How to Get the Benefits of HIIT Workouts—Without Burning Out#

Remember the buzzy boutique fitness classes that soared in the mid to late-2010s? There was a time when you couldn’t skim a stone down 23rd Street in Manhattan without it ricocheting off three different studios, each offering their unique spin on high-intensity interval training, or HIIT.

I pretty much lived in those studios, hitting three or four classes a week—oftentimes more. But now? Those classes just feel like, well, a lot. Honestly, I get tired just thinking about it. And it turns out, I’m not the only one.

According to a 2025 report from the Sports and Fitness Industry Association, participation in high-intensity interval training (HIIT) and bootcamp-style workout classes has been slipping since 2019, while functional fitness and low-impact workouts like Pilates and yoga have been gaining ground.

“You’re definitely hearing it and seeing it, along with the rise of strength and Pilates,” says Sam Tooley, a performance coach and the co-founder and CEO of group fitness studio Alpha Fit Club. “I think they’ve given what appears to be the same customer base that would have attended HIIT classes, which were way more prominent, a different alternative that is resonating.”

While it’s normal for fitness trends to come and go, industry experts think there’s something else going on when it comes to the drop-off of interest in HIIT workout classes.

“HIIT sessions tax both our aerobic and anaerobic capacity, while also putting a significant physical load on multiple muscle groups at the same time,” says Jesse Shaw, DO, USAW, sports medicine physician and associate professor of sports medicine at the University of Western States. “Due to the unique stress and the often heavy and intense movement required, people burn themselves out.”

But there’s nothing inherently wrong or unsustainable about HIIT workouts. In fact, with benefits to V02 max, cardiovascular health, and overall athletic performance, it’s one of the more valuable components of any well-rounded fitness regimen. So we talked to the experts to find out why people are losing interest, and how you can take advantage of everything these workouts have to offer—without burning out.

Make sure your ‘HIIT class’ is actually a HIIT class#

Turns out, that boutique studio workout you’ve come to know as HIIT might not be HIIT at all, but rather a watered-down, less effective version that’s probably putting unnecessary strain on your body.

“What most workout classes are calling HIIT is not really HIIT,” says Danny King, director of performance and recovery at Life Time. “High-intensity interval training, in scientific terms, is short-duration, high-intensity intervals—with long rest periods,” the latter being a key component,” he says. “If you aren’t resting enough, the intensity drops, not allowing a person to push hard enough to create the stimulus we are looking for.” In many popular workout classes that advertise themselves as HIIT, rest periods are typically between 30–60 seconds long, with work periods sometimes lasting more than twice that.

So why don’t all fitness studios just build their workouts according to the actual definition of what HIIT training is? According to King, it’s mostly a marketing issue. “No one wants to show up to a class where you work your butt off for 45 seconds, and then socialize for three and a half minutes,” he says. “It's a hard thing to package, so studios started to kind of blur the lines. It's hard enough to make you really tired, but it's not quite hard enough to get the proposed benefits.”

And while you might still be benefiting from moving your body and burning calories, it’s worth considering how these lesser-intensity interval workouts might be affecting you outside the studio. According to Dr. Shaw, “an improperly organized session can lead to an increased rate of perceived exertion and require prolonged recovery,” leaving you feeling burned out, without any real results to show for it.

When looking for a HIIT class, talk to the studio staff and ask about the interval format. A 2019 study published in the International Journal of Sports Medicine found that a 1:4 ratio (as in, one part work to four parts rest) to be optimal for increasing cardiovascular fitness and athletic performance. At the very least, rest periods should outweigh work intervals.

Understand what you’ll get out of it#

One reason why some people may lose interest in HIIT over time is a simple misalignment of expectations. Regular HIIT training can improve your overall cardiovascular health and athletic performance. And during these intense bouts of exercise you can count on a fair amount of extra calories to get caught in the crossfire—both while you’re training and in the days following.

That said, while making it to the end of an intense class might feel like a feat of fortitude, it’s not single-handedly going to do much for your endurance, says King. Similarly, if you’re expecting to see bar-bending strength gains, you’re looking for them in the wrong place.

"From a cardiovascular perspective, elevating your heart rate and coming back down is going to help you improve things like your V02 max, but you're not really going to build that raw strength that you would experience in pure strength training,” says Tooley.

In fact, if building muscle is a priority for you, your HIIT workouts could actually be working against you by way of raising cortisol levels, which we know from research, like this 2022 study published in The Journal of Clinical Endocrinology and Metabolism, can actually lead to muscle loss. "The acute stress from a HIIT session is much more than steady-state resistance training or cardio. Because of this, we see a much sharper increase in cortisol,” says Dr. Shaw. “This effect can be cumulative and lead to a constant state of elevated cortisol—a result of the constant fight-or-flight state we put our body into when performing HIIT sessions."

Don’t skimp on recovery#

You’d think that a workout with the words “high intensity” in the name would lead most people to the assumption that a fair amount of post-workout recovery is in order. But that doesn’t seem to be the case.

"The major problem with HIIT workouts is that most individuals do not organize or appropriately schedule training sessions. With most individuals—especially those not trained, or without proper education in exercise science—we overdo it,” says Dr. Shaw. “Recovery allows our body to reset the muscles, and it allows our hormones and cells to return to homeostatic levels to prevent overtraining and burnout.”

To maximize recovery between HIIT workouts, Dr. Shaw recommends refueling with ample protein and carbohydrates as soon as possible following each session, and hydrating to replace fluids lost during your workout. From there, any stretching or mobility work you can squeeze in before your next workout can go a long way, he says, along with as much rest as possible. “Optimizing sleep will allow us to physiologically and psychologically recover and then prepare for additional exercise.”

Taking the time to recover properly between workouts at the HIIT studio can also help prevent cortisol from derailing your muscle-building efforts in the weight room, says King. “Cortisol in the short term isn’t a bad thing,” he says. “It’s the chronic overworking without the recovery periods that creates the problem.”

Still, even with the most dialed-in recovery protocol imaginable, there’s a limit to how much HIIT your body can handle. “At some point, training volume becomes high enough that no sleep, food, or other recovery modality can help,” says King. “So choose the days you plan to hit it hard, go after it, and then take it easy for a day or two.”

Look for a studio that offers progression#

If the occasional HIIT class is just one of many things you do to stay fit, this is less important. But if you’re the type of person who treats your local HIIT studio like a one-stop-shop for all your fitness needs, it’s critical.

“This is a huge problem for boutique fitness studios,” says King. “They tend to sell one style of class, so it’s hard for them to offer a really balanced workout program.”

Of course, there are many possible configurations for what a balanced program could look like. According to King, an ideal workout week could look something like 1–2 HIIT workouts, 2–3 traditional strength workouts, 1–2 lower-intensity cardio workouts, and 1–2 active recovery or flexibility workouts. “This doesn’t work in many of those HIIT boutiques, because of schedule and branding,” he says. “So people join, overcook, and then move on.”

But there are studios out there that prioritize progression. At Tooley’s Alpha Fit Club, where classes blend traditional strength training with HIIT-based cardio, members move through four-week cycles, during which variables like interval times and overall intensity are adjusted to keep progress trending in the right direction. And Tooley credits other gyms like The Yard, Fitstop, MADabolic with offering similar approaches to progression that serve not only to spur consistent gains but to also keep members mentally engaged and excited to come back for more.

“If you just keep pushing it full-tilt every day, your body's never gonna be able to recover, and you're never really gonna reap the rewards,” he says. “You should feel like you're moving through something that, again, has that intention.”