Original hot yoga is the fixed 26 and 2 class: 26 postures and 2 breathing exercises, in the same order, for 90 minutes at about 40°C. The research on original hot yoga is real but modest. Studies report better flexibility, lower depression scores and a high heart rate. None of them shows it beats other exercise.
That gap between the headlines and the data matters if you plan to teach the class, because students will ask what the studies found, and you'll need an answer that is accurate. This guide sorts five key studies by one question: how close was the class they measured to the original sequence?
Mr. Ian Terry, E-RYT 500, spent five years, 2014 to 2019, training with the founder of the Bikram Hot 26&2 method. He shapes how the YogaFX team reads this research, and the cautions below are his standard for any claim made in class.
Original Hot Yoga Research at a Glance: Five Studies Compared
How the studies line up
Most pages on original hot yoga list benefits and stop there. A more useful first step is to check what each study actually put people through. For example, some studies used the full Bikram-format class, while others used a heated Hatha class that resembles it. A few reviews mix many styles together.
Which class each study measured
The table sorts the five studies by how closely their class matches the original 26&2 format. Read the last column before you quote any result.
| Study | Class and who took part | Main finding | Match to the original class |
|---|---|---|---|
| Hunter et al., 2013, Journal of Alternative and Complementary Medicine | Bikram classes, 90 minutes, 3 a week for 8 weeks at 40.5°C; 24 young and 18 middle-aged and older adults | Sit-and-reach flexibility rose in both groups; artery stiffness fell in young adults; insulin resistance fell in older adults | Close: named Bikram class and heat, but no control group is described |
| Quandt et al., 2015, reported by ACE | One Bikram class of 26 poses at 105°F and 40% humidity; 20 healthy volunteers, aged 28 to 67 | Average heart rate about 80% of predicted maximum in men and 72% in women | Close: the full class, measured once |
| Nyer et al., 2023, Journal of Clinical Psychiatry | Heated Hatha yoga versus a waitlist for 8 weeks; 65 adults analysed | 59.3% of the yoga group had a 50% or greater drop in depression score, against 6.3% of the waitlist | Related: heated Hatha yoga, not the fixed sequence |
| Hui et al., 2022 | Hot yoga classes in healthy adults | Lower state anxiety | Unclear: we could not open the full text, so check the class used |
| Willmott et al., 2025, systematic review | 43 studies, 942 participants, many heated styles | Promising effects, but claims of superiority over other exercise are unsubstantiated | Mixed: a review of the whole field |
The numbers at a glance
Original hot yoga research in five numbers
What "Original" Means in an Original Hot Yoga Study
The word original is a description of a format, not a licence. For instance, in our October 2026 research report, R1a, we checked the US trademark register. Every old Bikram yoga mark we read was abandoned or cancelled, and we found no standalone "Original Hot Yoga" mark. Anyone may use the phrase, so the label alone proves nothing.
That is why a study needs checking against the class. Researchers rarely write "original hot yoga" in a methods section. Instead, they write "Bikram yoga", "hot Hatha" or "heated yoga", and those can describe very different rooms. Our UK partner site sets out what the original hot yoga label means on a studio timetable, which is a useful companion to this research view.
When we read a paper, we run it against five fixed elements, so we know what was really measured:
- The order. Twenty-six postures plus two breathing exercises, never reshuffled.
- The length. A full 90 minutes, not an express version.
- The heat. Roughly 40°C and 40% humidity.
- The voice. One scripted dialogue, with no playlist and no teacher demonstration.
- The room. A studio group class, not a private session or a flow.
A study that ticks all five is measuring original hot yoga. A study that ticks two is measuring something nearby. Both can help, but you should say which one you mean when you quote it.
Heart Rate and Core Temperature: The Class as a Workout
The clearest evidence about the original hot yoga class comes from a University of Wisconsin-La Crosse study, reported in an ACE ProSource summary of the Bikram yoga study. The team recruited 20 healthy volunteers, seven men and 13 women aged 28 to 67. Each wore a heart-rate monitor and swallowed a core-temperature sensor for one 90-minute class.
The heart-rate result surprises people who assume the class is gentle. The average was about 80% of predicted maximum for men and 72% for women. Peak readings reached 92% for men and 85% for women. As a result, the class loads the heart, even though the postures look slow.
