High intensity interval training is undoubtedly one of the best metabolic boosters and your sure shot way to burn maximum fat/ calories in the shortest time. I just love the after burn also known as #EPOC (excess post exercise oxygen consumption) and the crazy bouts of endorphin release post HIIT session, be it in the form of cardio or circuit weight training.
A lot of people wonder how an intense workout session is superior to a steady state cardio session. Well it's actually true that during a long slower cardio session we may burn around 400-500 calories in 45 minutes whereas you may burn only 250 calories in 15 minutes during an HIIT workout.
Lets talk about the difference between these two styles of training to further understand.
HIIT workouts are slightly more complex since you perform activity as hard as you can (i.e 90 to 100 percent of maximal capacity) for a brief period (usually 60 seconds or less), then back off to recover for a predetermined rest interval (usually 30 seconds), and repeat the cycle 5 to 8 times.
As a matter of fact, after an intense workout the oxygen consumption is much greater long after the workout is done facilitating the body to return to its resting state. Only if there is an increased oxygen intake can the body repair and rebuild itself whilst burning that fat! While carrying out cell repair, replenishing the phosphate stores & metabolising lactic acid buildup, the body targets fatty acids and taps into the fat stores to release them into the bloodstream and finally into the cells to provide energy it needs to return to its normal state.
Steady-state cardio is primarily aerobic: It requires oxygen and is fueled mostly by stored fat. HIIT by contrast is anaerobic. The work intervals do not rely exclusively on oxygen, and are fueled mostly by stored carbohydrates. (Counterintuitively, HIIT makes you breathe harder and burns more fat than steady-state cardio.
Both types of cardio workouts measurably improve a number of important health and fitness markers, particularly when you are new to this style of training. Your blood pressure drops, blood sugar stabilizes, metabolism improves, and VO2 max which is a measure of the maximum amount of oxygen your body can process undoubtedly goes up!
So to conclude, on days you are looking to squeeze in that quick session, just remember the more intense the workout, the more energy required for the repair process, the more calories you burn and the more time you save! After all it's always good to mix things up a little to keep it interesting. Aren’t these enough reasons to throw in some HIIT on some days?