Bikram Yoga Does Not Affect Cardiovascular Risk Factors with Healthy Participants
By John M. de Castro, Ph.D.
“those with a regular yoga practice are likely to adopt a healthy lifestyle, and to experience lower levels of perceived stress and depression than runners or inactive adults.” – B. Grace Bullock
Cardiovascular disease is the number one killer, claiming more lives than all forms of cancer combined. “Heart disease is the leading cause of death for both men and women. About 610,000 people die of heart disease in the United States every year–that’s 1 in every 4 deaths. Every year about 735,000 Americans have a heart attack.” (Centers for Disease Control). A myriad of treatments has been developed for heart disease including a variety of surgical procedures and medications. But the safest effective treatments are lifestyle changes. These include quitting smoking, weight reduction, improved diet, physical activity, and reducing stresses. Other safe and effective treatments are contemplative practices, such as meditation, tai chi, and yoga, have also been shown to be helpful for heart health. These practices have also been shown to be helpful for producing the kinds of lifestyle changes needed such as smoking cessation, weight reduction, and stress reduction.
Yoga is a mindfulness practice that has been shown to improve physical well-being and cardiovascular health. Bikram Yoga is somewhat unique yoga practice as it employs a set sequence of 26 poses (asanas) and two breathing exercises. It is practiced in a heated environment (105°F, 40.6°C, 40% humidity) and there is a unique programmed instructional dialogue. The hot environment is thought to soften the muscles making them more pliable and loosen the joints making them more flexible allowing the practitioner to go deeper into poses. The sweating that occurs is thought to help remove toxins and impurities.
In today’s Research News article “Effect of a 16-week Bikram yoga program on heart rate variability and associated cardiovascular disease risk factors in stressed and sedentary adults: A randomized controlled trial.” See summary below or view the full text of the study at:
Hewett and colleagues examined the effectiveness of Bikram yoga to alter cardiovascular risk factors. They recruited sedentary, stressed, adults and randomly assigned them to receive either a 16-week, 90 minute, 3 times per week, Bikram Yoga program or a no-treatment control condition. They were measured before and after training for heart rate variability, resting systolic and diastolic blood pressure, and heart rate, c-reactive protein, triglycerides, total cholesterol, low-density- and high-density lipoprotein cholesterol, total cholesterol to HDL ratio, and fasting blood glucose, height, weight, waist circumference, body composition, health status, and attendance at yoga sessions.
Surprisingly, they did not find any significant group differences in any of the measures before or after training. But, when they looked at attendance ay the Bikram Yoga sessions they found that the more sessions attended the greater the decrease in diastolic blood pressure, body fat percentage, fat mass, and body mass index. So, there appeared to be some modest benefits of high levels of attendance to Bikram Yoga sessions.
These are disappointing results. But, the lack of change produced in cardiovascular risk factors by participation in a Bikram Yoga program may have resulted from the fact that the participants were healthy, although sedentary, to begin with. It is possible that significant effects would have been evident if unhealthy participants were examined. On the other hand, it is possible that this form of yoga is simply not an effective means of reducing cardiovascular disease risk in healthy, sedentary individuals.
“Yoga has a powerful effect on stress and hypertension and can help people reduce the amount of medication they need. . . researchers reported significant reductions in blood pressure for interventions incorporating three basic elements of yoga practice: postures, meditation, and breathing. “ – Amy Wheeler
CMCS – Center for Mindfulness and Contemplative Studies
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Hewett, Z. L., Pumpa, K. L., Smith, C. A., Fahey, P. P., & Cheema, B. S. (2017). Effect of a 16-week Bikram yoga program on heart rate variability and associated cardiovascular disease risk factors in stressed and sedentary adults: A randomized controlled trial. BMC Complementary and Alternative Medicine, 17, 226. http://doi.org/10.1186/s12906-017-1740-1
Chronic activation of the stress-response can contribute to cardiovascular disease risk, particularly in sedentary individuals. This study investigated the effect of a Bikram yoga intervention on the high frequency power component of heart rate variability (HRV) and associated cardiovascular disease (CVD) risk factors (i.e. additional domains of HRV, hemodynamic, hematologic, anthropometric and body composition outcome measures) in stressed and sedentary adults.
Eligible adults were randomized to an experimental group (n = 29) or a no treatment control group (n = 34). Experimental group participants were instructed to attend three to five supervised Bikram yoga classes per week for 16 weeks at local studios. Outcome measures were assessed at baseline (week 0) and completion (week 17).
Sixty-three adults (37.2 ± 10.8 years, 79% women) were included in the intention-to-treat analysis. The experimental group attended 27 ± 18 classes. Analyses of covariance revealed no significant change in the high-frequency component of HRV (p = 0.912, partial η 2 = 0.000) or in any secondary outcome measure between groups over time. However, regression analyses revealed that higher attendance in the experimental group was associated with significant reductions in diastolic blood pressure (p = 0.039; partial η 2 = 0.154), body fat percentage (p = 0.001, partial η 2 = 0.379), fat mass (p = 0.003, partial η 2 = 0.294) and body mass index (p = 0.05, partial η 2 = 0.139).
A 16-week Bikram yoga program did not increase the high frequency power component of HRV or any other CVD risk factors investigated. As revealed by post hoc analyses, low adherence likely contributed to the null effects. Future studies are required to address barriers to adherence to better elucidate the dose-response effects of Bikram yoga practice as a medium to lower stress-related CVD risk.