HIIT workouts, which alternate short bursts of vigorous exercise with short periods of active recovery, offer some impressive health benefits.
Even if you haven’t tried it, you’ve probably heard of high-intensity interval training, which alternates short bursts of vigorous exercise with short periods of active recovery.
An example of a HITT workout, says Chris Kolba, a physical therapist in the department of sports medicine at Ohio State Wexner Medical Center in Columbus, is “alternating a sprint followed by walking for a specific amount of time or one repetition. There is no set duration of HIIT training, but it’s usually less than 30 minutes.”
HIIT workouts can often be performed with no or very limited equipment.
What is HIIT?
In addition to being a shorter regimen than you would find with most continuous workouts, high-intensity interval aerobic training, or HIIT, allows you to increase your heart rate and burn more calories than with constant exercise. This may be an attractive proposition for U.S. adults who don’t get the 150 minutes of aerobic activity per week recommended by the Centers for Disease Control and Prevention.
“Many people feel they don’t have enough time to exercise,” notes Ivory Howard, a Washington, D.C.-based certified yoga and Pilates instructor. But HIIT workouts can be “effective bodyweight exercises that require very little time and no equipment, making these workouts accessible for more adults to train consistently and stay active throughout life.”
Benefits of HITT
In addition to simply being an efficient way to exercise, HIIT also confers some specific health benefits. Here are four benefits of HIIT workouts for your body and mind.
1. HIIT promotes better blood sugar regulation.
Like other forms of physical activity, HIIT can help you “lower your blood sugar naturally because it makes your body more sensitive to insulin,” says Howard. When your body is more sensitive to insulin, it decreases your risk of developing insulin resistance or type 2 diabetes.
“Physical activity causes your body to demand glucose for energy,” Howard explains, which causes your body to deliver that glucose to your muscles. “As a result, your blood sugar level drops.”
This fact was illustrated in a 2014 study in the Journal of Applied Physiology, Nutrition, and Metabolism, which found that a single HIIT session can do a better job of modulating the blood sugar spike that usually occurs after a meal than a continuous moderate session. intensity training does among overweight adults.
“Your muscles are like a big sink that soaks up blood sugar after exercise: when you do HIIT, rather than steady walking, for example, you draw on more muscle fibers to do the work,” explains the study’s lead author, Jonathan Little. , a professor in the Faculty of Health and Exercise Sciences at the University of British Columbia Okanagan. “As a result, you have a larger ‘sink’ that is hungry to absorb blood sugar after exercise.”
By the same token, HIIT can also be beneficial for those who already have type 2 diabetes. A 2017 study published in the European Journal of Applied Physiology found that people with type 2 diabetes who did 12 weeks of HIIT (walking or running uphill) achieved more significant increases in their aerobic capacity and more dramatic reductions in their hemoglobin A1C levels: an average blood sugar measurement over a three-month period, than those who did continuous moderate-intensity walking.
2. HIIT improves blood vessel function.
HIIT has also been shown to improve vascular (or blood vessel) function. A 2020 study in the American Journal of Physiology-Cell Physiology found that men with high blood pressure who performed HIIT training two to three times per week for six weeks showed marked improvements in blood pressure, with specific vascular benefits seen in the lower extremities. Exercise, in general, improves blood vessel function, but the study confirmed that HIIT also provided benefits in less time than conventional exercise.
Another 2021 study that also lasted six weeks found that HIIT training offers blood pressure benefits and improves blood flow in older adults (study participants were between the ages of 65 and 85).
“As we age, endothelial dysfunction (an imbalance in the substances that cause the lining of blood vessels to dilate and contract) tends to occur and is linked to elevated blood pressure and increased risk of heart attacks,” Little explains. Adding HIIT may help offset some of these natural changes.
3. HIIT reverses age-related muscle decline.
High-intensity interval (aerobic) training also has powerful anti-aging benefits at the cellular level in skeletal muscle. Specifically, HIIT causes cells to produce more proteins for their energy-producing mitochondria (the powerhouses of cells), according to a 2017 study in the journal Cell Metabolism.
When older adults did 12 weeks of high-intensity aerobic interval training (in this case, cycling three times a week), they got more robust improvements in their mitochondrial function and muscle protein content than their peers who did resistance training or a combined approach.
“For older adults, supervised high-intensity training provides the most benefits, both metabolically and molecularly,” says lead author Dr. K. Sreekumaran Nair, professor of medicine at the Mayo Clinic in Rochester, Minn. It appears that HIIT may help slow the aging process somewhat.
