Yoga has gotten hotter. An increasing number of yoga studios and gyms offer classes in Bikram yoga, developed by Bikram Choudhury (“guru to the stars”) in the 1970s, or other versions of “hot yoga,” such as CorePower Yoga and Evolation.
Hot yoga is done at room temperatures between 90° and 105°F (sometimes even higher), with humidity between 40 and 60 percent. During a typical class, which can last up to 90 minutes, you move through a series of linked flowing poses. Even for fit young people, hot yoga is a grueling practice, famed for leaving puddles of sweat behind.
Practitioners say that hot yoga will improve both mental and physical health—that it will enhance mental clarity and concentration, increase flexibility, build strength, promote weight loss, flush toxins, make skin look better, ease back problems, and even cure asthma, heart disease, and other ailments. But does it really have such benefits and, more important, is it a safe way to practice yoga? Will it leave you feeling energized and invigorated—or lightheaded and irritable?
Is hotter better?
There has been little published research on the health benefits and risks of hot yoga and none comparing it to other forms of yoga. A 2011 study in the Journal of Exercise Science and Fitness found that Bikram yoga (at least 20 sessions over eight weeks) increased mindfulness, lowered perceived stress, and improved balance and flexibility. And a small study in 2013 in the Journal of Bodywork & Movement Therapies found that middle-aged obese people who did Bikram yoga for eight weeks had improvements in glucose tolerance, with no adverse effects. On the other hand, a study in the Journal of Exercise Physiology in 2012 concluded that “Bikram yoga training has no effect on pulmonary function or maximal aerobic capacity”—not surprising, actually, since yoga is not typically done as a cardio workout.
What about claims that hot yoga improves flexibility more than other types of yoga? Sure, heat warms you up, so you may be able to get a better stretch compared to stretching in the cold. But this could also make it easier to overstretch and injure yourself.
Is it true that hot yoga will cleanse your body of toxins through sweating? The idea that sweating will “detoxify” the body lacks any basis in science. Though some toxins are eliminated through perspiration, the vast majority are processed by the liver and eventually excreted through urine and stool, not sweat.
Too hot to handle?
The safety of hot yoga depends on your fitness level and overall health, among other factors. But exercising in extreme heat can lead to dehydration and hyperthermia (elevated body temperature), both of which can cause nausea, dizziness, fainting, muscle cramping, and other symptoms. And if you become very dehydrated and drink too much water afterward without consuming electrolytes, you run the risk of developing hyponatremia (low blood sodium levels), which can also cause such symptoms as nausea and muscle cramping, along with general malaise and even seizures. That’s what happened to a 34-year-old woman who was hospitalized after she did a 90-minute hot yoga workout and then drank 3.5 liters of water, as was reported in the British Medical Journal Case Reports in 2012.
Then there is the stress that the heat, especially in combination with exercise, can put on the cardiovascular system. If you’re unfit or have been sedentary, or have hypertension or heart disease, for instance, you should not be doing hot yoga. The authors of a 2013 paper in PLOS ONE cautioned that hot yoga may be inappropriate for older adults and people with medical conditions in general.
Words to the wise: Hot yoga has risks. If you are physically fit and healthy—or otherwise have gotten your doctor’s okay—you can try it, but heed the following advice, which applies to all yoga training, especially more strenuous classes. Make sure the class is taught by a qualified instructor (certified Bikram instructors have nine weeks of formal training). Don’t work out beyond your capacity (it’s not a competition, even if some classes make it seem that way). Stop if you get lightheaded or begin to feel unwell in any way. Bring your own mat that provides good traction. And stay well-hydrated (drink at least two hours before class and even during class). Plain water is fine for most workouts (just don’t drink to excess). For classes lasting longer than an hour, a sports drink is good for replacing electrolytes like sodium that are lost in sweat.
Do not do hot yoga, however, if you have high blood pressure or a heart condition or are pregnant. Keep in mind also that other styles of yoga likely have the same psychological and physical benefits as hot yoga, without the added physical stress and risks associated with exercising in extreme heat. Lastly, don’t believe claims made by practitioners that hot yoga will cure heart disease, asthma, or other chronic illnesses. Bikram Choudhury has been a particularly controversial figure, making unsubstantiated claims—and millions of dollars, literally off people’s sweat.