For those who currently sweat it out in hot yoga class (formally known as Bikram yoga) on the regular, a new study sponsored by the American Council on Exercise (ACE) is shedding light on a few health-related reasons you may want to re-evaluate your practice.
In order to examine whether or not it’s actually safe to practice yoga in such a hot and humid environment (according to ACE a typical hot yoga class is held in a room set to 105 degrees F and 40 percent humidity), researchers monitored 20 apparently healthy volunteers (seven males and 13 females ages 28 to 67 years old) during a 90-minute hot yoga class at a Bikram yoga studio led by a certified instructor.
All 20 volunteers regularly practiced hot yoga, so they were familiar with the poses and the environment prior to the study.
The researchers recorded the subjects’ core body temperatures prior to the start of the class and every 10 minutes during the class via “core body temperature sensors” that the subjects swallowed before beginning. The subjects also wore heart rate monitors and their heart rates were recorded every minute during the class.
The results showed that while their heart rates fluctuated throughout class, depending on the difficulty of the pose, the participants’ core body temperatures increased progressively over the course of the 90-minute class.
“The average highest core temperature was 103.2 ± 0.78 degrees F for men and 102.0 ± 0.92 degrees F for women, with men having a significantly higher core temperature overall,” the study’s authors reported.
So, why did they find this to be problematic?
Essentially, a core temperature that high may be of concern for some people because the risk for heart-related illness increases when your core body temperature reaches 104 degrees F.
None of the study’s participants revealed signs of heat intolerance, but the authors still thought the results raised some cause for concern. The study’s lead author, Emily Quandt, M.S., said this is especially because the workout primarily focuses on balance and strength and there’s not much cardiovascular training involved.
“The dramatic increases in heart rate and core temperature are alarming when you consider that there is very little movement, and therefore little cardiovascular training, going on during class,” Quandt said.
The problem, she explained, is that while Bikram yoga participants often credit the increased sweat rate as a way to “release toxins” from the body, this study showed that the sweat isn’t doing its job, which is to cool the body down.
Ultimately, the researchers did not conclude that hot yoga is necessarily “unsafe” or "harmful,” but rather, practitioners should take more precautions to make sure they’re participating safely.
They said that ideally, class times should be reduced to 60 minutes and the temperature of the room should be reduced as well, but most importantly, those who participate should place a greater focus on hydrating properly—making sure to drink enough water before, during and after class.
Also, instructors should make sure to be aware of the early warning signs of heat exhaustion, like cramps, headache, dizziness and general weakness.
Additionally, the author’s didn’t fail to note that other studies have associated a hot yoga practice with a handful of health benefits, including reduced stress levels, improved cardiorespiratory endurance, decreased body fat and even improved deadlift strength. They also pointed to a 2013 study which found that hot yoga improved glucose tolerance and insulin resistance in older adults at high risk for metabolic disease.
At the end of the day, unless you have a health issue that would put you at risk when exercising in such an extreme environment, it’s OK to practice hot yoga and it may even help to improve your health as long as you make sure to practice safely and hydrate properly.
To be sure, always consult your doctor before starting a new form of exercise or a new exercise program.