CWU News

Hot Yoga on the Hot Seat

Woman in yoga poseCasey Mace, has practiced yoga for most of her life. She even took a prenatal yoga class while pregnant with her son. She swears it helped her during labor.

Mace is just one of an estimated 30 million Americans who practices the ancient art of total mind-body workout that combines stretching poses with deep breathing and meditation. She appreciates how yoga helps her relieve stress and maintain her fitness.

But when she tried a new type of workout known as hot yoga, she experienced something vastly different.

“I felt like I was going to pass out,” Mace said recently. “I felt really nauseous and sick, kind of how I feel when I get in a hot tub.”

Mace, who is an assistant professor in the Department of Public Health, has low blood pressure. She knew that doctors advise against using hot tubs for those with this medical condition. However, no one warned her that she could experience similar effects by doing hot yoga.

The experience led her to look into the research on hot yoga and its potentially negative effects.

“I was surprised; there was nothing,” Mace recalls.

The only thing she could find was the occasional trendy article in which doctors commented, “If you can’t sustain heated exercise than you probably shouldn’t do this.”

Mace deduced that hot yoga was not for her, but wondered, whom is it safe for?


Although the practice of yoga has been around for centuries, little is known about its most recent spin off.

Hot yoga is like traditional yoga. The main difference is that the room temperatures can range between 80 and 108 degrees—depending on the studio’s yoga teaching style—with classes lasting up to 90 minutes. For example, Bikram Yoga, which was the original type of hot yoga, is particularly hot and heavy, with the studio heated to 105 degrees, with 40 percent humidity.

Mace recalls her experiences with hot yoga as “intense.” The room was sweltering and little instruction was provided beyond what pose to take. She felt ill-equipped.

Her research turned up no scientific data about the health benefits or the risks. And of the few journals and papers on the subject, the information was not entirely helpful because of low sample size.


With no scientific data on hot yoga, Mace quickly recognized a research field that was uncharted.

Her pilot study analyzed the effects of participation of 157 people in hot yoga. It looked at both the benefits of hot yoga as well as injuries or adverse outcomes that occurred after its practice. The resulting paper, “Self-Reported Benefits and Adverse Outcomes of Hot Yoga Participation,” attracted the attention of The New York Times, which referenced her study in a hot yoga safety article last December. But when she submitted the study to a prestigious research journal, the study was rejected because of the low sample size.

What she needed was a larger sample. But the challenge was obtaining a measurable sample from a small rural community like Ellensburg—you can only sample students so many times. She would need greater reach and that would cost money.

“It’s a chicken and egg thing,” she explained. “They want evidence, but we can’t get any because we don’t have any previous evidence to apply for funding to get more evidence.”

Mace applied for a $3,000 seed grant through the CWU School of Graduate Studies and Research. Her proposal, Risks and Safety Behaviors of Hot Yoga Practice, aimed to answer the questions: What are the risks? Who might be at risk? And what preventive measures can people engage in to protect themselves?

The small grant allowed Mace to expand her survey sample using Qualtrics, an online survey software. It also enabled her to gather data from across the U.S. In all, she obtained a 700-person sample, the largest sample for this subject matter to date.

“I really appreciate the school of research, that they took a chance on my research,” Mace said.


The larger, 700-person sample was highly diverse. Ages ranged from 18-72, with the average age of 32. Mace intentionally sought a balanced, 40/60, male/female gender split.

According to Mace, most yoga research focuses on white women in their 40s. And while that’s not necessarily the average demographic for the activity anymore, no one really knows who’s Dehydration warning signsdoing hot yoga. Now, as a result of her research, we have a better idea.

In this ground-breaking study, Mace collected a massive amount of data to better understand those practicing hot yoga. She believes she has at least three years of data to analyze.

“In a way, I’m a little overwhelmed by the amount of data that I have now, but it’s a good overwhelmed,” Mace laughed.

She has already divided the survey into tracks and begun publishing her findings.


Mace said the most shocking finding in both chronic disease populations and others in general,is the misunderstanding or disconnect between people’s understanding of adverse reactions to hot yoga.

When asked: “Have you ever had an adverse reaction to hot yoga?” 60-70 percent said “no.” But when further prompted to identify if they had experienced these specific symptoms—dizziness, nausea, or light-headedness—more than half had.

“People may think that feeling light-headed or dizzy is a normal part of hot yoga practice, but it’s not or it shouldn’t be,” Mace warns.

According to John Hopkins Medicine, dehydration and heat stroke are two common, heat-related diseases that can be life-threatening if left untreated.

Keeping hydrated and watching for symptoms are key, Mace says.


While exploring additional data, Mace noticed something she hadn’t originally considered. There was an entire group of people in the study who said they suffer from anxiety and depression disorders.

Fifty percent of her sample, in fact, had some type of lifetime prevalence of anxiety or depression. Not surprising, a high number of people reported practicing hot yoga because of the benefits to their mood.

What was unexpected, was finding that people with anxiety and depression disorders experienced a higher risk of dehydration—feeling light-headed, dizzy, or confused. Whether it’s exacerbating some symptoms that are part of a mood disorder or a side-affect to medication, Mace said she was unable to draw any conclusion based on the data.  But, she added, this information is available and now someone can use this evidence to perhaps explore it further.

In fall 2016, Mace completed her research on an aspect of this larger discussion. Her May 2017, article on “The Risks and Mental Health Benefits of Hot Yoga Participation for Adults with Anxiety and/or Depression” was accepted in the International Journal of Health, Wellness, and Society.


Woman holding water bottleMace, published a second paper in May, “Hot Yoga and Hydration: Encouragement, Behaviors, and Outcomes,” in the International Journal of Yoga. This article looks at whether hot yoga instructors are encouraging people to properly hydrate. What she found in her larger sample of 700 people, is that 91 percent of the participants reported that their yoga teachers were encouraging hydration. That’s good news. As yoga instructors play a key role in encouraging hydration and students coming to class hydrated.

Mace’s ultimate goal is to share her safety and risk assessments with hot yoga instructors and the public. She knows all too well the importance of needing information to make safe decisions.

Her research, while still underway, has the potential not only to change the safety practices in hot yoga studios but to also save lives.

Read additional articles in Connections Magazine.

Media Contact: Dawn Alford, Public Affairs, 509-713-5378,