Hot Yoga During Pregnancy: A Mixed-Methods Study Examining Perspectives of Studio Management.

Research provides evidence on the benefits and safety of prenatal yoga as well as hot yoga among nonpregnant individuals. However, limited literature on hot yoga during pregnancy exists. The present study aims to (1) describe knowledge, attitudes, and beliefs of hot yoga studio management regarding hot yoga during pregnancy; and (2) examine how management teams rank the credibility of information sources (e.g., obstetricians) regarding the safety of hot yoga during pregnancy. Inclusion criteria included being at least 18 years of age and on the management team at a U.S. hot yoga studio. Studios were recruited via emails from publicly accessible websites of major hot yoga studio communities. Thirty-five participants completed a cross-sectional online survey addressing the study aims, and 10 (28.57%) participants reported trying hot yoga themselves while pregnant. Participants reported a median of 4 (interquartile range 1.5-8.5) pregnant individuals at their studio in the past year. All participants reported at least one hot yoga class type that they would recommend to pregnant individuals. Three qualitative themes emerged regarding deciding whether a pregnant individual may practice hot yoga: (1) integration of healthcare and individual knowledge, (2) emphasis on prior practice, and (3) individual bodily intuition and choice. Obstetricians were ranked the highest for credibility, although inferential tests suggested that their rankings were equivalent to those for academic journals, one's own knowledge/experiences, and a friend/acquaintance who had practiced hot yoga during pregnancy. These findings suggest recommendations for future yoga teacher trainings to include specific needs and considerations for pregnant individuals who choose to practice hot yoga.

Hot Yoga Leads to Greater Well-being: A Six-week Experience-sampling RCT in Healthy Adults

Practicing hot yoga may bring significant psychological benefits, but it is largely unstudied. We examined the effects of hot yoga on multifaceted well-being indicators with 290 healthy yoga-naïve volunteers partaking in a six-week randomized controlled trial. Participants completed questionnaires pre- and post-intervention, and reported their emotional experiences four times per day throughout an experience-sampling study. Results revealed that the hot yoga group (n = 137) improved their well-being from pre- to post-treatment, comparing to the wait-list control group (n = 153). These improvements included life satisfaction, general health, mindfulness, peace of mind, and eudaimonic well-being (ΔR2 ranging from .01 to .08)—but not flourishing, which describes major aspects of social-psychological functioning. Multilevel analyses demonstrated that momentary positive emotional experiences increased significantly throughout the trial in the yoga group only (conditional R2 = .68), particularly when attending a yoga class (conditional R2 = .50). Interestingly, this increase in momentary positive emotion explained the improvement in post-intervention mindfulness, peace of mind, and general health by 21%, 31%, and 11%, respectively. Finally, the benefits of hot yoga were more notable in individuals with lower levels of baseline eudaimonic well-being (conditional R2 = .45), flourishing (conditional R2 = .61), and mental well-being (conditional R2 = .65), even after ruling out any possible ceiling effects. To sum up, this study demonstrated multiple psychological benefits of hot yoga and its potential to be an effective positive psychology intervention. Future research—especially considering an active control group—is warranted. (AU)

