The technical composition of butterfly stroke:
First, the butterfly body posture
Second, the butterfly leg technique
Third, the butterfly arm technique
Fourthly, the butterfly stroke coordination technique is different from other strokes, because it has no fixed body position. During swimming, the parts of the trunk and head constantly change their relative positions. The head and trunk sometimes emerge from the water and sometimes dive into the water, forming undulating positions in the form of waves.
In butterfly stroke, the center is the horizontal axis (waist), the trunk and legs swing rhythmically, and the power point is in the waist and abdomen. Then the thigh drives the calf, and the two legs stir up and down together. These movements are closely related to the movements of the head and arms, forming a unique wave-like movement of butterfly, so the body has less resistance when moving forward. In butterfly stroke, the legs are naturally close together, and the heels are slightly separated into "inner characters". In the last stroke cycle, when the leg is kicked down, the foot is at the lowest point, the knee is straight, the hip is lifted to the water, and the hip joint is bent about 160 degrees (as shown in the figure).
Then the legs are straight up, the hip joint gradually expands and the hip sinks (pictured).
When the legs continue to go up, the thigh begins to press down, the knee joint and the thigh press down together, naturally bending, and the thigh continues to accelerate downward (as shown in the figure).
With the increase of knee flexion, when the foot is lifted to the water, the hip drops to the lowest point, and when the knee is bent to an angle of about 1 10- 130 degrees, the foot is lifted to the highest point, and the water is accurately thrown downward and backward (as shown in the figure).
When the foot hits the water downward, the ankle joint is relaxed, the foot surface is straight, and then the calf and thigh accelerate to push the water backward and downward. Feet continue to accelerate downward and backward to draw water. Before the end of the action, the thigh began to move upward again. When the knee joint is completely straightened, the downward pumping action ends (as shown in the figure).
The kick of the butterfly leg is completed by the waist, passing through the hips, knees and ankles, and coordinated with the trunk and spine. The movement direction of the foot is downward and backward, and the downward amplitude is greater than the backward amplitude (as shown in the figure).
When doing push-ups, the knees must be straight. If it is slightly bent, there will be great resistance on the back of the calf. In addition, when lifting your legs upward, don't use too much force to reduce resistance. The focus of kicking should be on the downward stroke, and the speed of the downward stroke should be about twice that of the upward stroke. The stroke action of butterfly arm is the main factor to produce propulsion, and it is greater than other postures. The stroke of butterfly arm is that the arms enter the water in front of the head and stroke along the sides of the body in a curve.
Its technical links are divided into several stages: entering the water, holding the water, paddling, pushing the water and moving the arm in the air.
enter
The entry point of butterfly arm is basically on the extension line of shoulder, and both arms enter the water at the same time. When entering the water, the elbow bends slightly higher than the forearm, and the palm is in front, making an angle of about 45 degrees with the water surface, and then driving the forearm and the big arm to enter the water in turn. In the entry stage, due to the lateral rotation of the forearm, the palm actively rotates from the outside to the back (see figure). hold water
After the arm enters the water, the hand and forearm continue to rotate outward and enter the water holding stage. When holding water, the hand moves outward-backward-downward. With the external rotation of the forearm, the palm rotates from the outside to the back (see figure), and then enters the paddling stage.
flabby
When the arm enters the paddling stage, the forearm and palm are the main surfaces of paddling. Bend your elbow and keep it in a high position. Forearm supination and increasing arm flexion are carried out simultaneously. When the two arms are below the shoulder, the included angle between the forearm and the big arm is about 90- 100 degrees. When the two hands are below the abdomen, the distance is closest (almost touching), and then the water is pushed.
Push water
When the distance between the hands is the shortest, the hands make an arc-shaped outward movement of water. The direction of hand movement is outward-upward-backward. In the first half of water pushing, the hand has a large backward movement, and the water pushing route is straight; In the second half of pushing water, the hand has a great outward and upward movement. When pushing water, due to the pronation of the forearm, the palm changes from backward stroke to lateral rear.
