William J. Broad, author of The Science of Yoga: The Risks and the Rewards, writes for the New York Times:
Hatha originated as a way to speed the Tantric agenda. It used poses, deep breathing and stimulating acts — including intercourse — to hasten rapturous bliss. In time, Tantra and Hatha developed bad reputations. The main charge was that practitioners indulged in sexual debauchery under the pretext of spirituality.
Early in the 20th century, the founders of modern yoga worked hard to remove the Tantric stain. They devised a sanitized discipline that played down the old eroticism for a new emphasis on health and fitness.
B. K. S. Iyengar, the author of “Light on Yoga,” published in 1965, exemplified the change. His book made no mention of Hatha’s Tantric roots and praised the discipline as a panacea that could cure nearly 100 ailments and diseases. And so modern practitioners have embraced a whitewashed simulacrum of Hatha.
New York Times: Yoga and Sex Scandals: No Surprise Here
Broad goes on to discuss some of the studies linking yoga to sexual stimulation and speculates about how that could relate to some of the various guru sex scandals that have plagued yogis for decades.
Broad also recently wrote for the times How Yoga Can Wreck Your Body, an extremely interesting piece that’s made frustrating by its lack of comparisons between the number of injuries in yoga and the number of injuries in other types of strength training. But here’s a taste:
Black has come to believe that “the vast majority of people” should give up yoga altogether. It’s simply too likely to cause harm.
Not just students but celebrated teachers too, Black said, injure themselves in droves because most have underlying physical weaknesses or problems that make serious injury all but inevitable. Instead of doing yoga, “they need to be doing a specific range of motions for articulation, for organ condition,” he said, to strengthen weak parts of the body. “Yoga is for people in good physical condition. Or it can be used therapeutically. It’s controversial to say, but it really shouldn’t be used for a general class.”