If you swim, according to the stroke, except the breaststroke, the leg strength and technical training of the other three strokes are similar. In the part of ligament stretching, the main training method is so-called meditation. The third kind of swimming is easy, commonly known as freestyle leg, just like Japanese kneeling on tatami. This action is relatively easy, even ordinary people can do it. The question is how long it will take. Breaststroke requires sitting like a breaststroke leg. The soles of your feet are everted and your knees are as close as possible. This action is more difficult, and most people can't do it. There will be pain in the upper part of the leg and pain in the ankle. But leg press is a must when practicing breaststroke. In swimming, except freestyle, the other three strokes have no long distance. Even in medley, the distribution of each stroke is no more than 200 meters at most, which reflects from one side that the long distance does more harm than good to the other three strokes, especially to amateurs. For example, breaststroke, the advantage of starting to practice breaststroke is that it is easy to control your balance and move forward easily. But technically speaking, breaststroke is the most difficult. Especially in the moment of exertion, it is required that the upper body, hips and kicks should be explosive. Amateurs are easy to get hurt when they can't control their strength, and this kind of injury is not easy to detect. Especially the knee, it is easy to cause dislocation of stagnant water. In addition, many beginners are used to putting their heads on the water to facilitate breathing. People think it is helpful for long-distance swimming. In fact, keeping your head up will not only increase energy consumption, but also damage your spine. I once saw a case where this swimming style also caused a broken rib.