high elbow. 2. Precautions 1. How to prevent water from entering the ear when swimming 1. Have a physical examination before swimming. If there is cerumen in the external auditory canal, it should be taken out, otherwise it will easily cause pain and inflammation after swelling. People with otitis media, such as tympanic membrane perforation, will aggravate otitis media if dirty water enters the middle ear. Therefore, patients with otitis media can only swim with the consent of the doctor. 2. When swimming, plug the external auditory canal with absorbent cotton dipped in vaseline oil, which can play a protective role. 3. After swimming, the accumulated water in the external auditory canal should be discharged in time. When draining, the head leans to the side where the accumulated water is accumulated, and the head can be drained by gently patting it with the palm of the same side. If the ear is itchy, you can gently wipe the external auditory canal with 75% alcohol cotton, and it is forbidden to dig by hand. If you feel earache, you should go to the hospital in time. 4. Pay attention to the posture and method of diving, and don't let your ears be directly hit by water to avoid tympanic membrane injury. 2. Prevention and self-help methods of swimming cramps often occur in calves and toes when swimming, but cramps can also occur in fingers, thighs and even abdomen. The prevention and self-rescue methods of swimming cramps are: do necessary preparatory activities before swimming and massage the parts that are prone to cramps properly. Before entering the water, shower with cold water or pat your body and limbs with cold water to adapt your body to low temperature. Swimming time should not be too long, and it is not appropriate to swim again when you are tired or hungry. People who sweat a lot in summer and are prone to cramps should pay attention to supplementing light salt water and vitamin b 1. Strengthening a variety of exercises (such as cold water bath) at ordinary times can effectively avoid cramps when swimming after improving the adaptability of the body. Be sure to keep calm when swimming cramps, and don't panic, choking water will aggravate the cramps. Shout for help when cramping, and actively cooperate with those who come to rescue to get away safely. Don't hold on to the rescuer and cause an accident to both of you. You can also take the initiative to save yourself and avoid cramps when swimming, especially when swimming in rivers, lakes and seas. The self-rescue of cramps generally adopts the method of prolonging spasmodic muscles. When the spastic muscles are stretched to a certain extent by external forces, spasms can generally be relieved. For example, if the calf, toe or hind leg muscles cramp, the swimmer can take a deep breath to make the body float on the water, hold the toe of the cramped limb with the hand opposite to the cramped limb, and pull it in the direction of the body, and at the same time press the palm of the same side on the knee of the cramped limb to help the cramped limb straighten, which can generally be relieved. On the contrary, the muscle cramps on the front side of the thigh should be pulled in the direction of the arm with a fist, so that the muscles on the front side of the knee joint can be lengthened and relieved. If your fingers cramp, you can clench your fist hard first, then open it hard, and it can be relieved after repeated several times quickly. Swimming cramps, do not continue swimming after relief, otherwise it is easy to cramp again and have an accident. That is, dry your body and rest in time when you go ashore, keep warm, and massage the parts that still feel pain properly to further relieve it. Finger cramps: Swimmers can take a proper rest by treading water or backstroke, and the cramped hands can be relieved by repeatedly clenching their fists and relaxing. If the palm cramps, you can also step on water or backstroke. Press the cramped palm with a healthy palm and shake it several times, then straighten the cramped palm and relax it again, and repeat it several times to return to normal. Toe or sole cramp: It can be relieved by pressing ankle ligament with both hands or rubbing the cramped toe back and forth. Leg cramp: the cramped calf knee can be pressed down, and the forefoot can be pulled up and back with the other hand, so that the calf muscles can be stretched and recovered; You can also grab the cramped calf with your hands and rub it hard to help you recover. Leg muscle cramp: Swimmers can keep floating like jellyfish, that is, the upper body naturally bends, the chest bends, the hands droop, the knees naturally bend and bend, and quietly climb down in the water. After stabilizing the body, you can press the cramped thigh muscles with your hands and rub them, or bend the cramped legs backwards, and pull your toes to your hips with your hands to stretch the thigh muscles, thus relieving the cramps. Abdominal muscle spasm: the swimmer stops floating on the water with backstroke, relaxes the whole body, then does a vigorous abdominal lifting exercise, and at the same time stretches his legs as far as possible, so that the abdominal muscle fibers are passively elongated, pauses for a moment, and then relaxes.