Who willingly works out inside a 125-degree box? I did.

Testing out HOTWORX, a fitness studio that recently opened its 5th Atlanta location

Hotworks Atlanta

Illustration by Zebu

While holding a two-minute squat against the wall inside a small, overheated box, I couldn’t help but think of the 1967 Paul Newman film Cool Hand Luke.

Them clothes got laundry numbers on ’em. You remember your number and always wear the ones that has your number. Any man forgets his number spends the night in the box. These here spoons, you keep with ya. Any man loses his spoon spends a night in the box.

That’s what Carr, the Florida prison camp’s “floor walker,” says to the inmates upon their arrival. In my case, I hadn’t been sent to the box for losing my spoon. But I’d maybe lost my damn mind, given that I’d willingly stepped inside a 125-degree infrared sauna for a 30-minute isometrics class, led by an instructor on a screen.

This is just one of the many workouts you can sign up for—day or night, alone or alongside as many as two other people—at HOTWORX, a Louisiana-based studio which recently opened its fifth 24-hour location in metro Atlanta. The company says that exercising in heat and infrared energy raises core body temperature and heart rate, allowing you to burn more calories in less time.

As I recently learned when I tried Perspire, hot boxes—or tents or other heated chambers—have been used as a form of therapy for thousands of years, starting as early as the Mayans. Finland, it turns out, is particularly big on saunas; there, one in three people use them. Some studies suggest that the dry heat of infrared technology can increase circulation and flush out toxins.

Typically, in these saunas, you’re lying very still in a pool of your own sweat. But at HOTWORX, you’re moving. In addition to the Hot Iso class, I tried the 15-minute cycling session. Though I didn’t love the instructor and her two on-screen classmates—who looked to be as bored as I was with the generic music—the class definitely felt like a fast-forwarded version of an unheated Spin session, getting me to a calorie burn at a quicker rate. And the shorter duration kept me from feeling sick from the heat.

So if you’re looking for a super-sweaty but quicker fitness fix—and don’t see spending time in the box as hot, cramped torture—you’ll likely enjoy the calorie-torching sessions at HOTWORX.