Hot Yoga Leads to Greater Well-Being: A Six-Week Experience-Sampling RCT

Hot yoga is a style of yoga performed in a heated room, usually around 40°C (104°F), with a humidity of around 40%. It consists of a series of 26 postures and breathing exercises designed to strengthen the whole body and provide both physical and mental benefits.

The heat allows for deeper stretching and the elimination of toxins through sweat. Advocates claim hot yoga improves flexibility, strength, circulation, weight loss, and mood. The most popular style of hot yoga is Bikram yoga, which Bikram Choudhury created in the 1970s.

Hui, B. P. H., Parma, L., Kogan, A., & Vuillier, L. (2022). Hot yoga leads to greater well-being: A six-week experience-sampling RCT in healthy adults. Psychosocial Intervention, 31(2), 67–82. https://doi.org/10.5093/pi2022a4

Key Points

1. Hot yoga practice over six weeks significantly improved most well-being indicators in healthy adults compared to a waitlist control group. Benefits were seen in life satisfaction, general health, mindfulness, peace of mind, and eudaimonic well-being.
2. Positive emotions increased throughout the study in the hot yoga group only, especially when attending a hot yoga class. Higher baseline well-being was associated with less emotional benefit.
3. Increased positive emotions during the study mediated improvements in mindfulness, peace of mind, and general health.
4. This rigorously designed randomized controlled trial proves that hot yoga enhances well-being by increasing positive emotional experiences.

Rationale

Yoga has become increasingly popular for health and well-being, with over 55 million practitioners in the US (Zuckerman, 2020). Hot yoga in heated rooms (40°C) is a popular form claiming physical and mental benefits.

However, research has mostly focused on clinical groups, used small samples, and lacked comprehensive well-being measures (Brinsley et al., 2020).

This rigorously designed randomized controlled trial (RCT) with 290 healthy adults addresses these limitations to evaluate whether hot yoga improves multifaceted well-being.

Method

290 healthy yoga-naïve adults were randomly allocated to a hot yoga group (n = 137, 78% female, mean age 29.5 years) or waitlist control group (n = 153, 80% female, mean age 29.3 years).

The yoga group attended 24 hot yoga classes over six weeks. All participants completed surveys assessing well-being at baseline and six weeks, and the experience sampling method (ESM) reported emotions four times daily.

Hot Yoga

The hot yoga group was offered 24 Bikram hot yoga classes held over the 6-week study period. Bikram is a standardized sequence of 26 poses and 2 breathing exercises conducted in a room heated to 40°C with 40% humidity (Choudhury, 2007).

Participants attended sessions at a yoga studio in central Cambridge, UK. Each class followed the standard Bikram sequence led by experienced instructors and lasted 90 minutes.

There was no minimum class attendance mandated, but participants could attend up to 4 classes per week.

ESM

Participants were asked about their emotional experiences, specifically rating the extent to which they felt various positive emotions (glad, happy, grateful, interested, proud) and negative emotions (angry, ashamed, disgusted, repentant).

Self-Reports

The surveys assessing well-being indicators were given at baseline and the 6-week timepoint.

• Mindfulness – tendency to pay attention to the present moment measured using the 24-item Five Facet Mindfulness Questionnaire (Bohlmeijer et al., 2011). Higher scores indicate greater mindfulness.
• Peace of mind – feelings of internal peacefulness and harmony measured by the 7-item Peace of Mind Scale (Lee et al., 2013). Higher scores mean more frequent peace of mind.
• Life satisfaction – cognitive judgment about life quality measured by Diener’s 5-item Satisfaction With Life Scale (Diener et al., 1985). Higher scores show greater satisfaction.
• General health – mental health status was measured using the 12-item General Health Questionnaire (Donath, 2001). Lower scores indicate better health.
• Eudaimonic well-being – having purpose and meaning in life assessed using Waterman’s 21-item Questionnaire for Eudaimonic Wellbeing (Waterman et al., 2010). Higher scores mean greater well-being.
• Flourishing – social-psychological prosperity measured by Diener’s 8-item Flourishing Scale (Diener et al., 2010). Higher scores show greater flourishing.
• Mental wellbeing – positive aspects of mental health measured by the 14-item Warwick-Edinburgh Mental Wellbeing Scale (Tennant et al., 2007). Higher scores indicate better well-being.

Data Analysis

Survey data was analyzed using linear regression models. ESM data was analyzed using multilevel modeling given the nested data structure.

Multilevel mediation models also tested whether increased positive emotions mediated well-being improvements.

Results

• The hot yoga group improved significantly more than controls from baseline to six weeks on most wellbeing indicators: life satisfaction, general health, mindfulness, peace of mind, and eudaimonic wellbeing (small effect sizes, R2 .01 to .08). Flourishing did not improve.
• In ESM data, positive emotions increased over time in the hot yoga group only (conditional R2 = .68), especially during hot yoga classes (conditional R2 = .50). Those with lower baseline well-being benefited more emotionally.
• Increased positive emotions mediated improvements in mindfulness (explained variance 21%), peace of mind (31%), and general health (11%).

Insight

This rigorously designed RCT provides strong evidence that hot yoga enhances well-being in healthy adults by boosting positive emotional experiences during practice.

The hot yoga group specifically showed bigger increases in life satisfaction, health, mindfulness, calmness, and purpose in life. The increases were small to medium-sized. However, there was no extra improvement in positive social relationships.

