Hot Yoga

Heated-room yoga and the Bikram format

A 2015 critical review describes Bikram yoga as a standardized style of hatha yoga: a class of about 90 minutes with a set sequence of 26 postures and two breathing exercises, practiced in a room heated to 40.6 °C at 40% humidity. The review attributes the style to Bikram Choudhury and reports more than 600 studios worldwide when it was written. The review as read here gives no date for the style's development, and none of the sources opened for this page establishes when or where heating was first added to yoga classes.

A 2025 systematic review treats hot yoga more broadly, as any yoga done in warm to hot conditions, typically at air temperatures of 25 °C or higher. Of its 43 included studies, 74% examined the Bikram format, 19% generalized hot yoga, 5% Hatha and 2% Vinyasa, so the research record is weighted toward one standardized sequence. The separate Machipedia page Bikram Yoga covers that sequence, and this page covers the wider group of heated classes.

Growth of the research record

In 2015 the critical review found only one randomized trial of Bikram yoga, with 21 participants, and called for better-reported controlled trials. By the 2025 review, 15 of 27 chronic-intervention studies were randomized controlled trials and 3 of 10 acute studies compared hot yoga with non-heated yoga. The review's authors still describe many designs as weak, citing small samples and missing controls. Hot yoga is one of the formats covered on the Yoga Styles page, and the general history of yoga is on the Yoga page.

Hot, heated and Bikram

Sources use several overlapping labels. The 2025 review uses hot yoga for any yoga in warm or hot conditions and uses Bikram, or 26/2, for the traditional format. Trial reports also use heated yoga, for example for a community-based 90-minute class in a trial in adults with depression. Conditions across the 43 studies in the review ranged from 30 to 52 °C and from 20 to 60% relative humidity, with sessions of 20 to 90 minutes, so the label alone does not identify a temperature or class format.

Heat as a setting, not a lineage

The 2025 review found hatha and vinyasa classes in heated settings, which indicates that heat is a condition applied to existing yoga formats rather than a separate lineage. Related Machipedia pages include Yoga, Yoga Styles, Hatha Yoga and Vinyasa Yoga. The Bikram format includes two breathing exercises, and breathing practices are covered on the Pranayama page. Passive heat exposure without yoga postures, such as an Infrared Sauna session, is a different practice and its findings should not be carried over to yoga.

Class conditions in the studies

In the standardized Bikram format described in the 2015 review, a class runs about 90 minutes in a room at 40.6 °C and 40% humidity, led with an instructional dialogue. Other studies used different conditions. A crossover study of 14 participants compared a roughly 20-minute session at 35.3 °C and 20.5% humidity with the same session at 22.1 °C, and a 52-person trial compared Bikram classes at 40.5 °C with the same classes at 23 °C, three times a week for 12 weeks.

Physiological demand reported in heated classes

The 2025 review reports that peak core temperature during a 90-minute Bikram class ranged from 38.2 to 40.1 °C across studies, with females averaging 38.9 °C and males 39.6 °C. Average heart rate was about 75% of predicted maximum, and oxygen uptake was about 25 to 31% of maximal capacity. In the 14-person crossover study, oxygen uptake was similar in hot and thermoneutral yoga (30.9% and 30.5% of maximum), while heart rate (67.0% versus 60.8% of maximum) and perceived exertion were higher in the heat.

The authors of the crossover study classified both conditions as light-intensity exercise by oxygen uptake, and they note that the heat added cardiovascular strain. These are findings from a small laboratory study in healthy young adults, and the review authors note that they come from varied protocols.

Benefits participants report

In an online survey of 157 hot yoga participants recruited through yoga websites and forums, the most frequently reported benefits were increased flexibility (63%), improved mood (58%), increased fitness (43%) and improved stamina (42%). The authors describe the survey as exploratory, using a questionnaire they designed, and a convenience sample cannot show how common these experiences are among all participants or whether the heat caused them.

Uses that research has examined

Studies of heated classes have looked at depression and stress, general well-being, flexibility, cardiovascular risk factors, glucose tolerance, bone density and body composition. A 2015 review noted that non-randomized studies suggested possible benefits for glucose tolerance in older obese adults, blood lipids, arterial stiffness and perceived stress, and listed limits including small samples and unmeasured diet and activity. The sources reviewed for this page do not examine claims that sweating removes toxins, so no finding on that claim is reported here.

What the reviews conclude

The 2025 systematic review searched PubMed and Scopus and included 43 studies with 942 participants, 76% of them female. It did not use a formal risk-of-bias tool or certainty grading, and it synthesized findings narratively. Its authors conclude that claims of hot yoga being superior to other yoga or exercise are unsubstantiated, and that psychological and cognitive findings are promising but inconclusive.

