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.

Kickboxing consists of "rounds" (similar to regular boxing); when you're starting out the rounds last two minutes, at more advanced levels, they last three minutes. As anyone who's kickboxed knows, two or three minutes of all out intense exercise can easily feel like an hour.

The best way to train for the endurance component of this sport, according to Jimmy Fusaro, master trainer for boxing and kickboxing at the Equinox Fitness Clubs in New York City, is to mimic the round system on your aerobic apparatus. Get on the UBE (that's the "upper body ergometer" machine), or the stationary bike, or any other aerobic apparatus, and pump hard for two minutes. Then do a "one minute easy" interval. This is called a work: rest ratio of 2:1; you're working hard for two minutes, "resting" for one.

For example, you might run hard for two minutes and then walk (at cool-down levels) for one. (The walking is called "active rest" since you're not actually resting). Keep repeating the sequence until you can do it three or four times without taking a break. This is the best way to build endurance for the round system of kickboxing.