The temperature result needs more care. The average highest core temperature was 103.2°F for men and 102.0°F for women. Seven of the 20 people went above 103°F, and one man reached 104.1°F by the end of class. Because this was one class and 20 people, it works as a warning about pacing instead of a rule.
- Drink early. Do not wait for thirst in a 40°C room.
- Rest on purpose. Sitting out a posture is part of practising, not a failure.
- Know your limits. Heart conditions, pregnancy and some medication change the rules.
For the cardio side in more depth, our guide asks is hot yoga a cardio workout and breaks heart rate down posture by posture.
Flexibility, Arteries and Insulin: The 8-Week Studies
The best-known intervention on the original hot yoga format came from Hunter and colleagues. They studied 24 young adults (average age 30) and 18 middle-aged and older adults (average age 53). Everyone did 90-minute Bikram classes three times a week for eight weeks, in a room at 40.5°C and 40% to 60% humidity. The published record of the Hunter study is open to read.
The results were mixed, so they are easier to believe. Trunk flexibility, measured by the sit-and-reach test, rose in both groups. Carotid artery compliance rose and the stiffness index fell in young adults, but not in older adults. Insulin resistance fell in the older group but not in the young group.
- Improved: flexibility in everyone, artery compliance in young adults, insulin resistance in older adults.
- Unchanged: body mass, body fat, blood pressure, fasting glucose and triglycerides.
- Missing: a described control group, so the changes cannot be tied to the class alone.
So this paper is a good example of honest science. It shows that something changed over eight weeks, but it doesn't show why, and it doesn't show that the change lasts. If you want these studies in date order, our timeline of when researchers started measuring hot yoga walks through them.
Mood: What the Depression and Anxiety Trials Found
The mood result is the one people quote most in original hot yoga research. In 2023, Nyer and colleagues published an 8-week randomised trial in the Journal of Clinical Psychiatry. It compared community-delivered heated Hatha yoga with a waitlist. Among 65 adults analysed, 59.3% of the yoga group had a 50% or greater drop in depression score, against 6.3% of the waitlist group.
Two cautions apply. First, this was heated Hatha yoga, so it is only a close relative of original hot yoga rather than the fixed sequence itself. Second, a waitlist is a weak comparison, because people know they are waiting. The result is promising, not final. Because we couldn't open the journal page for this paper in this run, we name it here instead of linking it.
A separate 2022 trial by Hui and colleagues reported lower state anxiety after hot yoga in healthy adults. Again, we couldn't open the full text, so check which class the researchers used before you repeat the finding. Our longer read on hot yoga for depression sets out the limits of the evidence.
Yoga is not a replacement for medical care. Anyone living with depression or anxiety should speak to a healthcare professional before starting.
What the 2025 Review Says About the Whole Field
Willmott and colleagues pulled the heated yoga literature together in 2025. Their systematic review covered 43 studies with 942 participants. It reported promising effects on flexibility, balance and bone density, and it showed that a hot class raises body temperature and heart rate. For the safety side of that heat load, see what the research says about heat safety.
Then it made the statement every teacher should know. Claims that hot yoga gives greater health benefits than other forms of yoga or ordinary exercise are, at present, unsubstantiated. As a result, the fair summary of original hot yoga research is "may help, still early", not "proven better". For the direct comparison, see our guide to hot yoga versus regular yoga in three trials.
What Original Hot Yoga Research Does Not Prove
Good science writing says what a study can't show. Read across all five original hot yoga studies, the same limits keep appearing.
- Small samples. The single studies above had 65, 42 and 20 people.
- Short follow-up. Eight weeks is typical. None follows anyone through years of regular practice.
- Weak comparisons. Waitlists and no-control designs cannot separate the effect of heat from the effect of movement.
- Mostly one kind of volunteer. Findings for specific groups, such as men or people over 60, are thinner.
- Heat is a stress. The same temperature that suits one body can overload another.
In practice, then, you can say the class may help with flexibility, mood and artery function. You cannot say it treats any condition, and you should never describe sweat as removing toxins. If you have a heart condition, are pregnant or take medication, consult a healthcare professional before your first class.
How Teachers Can Use This Evidence in Class
Evidence helps an original hot yoga teacher in two ways. First, it keeps your claims honest, and second, it gives you better answers when a new student asks, "Is this good for me?" That's why a short, accurate reply builds more trust than a big promise.