La práctica del hot yoga puede aportar importantes ventajas psicológicas, aunque apenas se ha estudiado. Analizamos los efectos del hot yoga sobre una gran variedad de indicadores de bienestar en una muestra de 290 voluntarios sin experiencia en yoga que tomaron parte en un ensayo controlado aleatorio de seis semanas. Los participantes contestaron cuestionarios antes y después de la intervención, dando cuenta de sus experiencias emocionales cuatro veces al día a lo largo de un estudio de muestreo de experiencias. Los resultados mostraron que el bienestar del grupo de hot yoga (n = 137) aumentó del pretratamiento al postratamiento en comparación con el grupo de control de lista de espera (n = 153), mejorando la satisfacción en la vida, la salud en general, la atención plena, la paz mental y el bienestar eudaimónico (ΔR2 entre .01 y .08), aunque no en prosperidad psicosocial, que describe aspectos importantes del funcionamiento social psicológico. Los análisis multinivel desvelaron que se daba un gran aumento de las experiencias emocionales positivas momentáneas a lo largo de todo el ensayo únicamente en el grupo de yoga (R2 condicional = .68), sobre todo al asistir a clase de yoga (R2 condicional = .50). Es interesante ver que este aumento de la emoción positiva momentánea explicaba la mejora de la atención plena, la paz mental y la salud en general en un 21%, 31% y 11% respectivamente tras la intervención. Por último, los beneficios del hot yoga destacaban más en personas con menor bienestar eudaimónico base (R2 condicional = 45), prosperidad psicosocial (R2 condicional = .61) y bienestar mental (R2 condicional = .65), incluso tras descartar los posibles efectos techo. Resumiendo, este estudio ha demostrado los muchos efectos psicológicos del hot yoga y su potencial como eficaz intervención en psicología positiva. La investigación futura (en especial teniendo en cuenta un grupo de control activo) está justificada. (AU)

The Effects of Hot Yoga on Kidney Function: An Observational Pilot and Feasibility Study.

Yoga has been shown to have health benefits, whereas exercising in a hot environment has deleterious effects on kidney function. There are no long-term studies on the physiological effects of hot yoga. The purpose of this study was to investigate changes in renal function acutely and over time between practitioners of hot and non-hot yoga. Urine and capillary samples were collected for urinalysis, albumin-creatinine ratio, and serum creatinine at yoga studios preand postexercise over 1 year. Thirty-two participants in non-hot yoga and 19 participants in hot yoga were recruited. Difference in blood capillary creatinine (post-yoga minus pre-yoga) showed a 7.52 µmol/L (SD 11.46) increase for practitioners of hot yoga and a 4.07 µmol/L (SD 9.94) increase for practitioners of non-hot yoga, with a between-group difference of 3.45 µmol/L (95% CI -0.42, 7.32; p = 0.08). Over 1 year, the mean difference in blood capillary creatinine for the hot group increased by 0.91 µmol/L (SD 11.00) and by 3.08 µmol/L (SD 9.96) for the non-hot group, with a between-group difference of -2.17 µmol/L (95% CI -10.20, 5.86; p = 0.58). Over 1 year, the mean difference in albumin-creatinine ratio for the hot group was -0.16 mg/mmol creatinine (SD = 0.74); for the non-hot group the difference was -0.20 mg/µmol (SD = 0.80). The difference in difference between the hot and non-hot groups was 0.04 mg/µmol (95% CI -0.60, 0.68; p = 0.90). Urine collected for urinalysis could not be analyzed due to too many 0 values. This pragmatic observational study did not find a statistically significant change in renal function between participants in non-hot and hot yoga either acutely or over 1 year. A larger and longer study focusing on blood creatinine over time would help to inform the long-term effects of hot yoga on the kidneys.

Hot Yoga Leads to Greater Well-being: A Six-week Experience-sampling RCT in Healthy Adults.

Practicing hot yoga may bring significant psychological benefits, but it is largely unstudied. We examined the effects of hot yoga on multifaceted well-being indicators with 290 healthy yoga-naïve volunteers partaking in a six-week randomized controlled trial. Participants completed questionnaires pre- and post-intervention, and reported their emotional experiences four times per day throughout an experience-sampling study. Results revealed that the hot yoga group (n = 137) improved their well-being from pre- to post-treatment, comparing to the wait-list control group (n = 153). These improvements included life satisfaction, general health, mindfulness, peace of mind, and eudaimonic well-being (ΔR2 ranging from .01 to .08)-but not flourishing, which describes major aspects of social-psychological functioning. Multilevel analyses demonstrated that momentary positive emotional experiences increased significantly throughout the trial in the yoga group only (conditional R2 = .68), particularly when attending a yoga class (conditional R2 = .50). Interestingly, this increase in momentary positive emotion explained the improvement in post-intervention mindfulness, peace of mind, and general health by 21%, 31%, and 11%, respectively. Finally, the benefits of hot yoga were more notable in individuals with lower levels of baseline eudaimonic well-being (conditional R2 = .45), flourishing (conditional R2 = .61), and mental well-being (conditional R2 = .65), even after ruling out any possible ceiling effects. To sum up, this study demonstrated multiple psychological benefits of hot yoga and its potential to be an effective positive psychology intervention. Future research-especially considering an active control group-is warranted.

