The New York Times' science writer William J Broad's latest book, which examines the science behind claims for the benefits of yoga, has caused quite a stir among yoga practitioners with claims of serious health risks.
Mr Broad told Today presenter Sarah Montague that some yoga poses have "extremely high consequences" which can in some cases lead to strokes and ultimately death.
The danger is not anecdotal or a matter of "freak accidents", he claims.
But Pierre Bibby, chief executive of the British Wheel of Yoga, says he does not recognise this characterisation at all.
He accepts the evidence but says it is a question of "quantifying" it. It is not yoga that is bad for you, he explains, it is "bad teaching and bad practice".
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