HIIT, or High Intensity Interval Training, is where you alternate between periods of high intensity and low intensity exercise. Sometimes I like to call it "Heart Training" because your heart rate will be going insane during an interval workout.
Intervals help you boost your metabolic rate and burn fat. There are many great interval schemes out there, but if your goal is solely fat loss, then perform interviews that last just 20-30 seconds followed by 10-15 seconds rest or active recovery between each exercise.
Most individuals choose sprints or jump roping for there interval training workouts. I like to choose bodyweight and dumbbell exercises. This allows me to get a great fat loss and mass gain workout at the same time.
In order to create a great interval workout, all you need to do is choose 2-4 circuits and organize them into intervals. For example, I usually like to choose 2 dumbbell and 2 bodyweight exercises.
As mentioned earlier, there are some great interval schemes out there. But I would like to list some of the more common interval schemes out there. In the following list, the first number represents the work period, or how long you will perform the exercise.
The second number represents the period of time you will rest:
Beginners should start off with a 30/60 interval scheme. The hardest interval scheme out of all of these is the 20/10 interval scheme. The general rule is that beginners should start off with a 1: 2 interval to rest ratio.