How many people do you know who devoutly believe in the fat-burning capacity of cardio? Maybe you are or have been, one of those people: toiling away on a treadmill or stationary bike, wondering why all the time and effort you’re putting in isn’t paying off with weight-loss results. The thing is, steady-state cardio just won’t deliver the six-pack abs and toned, muscular physique you’re dreaming of. But high-intensity interval training (HIIT) appears to actually live up to the hype. Here’s what you should know about HIIT workout plans.
Originally developed by track coaches to train runners, HIIT workouts have now crossed over into the fitness industry at large and gained massive popularity. Exciting and compelling research indicates that this training method can help you burn significantly more body fat—and in a shorter amount of time—than steady-state cardio can.
During a high-intensity interval training, or HIIT, workout, you alternate between periods of intense, all-out exertion and periods of recovery. This workout approach is a total deviation from the slow-and-steady mentality most people bring to cardio. Rather than running on a treadmill at around 70% exertion for 30 minutes or an hour, you’ll instead sprint at 90% of your max heart rate, then walk or take a complete rest until your next interval of sprinting.
The quick bursts of exertion send your heart rate soaring, which unlocks a wealth of cardiovascular fitness benefits, dramatically alters your body composition, and delivers full-body fat-loss results in far less time than traditional training plans do.
And running is not a requirement for HIIT workouts. Anything that gets your heart pumping is fair game. Popular HIIT exercise options include:
You can mix and match exercises to suit your mood or work around injuries or soreness. The key to the impressive results HIIT workouts can deliver is following the work-to-rest intervals.
Decades ago, when interval training was first developed, it had a different name—”fartlek” training. While that may sound somewhat hilarious to English speakers, it makes perfect sense to Swedes. “Fart” means speed in Swedish and “lek” means play. Put them together and you get “speed play,” which is a very appropriate description for HIIT workouts.
The workout methodology formerly known as fartlek has been the subject of numerous rigorous research studies. Those who have looked into its benefits have consistently found that high-intensity interval training outperforms steady-state cardio, especially when it comes to fat loss.
Since the early 1990s, studies have shown that HIIT workouts for men as well as HIIT workouts for women can deliver tremendous results.
One of the first serious investigations of high-intensity interval training came in 1994 when a team of researchers at Laval University in Quebec compared the weight-loss results of a group of young men and women who followed a 15-week HIIT plan to those of a group who followed a 20-week steady-state endurance plan. Although the steady-state participants burned about 15,000 more calories during their workouts, the HIIT participants lost significantly more body fat.
Subsequent studies found that the reason high-intensity interval training burns fat so effectively is that it increases your resting metabolism even after you’re done working out, due to something scientists call excess post-exercise oxygen consumption.
According to findings published by a team from the Baylor College of Medicine, participants who carried out a HIIT workout on a stationary bike burned far more calories over the entire 24-hour period following the workout than those who cycled at a moderate intensity.
A separate study found that subjects who did HIIT workouts burned approximately 100 more calories each hour for up to a day after their workouts.
Research also shows that high-intensity interval training can boost your body’s fat metabolism by increasing the fat-burning capacity of your muscle cells and slowing fat production.
According to a study published in the Journal of Applied Physiology, HIIT workouts can increase both the levels of muscle enzymes responsible for fat oxidation (the technical term for fat burning), as well as lead to a 30% increase in the amount of fat burned.
And the Laval University study mentioned earlier showed that high-intensity interval training increased the number of markers for fat-burning processes in the participants’ muscle fibers.
Plus, HIIT workouts also decrease fat cell production. A team from the Norwegian University of Science and Technology discovered that when individuals followed a 16-week HIIT training program, their levels of a fat-producing enzyme called fatty acid synthase dropped by twice as much as those who adhered to a moderate-intensity exercise program.
Last but certainly not least, a recent study published in the American Journal of Physiology highlighted yet another way that high-intensity interval training maximizes fat loss. The authors found that after 6 weeks of HIIT workouts, participants had elevated levels of a special kind of protein found in your muscles that transports fat into your mitochondria, the powerhouses of your cells, where it’s burned for fuel. Levels of those proteins rose by a remarkable 50%—and the higher those levels go, the greater your fat-burning results during your workouts and after them too!