Even if you haven’t tried it, you’ve probably heard the buzz about high-intensity interval training, which alternates short bursts of vigorous exercise with brief periods of active recovery (as in: exercising at a slower pace). Besides being a shorter regimen than most continuous workouts are, aerobic high-intensity interval training, or HIIT, allows you to burn more calories and push your heart rate more than you could with steady-state exercise, thus boosting your overall aerobic capacity faster. Believe it or not, HIIT also confers specific health benefits, some of which are fairly surprising.
Here are four HIIT perks for your body and mind.
It Promotes Better Blood Sugar Regulation
HIIT can help lower your blood sugar levels and reduce abdominal fat, thereby lowering your risk of developing insulin resistance or Type 2 diabetes. In fact, a study published in the July 2014 issue of Applied Physiology, Nutrition, and Metabolism found that a single HIIT session does a better job of modulating the spike in blood sugar that typically occurs after a meal than a continuous moderate-intensity workout does among overweight adults.
“Your muscles are like a large sink that sucks up blood sugar after exercise: When you do HIIT – as opposed to steady state walking, for example – you call upon more muscle fibers to do the work,” explains study lead author Jonathan Little, an assistant professor in the School of Health and Exercise Sciences at The University of British Columbia Okanagan. “As a result, you have a larger sink that’s hungry to suck up blood sugar after exercise.”
For the same reason, HIIT also can be beneficial for those who already have Type 2 diabetes. A study published in the March 2017 issue of the European Journal of Applied Physiology found that people with Type 2 diabetes who did 12 weeks of HIIT (walking or running uphill) gained greater increases in their aerobic capacity and more dramatic reductions in their hemoglobin A1C levels – an average measure of blood sugar over a three-month period – than those who did moderate-intensity continuous walking.
It Improves Blood Vessel Function
HIIT has also been shown to improve vascular (or blood vessel) function. In a review of seven randomized trials, published in the May 2015 issue of Sports Medicine, researchers found that performing HIIT three times per week for 12 to 16 weeks improved measures of vascular function in the brachial artery – a major blood vessel in the upper arm and the primary supplier of blood to the arm and hand – twice as well as moderate-intensity continuous training did. This is significant because good vascular function helps blood vessels relax, which can lower blood pressure. “As we age, endothelial dysfunction (an imbalance in the substances that make the lining of the blood vessels dilate and constrict) tends to occur and is linked to elevated blood pressure and increased risk of heart attacks,” Little explains.
It Reverses Age-Related Muscle Decline
Believe it or not, high-intensity (aerobic) interval training has powerful anti-aging benefits at the cellular level in skeletal muscle: Specifically, HIIT causes cells to make more proteins for their energy-producing mitochondria (their powerhouses), according to a study in the March 2017 issue of Cell Metabolism. When older adults did 12 weeks of high-intensity aerobic interval training (in this case, cycling three times per week), they reaped more robust improvements in their mitochondrial function and muscle protein content than their peers who did resistance training or a combined approach. “For aging adults, supervised high-intensity training confers the most benefits, both metabolically and at the molecular level,” says senior author Dr. K. Sreekumaran Nair, a professor of medicine at the Mayo Clinic in Rochester, Minnesota. So it’s a good investment in aging slowly.
It Can Provide More Enjoyment
As challenging as they are, HIIT workouts appeal to people on a practical level, partly because they’re efficient and effective. But that’s not the only reason for their popularity. A study published in the Jan. 11, 2107, issue of PLoS One examined the differences in people’s enjoyment, mood and perceived exertion between moderate-intensity continuous exercise and HIIT on a cycle ergometer (or, a stationary bike). The study found that 92 percent of participants preferred the HIIT workouts. This may have to do with the structural differences between the two approaches: Moderate-intensity continuous exercise “requires a fixed intensity for a prolonged period of time, where the only sense of accomplishment comes at the end,” explains study co-author Todd Astorino, a professor of kinesiology at California State University–San Marcos. By contrast, HIIT offers a sense of “accomplishment after every single HIIT effort, which may improve how exercisers perceive it.” Plus, he adds, they have a “recovery” bout to look forward to as they’re pushing hard with each high-intensity effort, which can make the protocol more pleasant.
[Read: The Case Against the Weekend Warrior.]
How to Get With the HIIT Program
If you’re already in the exercise habit, you don’t need to work with a trainer to do a HIIT workout. You can do it on your own while jogging, running, cycling or using a cardio machine such as the elliptical trainer or stair climber. “It’s really just a matter of increasing the intensity of the movement ‘til you get to that zone where you feel really challenged while you’re doing it,” says exercise physiologist Cedric Bryant, chief science officer at the American Council on Exercise. If you’re not familiar with HIIT workouts, the key to doing them safely is to start slowly and build up gradually.
Bryant recommends starting with six to 10 repetitions of a 20-second high-intensity bout, followed by a one-minute recovery (doing the same activity at a more moderate intensity); once that becomes easy, reduce the recovery interval to 40 seconds, then gradually work up to a 1-to-1 ratio of high intensity to recovery bouts (20 seconds each). As you feel stronger, you can increase the high-intensity interval to 40 seconds, followed by a one-minute recovery, then work up to 40 seconds for each.
“While it’s a slower rate of progression [than many HIIT programs use], you’ll ensure you’ll stay in a pretty safe range in terms of what you can tolerate from a cardiovascular and a musculoskeletal standpoint, while still progressing,” Bryant says. “Ramp it up by listening to your body: As your body starts to positively adapt, you’ll be able to maintain that high intensity for longer periods of time, recover more quickly and feel ready for that next rep.”
Don’t want to go it alone? Many gyms offer their own versions of HIIT training in group-class settings. Among the perks: The classes are fun, condensed (but sweaty) and sometimes easier to bang out because of the pumping music and camaraderie. The best part? They’re often over in 30 minutes.
