HIIT (High-Intensity Interval Training) is a relatively new concept in the field of fitness. Some people consider it the fastest and most efficient way to burn fat quickly, while others still prefer to do more known approaches like walking or jogging. I will give you some brief information about this type of training and why is so efficient when it comes to fat burn.
What is HIIT?
HIIT stands for high-intensity interval training, which means that you do high-intensity interval (+ 80% maximum heart rate) followed by a low intensive interval. The most commonly practised technique is HIIT 30 second sprint followed by a 1-minute walk. Intervals are typically repeated for 10-15 minutes.
More about HIIT workouts you can read here: 4 Tips for Effective High-Intensity Interval Training
The benefits of HIIT over traditional cardio:
Increased after exercise oxygen consumption (IOC)
One of the adaptations that the body gets from the HIIT workout is the increased exercise oxygen consumption. The adaptations include balancing the hormones, restoring the energy depots, repair cells, innervation and anabolism. After training oxygen consumption recovers phosphagen system. The body burns extra calories in the next 48 hours after your HIIT session, depending on its intensity. One experiment found that IOC increases metabolic levels up to 13% three hours after the workout and 4% after 16 hours. HIIT can help you burn more calories throughout the day, even when you do not exercise, which will help you burn fat faster.
Release of hormones
HIIT dramatically increased levels of growth hormone, catecholamines and of epinephrine. These are all destroying fat hormones that have been shown to enhance the release of fat from the intramuscular fat stores. To maximise the release of hormones do not eat carbohydrates 1-2 hours before exercise, insulin response carbohydrates will limit the release of hormones. Growth hormone “hit the brakes” on the main enzyme for fat storage Lipoprotein lipase (LPL).
HIIT is usually in very short durations, most workouts are lasting in length between 12-25 minutes, considering that the usual time for traditional cardio can take from 45-90 minutes.
You can do it anywhere, with any equipment
HIIT can be done both outdoors and in the gym. The most popular form of HIIT is sprinting, which can be done on the road, on the football field or running track. A more intensive version of this exercise are sprints on a hill where sprinting up the hill followed by light jogging on the way down. Other variations can include kettlebells, jumps, squats, high jumps and cycling.
Increased oxygen consumption (VO2 Max)
VO2 max (also known as maximal oxygen consumption, maximal oxygen uptake, peak oxygen intake or maximum aerobic capacity) is the maximum capacity of the human body to transport and use oxygen during a single exercise that has an effect on the physical form. Studies have shown that HIIT increases levels of VO2 max much faster than traditional cardio.
Using aerobic and anaerobic systems.
Technically we are always using both systems during any exercise. However, doing the highly intensive part of your exercise (sprinting) you use almost exclusively anaerobic system. And at the low-intensity portion (walking) you use mainly the aerobic system. By using both systems, you burn glucose and fat and get the best of them.
Your metabolism will NOT adapt to HIIT
Our bodies are built for survival. 30-minute jogging which burns 400 calories probably will not burn the same amount after six months of consistent training. Your body will get used to the exercise and will use fuel more efficiently, which means that you will burn fewer calories and burn less fat.
On the other hand, HIIT forcing the body to work close to its maximal ability every time thus making it extremely difficult to adapt.