Right on Harry, the toe or heel theorem makes a huge difference also. I also have an double bass DVD instructional video I got for my son and did some research, and they all say that you need to balance yourself on that throne. Bottom line is that you need to invest on a really good throne. The method hat Drumkey was talking about was for those who use their leg instead of their ankle on the bass kicks. I found some good tips on the Musicians Institute on the web.
Here's the link:
Hollywood School of Music Provides Percussion Instrument Lessons