Bad weather, such as (), () and (), is not suitable for swimming.

Bad weather such as (thunderstorm), (gale) and (sudden change of weather) is not suitable for swimming.

Polluted (poor water quality) rivers, reservoirs, places with rapids, intersections of two rivers and lakes with gaps are not suitable for swimming. Generally speaking, all rivers and lakes with unknown water conditions are not suitable for swimming. Bad weather such as thunderstorm, strong wind and sudden change of weather is not suitable for swimming.

It is best to experience the water temperature before entering the water. If the water temperature is too cold or too hot, try not to rush into the water. The temperature of the pool water has an influence on blood circulation, heart, blood pressure, respiration, metabolism, human skin and muscles.

Before launching, do warm-up activities on the shore, warm up for 10 to 15 minutes, and exercise joints and muscles in all parts. Otherwise, it is easy to cause muscle injury or other accidents if you suddenly engage in more intense activities. Lift your legs, squat, and stand up.

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Swimming plays an important role in improving cardiovascular system. The stimulation of cold water can promote blood circulation through heat regulation and metabolism; In addition, the pressure and resistance of water during swimming also play a special role in the heart and blood circulation.

Breathing mainly depends on the lungs, and the strength of lung function is determined by the strength of respiratory muscle function. Exercise is one of the effective means to improve and increase 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.

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.

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.

When swimming, people usually use the buoyancy of water to lie prone or supine in the water, so that the whole body can be relaxed and stretched, so that the body can develop comprehensively, symmetrically and harmoniously, and the muscle lines can be smooth. There is not much clothing protection when swimming, which has a certain effect on the body to resist the cold, especially in winter swimming. Swimming can make children grow taller during their development.

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