Background Hot yoga is a collective term used to classify any form of yoga undertaken in warm to hot ambient conditions (≥25°C). This study systematically reviewed the literature concerning hot yoga, with particular focus on acute responses to a single session and identifying prospective health benefits associated with chronic practice across physiological, functional and psychology domains.
Methods The review was conducted in accordance with the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA), with searches performed across two main databases (PubMed and SCOPUS). Studies were included if they met the Population, Intervention, Comparison, and Outcome (PICO) criteria, were of English language, peer-reviewed, full-text original articles, and using human participants.
Results Forty-three studies investigated the effects of hot yoga (both acute and/or chronic), totalling 943 participants (76% female). The most common method of yoga performed in hot conditions was Bikram (76.7%), followed by generalised hot yoga (18.6%), Hatha (7.0%) and then Vinyasa (2.3%). Typical session duration ranged 20–90 min and occurred within 30–52°C and 20–60% relative humidity. Hot yoga training interventions consisted of 6–36 sessions, that were completed 2–6 times per week, over 1–16 weeks. Acute hot yoga increases body temperature and heart rate, but not the energetic demands when compared to other forms of non-heated yoga. Chronic hot yoga appears to elicit cardiometabolic (e.g. body composition, lipid profiles and macrovascular function) and functional adaptations applicable for health (e.g., bone mineral density, balance and flexibility) as well as physical performance (e.g., strength, submaximal exercise thresholds). Such adaptations appear to occur without negatively impacting kidney function, nor sleep quality across healthy, sedentary and athletic populations. Hot yoga presents promising, albeit inconclusive findings concerning the alleviation of psychological and affective disorders, and optimising markers of cognitive function.
Conclusion Investigations into hot yoga demonstrate intriguing health and functional benefits, albeit without mechanistic insights. Claims that hot yoga provides greater health benefits than other forms of yoga are at present, unsubstantiated. Literature describing the benefits of hot yoga are limited in research utilising high-quality experimental designs. Nonetheless, caution is advised when partaking in hot yoga, given various case reports of ill-health. Hot yoga warrants further investigation as a tool to improve health and wellbeing, however researchers should consider the highlighted methodological limitations and recommendations to enhance experimental control within future research.