Sorry for all the info, but came across this and it really clarifies the difference between true HIIT training and cardio. ENJOY!
"Here's what I'm proposing: commit eight measly weeks of your bodybuilding life to shedding excess fat and see if you don't look and feel a ton better. If you don't like the idea of doing aerobics, I understand your reluctance. I have good news for you. I've discovered a "better way" to burn off that unwanted bodyfat. And it takes only 4 to 15 minutes a day! If you think it's something you can deal with, then try sticking with it, and I bet you'll be wearing tank tops to the gym in no time. After all, the leaner you get, the bigger you look.
One of the great things about HIIT training is it can be applied to all sorts of activities—in or out of the gym. Personally, I like running stairs or sprinting, but it can also be done on a stationary bicycle, a stairstepper, or any activity where you can alternate periods of high intensity with periods of low intensity.
The following outline is a general routine for boosting fat loss, one that's worked well for me. Of course, you'll have to develop at your own pace according to your level of cardiovascular fitness. If you follow the program properly, three or four HIIT sessions a week should produce significant fat-burning effects. To prevent overtraining, try to incorporate the program on your weight training "off days." Your HIIT program will likely be most effective if performed first thing in the morning on an empty stomach, but if you can't do it in the a.m., do it at noon, night, whenever!
Let's assume you're going to apply HIIT training to running sprints or stairs, like I do. I work in intervals. For instance, I'll jog for a set amount of time, sprint for a set amount of time, followed by more jogging, more sprinting, and so on, until I've trained for a certain amount of time. Every other workout, you'll add another minute to your HIIT session. For instance, your first two HIIT sessions during week one will each take only four minutes. On the third workout of week 1, you'll add another 30-second sprint followed by a 30-second jog. Every other workout thereafter, you'll add another minute's worth of HIIT training until finally, by the end of week 8, you'll be doing a 15-minute HIIT session.
Of course, depending on your age, level of fitness, and how badly you want it, you'll periodically have to replace one of the jogging or sprint intervals with a brisk walk. After the 30- or 60-second "break," your heart rate will hopefully come back down off the ceiling, and you'll be ready to resume your sprint and jog intervals.
Let's say I'm just beginning. I'll put on my sweats and Nikes and grab my stopwatch and head out to the track. Table 1 indicates I'm supposed to begin with one 4-minute cycle.
There. That's it. Only four minutes! That's all for the day! After doing this same program twice the first week, I'll add another 60 seconds to my HIIT training. Every third HIIT workout is a little more intense, requiring that I add an additional 30-second sprint and an additional 30-second jog. No matter, by this time, my heart and lungs are starting to handle it.
As the weeks go by, I'll gradually add more and more minutes to my HIIT training, until finally, at the end of week 8, I'll be doing 15 minutes nonstop. By that time, the lines between my abs will be so deep I'll have to periodically clean the lint out with a Q-tip. (So that's where I dropped my car keys!)
The important thing to remember is sprinting is a very intense exercise. If you haven't tried to sprint for 30 seconds since you were a kid, you're in for a shock. Don't take off like you're doing a 40-yard dash. A groundskeeper will likely bury you on the spot where you collapse. Thirty seconds of sprinting should get you close to halfway around a quarter-mile track. Although you should ultimately strive to push yourself to run at 90% of your maximum, pace yourself as necessary in the beginning. "