Results from the Bikram Yoga Heart Study are finally in with a grand total of 81 participants enrolled and randomized to one of 3 groups: hot yoga (105 degrees); thermoneutral yoga (73 degrees) or control (no exercise). Participants in both yoga groups completed 3 Bikram yoga classes weekly consisting of the standard 26 postures and 2 breathing exercises. The total intervention was 12 weeks (36 classes total) and body composition, lipid profile, fasting blood glucose, and vascular health were all tested before and at the end of the study.
Results showed significant and equal improvement in brachial artery flow-mediated dilation (an index of vascular health and heart disease risk) with 12 weeks of both the heated (105-degree) yoga and non-heated (73-degree) yoga groups. However, while both yoga practices were equally beneficial on the vasculature, there were some differences in their effects on other variables with additional reductions in body fat percentage and a trend (almost statistically significant) toward a reduction in LDL (bad)-cholesterol being seen only in the hot yoga group alone.
While it is unlikely that the Bikram series will ever be practiced widespread in the absence of the hot room, it is good to know that the posture series alone is positively impacts the vasculature even if practiced outside of the traditional environment.
Postures of the Bikram series are thought to take the body through a series of compression-inducing postures temporarily occluding blood flow followed by restoration of blood flow in between the postures or in savasana. This could very well account for some of these improvements in arterial health. Repeated increases in blood flow or shear stress along the artery wall has been identified as a mechanism driving endurance/aerobic exercise-induced changes in vascular health and could also account for some of these improvements with Bikram yoga.
Additional reductions in body fat percentage in the hot yoga group alone may be the result of a higher energy demand for yoga practiced with added environmental stressor of heat and humidity. While not previously measured with yoga, studies have noted higher metabolic costs associated with exercise in the heat versus temperate conditions. Science is now showing us the amazing benefits of pure Bikram Yoga: 26 postures, 2 breathing exercises, 105 degrees, 40% humidity, 90 minutes.