Similar findings were published in 2019 in the European Journal of Sport Science. That study found that older adults who participated in HIIT sessions three times a week over a six-week period had favorable skeletal muscle adaptations and more robust mitochondria.
4. HIIT can provide more fun than other forms of exercise.
As challenging as they are, HIIT workouts appeal to people on a practical level, in part because they are efficient and effective. But that’s not the only reason for their popularity.
A 2017 PLoS A study examined differences in people’s enjoyment, mood, and perceived exertion between moderate-intensity continuous exercise and HIIT on a cycle ergometer (or stationary bike). The study found that 92% of participants preferred HIIT workouts.
This may have to do with structural differences between the two approaches. Moderate-intensity continuous exercise “requires a fixed intensity over an extended period of time, where the only sense of accomplishment comes at the end,” explains study co-author Todd Astorino, professor of kinesiology at California State University, San Marcos.
In contrast, HIIT offers a sense of “accomplishment after each HIIT effort, which can improve how users perceive it.” Plus, he adds, they have a bout of “recovery” to look forward to, since they are pushing hard with each high-intensity effort, which can make the protocol more enjoyable.
Challenges of HIIT workouts
However, Mike Matthews, a certified personal trainer, podcast host, and founder of Legion Athletics, a sports supplement company based in Clearwater, Florida, says that to really participate in HIIT workouts requires a lot of intrinsic motivation because you have to push yourself hard to reach the intensity demanded by the protocol.
“It’s an all-out effort, and after 30 to 60 seconds you’re completely exhausted. A lot of people just don’t want to do that and start to dread their workouts.” When that happens, you may be tempted to skip workouts or find it difficult to follow the protocol.
Matthews says he used to be “a bigger advocate of HIIT in the past than I am now” because while it can burn a lot of calories in a short period, this approach to exercise can be hard on the body. “If you go out and run sprints, you’re going to get really sore,” he says, a situation he has personal experience with when he did a lot of HIIT workouts when he was in his 20s. That soreness got in the way of his strength training workouts on other days. He eventually moved on to more moderate cardio workouts.
Getting there with the HIIT program
If you’re already in the habit of exercising, you don’t need to work with a trainer to do a HIIT workout. You can do it on your own while jogging, running, biking, or using a cardio machine such as an elliptical trainer or stair climber.
“It’s really just a matter of increasing the intensity of the movement until you get into that zone where you feel really challenged while you’re doing it,” says exercise physiologist Cedric Bryant, president, and chief scientific officer of the American Council on Exercise. which is based in San Diego.
If you’re unfamiliar 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 it becomes easy, reduce the recovery interval to 40 seconds, then gradually work up to a 1-to-1 high-intensity ratio for the recovery bouts (20 seconds each).
As you get 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. When you’re in the high-intensity zone, your heart rate should be 80% to 95% of your maximum heart rate. (Calculate your maximum heart rate by subtracting your age from 220. Talk to your doctor about any underlying conditions you may have that effect whether it’s safe for you to exercise at that level.) During the recovery portions of exercise, your heart rate should be around 55% to 65% of maximum.
“While that’s a slower rate of progression (than many HIIT programs use), you’ll be sure to stay in a fairly safe range in terms of what you can tolerate from a cardiovascular and musculoskeletal standpoint as you continue to progress,” Bryant. says.
“Get better at listening to your body. As your body begins to positively adapt, you’ll be able to maintain that high intensity for longer periods of time, recover more quickly, and feel ready for the next repetition.”
Don’t want to go it alone? Many gyms offer their own versions of HIIT training in group class settings. Among the advantages: the classes are fun, condensed, and sometimes easier to get along with because of the upbeat music and camaraderie. The best part? They’re usually over in 30 minutes.
Vary your workouts
Kolba notes that while HIIT is a good form of exercise, “it’s not the best or only way to exercise.” Consistency is more important than participating in a specific type of exercise, and “it’s important to find an exercise routine that you enjoy and that is in line with your goals. It’s also good to have a variety to help maintain interest and consistency.”
He also points out that when you’re participating in a HIIT workout, you really have to push yourself to achieve that maximum exertion range and get the results you expect. At the same time, you have to be careful not to injure yourself. Therefore, “beginners should seek qualified instruction and start slowly, working up to near maximum effort level, giving their bodies time to adapt and avoid injury.”
Howard adds that when doing HIIT workouts, remember that the best part is a key component of how it all works. “Take your rest days seriously. Rest days are just as important as training days because they help heal and prevent injury.”
While HIIT is an effective workout with many benefits, “it’s not right for everyone. Before making changes to your exercise plan, you should discuss your medical history and fitness goals with your health care providers so you can make an informed decision about your health.”