Champion swimmers have simply learned how to apply this same technique to their arm stroke to produce an increased thrust which propels them through the water faster than their competitors. As can be seen in the figure, the drag acts in the vertical direction. Therefore, the normally detrimental drag force is now applied to raising the body higher in the water to counteract the swimmers weight. To further increase the propulsive force, the hands pitch can be altered to take advantage of the greater resultant force as shown in the diagram below. Kick The kick provides a stabilizing effect in addition to the propulsive force.
Most swimmers only get a small amount of propulsive force from their kick.
The first way to improve the kick is to keep the feet in the water. When a swimmers feet enter the water, a significant amount of air enters as well. The air increases the drag as well as reducing the propulsive effect. The best swimmers go further by moving their feet during the kick to produce the same lift force achieved by their hands. This is much harder to visualize unless you look at the breaststroke kick.