There are three routes of paddling and pushing (see figure), depending on the individual's physical condition. Generally, athletes with higher level adopt the first and second types.
When the two arms push water to both sides of the hip joint, the elbow is lifted off the water surface by the inertia of pushing water. Elbow lifting starts before the end of water pushing. Before the two arms kick the water, the elbows have started to lift upwards, and then the palms are facing outwards (see figure).
Move one's arm in the air
After pushing the water, lift your elbows off the water and move your arms forward from the air. When moving the arm, the elbow is slightly bent, the palm is up, the elbow comes out of the water before the hand, the arms are relaxed and pronated, and swing forward along the low parabola on both sides of the body (see figure). When you start to move your arm, use the centrifugal force of your arm to swing forward with a little force. Move your arm quickly, or you will sink. The coordinated movements of the arms and breathing.
The breathing of butterfly stroke is to push the water on the back with the help of two arms, and at the same time, the muscles of the back need to be greatly extended, so that the head can be lifted to the water surface and inhaled. Inhale quickly, return your head to the original position before your arm enters the water, and exhale slowly or hold your breath a little before exhaling.
The breathing in butterfly stroke is usually one stroke and one breath, but in order to speed up swimming, the technique of breathing again after two strokes can also be adopted.
Coordination of breathing between arms and legs (that is, complete coordinated movements)
The matching ratio of butterfly arms, legs and breathing is generally 1: 2: 1, that is, one arm moves, two legs moves and one breath. Of course, in some cases, it is also done n times (n >；; 1) the skill of breathing again with both arms and legs (the following picture shows the skill of breathing again with both arms and legs). The strength of two kicks is generally light for the first time and heavy for the second time, which should be different.
The complete coordination technique is the first kick when the two arms enter the water (see the picture below); When the arms are holding water, the legs are up (see the picture below); When the arm is under the abdomen, start the second downward movement of water, raise your head and inhale. When the water push is over, the kick is over (see the picture below). When the arm moves, the leg is ready to kick for the next cycle; Move the front of your arm with your head still on the water, and lower your head when you move your arm over your elbow. Breathe when your body is moving, not chase the air with your head. If you raise your head and stretch your chin to breathe, it will destroy the streamline of your body and will not produce more strength. You should try to keep your head natural during and after breathing.
2) mobilize your own strength to move forward. When you swing your arm backwards, you feel that your arm is bouncing forward (the direction of momentum is), instead of pushing water in the direction of your feet. 3) Sink and hold hands early. "We asked to sink her hands early so that her body could sweep them like a whip. As soon as her body center of gravity passes through her hands, she immediately enters the ballistic swing arm stage. " Grasp the water in front of your body as far as possible with your hands. As soon as your body sweeps your hand, let go immediately and take your hand out.
4) Be quick and powerful in the process of moving the trunk, and accelerate the afterburner instead of kicking. You must feel that your leg is being dragged instead of being kicked.
Lower the center of gravity
The swing arm technique in butterfly is not easy, but it is not impossible to learn, as long as you always remember to throw your arm forward as far as possible instead of climbing out of the water to breathe. When you do the butterfly with your hands for the first time, you can breathe every three or four times, and always remember the following points:
1) The shoulders are close to the water, and the head is in a straight line with the spine. Swim to the other side of the pool with all your strength.
2) When you finish swinging your arm backwards, the direction of your arm in the water is forward rather than downward.
3) Hands sink early and sweep in the direction of chin. When your torso moves forward over your hand, immediately cut outward (like karate) to help eject your hand. 4) The wrist drives the arm forward and relaxes the hands and arms during the flight.
5) Once you can do the forward impact stroke smoothly, you can breathe again. Breathe with your body, not your head. Keep your head slightly down during the whole breathing, just like breaststroke. Try to hide your breath. Imagine someone watching you swim on the shore, trying not to find you breathing. When you start to learn to breathe with your body instead of your head, you can row your arms four or five times to breathe. You may want to stroke your arms and breathe at once without losing your balance. As Quick said, "If you can breathe correctly, you should be able to breathe as many times as you want. This can help you complete the game well. "