Do HIIT Workouts Live Up to the Hype?

Give a 10-minute HIIT workout a try for a new, fitter you

If you are a regular at the gym, then there is a good chance you’ve heard about a type of workout called “high-intensity interval training” or “HIIT” for short, which promises results from exercising for as little as 10 minutes. Skeptical? You might be surprised.

Although many exercisers think of HIIT as something new, it has been around for decades. “In the 1950s, it was very popular with Olympic athletes,” says Joyce Parsons, PT, CSCS, a physical therapist and certified strength and conditioning specialist at Elliot Rehabilitation Services in Londonderry. What is new about HIIT is that everyday exercisers in addition to elite athletes are including HIIT in their workout routines.

The hallmark of HIIT is alternating bursts of high-intensity, primarily cardiovascular, exercise with periods of lower-intensity movement that allow the body to recover somewhat, but not fully. Unlike some trends that quickly sweep through the exercise world only to quietly fade away, HIIT comes with a hallowed history and some convincing science behind it. But the most compelling aspect of HIIT for many exercisers is that it provides the same health benefits — plus extra — as a conventional workout, but in a fraction of the time.

Traditional aerobic activity such as brisk walking, jogging, cycling or swimming is performed at a fairly consistent pace, raising the speed of the exerciser’s heartbeat to around 60 percent of its maximum rate, says Dain P. LaRoche, PhD, associate professor of kinesiology at the University of New Hampshire. Such continuous, moderate-intensity exercise has been shown to provide a wealth of health benefits.

HIIT delivers the same benefits, but through a different exercise approach. HIIT’s high-intensity surges of activity are performed at about 80 to 90 percent of maximum heart rate, which is the highest number of times your heart should beat per minute during exercise, while the lower-intensity periods that are woven into HIIT allow your heart to slow to about 40 to 50 percent of your maximum heart rate. During the less-strenuous segments, the exerciser jogs or walks briskly or does something else to keep the heart rate elevated to the proper level. “It’s not like you’re sitting and resting,” LaRoche says. “You just lower the intensity way down.”

The tough parts of HIIT are demanding for sure, but the good news is that you don’t have to sustain that level of exertion for long. The duration of the high- and low-intensity portions can vary, but often a one-to-one ratio is used, with the exerciser working all-out for a minute or two, moving less vigorously for a minute or two, and then returning to the strenuous activity, continuing to alternate between the two exertion levels. “That work-to-recovery ratio will probably vary with the intensity” of the exercise, LaRoche points out. If you are working very hard during the high-intensity parts of HIIT, the “active recovery” portions might need to be longer to enable your heart rate to come down to where it should be.

But “the going back and forth” between the very difficult and easier activity is key, Parsons says, so don’t be tempted to skip the less-intense parts of your HIIT session. “It’s important that you’re achieving that low heart rate,” Parsons says. “You need that rest period in order to get the wonderful changes that HIIT provides.”

Commonly, a complete HIIT workout is as brief as 10 or 20 minutes, or up to an hour long. Done properly, even 10 minutes of HIIT “has been shown to have some pretty significant benefits,” LaRoche says. HIIT provides all of the usual health perks of aerobic exercise, such as strengthening the heart, increasing blood volume, improving muscle capacity to generate energy and process carbohydrates and fats as fuel, lowering blood glucose and blood pressure levels, and changing the exerciser’s body composition to one that has less fat and more muscle mass.

But HIIT can do all that in less time than a steadily paced workout — and goes further by boosting the exerciser’s calorie burn after the workout has ended, while the body works to recover from the high-intensity exercise, Parsons says.

And don’t automatically let the “high-intensity” part of the workout scare you away. Check with your doctor to be sure HIIT is for you, of course, and although it’s true that the ideal candidate for HIIT is a committed, regular exerciser who is already pretty fit, just about anyone can do HIIT, Parsons says, because it can easily be adapted to suit individual needs and preferences. “You can do a HIIT program on a bike, on a rower, on a treadmill, speed walking — as long as you’re getting the heart rate up to a certain level and then bringing it down for a rest period, you’re doing a HIIT program,” Parsons says. Being able to tailor the type of activity and intensity level to the individual makes HIIT a great option for serious athletes and former couch potatoes alike.

Indeed, HIIT is being used by obese people who haven’t exercised in many years, cardiac patients and people with diabetes, LaRoche says. “It’s being used in clinical settings and it’s also being used by the average person who is looking to make health and fitness gains,” he says.

HIIT’s universality makes sense because, if you think about it, the structure of HIIT parallels our natural inclination to take exercise down a notch when we can’t sustain the work. Beginning joggers, for example, often intersperse jogging with walking breaks when they feel too winded. So perhaps it’s not a complete surprise that those who struggle to get through a continuous bout of activity often find that they tolerate HIIT better than a conventional exercise approach that requires them to sustain steady physical work for 15 or 20 minutes or more, LaRoche says.

If starting the new year with shorter, customizable workouts that bring great results sounds appealing, then add HIIT to your exercise routine once or twice a week while sticking with more moderate, longer-duration activity the rest of the week. You might not exactly look forward to HIIT, but you might enjoy it more than slogging through a long, moderately paced workout.

Track your heart rate for the best results

With today’s technology, tracking your heart rate is easy, but accuracy among tracking devices can vary. Studies show that wrist-worn heart rate monitors “are not nearly as good” as devices that require a chest strap, and gym equipment that has heart rate sensors built into the handgrips are not reliable, says Dain P. LaRoche, PhD, associate professor of kinesiology at the University of New Hampshire. “The farther away you get from the heart, the lower the level of accuracy of those sensors,” LaRoche says.
If you don’t mind doing a little math, you can always skip the tech and keep tabs on your heart the old-fashioned way:

First, determine your maximum heart rate by subtracting your age from 220. The maximum heart rate of a 20-year-old, for example, is 200 beats per minute.
Next, since you don’t want to exert yourself too much or too little during exercise, determine the heart rate range you should stay in. Find the high end of your range, let’s say 80 percent of your maximum heart rate, by multiplying your maximum heart rate by .8. A 20-year-old performing HIIT, for example, should aim for 160 beats per minute during the intense parts of the workout.

Finally, to figure out how fast your heart is beating per minute, find your pulse on your wrist or neck and count the number of beats that occur in 10 seconds, and then multiply that number by six. That number will likely be accurate enough to help you know if you’re in the right range during your workout, LaRoche says.

You can also judge how hard you’re working by how hard you think you’re working. Perceived exertion can be an effective benchmark, LaRoche says. Just aim for a high level of exertion if you are trying to perform at a high intensity — say, an eight out of 10, with 10 being the most difficult. “If you’re trying to have a conversation and you can’t get too many words out, you’re probably in that [high-intensity] range,” LaRoche says.

In contrast, your effort during less-intense activity should feel something akin to a three, four, or five on the exertion scale, the way you would feel if you were walking briskly, says Joyce Parsons, PT, CSCS, a physical therapist and certified strength and conditioning specialist at Elliot Rehabilitation Services in Londonderry.
“One of the best ways to train is based on your heart rate,” Parsons says. Paying attention to how fast your heart is beating can help make your workouts more effective, as well as safer.

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