High-intensity interval training (
HIIT) or
sprint interval training is an
exercise strategy that is intended to improve performance with short training sessions. HIIT is a form of cardio which is beneficial to burning fat in a short and intense workout. Usual HIIT sessions may vary from 15-30 minutes. Most HIIT sessions have a 2:1 ratio in terms of time. For example, for running, a HIIT session may be something as 60 seconds jog, 30 seconds sprint.
An example of a HIIT session may be as follows: Use this scale of 1-10 (1 being a casual walk and 10 being sprinting as hard you can) to help clarify the intensity level of the run. For this exercise, it is most efficient if it is done on a track or at least outdoors instead of on a treadmill. Begin with a five minute warm up jog at about a 4-5 followed by a couple of minutes of stretching. Then start with a jog at about a 5-6 intensity level for 60 seconds and then sprint at an 8-9 intensity level for 30 seconds. Repeat this cycle 6-8 times depending on how fit you are (Beginners should limit themselves to 6 cycles and more advanced HIIT users should strive for 8 cycles). Your HIIT session will look something like this: Jog (level: 5-6, 60 seconds) then Sprint (level: 8-9, 30 seconds), Jog (level: 5-6, 60 seconds) then Sprint (level: 8-9, 30 seconds), Jog (level: 5-6, 60 seconds) then Sprint (level: 8-9, 30 seconds), Jog (level: 5-6, 60 seconds) then Sprint (level: 8-9, 30 seconds), Jog (level: 5-6, 60 seconds) then Sprint (level: 8-9, 30 seconds), Jog (level: 5-6, 60 seconds) then Sprint (level: 8-9, 30 seconds). After you complete your cycle, you should also have a cool down run to help your heart rate return to normal.
A HIIT session involves a warmup period, several short, maximum-intensity efforts separated by moderate recovery intervals, and a cooldown period. The period of alternating effort and recovery intervals typically lasts a total of 15 minutes. HIIT is an excellent way to maximize your workout if you are limited on time as well.
Studies by Tabata
[1], Tremblay
[2] and others have shown this method to be more effective at burning fat and maintaining, or building, muscle mass than high-volume, lower intensity
aerobic work-outs. A study by Gibala et al
[3] demonstrated 2.5 hours of sprint interval training produced similar biochemical muscle changes to 10.5 hours of endurance training and similar endurance performance benefits. According to a study by King
[4] , HIIT increases the
resting metabolic rate (RMR) for the following 24 hours due to
excess post-exercise oxygen consumption, and may improve
maximal oxygen consumption (VO2 max) more effectively than doing only traditional, long aerobic workouts.
[5][6][7][8] Long aerobic workouts have been promoted as the best method to reduce fat, as
fatty acid utilization usually occurs after at least 30 minutes of training. HIIT is somewhat counter intuitive in this regard, but has nonetheless been shown to burn fat more effectively. There may be a number of factors that contribute to this, including an increase in RMR, and possibly other physiological effects.
