WHAT IN THE WORLD IS HIGH INTENSITY INTERVAL TRAINING?High Intensity Interval Training (HIIT) occurs when exercise is performed in such a way that you are recovering from the oxygen deficit (you panting for air) for many hours longer than the period you were exercising. This intense exercise has now caused excess post-exercise oxygen consumption (EPOC), which is defined as a measurably increased rate of oxygen intake following strenuous activity intended to erase the body's "oxygen debt." EPOC is accompanied by an elevated consumption of fuel. In response to exercise, fat stores are broken down and free fatty acids (FFA) are released into the blood.
In layman's terms, since you were panting so darn hard, your body is struggling like hell to put the oxygen back into your blood that you just used up so quickly and as a result, you burn fat like crazy! You not only burn fat while exercising, as a result you will burn fat for up to 36 hours after that one workout. In addition to the amount of time that you continue to burn fat after a HIIT session, the rate that you burn fat is 9 times more when you are at rest after exercise than if you had gone for a jog or had jogged on a treadmill at a moderate pace for an hour. When you perform steady state cardio you are mainly burning fat during the exercise period, and burn very little afterward.
I want to be totally frank about this. HIIT is neither easy nor comfortable. You're really going to have to put forth some effort to make it happen. But if you are successful, you will spend about half as much time working out and you'll have a much tighter, "ripped" look.
WHY SHOULD I DO HIIT?
First, HIIT increases maximal oxygen consumption (VO2 max) more effectively than doing only traditional, long aerobic workouts. That's why I used this method to condition my high school soccer players and wrestlers who need to have plenty of endurance for their sports.
Secondly, steady state cardio will eventually consume muscle! When you push your body for a long period of time, for long distances, it will actually switch over to burning your muscle for energy. The most vivid example I can give you is a track meet. When you are at a track meet or are watching the track events on the Olympic broadcast on television, who is more muscular, a sprinter, or a distance runner? The sprinter is more muscular of course. He goes all out for short bursts. As a result, he can preserve and enhance a lot of the fast twitch muscle he has developed for explosive power. The distance runner has burned his fat off, but he has also burned his fast twitch muscle off along with it. Though this is an extreme example, it is a good illustration. Do steady state cardio for a long time and there is a very good chance you will suffer from overuse injuries that come with the repetitive motion of running, elliptical training, exercise biking, etc.
High-intensity interval training has also been shown to improve athletic performance. For well conditioned athletes, improvements in performance become difficult to attain and increases in training volume may not yield significant improvements. Previous research would suggest that, for athletes who are already trained, improvements in endurance performance can be achieved through high-intensity interval training. If you are novice, you will need to be careful not to over exert yourself when starting a HIIT workout regimen. But once you begin to burn additional amounts of fat and gain greater levels of fitness, you should adopt an advanced HIIT training program so that you reap the benefits of greater endurance and fat loss.