How Yoga Can Wreck Your Body

Members of the Broadway cast of “Godspell” do their flexible best. From left: Uzo Aduba (doing the wheel), George Salazar (extended-hand-to-big-toe pose) and Nick Blaemire (headstand).

On a cold Saturday in early 2009, Glenn Black, a yoga teacher of nearly four decades, whose devoted clientele includes a number of celebrities and prominent gurus, was giving a master class at Sankalpah Yoga in Manhattan. Black is, in many ways, a classic yogi: he studied in Pune, India, at the institute founded by the legendary B. K. S. Iyengar, and spent years in solitude and meditation. He now lives in Rhinebeck, N.Y., and often teaches at the nearby Omega Institute, a New Age emporium spread over nearly 200 acres of woods and gardens. He is known for his rigor and his down-to-earth style. But this was not why I sought him out: Black, I’d been told, was the person to speak with if you wanted to know not about the virtues of yoga but rather about the damage it could do.Many of his regular clients came to him for bodywork or rehabilitation following yoga injuries. This was the situation I found myself in. In my 30s, I had somehow managed to rupture a disk in my lower back and found I could prevent bouts of pain with a selection of yoga postures and abdominal exercises. Then, in 2007, while doing the extended-side-angle pose, a posture hailed as a cure for many diseases, my back gave way. With it went my belief, naïve in retrospect, that yoga was a source only of healing and never harm.

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Danielle Levitt for The New York Times

Salazar: I would say I’m a 7 out of 10 on the flexibility scale.

Danielle Levitt for The New York Times

Aduba: You know when people jump up into those crazy positions, like they stand on their eyeballs or something, while you’re sitting there just trying to figure out which side of the mat you used the last time? I envy them.

Danielle Levitt for The New York Times

Blaemire: The plow was the easiest position of the day — though it is quite a strange feeling having your face that close to your knees.

This article is adapted from “The Science of Yoga: The Risks and Rewards,” by William J. Broad, to be published next month by Simon & Schuster. Broad is a senior science writer at The Times.