Yoga teacher Mande White spent three years studying Iyengar yoga and has taught for more than two decades. She said a lot of teachers were becoming qualified within two months.
"The new styles of yoga are fraught with danger. Every year a lot of new teachers come out with new styles of yoga."
She said fads such as Bikram yoga, which is taught in rooms heated to up to 40C, were worrying.
She said classes had changed over the past few years from 80 per cent female to about 50/50.
"A lot of teachers are working on the flexible side of the pose. They don't pay attention to the anatomical side."
Kara-Leah Grant, of The Yoga Lunchbox magazine, said proper supervision was critical.
"When you push yourself into something and your alignment is not right, doing that repetitive action for weeks and months can do damage."
The only New Zealand study on yoga participation levels was undertaken in 2007. It found about 9 per cent of adults had done yoga or pilates exercise in the previous year.
Grant had noticed that the number of yoga practitioners soared in recent years.
In the United States, about 20 million people were estimated to be regular participants last year, on the back of celebrity endorsements from the likes of Jennifer Aniston, Sting and Gwyneth Paltrow.
A contentious New York Times article, "How yoga can wreck your body", suggested it could cause strokes and organ failure.
Among the reasons cited for high injury counts was the changing demographics of those who studied yoga.
Indian people who originally practised yoga often squatted and sat cross-legged in daily life - and yoga poses were an extension of these postures - rather than the desk-bound lifestyles predominating in Western societies.
ACC receives about 1.6 million claims annually, about 300,000 of which relate to sporting/recreational activities.
So in the bigger scheme of things, yoga-related claims make up a relatively small percentage of claims overall.
