The hotter you are when you work out, the more you sweat—which means you’re getting a better workout, right? Well, not necessarily.
In fact, the latest workout trend involves doing the opposite: Turning the temperature down. So far down that gloves are recommended indoors. But is this just a new boutique fitness fad or a real science-backed way to improve your performance (and results)? We found out.
The Science Behind Body Temperature
Quick science lesson: When you start to exercise, experts say your core body temperature can reach 102 degrees Fahrenheit or higher within minutes. Sweating, a process of evaporation, is how the body cools itself down. “When a sweat droplet evaporates, it lowers your skin temperature, which helps pull the heat out of your body more efficiently,” says Doug Casa, Ph.D., CEO of the Korey Stringer Institute, which provides research on exertional heat stroke prevention.
That’s not a sign of how hard you’re working. That’s just a physical reaction—one you’re just as likely to experience during a HIIT workout or during a stroll on a hot summer day.
But what if your body didn’t have to cool itself down during exercise? You’d actually perform better, says Casa.
Here’s why: “Somewhere around a body temperature of 104 degrees, your body reaches a point called volitional fatigue, where you start to back off on your intensity to protect yourself,” says Casa. This is a subconscious protective move so you’ll avoid things like dehydration, heat exhaustion, or heat stroke. But for safety’s sake, your performance suffers. “If you can keep your body temperature down during the activity, then you’re going to be able to maintain the performance for a longer period of time or for a higher intensity for a given period of time,” he explains. (Related: How to Protect Yourself Against Heat Exhaustion and Heat Stroke)
We already know that your body works harder in the cold to keep your core temperature up, burning more calories in the process. Unfortunately, though (actually, fortunately), it’s not winter all year round. But companies and studios are coming up with new ways to bring the cold to you, no matter what the outside temperature is.
The Cold Workout Trend, Explained
At Brrrn, the first cold workout studio, located in New York City, you can take three different types of classes: 1st° (a yoga-inspired mobility and strength workout with a room temp of 60°F), 2nd° (a core and cardio slide board workout at 55°F), and 3rd° (a battle rope/HIIT workout at 45°F). With plenty of studios providing heated classes, Brrrn’s founders wanted to provide exercisers with a stressor at the other end of the spectrum. “When you’re exercising in the heat, you’re putting your body through a certain type of stress—so I thought, why not use another type of positive stress to encourage movement?” says Brrrn cofounder Jimmy T. Martin, a certified personal trainer.
Think about it: Heat typically discourages movement. (How often have you looked at the temperature on your weather app just to say “ugh, definitely not running outside today”?) “Cold temperatures actually make you want to move because your body wants to stay at 98 degrees,” adds Brrrn cofounder Johnny Adamic, a personal trainer and former public health official for Mayor Michael Bloomberg’s Obesity Task Force.
Plus, the cool temperatures at Brrrn help your body have a more focused exercise experience, according to the co-founders. “When you’re in hotter temperatures, the perceived rate of exertion is higher, so it feels like you’re working out harder,” says Adamic. “But that’s actually not the case. You’re literally just dumping heat via sweat and that’s dehydrating you. You’re also losing electrolytes, which are how our cells communicate to one another. So when you preserve hydration and electrolytes in a cooler room, you then allow your muscles to fire better.”
Of course, this isn’t to say heated classes are bad for you or that you should scale back on your beloved hot yoga class (studies have shown that hot yoga, for example, can increase your fitness, stamina, and flexibility, in addition to boosting your mood). Both temperature extremes are simply new stressors for your body to adapt to—similar to the way you would challenge your muscles with new weights or exercises in strength training, says Casa. “I actually think there is a big advantage to exposing yourself to different extremes of environmental conditions,” he says. “That’s especially true if you’re training for a race or competition where you can’t control the temperature—acclimating your body to the heat and cold can help better prepare you for those kinds of exposures.”
Other Ways to Reap Those Chill Benefits
Brrrn plans to open more studios soon, but it is possible to get similar cooling effects while working out on your own. Companies like Mission apparel, Arctic Cool, and BioLogic (a collaboration between at the MIT Media Lab and New Balance) are actually developing fabrics with built-in cooling technology.
Mission, for example, has an apparel line called VaporActive, which features advanced thermoregulation technology to actively cool you down while you work out. It’s powered by 37.5 Technology, explains Scott Birnbaum, the chief marketing officer at Mission. “Active particles are embedded in the fiber, and as your body heats up, these particles rapidly attract and evaporate moisture, cooling you down and keeping you comfortable,” says Birnbaum. “Superior to traditional wicking technologies that just move the sweat around, Mission VaporActive actually removes the sweat in the vapor stage before liquid sweat forms.”
Considering the fact that you use 80 percent of metabolic energy to regulate temperature, he says, products that help the body more efficiently cool can help you direct more energy used toward improving performance and reaching new goals.
Mission also uses that cooling technology in headbands and hats. “Simply wet one the items, in any temperature water, and the headwear will deliver an instant refreshing cool and stay cool for hours.”
It’s not just during workouts that cold technology can help. Considering the fact that the most important part of exercise, recovery, happens outside the gym, cryotherapy—or short exposure to sub-zero temperatures—can be a powerful tool in your pre- and post-workout routine. What originally started as a treatment for rheumatoid arthritis is now mostly used for therapeutic purposes in the United States; since 2014, the global popularity of cryotherapy has grown by 36 percent.
“The extreme cold of the cryotherapy tank causes constriction of the blood vessels, which clears the blood away from your extremities and pushes it towards your vital organs,” says Ben Feinson, CEO and co-founder of Cryofuel in New York City. “When the blood is pumped back into the body, it carries more oxygen and minerals.” In other words, you’ll jump-start your system and feel fired up for your workout. That same process of increasing the oxygen in the blood vessels means it’s also a powerful recovery tool, Feinson explains.
The Bottom Line
While cold is having its moment, that doesn’t give you a free pass to skip breaking a good sweat during the dog days of summer. It’s beneficial to keep your body primed at both temperature extremes, but if you truly hate slogging it out in the heat, there’s really no downside to spending most of your workouts in a cooler environment, says Casa.
And, FYI: You’re still going to sweat when you work out—even if you’re working out in a 45-degree room. The major difference between hotter and cooler workouts is that in the cold, your sweat won’t get in the way of the workout.