The 2015 critical review reached a similar position for Bikram yoga, concluding that there was no scientific consensus on its effectiveness for health, and its authors disclosed that the lead author co-owned a Bikram studio. Both describe small samples.

Does the heat add anything

A randomized trial of 52 sedentary adults aged 40 to 60 compared Bikram classes at 40.5 °C, the same classes at 23 °C, and a control group for 12 weeks. Flow-mediated dilation, a measure of blood vessel function, increased in the thermoneutral group and tended to increase in the hot group (P = 0.056), with no significant difference between groups. The authors conclude the postures alone were enough to improve this measure. Body fat percentage was lower in the hot group afterward.

In a 12-session randomized comparison of 22 healthy, yoga-naive adults, maximal oxygen uptake rose only in the hot group, and a cellular heat-shock protein marker was higher in that group, while perceived stress and heat tolerance did not change. The authors note the small sample.

Mood and depression

A 6-week trial of 290 healthy, yoga-naive adults found improvements in life satisfaction, general health, mindfulness, peace of mind and eudaimonic well-being in the hot yoga group (137 participants) compared with a wait-list group (153), but not in flourishing. The control group had no activity, so the trial cannot separate heat or yoga from exercise or attention, and the authors call for an active control.

In an 8-week trial of 53 women with depression, response rates were 61.1% for Bikram yoga, 60.0% for aerobic exercise and 6.7% for waitlist (intention-to-treat), and the authors describe Bikram yoga as descriptively similar to aerobic exercise. A separate trial of 80 adults with moderate-to-severe depression used a waitlist control, and a secondary analysis found that each additional class attended was associated with a 0.72-point improvement on a clinician-rated scale. That attendance was self-selected, so it does not show an optimal dose.

Blood pressure, glucose and flexibility

A 16-week randomized trial in 68 stressed, sedentary adults (63 analyzed) found no group differences in heart rate variability, systolic or diastolic blood pressure, resting heart rate, fasting glucose, lipids or arterial stiffness. Attendance averaged 27 classes, about 56% of the 48-class minimum, and the authors say low adherence likely contributed to the null result. The 2025 review reports little blood pressure data, no significant change in fasting glucose, a fall in insulin in older adults, and sit-and-reach gains of 16% (younger) and 33% (older adults).

Heat illness, dehydration and hyponatremia

The National Center for Complementary and Integrative Health states that hot yoga carries special risks of overheating and dehydration. The 2025 review summarizes case reports of sudden cardiac arrest with suspected heat stroke in a 35-year-old woman, and of exercise-associated hyponatremia with seizure after about 3.5 liters of water in a 34-year-old woman. In the survey of 157 participants, just over half reported an adverse event during a session, most often dizziness (60%), light-headedness (61%), nausea (35%) and dehydration (34%).

A web survey of 700 adults found that drinking water during class and using electrolyte drinks were associated with fewer self-reported dehydration symptoms and adverse reactions, but it was self-reported. The 2025 review's authors recommend hydration, screening, gradual acclimatization over roughly 7 to 14 sessions, and avoiding more than 3 liters of water around class. No source gives an incidence rate for serious events.

Cardiovascular conditions and medications

The 2015 review lists a case of acute coronary syndrome in a 53-year-old man during a heated class and advises medical clearance and pre-participation screening for at-risk people. Case reports cannot show how often such events occur. The US Centers for Disease Control and Prevention lists medicines that can impair heat tolerance, including diuretics, ACE inhibitors, beta blockers, anticholinergics, antipsychotics and lithium, through effects on thirst, sweating, blood volume and electrolytes. That page addresses heat exposure generally, not yoga, and it advises people not to stop medicines abruptly without a plan.

Pregnancy and older adults

The National Center for Complementary and Integrative Health advises pregnant people to avoid hot yoga while describing yoga in general as desirable for most pregnant people with precautions. A 2023 survey of 35 US hot yoga studio managers found limited published literature on hot yoga in pregnancy and described managers' beliefs rather than safety outcomes. The same page notes that adults aged 65 and older have more yoga-related injuries treated in emergency departments.

Injuries and musculoskeletal events

A 2026 systematic review of 84 adverse events in yoga case reports and series found 40% musculoskeletal and 14% cardio-respiratory, called yoga adverse events uncommon, and noted that Bikram, Ashtanga and Hatha yoga were the styles most often reported. Case reports do not give rates, and the review covers yoga in general. In the 16-week Bikram trial, six yoga participants had flare-ups of existing back, knee or foot pain, and three of them stopped.

Care boundaries and teacher training

The sources reviewed describe no training standard or professional register specific to hot yoga teachers, and the 2026 review calls for pre-practice screening, tailored instruction and instructor training. People with heart disease, blood pressure problems, heat sensitivity or other conditions, and those who are pregnant, are advised in the reviewed sources to seek medical advice before heated classes. Hot yoga should not delay or replace necessary medical care.