When swimming crawl on the chest, leg movements are performed alternately from bottom to top and from top to bottom. The plane of motion lies close to the vertical. The range of motion reaches 1/3 of the length of the swimmer’s elongated body, excluding arms. The time it takes to complete the movement depends on the speed of the swim, and thus on the length of the cycle. The basic coordination of movements when swimming with a crawl on the chest is six-stroke. Therefore, while swimming, if we take a cycle time of 1.8 seconds, then the duration of each movement will be 0.3 seconds. With a high speed of crawl swimming on the chest, these indicators will be equal to 1.2 and 0.2 seconds. At a time when the swimmer with one foot performs movements from the bottom up, with the other leg he makes movements from the top down.

Considering the technique of leg movement when swimming in front crawl, you should pay attention to the bending of the legs at the knees and to the forward movement of the hips in relation to the lower leg. In the initial training of leg movement technique, training swimmers are usually asked to perform movements with straight legs. What is needed in order to avoid errors in technique associated with excessive bending of the legs at the knees. In fact, when swimming on the front crawl, professional swimmers perform movements by bending and unbending their legs at the knees.

In the lower starting position, after moving from top to bottom, the leg should be straight, the toe drawn out. To a horizontal position, the leg moves straight, then bending at the knee occurs. Bending the leg should occur until the back of the foot and the front of the lower leg are at an angle of 30-45 degrees relative to the horizontal. The hip begins to move down at the moment when the feet move up. Thus, there is an advancing movement of the thigh in relation to the lower leg.

Essentially, the top-down motion of the front crawl begins before the bottom-up motion is completed, as the hip moves downward while the knee is still bent. The main, most effective part is performed with leg extension at the knee. The extension is usually completed by the time the swimmer’s leg passes the horizontal position. Next, the leg moves straight. Since some hyperextension can be observed in the knee, the thigh, not reaching the extreme position, begins to move up a little before the end of the movement of the foot and lower leg down. Thus, in the lower position, some advancing movement is also possible.

The effectiveness of strokes from the bottom up and from the top down when swimming on the front crawl is unequal. Because the top-down motion can be performed with leg extension at the knee joint, it creates a much greater force to propel the swimmer forward.

The swimmer’s foot movement technique varies depending on the pace of movement and swimming speed. When swimming slowly on the chest, the legs practically do not show on the surface (only a small part of the foot comes to the surface) and bend at the knee joints in such a way that the angle between the horizontal in the extreme upper position and the front of the lower leg does not exceed 30-35 degrees. The thrust created by the legs during slow swimming is small compared to the thrust of the arms. A similar technique of leg movements when swimming on the front crawl is typical for many athletes who specialize in swimming over long distances.

When swimming front crawl at maximum speed, the technique of leg movements changes. The legs begin to bend more strongly at the knees. The angle between the horizontal in the upper starting position and the front surface of the lower leg and foot increases by 5-8 degrees, and in some cases reaches 40 degrees. The foot comes out of the water to the ankle. The thrust from leg movements is relatively increased and has a marked effect on sustaining high speed in sprinters.