- Quote the class, not the brand. Say "in a study of 90-minute Bikram classes", then give the number and the sample size.
- Use cautious verbs. Write "may help" and "was associated with", and drop any promise you can't back with a study.
- Name the weak spot. A single sentence about the waitlist or the small sample shows you have read the paper.
- Protect the beginner. The heart-rate and temperature data are the reason to teach pacing and water from day one.
The delivery matters too. Because the scripted dialogue keeps every original hot yoga class the same, researchers can compare one study with the next. So a teacher who changes the sequence changes what the science describes.
Mr. Ian Terry and the Sequence Behind the Studies
Mr. Ian Terry, E-RYT 500, founded YogaFX in 2017. He has logged 12,000+ teaching hours and has trained 1,500+ graduates from 80+ countries. In June 2026 he also became Master Trainer of the Republic of Indonesia Yogasana Sports Federation. For him, original hot yoga means each posture held with correct form and in its proper place.
That standard is why YogaFX treats research as part of teacher training. Trainees learn the dialogue word for word, and they learn the studies with their limits attached. We'd rather lose a sign-up than overstate a result.
What YogaFX Students Say
Reviews are not research, but they show how the method feels from the student side. For example, here are two recent Google reviews, in the students' own words.
For me, it was the hardest thing that I have ever done...emotionally, physically and mentally. It tore me down and built me back up.
Britt, Google review, 2026
Just finished my Bikram yoga teacher training at YogaFX and it was such an incredible experience! I came in nervous and leaving certified and confident.
Xuan, Google review, 2026
Learn the Original Hot Yoga Sequence Online
If this research made you curious about teaching original hot yoga, YogaFX online hot yoga teacher training is led by the science and graded evidence. You learn the sequence and the studies on the same page, with the limits attached to every claim. Our honest 8-week breakdown of online yoga teacher training shows how that works week by week.
- You learn the dialogue the way it is delivered in a real class.
- You learn the research and how to quote it without overclaiming.
- You get a clear next step from Mr. Ian and the team.
Because the evidence is still early, new teachers who can read a study critically stand out. When you are ready to ask about the next intake, message Mr. Ian on WhatsApp.
FAQ
What is original hot yoga?
Original hot yoga is the fixed 26 and 2 class. It has 26 postures and 2 breathing exercises, in the same order, for 90 minutes. The room is about 40°C with around 40% humidity, and the teacher follows a spoken dialogue with no music. Original means nobody has shortened or changed the sequence.
Is original hot yoga the same as Bikram yoga?
In format, yes. Both names describe the same 26 and 2 sequence, 90 minutes long, in a heated room. Original hot yoga is the newer label many studios now use. Research papers often still say Bikram yoga, so read the methods to confirm the class matches before you compare results.
What do studies say about original hot yoga benefits?
Small studies report better flexibility, lower depression scores in one trial and a high heart rate during class. A 2025 review of 43 studies found promising effects but called claims of superiority over other exercise unsubstantiated. Yoga may help, but it is not a treatment, so consult a healthcare professional.
How hot is an original hot yoga class?
The standard is about 40°C with around 40% humidity. One Bikram class study used 105°F and 40% humidity, and average highest core temperatures were 103.2°F in men and 102.0°F in women. Drink early, rest when you need to, and check with a healthcare professional if you have a heart condition.
Is YogaFX official Bikram Choudhury teacher training?
No. YogaFX is independent training, not official Bikram Choudhury teacher training. Mr. Ian Terry, E-RYT 500, trained for five years, from 2014 to 2019, with the founder of the Bikram Hot 26&2 method, and now teaches the method with more than 12,000 teaching hours behind him.
Still have questions? Message Mr. Ian and the YogaFX team on WhatsApp and we will answer them personally.
Founder and lead trainer of YogaFX International Yoga Teaching Academy, with more than 12,000 hours of teaching. He trained for 5 years, from 2014 to 2019, with the founder of the Bikram Hot 26&2 method.
You may also like
Explore all articles ↗
Teacher Training Guides11 min read14 Nov 2026International Yoga Sports Federation and Yoga as a Sport: What Recognition Requires
Read article ↗
Teacher Training Guides11 min read13 Nov 2026Sauna After Hot Yoga? What Core Temperature Data Suggests
Read article ↗
Teacher Training Guides10 min read13 Nov 2026