La práctica del hot yoga puede aportar importantes ventajas psicológicas, aunque apenas se ha estudiado. Analizamos los efectos del hot yoga sobre una gran variedad de indicadores de bienestar en una muestra de 290 voluntarios sin experiencia en yoga que tomaron parte en un ensayo controlado aleatorio de seis semanas. Los participantes contestaron cuestionarios antes y después de la intervención, dando cuenta de sus experiencias emocionales cuatro veces al día a lo largo de un estudio de muestreo de experiencias. Los resultados mostraron que el bienestar del grupo de hot yoga (n = 137) aumentó del pretratamiento al postratamiento en comparación con el grupo de control de lista de espera (n = 153), mejorando la satisfacción en la vida, la salud en general, la atención plena, la paz mental y el bienestar eudaimónico (ΔR2 entre .01 y .08), aunque no en prosperidad psicosocial, que describe aspectos importantes del funcionamiento social psicológico. Los análisis multinivel desvelaron que se daba un gran aumento de las experiencias emocionales positivas momentáneas a lo largo de todo el ensayo únicamente en el grupo de yoga (R2 condicional = .68), sobre todo al asistir a clase de yoga (R2 condicional = .50). Es interesante ver que este aumento de la emoción positiva momentánea explicaba la mejora de la atención plena, la paz mental y la salud en general en un 21%, 31% y 11% respectivamente tras la intervención. Por último, los beneficios del hot yoga destacaban más en personas con menor bienestar eudaimónico base (R2 condicional = 45), prosperidad psicosocial (R2 condicional = .61) y bienestar mental (R2 condicional = .65), incluso tras descartar los posibles efectos techo. Resumiendo, este estudio ha demostrado los muchos efectos psicológicos del hot yoga y su potencial como eficaz intervención en psicología positiva. La investigación futura (en especial teniendo en cuenta un grupo de control activo) está justificada.

Photo urticaria caused by exposure to LED emitting 633-nm wavelength during hot yoga exercise.

Photo urticaria (PU) is a rare type of urticaria that develops after exposure to various wavelengths of light. Inducing urticarial wheals using light sources of pertinent wavelengths can help make the definitive diagnosis of PU. The action spectra (AS) in Japanese patients with PU commonly fall within the ultraviolet radiation A and visible light range. Herein, to the best of our knowledge, we present the first case of PU caused by 633-nm wavelength within the visible light spectrum. Our patient worked as a "hot yoga" instructor, where light-emitting diodes (LEDs) on the ceiling were used to irradiate the entire room with 633-nm wavelength of light for "light treatment." She reported itching and wheals on the face and neck during her "hot yoga" sessions. "Hot yoga" has recently gained popularity globally. The "light treatment" is based on the theory that 633-nm wavelength light within the visible light spectrum reportedly prevents the skin from aging. We induced wheals with erythema by irradiating her skin using a 633-nm LED at a dose of 0.008 J/cm2 /s for 1 h. Her condition was diagnosed as PU caused by exposure to 633 nm. Light. Her symptoms have not recurred since she has avoided being exposed to the 633-nm wavelength of LED light.

Cardiovascular, Cellular, and Neural Adaptations to Hot Yoga versus Normal-Temperature Yoga.

