What’s Best for Weight Loss: Sprints, HIIT, or Steady-State Cardio?

New research pulls in data from 36 studies to answer the question.

By Danielle Zickl

• Interval training could help you lose more weight than a continuous moderate-intensity workout, according to a new review and meta-analysis published in the British Journal of Sports Medicine.
• Interval training may make your body more efficient at burning fat, the researchers believe.
• Still, because interval training is more taxing on your body, you need two to three days of recovery between sessions. So you shouldn’t do them daily.

As cyclists, we’re always looking for ways to get faster—and incorporating interval training into our regular routines definitely helps. But new research shows that interval training can do more than just give your performance a boost: It can also help you shed pounds, if that’s your goal.

In the review and meta-analysis, which was published in the British Journal of Sports Medicine, researchers crunched the data from 36 previous studies involving 1,012 people that compared the effects of interval training with continuous moderate-intensity exercise over at least four weeks’ time.

Study authors split interval training into two categories: HIIT and sprint interval training. They defined HIIT as exercise that’s done at 80 percent or more of your max heart rate, and sprint interval training as exercise that’s equal to or higher than your VO2 max (in oth

er words, an all-out effort). While the protocols for each varied among the studies, the most widely-used HIIT routine included 4 minutes of high-intensity work followed by 3 minutes of recovery. As for sprints, most used 30 seconds of “all-out” effort alternated with 4 minutes of recovery, or 8 seconds of work with 12 seconds of recovery.

Moderate-intensity exercise is defined as a continuous effort that where you hit 55 to 70 percent of your max heart rate or 40 to 60 percent of your VO2 max. Again, steady-state routines varied, but ranged from 10 to 60 minutes, with those of 40 to 45 minutes, and 29 to 35 minutes, as the most common.

The findings? While people lost weight and body fat from both types of interval training (HIIT and sprint) and continuous moderate-intensity exercise, interval training as a whole was more effective. Those who did either kind of interval training lost about 29 percent more weight than those who did continuous moderate-intensity exercise.

“Interval training seems to change your metabolism, and higher intensity exercise seems to promote many physiological changes that might favor long-term weight loss,” study coauthor Paulo Gentil, Ph.D., a professor in the department of physical education and dance at the Universidade Federal de Goiás in Brazil, told Runner’s World. “In other words, it makes your body more efficient in burning fat.”

Moderate intensity, on the other hand, doesn’t cause the same changes to your metabolism as higher intensity training does, according to Gentil.

“While [moderate-intensity exercise] burns fat and calories during its performance, it’s been shown that, after its cessation, there are metabolic changes that might make fat loss difficult and favor fat accumulation,” he said. “While that does not mean that low to moderate intensity exercise will make people gain fat, it suggests that the metabolic adaptation to this form of exercise might, at least partially, compensate for the fat [burned] during exercise.”

But just because the research found that intervals are better for weight loss, it does’t mean more intervals are even better. Because these kinds of workouts are more taxing on your body, you shouldn’t do them as often as you do easy runs.

So if you did a really tough speed workout, for instance, that depleted most of your glycogen stores, you will need two to three days of recovery time before you do another one, according to Gentil.

And if you do have a weight-loss goal, you also need to pay attention to what you’re putting on your plate in addition to what kind of exercise you’re doing. Gentil also points out that healthy eating is an important part of weight loss, too, and that pairing a good diet with interval training is the best way ensure weight loss success.

From: Runner's World US