George it is very true that many people take up sports as hobbies and I agree that there are many ways to improve the power and effectiveness of one's kick with out just kicking.
In fact there are many things a person could add right into their Karate class that would not take a lot of time but done on regular basis would improve kicking ability.
When I think of an effective kick I think of power.
Now looking at the formula for power
Power=Force x Distance / Time
In athletic terms this is:
Power=Strength X Flexibility / Speed
For now let’s look at the first element being strength. What has to be strong for kicking purposes? Well most people would say your leg is most important but really I believe it would be your core region (abdominals etc.) Our core is the center of mass and without a strong core it will drastically decrease power.
There are many drills to increase the strength of the core. I tend to break them down into 3 categories.
1. Crunch Routine:
Any number of crunches done slowly targeting all areas of the abs
2. Isolation and Functional:
These involve holding different positions while contracting the core region. To name a few:
push up position resting on your forearms.
side bridge= laying on your side you raise you body into the air with only two contact point on the ground your forearm and the side of your bottom foot.
coffee table=on all fours with you back parallel to the floor raise you right arm straight in front of you and your left leg. Hold for 5-10 sec the switch to left arm and right leg. All the time keeping your back flat and parallel to the floor
3. Resistance= Any number of slow drills done with a partner or weights.
Note: It is extremely important that when ever you train the front and sides of your core you train the back. A tree will not last through the storm with a rotten trunk on one side.
I can see now that explaining all these drills in detail can get lengthy so I will try to just name them and if people want more detail please ask. 