CONTEXT: Chronic heat exposure promotes cardiovascular and cellular adaptations, improving an organism's ability to tolerate subsequent stressors. Heat exposure may also promote neural adaptations and alter the neural-hormonal stress response. Hot-temperature yoga (HY) combines mind-body exercise with heat exposure. The added heat component in HY may induce cardiovascular and cellular changes, along with neural benefits and modulation of stress hormones. AIMS: The purpose of the present study is to compare the cardiovascular, cellular heat shock protein 70 (HSP70), neural, and hormonal adaptations of HY versus normal-temperature yoga (NY). SETTINGS AND DESIGN: Twenty-two subjects (males = 11 and females = 11, 26 ± 6 years) completed 4 weeks of NY (n = 11) or HY (n = 11, 41°C, 40% humidity). Yoga sessions were performed 3 times/week following a modified Bikram protocol. SUBJECTS AND METHODS: Pre- and posttesting included (1) hemodynamic measures during a heat tolerance test and maximal aerobic fitness test; (2) neural and hormonal adaptations using serum brain-derived neurotrophic factor (BDNF) and adrenocorticotropic hormone (ACTH), along with a mental stress questionnaire; and (3) cellular adaptations (HSP70) in peripheral blood mononuclear cells (PBMCs). STATISTICAL ANALYSIS: Within- and between-group Student's t-test analyses were conducted to compare pre- and post-VO2 max, perceived stress, BDNF, HSP70, and ACTH in HY and NY groups. RESULTS: Maximal aerobic fitness increased in the HY group only. No evidence of heat acclimation or change in mental stress was observed. Serum BDNF significantly increased in yoga groups combined. Analysis of HSP70 suggested higher expression of HSP70 in the HY group only. CONCLUSIONS: Twelve sessions of HY promoted cardiovascular fitness and cellular thermotolerance adaptations. Serum BDNF increased in response to yoga (NY + HY) and appeared to not be temperature dependent.

Acute Physiologic Effects of Performing Yoga in The Heat on Energy Expenditure, Range of Motion, and Inflammatory Biomarkers.

Performing yoga in a heated environment (HY) is a popular exercise mode purported to improve range of motion (ROM), body composition, and aerobic fitness. The purpose of this investigation was to compare a session of HY to room temperature yoga (RTY) with regards to ROM, oxygen consumption, caloric expenditure, and biomarkers of acute stress and inflammation. Sixteen experienced yoga practitioners (F14, M2; 40 ± 11yr; 22.6 ± 1.8 kg/m2) completed a 1-hour standardized Bikram sequence in HY (105°F, 40°C) and RTY (74°F, 23.3°C) conditions (order of conditions randomized, humidity standardized at 40%). Intra-exercise metabolic gas exchange and heart rate (HR) was monitored using a metabolic cart. ROM measures were taken pre and post-exercise at the elbow, shoulder, hip, and knee. Cytokines interleukin 6,10 (IL-6, IL-10) and tumor-necrosis-factor alpha (TNF-α) were analyzed from blood samples collected pre- and 30-minutes post-exercise. Intra-exercise metabolic gas exchange and heart rate (HR) was monitored using a metabolic cart. Both bouts elicited similar acute changes in ROM although HY elicited a greater increase in hip abduction (RTYΔ° = 2.3 ± 1.3|HYΔ° = 6.6 ± 1.5; p < 0.05). Mean VO2, peak VO2, %VO2max, HR, and kcal expenditure did not differ between conditions. RER was lower during the HY (RTY = 0.95 ± 0.02| HY = 0.89 ± 0.02; p < 0.05) with a concomitant elevation in fat oxidation (RTY = 0.05 ± 0.01|HY = 0.09 ± 0.01, g·min-1; p < 0.05) and decrease in carbohydrate oxidation (RTY = 0.51 ± 0.04|HY = 0.44 ± 0.03, g·min-1; p < 0.05). Serum IL-6 was increased (15.5 ± 8.0-fold) following HY only (p < 0.05). HY does not significantly elevate aerobic energy cost compared to RTY but may acutely increase fat substrate utilization and hip ROM. Future studies remain needed to establish dose-response relationships for including HY or RTY into well-rounded fitness programs.

