You're sweating out water and salt, not toxins.
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While the trend surged years ago, hot yoga is still fucking everywhere. On a recent visit to SoCal, I was hard pressed to find a yoga class under 100 degrees (and under $30, but that’s another matter). As a yoga teacher for more than a decade, I was curious: What’s up with this persistent trend and why is it trumping other forms of yoga?
Hot yoga is widely touted as being “detoxifying,” only “detoxifying” is a pretty meaningless word in this context. “A lot of people say that it’s good for eliminating toxins from your body, which is not true,” says Daria Long Gillespie, clinical assistant professor at the University of Tennessee and senior vice president of clinical strategy at ShareCare, an online health profile database. “We metabolize toxins in our body via the liver and via the kidneys and via the intestines, not via what we sweat out.” The truth is that the body removes toxins all on its own and what comes out in your sweat is water and salt.
The intense sweatiness of hot yoga is another issue. It can work against the body’s natural efforts to control temperature. Your body is usually pretty smart about making sure that you don’t get too hot or too cold. But hot yoga works against you. “Normally your body [regulates heat] by sweating and as cool air hits you the body cools, but because the room is very hot you don’t really get the opportunity to off that heat,” says Noah Greenspan, a cardiovascular and pulmonary physical therapist in New York City. “Basically, you sweat to cool the body, but because the room is so hot, the body doesn’t cool.”
And so you sweat more. And more and more. And then you potentially end up dehydrated. Loren Fishman, assistant clinical professor at New York Presbyterian Hospital, Columbia University, tells me that 50 percent of participants in hot yoga classes were found to be dehydrated. Dehydration may seem like no big deal, but the truth is that it can be very dangerous.
Let’s not overdramatize the situation, but think about it: If you’re practicing hot yoga five or six times per week and are becoming chronically dehydrated, there are real potential risks. Fishman says stroke could occur, and goes on to list the potential hazards of chronic dehydration: “Pulmonary Embulli, all kinds of coagulopothies, where your blood coagulates and it’s not supposed to.”
My own experiences practicing hot yoga have not been this dramatic, but they have been pretty lame. I went to a lot of Bikram classes in the early aughts. I moved from Miami to NYC in the middle of winter and even though I felt dubious about Bikram, I really wanted to get warm. It did warm me up, but I also found that, even though I am a body aware person, I would find myself taking things too far in Bikram classes and feeling shitty for a few days afterwards.
It turns out that the shitty feeling I got was probably just due to the dehydration. Gillespie tells me that she had experienced similar effects. “I’ve done hot yoga myself,” she says, “and I came out and felt dehydrated and fluid imbalanced—I lacked electrolytes—for about two to three days.” She recommends hydrating both before and after class, not just with water, but with a fluid that contains electrolytes like Gatorade or Smartwater. The question, then, is really how much time do you want to take to prepare for or recover from your yoga practice? I practice six days a week and, personally, I just don’t want to have to think about it that hard.
None of the doctors were particularly concerned about injury in hot yoga for healthy people who are in good shape. Greenspan, who is himself an avid hot yoga practitioner, was more concerned about people who have high risk factors, such as cardiovascular disease or respiratory issues, and people who don’t pay attention to the physiological signals the body sends when we are taking things too far. “Pain,” he says, “is not something that we like, but pain serves a purpose. Pain is a warning signal.”
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A potential hazard of hot yoga is that the heat may reduce our ability to sense the pain signals our bodies are sending. “The things that make hot yoga so great are the things that make it a little more risky,” Greenspan says. “Because it’s hot, your muscles are naturally going to be a little bit looser, they’re going to have the ability to stretch a little bit more than they might if it wasn’t so hot and you might not have the same level of pain or discomfort than you would have if the room were a normal temperature.”
Greenspan also pointed out that people who regularly practice hot yoga are more at risk for getting sick rather than getting hurt—and all the doctors I spoke with agreed. He went on to describe how the high heat and close quarters of many classes can create the perfect environment for illnesses to spread. “I was in line for a class,” he says, “and a man in line told me that he had a bad cold and was hoping the class would clear out his chest. I left, because I don’t want whatever’s clearing out of his chest coming into mine.”
In other words, hot yoga classes can also be kind of gross. The combination of heat and sweat can make for the perfect breeding ground for bacteria. And a regular perspiration-heavy practice can be dangerous if you have other risk factors or if you don’t listen to your body’s signals.
Hot yoga may not be inherently any more dangerous than other kinds of yoga or other kinds of physical activity—it just may not be any better, either, Fishman says. “Yoga is done in the steamy jungles of Ceylon, but it’s also done in the snowy Himalayas. Yoga is done in all kinds of climates. You can’t come to the conclusion that hot yoga is anything more than a gimmick.”
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