The kick of freestyle leg is almost perpendicular to the horizontal plane. Seen from the vertical plane, the distance between the legs is about 30-40 cm, and the knee joint bending angle is about 160 degrees. When swimming in, when the legs are pumping up, the feet should be close to the level; When you draw water down, don't go beyond the lowest part of your body in the water The correct kicking action is that the foot is slightly turned inward and the ankle is naturally relaxed. The upward and downward kicking action starts from the hip joint, and the thigh exerts force, which passes through the whole leg and finally reaches the feet to form a "whip-like" kicking action. Downward pumping has the greatest effect, so it should be carried out with greater force and faster speed; On the other hand, upward demands are relaxed and natural, as effortless as possible, and the speed is relatively slow. Starting from the upward movement of the leg, when the thigh drives the calf to move upward from the lower straight leg until the ankle joint, knee joint and hip joint are parallel to the horizontal plane, the thigh stops moving slightly upward and starts to draw water downward. When the thigh begins to pump water downward, due to inertia, the calf and foot continue to move upward at this time, making the knee joint bend to form an angle of about 160 degrees. This makes the calf and the foot reach the highest point, and as the thigh continues to move downward, it drives the calf and the foot to complete the downward movement of water. When the thigh draws water down to the lowest point and is lifted, the calf and foot still keep an angle with the thigh, continue to draw water down until it is completely straight, and then move up with the thigh to start the second circular action.