It's crazy hard. That's the first thing you should know. And it's over quickly. High-intensity interval training is the new kid on the block for training. In its simplest sense, high-intensity interval training, or HIIT, is essentially a series of exercises that use alternating periods of work and rest.
The effort required is "all-out" and the entire session is about 15 minutes. Recent evidence suggests that a surprisingly small volume of high-intensity intervals produce many of the cardiovascular adaptations normally associated with traditional high-volume endurance training.
Why it enables people to lose weight is all in the mitochondria, cellular structures that convert food and oxygen into energy. It's like a traffic controller giving an "all-systems-go!" to your metabolism.
A recent study showed that only seven sessions of HIIT over two weeks increased fat-burning during exercise by more than 30 percent. Although the rest period involves doing exactly that, you are burning more calories then, as well as post-exercise.
Martin Gibala, chair of the department of kinesiology at McMaster University in Hamilton, Ontario, hopes that this factor buries myths such as the "fat-burning zone" and "it takes about 30 minutes of exercise before you start burning fat."
Time flies, he says. Not only will you be able to reduce your training time, but the actual exercise time zips by. You don't have to be an elite athlete to try it, either. The basic concept, because it is based on a subjective effort, can be applied to almost any fitness level. What makes it work is that you leave your "workout comfort zone."
This kind of training has actually been around since 1937, when Swedish coach Gosta Holmer started using "speed play," or Fartlek training, for his flailing runners. Coaches have been using this model since.
In 1994, Dr. Angelo Tremblay and his colleagues at Laval University in Montreal, Quebec, tested the common belief among weight watchers that low- intensity, long-duration exercise is better than higher intensity intervals for losing fat. In short, the interval training group saw an impressive nine-fold improvement in fat loss due mostly to the after-burn: More calories and fat were burned after the workout. Plus, Tremblay found, appetite is suppressed more after intense intervals.
This type of training is cool, but not right for everyone, said Dr. Michael Bracko, in his keynote address at a recent American College of Sports Medicine Health and Fitness Summit in California. (Check out his creative version of HIIT at www.youtube.com/watch?v=JSmP3UBurbQ.) While HIIT is safe for most people, including patients with coronary artery disease, it does come with an increased risk of injury and may not be safe for some, he said.
Researchers still feel that the best approach to fitness is a varied approach that incorporates strength, endurance and speed sessions, as well as flexibility and good nutrition. New studies still prove that traditional endurance training plays a larger role for lowering cholesterol and fat percentages. But if you feel like a little crazy hard work, in a very short time, what's 15 minutes?
Connie Aronson is a health and fitness specialist and certified personal trainer in Ketchum.