I’ve seen a lot of talk lately about the benefits of high intensity interval training. It is described as the key to fast weight loss, the most efficient use of time in the gym, and the way to the fastest gains in fitness. Since I confine most of my workouts to my lunch break, I decided to explore adding a HIIT routine to my workouts.
I’m not really a fan of most “fast” weight loss plans, for one simple reason. Most of the research shows people who lose weight fast can’t maintain it for more than 12 months. Why? In many cases, people who lose weight quickly do so with “fad” diets, which are can’t be sustained over the long term. After all, who wants to be permanently banned from eating ice cream or bread?
Ultimately, weight loss is about how much you eat, and how many calories you spend. If your average daily calorie consumption stays constant, the only way to lose weight is to exercise more. This means either longer workouts, or workouts at higher intensity.
HIIT high intensity interval training is an approach to workouts intended to provide the greatest benefit with the least time investment. Sessions usually last 10-30 minutes, and are built with a brief warm-up period, followed by altering between high intensity and moderate intensity periods, then ending by a brief cool-down.
The effect of HIIT sessions on seasoned athletes was studied in 1996 by Tabata, where participants exercised at 170% of their VO2 max. In this study, they engaged in high intensity sessions 4 times/week. The control group used steady-state training 5 times/week at 70% of their VO2 max. Over the course of the study, both groups saw gains in their VO2 max, but only those who used high intensity methods realized gains in their anaerobic capacity. It’s worth noting that working out at such a high intensity level 4 times/week is a recipe for injury for the untrained athlete.
Later studies have looked at the effect of the high intensity sessions when done at lower intensity levels. Overall, studies have shown that high intensity sessions performed in the range of 90% of VO2 max provides similar benefits. Curiously enough, a quick VO2 max conversion shows how this compares to a more easily measured heart rate. For me, I’m nearing 95% of my theoretical max heart rate. There’s no doubt that at that intensity level, I would be burning calories at the highest possible rate.
The Bottom Line
These workouts are really no different than classic interval training. Familiar to runners, the use of intervals to improve anaerobic capacity (and therefore speed) is a common training tool. For runners, these techniques help them break through training plateaus and increase their anaerobic threshhold. The result is the ability to run faster, longer, which is reflected in the body’s ability to rid itself of lactic acid. The principles will translate to any form of exercise, and if you’re trying for fast weight loss, this approach is certainly going to burn more calories per hour than a more standard “steady state” workout.
Having said all that, there are two important caveats to consider. First, its commonly accepted that exercising at such high intensities puts you at greater risk of injury. The risk goes up quickly for less well-trained athletes. Finally, its worth remembering that no matter how hard your HIIT session, you can’t lose weight if your habits in kitchen aren’t up to snuff.