Calcium loss in sweat does not stimulate PTH release: A study of Bikram hot yoga.

It has been hypothesized that sweat loss during exercise causes a disruption in calcium homeostasis that activates bone resorption and over time leads to low bone mineral density. The purpose of this small pilot study was to determine whether dermal calcium loss from a bout of excessive sweating during light intensity physical activity triggers an increase in biomarkers of bone resorption. Biochemical markers related to bone homeostasis were measured before and after a 90 min Bikram hot yoga practice performed in a room heated to 105 °F with 40 % humidity. Participants were five females with a mean age of 47.4 ± 4.7 years. Nude body weight, serum total calcium (Ca2+), free ionized calcium, albumin, parathyroid hormone (PTH) and CTX-I were measured before and after a Bikram hot yoga practice. Mean estimated sweat loss was 1.54 ± 0.65 L, which elicited a 1.9 ± 0.9 % decrease in participant's body weight. Mean Ca2+ concentration in sweat was 2.9 ± 1.7 mg/dl and the estimated mean total calcium lost was 41.3 ± 16.4 mg. Serum ionized Ca2+ increased from 4.76 ± 0.29 mg/dl to 5.35 ± 0.36 mg/dl after the Bikram hot yoga practice (p = 0.0118). Serum PTH decreased from pre- 33.9 ± 3.3 pg/ml to post- 29.9 ± 2.1 pg/ml yoga practice (p = 0.0015) when adjusted for hemoconcentration (PTHADJ), implying a decrease in PTH secretion. We conclude that calcium loss in sweat during 90 min of Bikram hot yoga did not trigger an increase in PTH secretion and did not initiate bone resorption.

Predictors of and barriers to adherence in a 16-week randomised controlled trial of Bikram yoga in stressed and sedentary adults.

BACKGROUND: Bikram yoga may enhance health outcomes in healthy adults and those at risk for chronic disease, however, challenges remain in achieving optimal adherence to this practice. This study investigated factors influencing adherence to a 16-week Bikram yoga intervention in stressed and sedentary adults. METHODS: Experimental group participants (n = 29) were instructed to attend 3-5 Bikram yoga classes weekly for 16 weeks. Baseline demographics, behaviours and health measures were investigated as predictors of adherence. Barriers were assessed via documentation of adverse events, and exit survey responses. RESULTS: Participants (38.2 ± 10.1 years) were predominantly overweight-obese (83%), female (79%), and attended 27 ± 18 classes. Higher adherence was associated with older age (p = 0.094), less pain (p = 0.011), fewer physical limitations (p = 0.011), poorer blood lipid profile, and higher heart rate variability (HRV; total power, (p = 0.097)). In multi-variable analysis, three variables: age (ß = 0.492, p = 0.006), HRV (ß = 0.413, p = 0.021) and pain (ß = 0.329, p = 0.048) remained predictors of adherence. Difficulty committing to the trial, lack of enjoyment and adverse events were barriers to adherence. CONCLUSIONS: These findings should be considered in the development of future Bikram yoga trials to facilitate higher levels of adherence, which may enhance health outcomes and inform community practice. Future trials should investigate and address additional barriers and facilitators of Bikram yoga practice.

Effects of yoga interventions practised in heated and thermoneutral conditions on endothelium-dependent vasodilatation: The Bikram yoga heart study.

