A true HIIT session will incorporate several rounds of short high-intensity cardiovascular bursts followed by brief periods of rest. Photo / Gritchelle Fallesgon, The New York Times
Done correctly, high-intensity interval training is one of the most efficient forms of exercise. Here’s how to do it.
Workout trends come and go, but when it comes to the biggest bang for your buck, high intensity interval training, or HIIT, has staying power.
HIIT’s specific origins are uncertain; some say it dates back to at least the early 1900s and Finnish Olympic runners who would use alternating short bursts of intensity with brief bouts of recovery to bolster their overall speed. Today, it remains one of the “Top 20 Worldwide Fitness Trends” according to the American College of Sports Medicine.
But ask 10 people what a HIIT workout is, and odds are, you’ll get 10 different answers. The fitness industry has created a wide variety of iterations that aren’t actually HIIT.
A true HIIT session will incorporate several rounds of short high-intensity cardiovascular bursts — usually not more than 20 seconds — followed by brief periods of rest. This allows you to complete a workout that delivers substantial fitness results in just 30 minutes or so. It usually requires little to no equipment, and you can pick your preferred method of cardio.
To achieve true high intensity, however, you have to work hard. You must get your heart rate above 80 per cent of your absolute maximum before letting it barely recover, and then doing it all over again. “Make your intensity hard enough that you can’t hold a conversation, then recover and begin again,” said Danyele Wilson, a trainer and coach for the fitness app EvolveYou.
“That’s key, and what sets HIIT apart from other workouts,” Wilson said. “Holding a plank for a minute isn’t going to get your heart rate there, for instance. You need to feel like you couldn’t go all out with this movement for more than eight to 10 seconds at a time.”
When added to a regimen of standard cardio exercise and strength training, HIIT can boost your overall fitness, improve health metrics, increase your calorie burn rate and lead to better performance in competitive sports. Here’s how to reap those benefits.
The chief argument for a HIIT workout is its potential to produce cardiovascular fitness gains in a short amount of time.
A 2019 review of research studying the health benefits of HIIT found that it was a more efficient approach to aerobic training, compared to steady-state cardio exercise — which keeps your heart rate in the same general range for an extended period. A small 2020 study of sedentary men between the ages of 43 and 73 found that performing HIIT over just six weeks significantly decreased their high blood pressure.
In addition to improving heart health, many people choose HIIT as a means to lose weight, said Cedric Bryant, president and chief science officer of the American Council on Exercise. “You’re getting a higher average calorie burn from HIIT than a steady-state session for the same amount of time.”
And while this may be true, the best reason to incorporate HIIT into your exercise routine, according to Wilson, is to improve performance, whether you’re a competitive athlete or not. Performance, she explained, means training your whole body to move efficiently and with more agility.
“It’s improving your capacity to move well in different directions,” she said. “That can mean anything from LeBron James on the basketball court to an elderly man preventing himself from falling after tripping. It’s about quality of life.” That said, you may want to talk to your doctor or physical therapist before incorporating HIIT into your workout.
For Sunna Yassin, a 42-year-old event planner from San Francisco, HIIT was a way to allow her body to do other activities she liked. In the beginning, she found the exercise hard on her knees, but that changed as she grew stronger.
Over the course of 18 months, Yassin said, “my body became better able to take the pressure of activities like kickboxing or jumping.”
There’s a lot of confusion around what counts as HIIT. Some gyms or trainers refer to any circuit training — a variety of exercises done one after the other — as HIIT. While these workouts might be difficult, most won’t get your heart rate high enough to qualify. For instance, a runner sprinting for 3- to 5-minute spurts with rests in between is running intervals, but not doing HIIT.
CrossFit is another workout people commonly mistake for HIIT, Wilson said. “CrossFit is not HIIT, although a CrossFit workout may enlist an HIIT circuit within it,” she explained. “But they are not one and the same.”