When tracking people’s emotions throughout the study, the hot yoga group felt more positive emotions over time, especially right after doing a hot yoga class. People who were less happy at the start of the study increased their positive emotions the most from the hot yoga.

The increases in positive emotion accounted for some of the well-being improvements after 6 weeks of hot yoga.

Specifically, 21% of the increased mindfulness, 31% of increased calmness, and 11% of improved health were explained by improved positive mood from yoga.

Strengths

• Large sample size
• Random allocation to hot yoga or waitlist control group
• Comprehensive wellbeing indicators
• Experience sampling methodology
• Longitudinal mediation analysis

Limitations

• The study lacked an active control group undertaking another exercise intervention, limiting the ability to attribute benefits specifically to hot yoga versus exercise.
• As the predominantly female sample limits generalizability, further research should ensure balanced gender representation.
• Self-selection biases for positive attitudes toward yoga may have inflated benefits.

Implications

This RCT provided strong evidence that a relatively brief hot yoga intervention can significantly improve multifaceted well-being in healthy people by boosting positive emotional experiences. Individuals with poorer mental health may stand to benefit even more.

The accessible and cost-effective nature of hot yoga makes it a promising public health approach for enhancing wellbeing.

Less emotionally responsive individuals may require more intense or longer interventions. Hot yoga shows promise as an accessible and effective self-care approach to improve multifaceted well-being.

Advocates of hot yoga believe it has several advantages over traditional yoga done at normal room temperature:

1. Improved flexibility – The heat allows muscles and joints to stretch more deeply and safely during poses. The humidity also prevents overstretching. This greater range of motion helps prevent injury.
2. Enhanced detoxification – Profuse sweating induced by heat and exertion helps eliminate toxins and waste products from the body. This therapeutic perspiration is said to purify the skin and blood.
3. Cardiovascular fitness – Added cardiovascular strain and energy demands from performing yoga poses in intense environmental heat augment fitness benefits, such as maximal oxygen uptake (VO2max).
4. Builds mental strength – Coping with physical challenges in intense heat is uncomfortable and requires heightened mental resolve and focus, fostering willpower, determination, and stress resilience.
5. Improved mood – Due to greater exertion and overcoming discomfort, endorphin and dopamine release may be elevated, amplifying the “runner’s high” and mood enhancement from yoga.

References

Primary reference

Hui, B. P. H., Parma, L., Kogan, A., & Vuillier, L. (2022). Hot yoga leads to greater well-being: A six-week experience-sampling RCT in healthy adults. Psychosocial Intervention, 31(2), 67–82. https://doi.org/10.5093/pi2022a4

Other references

Bohlmeijer, E., Klooster, P. M., Fledderus, M., Veehof, M., & Baer, R. (2011). Psychometric properties of the five facet mindfulness questionnaire in depressed adults and development of a short form. Assessment, 18(3), 308-320.

Brinsley, J., Schuch, F., Lederman, O., Girard, D., Smout, M., Immink, M. A., Stubbs, B., Firth, J., Davison, K., & Rosenbaum, S. (2020). Effects of yoga on depressive symptoms in people with mental disorders: A systematic review and meta-analysis. British Journal of Sports Medicine, 55(17), 992–1000.

Choudhury, B. (2007). Bikram yoga: The guru behind hot yoga shows the way to radiant health and personal fulfillment. HarperCollins.

Diener, E., Emmons, R. A., Larsen, R. J., & Griffin, S. (1985). The Satisfaction With Life Scale. Journal of Personality Assessment, 49(1), 71-75.

Diener, E., Wirtz, D., Tov, W., Kim-Prieto, C., Choi, D., Oishi, S., & Biswas-Diener, R. (2010). New well-being measures: Short scales to assess flourishing and positive and negative feelings. Social Indicators Research, 97(2), 143-156.

Donath, S. (2001). The validity of the 12-item General Health Questionnaire in Australia: A comparison between three scoring methods. Australian and New Zealand Journal of Psychiatry, 35(2), 231-235.

Lee, Y. C., Lin, Y. C., Huang, C. L., & Fredrickson, B. L. (2013). The construct and measurement of peace of mind. Journal of Happiness Studies, 14(2), 571-590.

Tennant, R., Hiller, L., Fishwick, R., Platt, S., Joseph, S., Weich, S., Parkinson, J., Secker, J., Stewart-Brown, S., Ryan, R., Deci, E., Goldberg, D., Williams, P., Compton, W., Smith, M., Cornish, K., Qualls, D., Keyes, C., Shmotkin, D., … Rutter, C. (2007). The Warwick-Edinburgh Mental Well-being Scale (WEMWBS): Development and UK validation. Health and Quality of Life Outcomes, 5(1), e63.

Waterman, A. S., Schwartz, S. J., Zamboanga, B. L., Ravert, R. D., Williams, M. K., Bede Agocha, V., … & Brent Donnellan, M. (2010). The Questionnaire for Eudaimonic Well-Being: Psychometric properties, demographic comparisons, and evidence of validity. The Journal of Positive Psychology, 5(1), 41-61.

Zuckerman, A. (2020, August 2). Significant yoga statistics: 2019/2020 benefits, facts & trends. CompareCamp. https://comparecamp.com/yoga-statistics/#TOC2

Keep Learning

1. What psychological mechanisms might explain the benefits of yoga for wellbeing?
2. Could the social aspects of group yoga classes contribute to the benefits as much or more than the physical practice itself?
3. What cautions should people consider before adopting an intensive hot yoga practice?
4. How could this research inform public policy regarding funding of recreational/wellbeing activities?