NEW FINDINGS: What is the central question of this study? Does the heated practice environment enhance the effects of Bikram yoga on endothelium-dependent vasodilatation in healthy, middle-aged adults? What is the main finding and its importance? The primary finding from this investigation is that the hatha yoga postures in the Bikram yoga series produce similar enhancements in endothelium-dependent vasodilatation in healthy, middle-aged adults regardless of environmental temperature. These findings highlight the efficacy of yoga postures in producing improvements in vascular health and downplay the necessity of the heated practice environment in inducing vascular adaptations. ABSTRACT: We have previously documented improvements in endothelium-dependent vasodilatation with a Bikram (hot) yoga intervention in middle-aged adults. At present, the effect of environmental temperature in hot yoga on endothelial function is unknown. The purpose of this investigation was to determine the effects of Bikram yoga interventions performed in heated or thermoneutral conditions on endothelium-dependent vasodilatation. Fifty-two sedentary but apparently healthy adults aged 40-60 years were randomly assigned to one of three groups: Bikram yoga practised at 40.5°C (n = 19), Bikram yoga practised at 23°C (n = 14) or sedentary time control (n = 19). The yoga interventions consisted of 90 min Bikram yoga classes three times a week for 12 weeks. Endothelium-dependent vasodilatation was measured non-invasively using brachial artery flow-mediated dilatation (FMD). Body fat percentage determined via dual-energy X-ray absorptiometry was significantly lower in the hot yoga group after the intervention than in the thermoneutral yoga and control conditions. Brachial artery FMD increased (P < 0.05) in the thermoneutral yoga group and tended to increase in the hot yoga group (P = 0.056). No changes occurred in the control group. There were no significant differences in FMD change scores between groups. We conclude that Bikram yoga practised in thermoneutral conditions improved endothelium-dependent vasodilatation in healthy, middle-aged adults. These new findings highlight the effectiveness of hatha yoga postures alone, in the absence of a heated practice environment, in improving vascular health and are of clinical significance given the increased propensity for heat intolerance in ageing adults.

Hydration and Hot Yoga: Encouragement, Behaviors, and Outcomes.

CONTEXT: Currently, the literature on hot yoga is lacking, and there is still much to understand regarding the safety of these practices. However, one point of safety often emphasized is hydration during the practice of hot yoga. AIM: The aim of this study was to examine hydration encouragement by hot yoga instructors and hydration behaviors and related outcomes by hot yoga participants. METHODS: A cross-sectional study (n = 700) collected self-report data on demographics, types and frequency of yoga practiced, hydration behaviors, and self-report measures of adverse outcomes experienced by participants during hot yoga. Associations between hydration encouragement, protective behaviors, and adverse outcomes were analyzed through Chi-square tests. RESULTS: Every protective hydration behavior was significantly associated with instructor encouragement (P < 0.05). Hydration before or during hot yoga participation was associated with a lower occurrence of dehydration symptoms (P < 0.05). CONCLUSIONS: Hot yoga instructors hold a key role in encouraging hydration and student safety outcomes.

Self-Reported Benefits and Adverse Outcomes of Hot Yoga Participation.

BACKGROUND: There is little to no scientific data about the health benefits or risks to participating in hot yoga, in particular distinguishing it from the practice of non-hot yoga. AIMS: This study aims to provide some preliminary evidence about the risks and benefits of participating in hot yoga. Future studies will be able to build off the findings herein. METHODS: This study utilized online survey software (Qualtrics) and recruited participants through convenience sampling (n = 157) by targeting yoga websites and online forums. As there is currently no known questionnaire that has been developed to assess the risks and benefits of hot yoga participation, an exploratory measure was designed to gain more detailed responses from participants. Descriptive epidemiological analyses we re conducted. RESULTS: Participants of hot yoga had a number of pre-existing health conditions. Both benefits and adverse outcomes were reported. The most frequently reported health benefits of hot yoga in this sample included increased flexibility (63%), improved mood (58%), increased fitness (43%), and improved stamina (42%). Just over half of the participants reported some sort of adverse event during a hot yoga session (n = 82). The most commonly reported adverse events included dizziness (60%), feeling light headed (61%), nausea (35%), and dehydration (34%), amongst others. CONCLUSIONS: Further study on the risks and benefits of hot yoga participation is required.