I used to love the Thursday evening yoga classes at my no-frills New York City gym. The class was super beginner-friendly, it was a great way to wind down from the week, and the flow was heavy on the vinyasa with a blissfully long savasana. (I’m pretty sure I fell asleep 92 percent of the time.)
By the end of each 60-minute class, I usually felt both refreshed and invigorated. But I never felt like I got a workout. In spite of all the chaturangas (so. many. chaturangas.), planks, and thigh-quivering Warrior IIs, I rarely left class feeling desperate for a shower before going on with my night.
When I discovered hot yoga, though, it was a completely different story. I fell in love with Lyons Den Power Yoga, a Baptiste-style studio in Tribeca (it’s since opened a second location in Chelsea), and it most definitely counted as a workout. The flow was remarkably similar to the vinyasa-style class I used to take with chaturangas, planks, and Warriors aplenty—but in my mind I counted one as “restorative, rest-day yoga” while the other I’d categorized firmly in the “I’m dying” category.
I feel like I’m getting a tougher, more satisfying workout when my pores are practically water fountains. But does it actually make for a more effective workout?
Why? Sweat. I feel like I’m getting a tougher, more satisfying workout when my pores are practically water fountains. But does it actually make for a more effective workout? I asked some experts, and it turns out: not really.
“Sweat is not a reliable indicator of the effectiveness of your workout,” says exercise physiologist Jonathan Cane, who’s the founder of City Coach Multisport in New York City, where he coaches elite athletes. “Since sweating is your body’s way of cooling itself, it’s largely influenced by the conditions in which you’re exercising.”
Case in point: my yoga experience. Or, Cane suggests, if you run five miles at a nine-minute-per-mile pace on a cool day, you’ll produce significantly less sweat than doing that same run on a hot day—but the caloric expenditure will be very comparable.
Of course, calories burned is only one lens for determining the effectiveness of a workout. But it can be the measurement that people lean on the most—versus the slower gains of developing muscle and endurance.
Why do I feel like I worked so much harder after a 94-degree yoga class than after an air-conditioned one?
“People sometimes get confused because there’s a temporary weight loss associated with sweating,” Cane adds. “But since it’s just ‘water weight,’ it’s not indicative of fat loss, and the weight loss won’t last longer than it’ll take you to drink some water. Sweating does not correlate with fat loss.”
Sounds logical enough: So why do I still feel like I worked so much harder after a 94-degree yoga class than after an air-conditioned one?
“We all want instant gratification,” says Refine Method founder Brynn Putnam, an exercise-science geek and HIIT workout savant (as well as a Harvard grad and former professional ballet dancer). “But using sweat to gauge the success of your workout is falling for the easy pat-on-the-back. Of course a heated studio is going to have you dripping, but that’s related to your own metabolic processes, not whether you’re burning more calories or building muscle,” she says.
In terms of the science behind your sweat, “when you exercise, all of your cellular processes speed up as your body works to convert carbs and fat into ATP [adenosine triphosphate]—your body’s energy currency—to power your muscles,” Putnam explains. “That process produces heat as a byproduct, and sweating is your body’s ingenious way of dissipating that heat to maintain a safe body temperature. That’s it: No bonus calories burned, just water loss.”
“Sweat alone is not an indicator of how hard someone is working.”
So, would my beloved, heat-loving yogi-owner of Lyons Den, Bethany Lyons, agree? Turns out, no one’s going to argue with science. “You do not have to sweat to get a workout,” she says. “Sweat is the body’s natural cooling system, and a bunch of factors contribute to how much an individual will perspire. And sweat alone is not an indicator of how hard someone is working. I can sit in a sauna and sweat like a banshee—but I’m not burning anything. If you’re looking to boost your burn factor, the two most important factors are duration and intensity.”
While sweat may not be indicative of the intensity and effectiveness of your workout, it’s definitely not a bad thing. “Sweat helps flush out the toxins in your body,” Lyons says, and studies on detox support her. And some research suggests that sweating actually contributes to mood control and a sense of well-being, she adds.
Plus, it’s satisfying. “For me, nothing feels more fulfilling than being completely drenched and wringing out my shirt, like I’ve been totally rinsed after a workout,” Lyons says. And, for the same reason, I guess that’s why I have the pile of laundry that I do.
If “organ melting experiences” are your thing, this is what it’s really like to sit in an infrared sauna for 30 minutes. You can also add “sweating out toxins” to the list of reasons you should hit the gym.