Kicking Has Many Functions in Freestyle
In freestyle, kicking is a very important motion. Kicking is often mistaken as to merely propel the body. However, top competitive freestyle swimmers in the world only use 10-15% of their strength in kicking, which is of rarely high efficiency. In contrast, beginners have lower kicking efficiency.
Therefore, we have to realize that the purpose of freestyle kicking is not only propelling but also keeping balance and the right position in water while we are learning freestyle swimming. Unless you are a short-distance sprint swimmer, never make use of kicking to propel, because it is a low-efficient method, which consumes much of body's energy. As a result, the more strength you kick with, the more resistance you will meet. And that is inevitable. So the primary goal of kicking is to reduce resistance, keeping balance and correct position of the body.
Does it mean that we can ignore freestyle kicking? This is not the case. Beginners should enhance kicking practice during training as there are some other purposes of kicking except for propelling. It is necessary for you to improve your kicking efficiency, which can make your swimming motions better.
Other than propelling your body, the prime objective of kicking is to elevate your buttocks and legs, which can keep your body at a position of low water resistance, decreasing the resistance brought by your legs, helping your body rotate and reducing energy consumption. As our legs are not like fishtail, we have hips, knees and ankles which lower the advancing efficiency when swinging under water, so that we should lay stress on the above points we have mentioned.
The final goal—reducing energy consumption, is actually a result of three actions referred above. If you can rotate your body in virtue of kicking legs to reduce resistance brought by your legs, and elevate your buttock and legs in order to keep your body at a position with low water resistance. Then the energy consumption will decrease naturally, which can improve your kicking efficiency as a result.
