Perfomed in studios heated to 40ºC, it is the trendy yoga designed to open your pores - and your purse.
But a study has found that hot yoga, also known as bikram yoga, is no better for you than doing it at room temperature.
The practice, which was developed in the 1960s, is popular with sports stars David Beckham and Andy Murray, as well as actresses Demi Moore and Anne Hathaway.
Yoga practitioners claim the heat causes blood vessels to dilate, lowering blood pressure, which could protect against heart attacks and strokes.
This might also delay hardening of the arteries, which leads to a heart attack or stroke. Some also claim the heat can help to burn calories faster.
However, a Texas State University experiment that examined the blood vessels of those doing hot yoga and normal yoga found no difference in function. Instead, yoga postures are responsible for better health, and not the temperature.
The study, published in Experimental Physiology, found exercise forces the lining of blood vessels to dilate, and so the benefits are the same as traditional yoga.