Bikram yoga — a style of yoga that’s done in a very hot and humid room — has become hugely popular in recent years. But is it actually any better for your health than yoga practiced in a cooler setting?
Not according to a small study published last week in the journal Experimental Physiology. The study found that although Bikram yoga appears to improve vascular health — specifically, the ability of blood vessels to “relax” and expand when there’s extra blood flow — the benefits are not any greater than if the workout was done with the thermostat turned down.
Bikram yoga involves a highly standardized sequence of 26 hatha yoga poses and two breathing exercises. It’s done in rooms in which the temperature is set at 104 degrees Fahrenheit and the relative humidity is between 40 and 60 percent.
Past research has suggested that doing yoga in such a hot setting contributes to healthier blood vessels by relaxing the muscle cells on their interior walls. That process helps keep the blood vessels from narrowing, and thus enables blood to flow more freely through them.
But concerns have also been raised that Bikram yoga can increase internal temperatures and heart rates to levels that put people at risk for heat-related illness, particularly if they fail to drink sufficient amounts of water before, during and after doing the yoga. (Individuals must be careful not to drink too much water, however. A 34-year-old woman was hospitalized for five days after drinking 3.5 liters of water at the end of her first Bikram yoga class. She developed hyponatremia, a potentially life-threatening condition in which excess fluid in the body causes abnormally low levels of sodium in the blood.)
For the current study, researchers at Texas State University and the University of Texas at Austin recruited previously sedentary adults, aged 40 to 60, and randomly assigned them to three groups. One group (19 participants) attended 90-minute classes of “hot” Bikram yoga three times a week for 12 weeks. Another group (14 participants) took the same classes, but in a room-temperature (73 degrees Fahrenheit) setting. A third group (19 participants) took no yoga at all. They were the “control” group.
At the start and the end of the study, all the participants had their vascular health assessed, specifically the ability of their blood vessels to expand in response to increased blood flow. That data revealed that both yoga groups experienced similar positive vascular changes by the end of the 12 weeks — ones that point to a lower risk of heart disease, according to the researchers. No vascular changes were observed in the control group.
The findings suggest that any heart benefits resulting from Bikram yoga come from the physical movement associated with the hatha yoga postures, not from the heat.
Interestingly, the data also revealed that the participants in the hot yoga group — but not those in the room-temperature group — experienced a small but statistically significant average reduction in body fat. That finding counters other research that has found that Bikram yoga is not that great at burning extra calories.
Limitations and implications
The current study comes with plenty of caveats. Most notably it was a small study, involving sedentary but otherwise healthy people. The results might not be the same if the group were larger and more representative of the general public’s diverse set of health problems.
Still, plenty of other research (including some done at the University of Minnesota) has shown that yoga offers both physiological and psychological benefits.
As one cardiovascular expert not involved in the study told Forbes reporter Alice Walton, “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. 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.”
FMI: You can download and read the study in full on Experimental Physiology’s website.