Yoga could help to improve function of artery linings regardless of room temperature, researchers conclude

While the popularity of practising yoga in sweltering rooms is booming around the world, researchers say benefits to blood vessels are the same whether the moves are performed in the heat or not.

Bikram yoga was founded by controversial instructor Bikram Choudhury and involves 26 poses and two breathing exercises, performed in a room heated to just over 40C (104F).

Having first taken off in the 1970s, Bikram yoga classes are now widespread, with some research suggesting they could offer health benefits including improving the function of the inner lining of blood vessels – problems with which are linked to increased risk of fatty plaques building up inside arteries.



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But now researchers say the potential vascular benefits of Bikram are not down to the heat.



“The postures and the breathing exercises are enough in the absence of the heated environment to elicit some beneficial adaptations that could reduce the risk of heart disease,” said Dr Stacey Hunter, co-author of the research from Texas State University and research director for yoga-promoting organisation Pure Action Inc, which funded the study.



It is not the first time that yoga has been linked to health benefits, with previous studies suggesting it could be as good as cycling or a brisk walk in reducing the risk of cardiovascular disease, for example.



However little work has gone into unpicking the impact of different types of yoga, some of which are more intense that others, or how much yoga is needed for benefits to be seen.

Writing in the journal Experimental Physiology, Hunter and colleagues describe how they randomly assigned healthy but sedentary middle-aged adults to one of three groups. While 19 participants carried on as usual, 14 undertook 12 weeks of three 90-minute Bikram classes at room temperature and 19 participants undertook Bikram classes at 40.5C.

A range of measurements were taken as part of the study including weight, cholesterol levels, blood pressure and the ability for the main artery in the forearm to dilate in response to increased blood flow – a measure of the function of the inner blood vessel lining.

The results reveal that while both yoga groups showed improvements in function of their artery lining, the size of the benefits was the same regardless of the temperature of the classes. Those who did not do yoga showed no improvements.



No significant effect on blood pressure, cholesterol, blood lipids, weight or blood glucose was seen for any of the groups, but the team note that those undertaking hot yoga showed a small drop in body fat, possibly due to extra energy being used.



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Paulus Kirchhof, professor of cardiovascular medicine at the University of Birmingham, said that, generally speaking, the impact of yoga on health was not yet clear.

“Yoga, similar to other behaviours, can help to improve vascular health. Whether yoga per se is particularly effective to reduce blood pressure, or whether yoga has similar effects as regular physical exercise [for example], is less clear,” he said, adding that he would advise people undertake the recommended 30-45 minutes of moderate activity five times a week, with yoga as an optional addition.

Julie Ward, senior cardiac nurse at the British Heart Foundation, said previous studies had shown some improvements in measures including blood pressure and cholesterol, but that high temperatures could be dangerous for those with underlying heart conditions.

“This study, although interesting, is a very small study and has significant limitations, so more research would be needed to confirm the findings,” she told the Guardian.

But that doesn’t mean people should roll up their mats. “The benefits of yoga on emotional health are well established and any physical activities that can help reduce our risk of a deadly heart attack or stroke should be encouraged,” said Ward.