One thing that is certain when it comes to any type of technique in any style of martial art, is the importance of hip rotation. This hip rotation can apply to different axes. We can rotate our hip forward and backward as well as side to side.
When it comes to kicking, in particular the longtitutinal kicks like front kick, side kick and back kicks, but also in lateral kicks like the round house kick, there is an importance rotating the hips forward when executing the kick.
In stand up striking arts, when we lack hip motion on hand techniques the main consequence is that the technique becomes anemic or lacking in power, but when lacking hip motion in kicks or having the opposite of the correct hip motion with the kicks there is bad news! We can lose our balance on the rechamber after the kick, or when actually making contact with something, we will find that we are pushing ourselves backwards instead of piercing or pushing the target.
This emphasizes the importance of kicking a weighted target either via the heavy bag or through a partner holding a pad or shield with some sort of feedback when we execute a kick, but even then so, we may feel the consequences of not having the correct hip motion without learning what the correct hip motion is. Correct hip motion on a lick means different things to different styles. Today I will explain proper hip motion in the style that I have been training in the longest: Tang Soo Do.
To have correct hip motion, the hip of the base leg must be in front of the foot of the base leg. If the hip is behind the foot of the base leg, that is when we see ourselves fall back when we rechamber or push off the heavy bag. When done correctly, initially the student will feel this in their hip flexors.
Many times students believe they are using their hips, but in reality they are just leaning back with their upper body. Many times instructors including myself will tell their students not to lean back when they kick to avoid the misunderstanding of hip motion, but recently I have been conveying to my college aged students that leaning back might happen when hip motion is applied to a kick, but leaning back with the upper body better not be the ONLY thing that is happening during a kick.
Like many things in life we use our prior knowledge to create analogies and help us learn and improve on other possibly newer things to us. When we understand the hip motion in our kicks, we can apply that same idea of moving our hips forward to our hand techniques and stances. Take the opportunity to go for it in your training and apply more (correct) hip motion to your kicks, you will be glad you did!