1. Body posture:
When swimming and crawling, the body is flat and prone in the water, the longitudinal axis of the body keeps an angle of 3-5 degrees with the horizontal plane, and the head is raised. This straight posture can reduce the cross section when moving forward and help reduce the resistance. The neck bends back naturally, making an angle of 20-30 degrees with the horizontal plane. Keep your eyes on the front and back, paddle your arms back and forth alternately, and paddle your legs up and down alternately to keep your body straight, that is, don't tuck in, lift your hips, and bend your chest.
2. Leg movement:
The kick of crawl is mainly to keep the body balanced, which is beneficial to paddling and plays an important role in the whole crawl coordination technology.
The kick of crawl is that the leg keeps swinging up and down. When going down, the legs are naturally straight, and the hips are used to exert force, and the thighs drive the calves to draw water. Generally, the gap between the legs is about 30-45 cm. Move quickly and forcefully when you draw water, and relax when you lift your legs. When kicking water downward, due to inertia, the calf and foot still move upward at this time, which makes the knee joint slightly bent, and the bending degree is generally between 140- 160 degrees. When you draw water, your toes should be straight naturally, and when you draw water downward, your feet should be turned inward naturally (within eight characters).
Generally, the number of times to draw water is a complete stroke of six times, but some people draw water four times and two times, depending on personal characteristics.
3. Arm movement:
The arm movement of crawl is the main driving force to produce propulsion. The whole arm movement can be divided into three inseparable parts: entering the water, holding the water, paddling, exiting the water and air movement. But there is no obvious boundary between them, but a complete action.
1) Water entry: After the air arm movement is completed, the hand should enter the water forward and relax naturally. The water entry point is generally between the longitudinal body and the front extension line of the shoulder joint. When you enter the water, your fingers naturally straighten and come together. Raise the elbow joint by internal rotation of the arm, and bend it into an angle of 130- 150 degrees, so that the palm of the elbow joint is at the highest point and the fingertips are downward. This posture has the least resistance.
2) Holding the water: After the arm enters the water, the palm of your hand turns from the oblique outer lower part to the oblique inner rear part, and you start to bend your wrist and elbow, and keep your elbow up. When holding water, the angle between the upper arm and the horizontal plane is about 30 degrees, the angle between the forearm and the horizontal plane is about 60 degrees, the palm of your hand hangs directly into the water, and the elbow joint bends about 150 degrees. The whole arm is like holding a ball.
) paddling: paddling is the main link of the whole arm movement to produce propulsion. On the basis of holding water, the arm forms an angle of about 35-45 degrees with the water surface when paddling.
When paddling, the arm bends, and the degree of arm bending can be determined according to one's physical condition: people with long arms and weak arms can bend their arms to a greater extent, and vice versa.
At the beginning of paddling, elbow flexion is about 100- 120 degrees. At this time, the forward movement is faster than the upper arm. When rowing to the vertical plane below the shoulder, the elbow bends 90- 120 degrees. The forearm quickly pushes the water back to the side leg and ends the stroke. In the process of paddling, the palm of your hand is concave.
Paddling route: when paddling, the hand moves to the central axis of the body first, and then paddling sideways when paddling below the chest and abdomen.
4) Out of the water: After paddling, the arm uses the speed inertia after pushing the water, as well as the contraction of deltoid muscle and shoulder strap muscle and the rotation of the body along the longitudinal axis to lift the elbow upward and quickly lift the arm off the water. At this time, the arms and wrists should be soft and relaxed.
5) Air moving arm: It is a rest and relaxation stage of the arm in the paddling cycle. When moving your arms, bend your elbows slightly and keep them higher than your shoulders and hands. Don't swing your arms sideways, and don't drive your arms to bend your elbows and move your arms with your hands. This is tense and incorrect, you can't relax.
6) Two-arm coordination: Whether the two arms are coordinated during crawling is an important condition for uniform forward speed. There are usually three ways to cooperate with your arms.
Front crossing: it means that when one arm enters the water, the other arm is in the sliding stage, which is a technology with sliding stage.
Midway: refers to the middle part when one arm enters the water and the other arm has entered the paddling stage.
Back crossing: refers to the second half of the paddling stage when one arm enters the water.
Generally speaking, for swimmers, it is appropriate to jump first and then learn, because jumping first and then learning can better maintain the balance of the body, easily master breathing techniques, save physical strength and reduce fatigue.
4. Coordination between breathing and arm movements:
Breathing in crawl is breathing through the mouth by turning your head to the left or right. Take breathing to the right as an example. After the right hand enters the water, the nose and mouth begin to exhale slowly. When the arm reaches the shoulder and turns to the right, the expiratory volume begins to increase. When the right arm pushes the water, the expiratory volume further increases. When the right arm comes out of the water, immediately open your mouth and inhale. When the arm moves halfway, the inhalation ends and the head begins to recover. At this point, hold your breath again, continue to turn your head and move your arms, and turn your face forward and downward. When the head posture is stable, the right arm enters the water again to start the next breath. Repeat this cycle to breathe.
5. Coordination of breathing and complete movements:
Generally speaking, the coordinated movements of legs, arms and breathing in crawl are one stroke with both hands, one breath and six strokes with both legs. In order to give full play to the role of both hands and improve the swimming speed, there is also a coordination method of one stroke with both arms, one breath and four kicks.