What Is HIIT?
We think of interval training as boring and easy, but in the body-fat-reduction business, HIIT stands for high-intensity interval training. Also known as HIIT Core, this workout style is high-intensity, short bursts of intense activity followed by periods of recovery.
The timing of the intervals can vary—and so can the intensity. In my sessions, I build on my cardiovascular strength to help balance out the intensity of the exercise. I will alternate high-intensity interval cardio with low-intensity interval strength training, a set-up that is usually over within 20 minutes or an hour.
There are no scientific studies or a whole lot of research to back up the benefits of HIIT, so it’s difficult to say how it compares to other types of high-intensity exercise.
We could make the case that running or high-intensity cycling is just as effective as HIIT, but there are fewer (and less rigorous) attempts at combining those two activities with HIIT, meaning the combined work is a little bit harder.
The Benefits of HIIT
As suggested by its name, it does involve more work than other types of exercise. But experts say that it works because it is high-intensity. Studies show that a higher intensity of workout can help burn more calories during a workout, leading to weight loss. And we know that low levels of activity (your typical burn rate for jogging, say) can cause the body to fail to function as efficiently as it should. And at what intensity? At maximal physical effort levels, this is the subject of heated debate. And it’s almost impossible to put together an 80 percent rating for everyone.
But HIFT is known to work wonders on healthy people as compared to other types of exercise. The moderate intensity requires brief, repeated bursts of activity, with greater repetition before rest than with some other forms of exercise, such as dancing. Regular moderate-intensity intervals are cited as the gold standard by physicians for the type of exercise with the most potential for damage-reduction.
The calorie-burning effect has not been verified, but it has been observed. One recent study put 132 university students through 25 minutes of HIIT three times a week for a week. It found they burned as many calories as 120 people who were taking part in traditional aerobic exercise and two-thirds the calories of 65 people on two-hour brisk walking sessions. The motivation is simple—more work and thus, more calories burn.
“When we add intermittent workouts into our normal routines, we increase our speed of physical activity throughout the day—exactly what we’re looking for,” wrote Fitness Magazine in an article about the study.
Another study of 70 men and women who were in middle age, with baseline Body Mass Indexs of 18.5 to 21.5, found that of those on HIFT, 55 percent had less body fat after six months; 31 percent had no more than 10 percent body fat. The HIIT training group also reduced waist circumference and men lost more fat than women; men tended to be more active (like “more dense” in the parlance of scientific jargon) and had higher energy expenditure.
One caveat: Results in younger people can be tempered by their age and the fact that many obese people also often have high levels of body fat. So cutting out high-fat snacks and low-carb fare could help.
Could HIIT Work for You?
Most gym memberships don’t offer anything very fancy and require a fair amount of work up front. But although it isn’t easier, HIIT may actually be easier to tolerate because it doesn’t have a lot of pre-workout preparation—hopefully you haven’t been running or lifting weights for the past few months.
In addition, with intermittent workouts, you can nudge your routine to fit into your daily life more. It’s less inconvenient to take a bike ride than it is to exercise on a piece of equipment—and easier to find time each day to do it.