Kickboxing. Once the word connoted bad Oriental kung-fu movies, early Jean Claude Van Damme, lots of testosterone and a loyal audience of 14-year-old boys. In the cultural pantheon it was right up there with comic books and bowling. Kickboxing had about as much association with "women" and "fitness" as Bill Gates had with Gregorian chants.

Not any more.

More women than ever are enrolling in self defense courses. Women's boxing has never been more popular, Christy Martin is a superstar, Zena has a cult following, and nearly every urban area has experienced an increase in the number of available martial arts classes. Kickboxing has come to be seen as the incredibly difficult, artful, intense form of combat that it is, and has gained a huge measure of public respect and acceptance.

Martial arts have invaded the gym. No longer relegated to remote outposts or musty, converted boxing gyms, kickboxing has moved into the mainstream.

If you're thinking of taking up kickboxing, let me be the first to congratulate and encourage you. But let me also be the first to warn you that you've got some rigorous training ahead of you.

First let's talk about the endurance component. Although basic aerobic training (i.e. 20 minutes and up at a consistent clip on a treadmill, stationary bike, etc.) is always a good idea for the heart and for general health and conditioning, it's not the way to train for this sport.

Kickboxing, like regular boxing, uses primarily what's called the lactic acid energy system. What this means in English is intense exercise for relatively short periods of time, followed by even shorter periods of rest. This is the hardest "energy system" to train because it's the most grueling and the burn is intense.