You can always rely on a high-intensity workout to leave you feeling sweaty and exhausted. But a longer workout isn’t necessarily better. And a new approach that’s gaining fans on social media only requires a few minutes of your time to get major health benefits.
The workout, reduced-exertion high-intensity training (REHIT) workout, is still intense, but it’s shorter than a typical high-intensity interval training (HIIT) workout, explains Stephanie Mansour, certified personal trainer and TODAY fitness contributor, tells TODAY.com.
While a regular HIIT workout can of course be short too, “these REHIT workouts have to be short,” she says, “So they’re like, 10 to 15 minutes max.” Not only is the total workout time shorter, but so are the intervals of work that you’re doing, Mansour says.
Is it really possible to get a good workout in such a short amount of time? Experts and research suggest that, actually, yes, a short workout like this — when done in a specific way — can be extremely beneficial.
And it’s likely to be especially helpful for certain groups of people.
What Is a REHIT Workout?
Interest in HIIT started to grow about a decade ago because people saw it as a way to get “more bang for your buck in terms of a shorter time commitments and greater gains,” Lance C. Dalleck, Ph.D., professor of exercise and sport science at Western Colorado University and member of the American Council on Exercise Scientific Advisory Panel, tells TODAY.com.
And HIIT is generally more efficient at burning calories than continuous or steady state workouts. But, he explains, even with the shorter time commitment, people tend to find HIIT really hard and taxing. That’s where REHIT — reduced-exertion high-intensity training — comes in.
It’s a type of high-intensity interval training, a format of exercise that relies on periods of work alternated with periods of rest. In a normal HIIT workout, it’s common to exercise for 45 minutes with escalating intervals of work, Mansour explains.
But with REHIT, both the total workout time and the intervals of intense training within the workout are shorter than in a normal HIIT session, says Dalleck, who has published multiple studies investigating the potential benefits of REHIT.
“It’s not like you’re building up your speed or building up your strength,” Mansour says. “It’s an all-out sprint for the 20 seconds of that interval.” On the flip side, your rest periods are longer than you’d get in your usual HIIT class, typically around 3 full minutes.
Even though you’re working at your maximum of exertion during those short bursts, the overall shorter duration and extended rest time make it feel more doable, Dalleck explains.
In a HIIT class, you might only be given 30 seconds or a minute of rest before your next interval starts, he says, and “your heart rate and your breathing is still elevated.” Allowing yourself to more fully recover in REHIT both makes the workout feel less subjectively taxing and “allows for that subsequent maximal effort to be what it should be, which is pretty hard,” Dalleck explains.
The REHIT protocols used in research, performed on a specific type of stationary bike that utilizes AI, typically follow something along the lines of this format:
- Warm up for 2 minutes.
- Sprint for 20 seconds.
- Rest for 3 minutes.
- Sprint for 20 seconds.
- Cool down for 3 minutes.
The total workout time is just 8 minutes and 40 seconds, and is performed three times a week.
But, as with traditional HIIT, the REHIT format is versatile enough to be applied to just about any type of workout you enjoy doing — as long as you can safely perform it at a high level of intensity.
The Science Behind REHIT
While REHIT might sound like a gimmick, there is some solid scientific evidence to back up the way it works, Dalleck says.
“What it boils down to is our mitochondria, where we are regenerating or creating our energy currency, which we call ATP,” he explains. Turning on the bodily systems that increase the activity of mitochondria is based on our use of muscle glycogen, our main carbohydrate.
All it takes to use up enough of that muscle glycogen to flip the switch is a few 20-second intervals of maximum effort activity. “That signals our body … we’re using a lot of energy really quick, and we have a need to make more energy really quick, so we need to make more mitochondria,” Dalleck explains.
Essentially, your body adapts. And this is one of the processes that contributes to the cardiorespiratory benefits of exercise, and it promotes heart health and even longevity.
REHIT is really an attempt to find the minimum dose of interval training to get you this type of mitochondrial response, Dalleck says. So, doing additional sprints doesn’t have any additional benefit because you’ve already hit the threshold to activate this system.
REHIT Workout Benefits
The most obvious benefit of REHIT is the short time. These workouts are intentionally short, meaning you can squeeze them in before or after work or while traveling.
“You can get that workout in, pretty quickly get some fitness gains or even maintain fitness,” Dalleck says. Maybe you can’t do your normal runs over the holidays, for instance, but a REHIT session here and there can help ensure you don’t lose fitness progress.
REHIT is also ideal for people who are experiencing a weight-loss plateau, Mansour says. If you do a lot of high-intensity workouts without much rest, you’re likely taxing your body more than you need to in order to get the benefits of exercise, she explains.
That, along with other kinds of mental and physical stress, can cause your levels of cortisol to rise, a hormone that may actually impede weight-loss efforts.
If that’s the case for you, Mansour says, “lowering the amount of time that your body’s under stress (during the workout) and also lowering the amount of time of the workout in general can be really helpful.”
Those intervals of maximum effort will still cause a cortisol spike, she explains, “but it’s for a shorter amount of time, and then you have a longer recovery after. So the cortisol spike isn’t as high for as long of a time as with a traditional HIIT workout.”
REHIT workouts have also been shown to lower risk factors for type 2 diabetes and improve glucose metabolism, Dalleck says. Other research has shown improvements in insulin sensitivity following REHIT sessions.
You can also think of REHIT like a mental reset, Mansour says, or a way of retraining yourself and your body to get reacquainted with a healthy balance of work and rest intervals again.
And if you’ve been exercising intensely in one way for a long time, this can help you shake up your routine while still doing the type of fitness that you enjoy.
How to Start
You don’t need a fancy, AI-powered bike to get the benefits of REHIT. “Whatever you’re doing that you already like, you could apply this to your workout,” Mansour says.
And, Dalleck adds, his research team has found that many types of functional at-home workouts can provide benefits when performed with a REHIT format, including medicine ball drills and bodyweight exercises.
Whether you’re a fan of Pilates, strength training, running, cycling or walking, there’s a way to use REHIT “to make it a little bit more exciting or different, or change what your body expects,” Mansour says. For instance, see how many crunches or jump squats you can do during those sprint intervals, she says.
However, because REHIT involves max effort pushes and working at fast speeds, it’s important not to sacrifice your form in an effort to get more reps, Mansour cautions. If you know you’re going to be doing an exercise quickly with all-out effort, she recommends doing a few reps slowly in front of a mirror first to make sure your form is solid.
Dalleck emphasizes that people should not drop all of their favorite workouts in favor of doing REHIT for the rest of their lives. Instead, REHIT should be individualized to your preferences and experience level.
For example, rotate in a few REHIT workouts when the weather’s nice enough to be outside, when your spin classes have gotten stale, when you’re short on time or when you’re feeling stressed out. Think of it as “another tool in your kit of different options,” he says.
