By Melanie Radzicki McManus, CNN
For many people aiming to burn a lot of calories, high-intensity interval training is the way to go.
Also known as HIIT, these popular workouts feature bursts of intense activity, such as squats or lunges, followed by recovery time. A HIIT routine can torch more calories than a traditional endurance workout while being performed in a shorter amount of time. Numerous studies also show interval training can provide the same health benefits as one continuous workout at a moderate intensity, according to a review published last year in the International Journal of Environmental Research and Public Health.
With all of these positives, it’s not surprising that HIIT workouts were one of the top 10 fitness trends predicted for 2022, according to the annual survey of health and fitness trends conducted by the American College of Sports Medicine, and they have been among the top 10 fitness trends since 2014. Yet HIIT workouts require maximum exertion, which means they aren’t for every day — or necessarily for everyone.
There are three similar forms of interval training that may be a better fit for your training goals and needs — and you may even inadvertently be doing them, said certified fitness instructor Austin Brock, cofounder of Slash Fitness in Delray Beach, Florida.
“Since there are so many different variations of these types of workouts, facilities tend to use the acronym people are most familiar with, and that’s HIIT,” Brock said. “But that might not be what you’re really doing.”
True HIIT workouts last 20 to 60 minutes and feature intense work periods ranging from five seconds to eight minutes, according to the American College of Sports Medicine. These routines are performed at 80% to 95% of your maximum heart rate, which is a state where you can talk but need to take breaths every few words, Brock said. Recovery periods may last as long as the workout phases.
Here’s one example. After warming up, pedal a stationary bike — set to some level of resistance — as fast as you can for 30 seconds, then pedal slowly for one minute. Repeat 10 to 20 times, finishing with a cooldown. You can also perform HIIT workouts using body weight, via circuits of exercises such as air squats, burpees (a combination of a squat thrust, plank and a squat jump) and lunges.
Read on for the different forms of interval training and how they can help you accomplish your fitness goals.
Important note: Whether you’re performing these workouts at maximum intensity or in an easier, modified form, they’re still demanding. Experts recommend doing them only two or three times a week, with at least 48 hours in between sessions to allow a full recovery.
Boost endurance: High-volume intensity training
An HVIT workout, designed to increase endurance, emphasizes volume over intensity and is longer than a HIIT session. While these workouts typically start with high-intensity repetitions, the intensity levels decrease as the workout continues, said Hannah Daugherty, a certified personal trainer and health coach based in Richmond, Virginia.
Here’s an example: Alternate 60 seconds of jump squats, burpees, mountain climbers and jumping lunges with 30 seconds of rest. Since you’re doing a higher volume of exercises with shorter rest breaks, your effort will naturally decrease over time.
“The jump squats might start at 100% effort, but then the burpees might be at 90%, then the mountain climbers at 85% and so on,” Daugherty said.
Full-body workout: Variable-intensity interval training
A VIIT workout is the sweet spot between HIIT and HVIT sessions, Brock said, featuring intervals of hard, medium and low intensity. During a typical VIIT workout, you’ll begin with a high-intensity interval, segueing into a medium-intensity interval with an emphasis on strength and endurance — think a series of squats. The final phase is a low-impact, low-intensity recovery activity, such as holding a plank position. This series is repeated several times.
“Variable intensity workouts are great because they use the entire gauntlet,” Brock said, offering a more complete, full-body workout.
The next level: Sprint-interval training
A SIT workout, geared toward serious athletes, involves pushing your body to its limits multiple times, followed by long periods of recovery. During a SIT workout, you might run as fast as you can for 30 seconds, then rest or walk for four or five minutes, repeating four to six times. Such intervals can be done while swimming, cycling, rowing, etc., with the purpose of enhancing your athletic performance.
Which workout is best?
The workout best for you depends on your goals and fitness level. If losing weight is your aim and you don’t have much time, the shorter, calorie-busting HIIT workouts may be the way to go. If you’ve got a long hike or endurance event in your future, consider HVIT workouts. A VIIT routine may be an option if you’re looking to improve overall fitness.
No matter which option you select, proceed with caution as they all include high-intensity work. “A box jump might not seem hard in the beginning,” Brock said, “but as you tire, your form can become compromised, and you can injure yourself.”
The good news is that HIIT, HVIT and VIIT workouts can be modified to work for anyone, even novices. Doing so is accomplished through shorter work intervals, lower intensity levels or fewer repetitions. You can also adjust the actual exercise.
“If the exercise for a specific interval is squat jumps, switch to regular squats,” Brock said. “Over time, you can increase the intensity level, depending upon your goals and health history.”
Dialing back these workouts will mean a lower calorie burn and a less intense heart workout, but that doesn’t render them useless. You’re still using the same musculature and getting the same strength benefit, Brock said.
You can also raise your heart rate in safer ways until you become fitter. For example, swap out jumping lunges with regular lunges performed while holding weights. Or cut your rest periods from 30 seconds to 15.
Don’t feel bad if you discover these workouts are not your style. Many people don’t enjoy high-intensity work. However, it’s important to find another exercise you do enjoy, said Dr. Tamara Hew-Butler, associate professor of exercise and sport science at Detroit’s Wayne State University.
“People need to move to reap the many mental and physical benefits associated with regular physical activity,” Hew-Butler said, “regardless of what we call it or what exercise fad is currently marketed.”
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Sign up for CNN’s Fitness, But Better newsletter series. Our seven-part guide will help you ease into a healthy routine, backed by experts. Melanie Radzicki McManus is a freelance writer who specializes in hiking, travel and fitness.