Bikram Yoga has been in the spotlight for some not-so-wholesome reasons in recent years, but many people still believe that the brand of “hot yoga” is uniquely good for them. One of the health claims is that it’s good for the heart—better than yoga at room temperature. A new study in the journal Experimental Physiology suggests, however, that most of the heart healthiness of hot yoga doesn’t come from the heat at all. The heat may be good for us in other small ways, but heart health isn’t unique to hot yoga.
The new study, from Texas State University, recruited participants, aged 40 to 60, who were sedentary but otherwise healthy. A third of the 52 participants took 90-minute Bikram yoga classes at 105°F, three times per week for 12 weeks. The Bikram routine consists of 26 poses that are repeated twice, along with some breathwork. The other yoga group practiced the same Bikram routine at room temperature, and a control group were told not to change their daily habits at all.
Several health measures were taken before and after the intervention, including blood vessel function (via brachial artery flow-mediated dilation), body fat composition, and cholesterol.
The researchers found that heart health, as measured by blood vessel function, improved significantly in both yoga groups (it didn’t change in the control group), which may suggest that it’s the yoga itself and not the heat that has an effect.
“The seminal finding from this investigation,” the authors write, “was that yoga practiced in both heated and [room temperature] environments produced significant improvements in endothelium-dependent vasodilation in middle-aged adults and that there were no differences in the magnitude of the increases between the two environmental conditions. These results indicate that the set sequence of 26 postures and 2 breathing exercises may be the key ingredient in producing favorable changes in endothelial function with yoga.”
But a couple of things did change for those doing hot yoga—they had more reduction in body fat percentage than those in the room temperature group. Additionally, their total cholesterol and LDL (“bad”) cholesterol readings improved, though the difference wasn’t statistically significant, meaning it could have been due to chance. The change in body fat was significant, however, which suggests that heat may do something for the metabolism.
Previous work has found that heat, apart from movement—i.e., hot tubs or saunas—has certain cardiometabolic effects. Which may explain why the hot yoga group did see some benefit, even though it was small.
“There are documented health benefits of heat (sauna and hot tub) including reductions in blood pressure and fasting blood glucose and improvements in blood vessel and heart health,” says study author Stacy Hunter.
Interestingly, previous research by Hunter’s lab had not found any change in heart health or body fat with regular yoga practiced at two times per week. So for a benefit to occur, three times a week may be the threshold. Work from other labs on hot yoga’s health benefits has led to somewhat mixed results.
One limitation of the study is that it was very small, which decreases its power. However, numerous previous studies have illustrated that room-temperature yoga in its many forms may have physiological benefits including heart health, in addition to the mental/psychological benefits that are more central to its long history.
Diehard Bikram fans will say the heat is good for you in other ways, like detoxing the body, but there’s not much evidence here. “I think the argument that it is detoxifying and cleansing to do hot yoga is weak and not scientifically valid—your kidneys and liver detoxify your body,” says University of Reading Cardiovascular Pharmacology professor Alister McNeish, who wasn’t involved in the current study. “However, some people may like the getting an extra sweat on. I think it would strictly fall in the realms of personal preference than evidence based!”
If you’re into Bikram yoga and its extreme conditions, the study results suggest you can continue it. But if the thought of hot yoga makes you queasy, you’d probably be just fine to do yoga at room temperature and still reap the benefits.
