The cardiovascular system includes what we know as the heart, lungs and blood vessels responsible for transporting inhaled oxygen to muscle cells. Swimming needs more energy to overcome the resistance of water, so as to speed up the heart rate and increase the cardiac output. After swimming for a long time, the heart volume increases with exercise, the myocardial contraction is strong, the quiet heart rate slows down, the stroke output increases, the blood vessel wall thickens, the elasticity increases, and the efficiency of the cardiovascular system improves.
In addition, when swimming, the human body is in the supine position, and the pressure of water on the skin forms a massage effect. Therefore, the blood of limbs, especially lower limbs, flows back to the heart more easily than when standing upright on land. Moreover, the resistance of water makes it difficult for muscles to exert explosive force as on land. These characteristics are very suitable for middle-aged and elderly people to exercise, which can not only enhance their physical fitness, but also avoid accidents caused by excessive exercise.
2. Improve the function of respiratory system
One of the main characteristics of water is incompressibility. Because the density of water is more than 800 times higher than that of air, the pressure on people in water is far greater than that in air. This is also the reason why beginners have difficulty breathing in the water. As the pressure in the chest and abdominal cavity increases in water, it forces the respiratory muscles to breathe with greater strength. Therefore, regular swimming can increase the strength of respiratory muscles and improve the function of respiratory system. The most obvious example is the value of vital capacity. A swimmer's vital capacity can reach 4000 to 6000 ml, or even 7000 ml, while the average person only has 3000 to 4000 ml.
3. Improve the ability of the muscle system
Swimming is a whole-body exercise, which can mobilize more muscle groups to participate in metabolism and energy supply than other sports.
Although swimming can't build thick and bulging muscles, it can improve the strength and coordination of many muscles, especially the muscles of trunk, shoulder straps and upper limbs. Because swimming in water needs to overcome great resistance, and swimming is a periodic exercise, long-term exercise can improve muscle strength, speed, endurance and joint flexibility.
Another great advantage of swimming is the improvement of flexibility. This allows people to continue swimming when they are unable to engage in other sports activities due to age restrictions. Because swimming has a wide range of physical activities, people who swim often become more flexible and soft. Moreover, the correct swimming technique requires the muscles to stretch before the contraction force, which is conducive to continuously improving flexibility and strength.
4. Make the proportion of all parts of the body more reasonable, thus shaping the body shape.
If you often watch swimming competitions, you will definitely admire the rounded, slender, symmetrical muscles and strong figure of swimmers. Due to the influence of muscle working mode, swimmers are generally slender, with broad shoulders, flexible waist and well-proportioned figure. Maybe someone will say, I want to lose weight by swimming, why not? In fact, if you want to lose weight through exercise, you must reach a certain intensity, persist for enough time and persevere. If you only fish for three days and swim leisurely in the swimming pool for two days, of course it won't help. If you run, ride a bike or do any other exercise in this way, the result will be the same.
5. Improve the thermoregulation mechanism
Because the temperature of water is generally lower than that of air, and the thermal conductivity of water is dozens of times stronger than that of air, people dissipate heat much faster in water than in air. Regular swimming can improve the ability of body temperature regulation, so as to be more able to withstand the changes of external temperature. Especially in winter swimming, this improvement is particularly obvious.