It is shown to speed up your slim-down process as it maximizes your fat loss without losing muscle mass.
Better yet, it enhances it.
This benefit is in fact a significant one as many aerobic exercises tend to solely do well on calorie burning, but poorly on muscle mass preservation.
Precision Nutrition has published a study that recorded this downside of typical cardio workouts for weight loss.
With HIIT, in addition to achieving major calorie burn and fat loss, you can condition your body in way that encourages development of lean muscle mass, which practically is the base of faster metabolism.
Considering all the benefits of HIIT, it's no wonder this training method is all the rage in the recent years.
Interested in learning how it works?
How does HIIT work?
HIIT is pretty simple.
You push yourself hard for a short period of time and follow up with a lower-intensity exercise (or recovery period) right after. You repeat this pattern for as many time as you want or until your time is up.
Two great examples of HIIT training are "4-minute Tabata workout" and "Chris Jordan"'s famous "7 minute workout".
Why Does It Work?
Using quick bursts, high-intensity training pushes your body to its limits to achieve muscle fatigue and maximum oxygen uptake.
It sounds complex, but it's really not.
The basic principle is the harder you push your muscles to work, the more oxygen they require, and more calories you burn.
The measure of the oxygen levels is VO2 max, which indicates the highest amount of oxygen your body consumes during exercise.
Working close to your VO2 max triggers the afterburn effect, where the body continues to consume oxygen (and burns additional calories) for up to 48* hours after the workout is completed.
Oxygen Intake and Calorie Burn
According to scientific studies, it takes approximately five calories to consume one liter of oxygen.
Because you alternate between a short, intense effort with a period of moderate-to-low intensity effort in high-intensity interval training, researches across the globe are finding how you can get more with less.
After extensive studies on the effectiveness and efficiency of HIIT compared to steady workouts, they found you can achieve comparable or more results in less time with this particular training method.
One study from Applied Physiology, Nutrition and Metabolism found that high-intense interval training increases fat and carbohydrate metabolic capacities in human skeletal muscle without spending hours at a gym.
This simply means that the body converts both carbohydrate and fat into energy more efficiently to fuel the muscles. In even simpler terms, it means it's effective at burning fat.
Another authority in exercise science, the American College of Sports Medicine (ACSM) states HIIT workouts provide similar fitness benefits as continuous aerobic endurance training but in shorter periods of time.
They elaborated by commenting, "This is because high-intensity interval training tends to burn more calories than traditional long steady workouts, especially after the workout."
If there is any hidden or secret benefit to HIIT exercises, this "after the workout" calorie burning is that.
And truthfully, that's where a majority of the efficiency and effectiveness of HIIT comes from.
By working your body harder with a very little rest period in between, you successfully elevate your body's metabolism for hours post-workout.
In a professional term, this effect is known as EPOC or excess post exercise oxygen consumption.
It means your body gets worked up hard that it takes hours and additional energy (calories!) to bring it back to pre-workout state.