An actual HIIT session — the short-bursts portion of the workout that causes a high heart rate — might be only 10 minutes long, especially for beginners. However, “you will also take 5 to 10 minutes to slowly warm up with gentler movement, perform the HIIT circuit, then cool down for 5 to 10 minutes,” said Sabrena Jo, an exercise and health scientist with the American Council on Exercise.
For those new to HIIT, once per week is a good starting point. While you can do a HIIT session by itself, Wilson often does one at the end of another workout. “I might pair it with leg day, for instance,” she said, doing “super sets” of combined movements like squats and lunges, and then finishing with a 10-minute HIIT workout.
Once you are comfortable with them, aim for two to three sessions per week, but not more, said Holly Roser, a personal trainer in San Francisco. “After that, you could become more susceptible to injury.”
Avoid HIIT if you have a cardiac condition, are recovering from injury or regularly experience vertigo. If you’re pregnant, consult with your doctor beforehand.
In the beginning, you might have to shorten the length of an interval or two to catch your breath, said Roser, or find yourself slowing down toward the end of a session. But after about a month of regular HIIT, you should be able to get through one and notice an improvement, for instance, in how fast you can run, bike or row on an ergometer. By then you can try tweaking the ratio of exercise to rest so that you rest for shorter periods of time.
You can perform HIIT at home, at the gym or in a group class setting, and it requires little to no equipment — though if you have access to a treadmill, bike or rowing machine, they work well. Short bursts of running, jumping jacks, burpees, mountain climbers or squat jumps can also be effective. This makes HIIT convenient, and also easy to do when travelling.
Remember, these workouts are meant to be hard. In the moment, pushing yourself to 80% of your body’s maximum heart rate may feel intimidating, but it can also feel rewarding, said Melissa Vasquez, a 31-year-old Brooklyn sales professional. “I like to do a workout that scares me a bit,” she said. “After finishing a HIIT session, I feel very satisfied for facing down that challenge.”
If you’re new to the HIIT format, a good way to ease in is to pick a single cardio-focused machine or exercise. The treadmill is often the least intimidating for beginners. After a warm up, try sprinting as fast as you can for 10 seconds, then walking or resting for 50 seconds. Repeat this six times.
That’s it, you’re on your way to mastering HIIT. As you get comfortable, try shortening the rests to 20 seconds, and then even 10.
An even more effective HIIT workout includes exercises that last longer than rest times. One standard format for this is Tabata, which often combines multiple movements over several rounds. One Tabata round lasts for 4 minutes and consists of eight sets — each containing 20 seconds of hard exercise and 10 seconds of recovery. Many trainers suggest doing four rounds in total, but if that is too difficult, start with two.
Begin with a 5-minute warm-up. Then perform one round of eight sets. During each set, do as many repetitions as possible. After each round, take a one-minute rest and then do another round until, ideally, you’ve reached four. Finish with a 10-minute cool down. Getting the timing right can be hard, so consider using a workout app to signal each break.
Because HIIT is so intense, be sure to keep your number of weekly sessions to just one or two in the beginning, slowly increasing them to up to three times per week once your body is more accustomed to the work. Always feel free to stop if you’re feeling lightheaded, dizzy or simply too out of breath to continue.
Here’s one version of Tabata-style HIIT that requires minimal equipment. Before trying the workout, do an easy run-through of each move to ensure you are comfortable with it. If any move proves difficult because of a mobility issue, feel free to swap it out for a different one. The goal is to get your heart rate up with these combination of exercises, so choose those that work for your body. As time goes by, swap in new exercises for variety.
Round 1 (4 minutes)
Rest for one minute
Round 2 (4 minutes)
Rest for one minute
Round 3 (4 minutes)
Rest for one minute
Round 4 (4 minutes)
This article originally appeared in The New York Times.
Written by: Amanda Loudin
Photographs by: Gritchelle Fallesgon
©2023 THE NEW YORK TIMES
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