Swimming is an activity skill of human body in a certain depth of water in a specific environment, relying on limb movements and using the buoyancy of water. It was produced by ancient human beings in the struggle for existence with nature, and developed with the continuous development of society, and gradually became an important competitive event of modern competitive sports. Fitness for middle-aged people is mainly practical swimming.
(1) Effects of swimming on physical and mental health
Swimming can make the heart get a good exercise, the myocardium is gradually developed, and the contractility is enhanced, which can better promote the metabolism of the body. Therefore, the heart rate of swimmers is slower and stronger than that of ordinary people. The average person's pulse is 70-80 times per minute when he is quiet, while the swimmer's pulse is between 42-60 times, and in some cases it will even drop to 36 times, which is a concrete manifestation of his good heart function. Some swimmers usually only have 40 ~ 50 heartbeats, and the amount of blood discharged during beating is equal to that of ordinary people with 70 ~ 80 heartbeats.
Swimming is one of the most influential sports on the respiratory system. The average person's breathing capacity is 60 ~ 100 mm Hg (8 ~ 13.3 kPa), while the athletes who have undergone systematic swimming exercise can reach more than 200 mm Hg (26.7 kPa). The vital capacity of swimmers is also much larger than that of ordinary people. According to inspection statistics, the vital capacity of ordinary people is only about 3000 ml, while that of swimmers can reach 5000 ~ 7000 ml. In this way, more oxygen can be inhaled and more carbon dioxide can be discharged with each breath. Large lung capacity and strong hypoxia tolerance.
Persisting in swimming exercise can also enhance the function of the nervous system, make the movements agile and flexible, and make the joints exercise and coordinate flexibly.
Swimming can effectively exercise the muscles and joints of the whole body, develop muscles and lose weight. And in strength, speed, flexibility, endurance and other physical qualities have been significantly improved.
Swimming can strengthen the body and prevent diseases. Swimming itself is a kind of physical therapy. Due to regular exercise in water, the body temperature regulation function is improved, and the body's adaptability to the outside world is obviously enhanced. It has the functions of relaxing muscles and activating blood circulation and treating low back pain and sprain. If the method is proper, it also has certain therapeutic effect on coronary heart disease, hypertension and gastrointestinal diseases.
Swimming can delay aging and keep people young. It can improve skin blood circulation and metabolism, delay skin aging and prevent skin diseases.
Middle-aged people can swim in any position, such as breaststroke, freestyle, backstroke and butterfly, but not too fast and for too long. Exercise at least 2 ~ 3 times a week, preferably no more than 500 meters each time. The amount of exercise should be appropriate and vary from person to person.
(2) Swimming posture selection and technical essentials.
① breaststroke
The body is prone in the water, the arms are symmetrically paddling backwards, and the legs are pedaling backwards and swimming forward. The whole movement is similar to frog swimming, hence the name breaststroke. It is easy to learn, labor-saving, durable, and has a broad field of vision, which is very suitable for middle-aged and elderly people to exercise.
The key action is the coordination of leg and arm movements. The main point is: "Pull back your legs after paddling, and push your arms straight.".
② Side swimming
It lies on its side in the water and paddles alternately by cutting off two legs and two arms. It is also very suitable for middle-aged and elderly people. You can practice side stroke on the basis of mastering breaststroke. Different from breaststroke, the posture of side stroke has changed, and the action has changed from kicking the breaststroke leg to cutting hair. The two arms change from symmetrical paddling to alternating paddling. When the body lies on its side in the water, the shoulder axis forms an angle of10 ~15 with the vertical line of the water.
③ freestyle
Because it moves like crawling in water, it is also called crawling. Its main features are high speed and great practical value. Middle-aged and elderly people can also use it. The leg-arm cooperation in freestyle is usually 6 kicks and 2 strokes, which can also be called 6∶2 cooperation. The difficulty lies in the close cooperation between breathing and stroke.
④ backstroke
A swimming style in which the body swims on the water. Its posture requires lying flat in the water, slightly retracted jaw and slightly raised chest, so that the body and the horizontal plane form an elevation angle of 4 ~ 6.
Beginners should focus on leg movements to keep their bodies in a good position and facilitate arm paddling. Then practice two arms, one up and one down, one paddling and one swinging.
(3) Problems that should be paid attention to in swimming fitness.
First of all, you should check your body before exercise. If you have serious cardiovascular diseases, skin diseases and infectious diseases, you should not take part in swimming.
Second, get ready for activities before launching, and do flexion and extension exercises of arms, legs and waist for 3-4 minutes.
Third, the water temperature should not be too low. Beginners had better start in summer, so it's easy to adapt.
Fourth, the amount of exercise should be appropriate. Beginners should not run for too long. They should stop to have a rest every 50 meters, and the speed should not be too fast.
Fifth, pay attention to self-supervision. If you feel dizzy, sick, tired or unwell after swimming, you should reduce your activities or suspend your exercise.
Sixth, pay attention to safety. We should go hand in hand and take care of each other. Don't swim in places with rapids and eddies, and don't swim in areas with dense aquatic plants to avoid accidents.
Seventh, you should swim slowly and don't jump into the water suddenly. First, wash your shoulders and chest with water and walk slowly to the swimming area. Beginners should be familiar with water first. Then learn the technical movements step by step, first decompose the whole set of movements and practice them separately; On this basis, do a whole set of coordination exercises. Old and infirm people should pay more attention to what they can do, move steadily, and should not exercise too vigorously.