Jenice Armstrong: Would you bare it all for naked yoga?

SIGN UP for naked yoga and you won't need trendy labels such as Lululemon or Athleta.

All you'll need is a yoga mat, maybe a towel and a willingness to get naked.

Bridge pose? In this class, no tight clothing will be in your way.

You may, though, feel self-conscious about having your bare crotch on full display.

That's enough to make anyone go "ommmm."

Classes are usually segregated by sex, such as the monthly, all-male Naked Yoga Philly that takes place Tuesday night in Center City.

"We leave judgment at the door," said a local Naked Yoga Philly teacher who asked not to be identified.

"Being without clothes can bring up judgments we may have about ourselves or other people, and this community environment helps us practice letting go of all that in order to simply be present to ourselves and others, just as we are. How many places in life can offer that?"

The practice reportedly began in ancient India with the monklike Naga Sadhus, who renounce worldly affairs and devote themselves to reaching their higher selves.

Naked yoga has been gaining in popularity in the United States since the 1960s, when alternative health centers such as the Esalen Institute in California incorporated it into its wellness programs.

Naked yoga really caught on, though, during the late 1990s in New York City's gay community with classes such as Hot Nude Yoga and Midnight Yoga for Men.

These days, you can find classes in Boston, San Francisco, Los Angeles, even Salt Lake City.

"A lot of people, especially living in New York, don't get the opportunity to connect with people in an intimate way," said Aaron Star, who's credited with helping popularize the naked-yoga movement. He's now based in Costa Rica.

Practitioners bristle at the idea that naked-yoga classes are about sex, not yoga.

Star does acknowledge, however, that partner work is a popular feature of his class Hot Nude Yoga and that "generates a certain amount of heat." His website is more explicit. He talks about spreading the benefits of yoga to nourish sensuality and sexuality.

Last year, naked yoga became a part of the nation's zeitgeist following an episode of the E! reality show "Kourtney & Kim take New York," when Kim Kardashian's then-husband, Kris Humphries, arrived home to find a naked yoga instructor leading a class of Kardashian's friends through some stretches. Humphries exploded, and we all know what happened to that marriage.

Can't completely blame him.

Naked yoga takes getting used to.

In Humphries' case, there was a naked stranger in his apartment.

I'm a free spirit, but I'm not sure how well I could concentrate while a bunch of naked strangers are practicing their downward dogs. Baring it all, practitioners say, encourages not only physical freedom but the dropping of inhibitions and judgment of others. When fitness expert Jennifer Kries took her first naked-yoga class in 2003 in a dim studio in San Francisco, there were 10 other women in the room, which had a spalike quality. Incense wafted and candles burned.

"I forgot I was naked because people were just talking to each other and I started to feel incredibly free," recalled Kries, who recently co-produced a series of DVDs called "Yoga Undressed." "I felt freer than I ever had since childhood, when I went skinny-dipping."

"I was crying afterwards actually. I also had an incredible epiphany in that class," said Kries, a former dancer who performed with the Pennsylvania Ballet and other companies. "I had an emotional release in which I recognized that I had been fighting with myself even in yoga. For me, it was still, 'How high can my leg go?' . . . When I took that class and started to cry, I felt like I had finally given up the fight. I felt really at peace."

Kries, who lives in Philadelphia, doesn't teach naked yoga and doesn't plan to start.

"I created 'Yoga Undressed' so that people could discover this beautiful union of mind, body and spirit and learn to appreciate and love themselves in the privacy of their own homes," she said. "In the hopes that perhaps it would spark a desire to join a group class at some future date, etc., and or so that it would become a ritual that they could engage in any time they wanted, again in their own space."

I mentioned to Kries that a colleague of mine took a quick look at the trailer for "Yoga Undressed" and said it looked pornographic. I watched it too, and the beginner DVD, and although it was tastefully done, I was startled by the full-frontal nudity and the amount of partner interaction on the trailer. There was less of that on the beginner DVD.

Kries defends the DVDs. "This is the opposite of porn," Kries said. "It's all about being free and having the right to be free . . . When people do naked yoga, there's no competition. There's no clothing. There's nothing to separate you from me. When you are in a naked-yoga class, you don't look at other people disparagingly . . . [and] you accept things about yourself that you never would."

Some yoga aficionados aren't convinced. Rajashree Choudhury, founder of Yoga USA (which is trying to get yoga into the Olympics), told me she was unfamiliar with naked yoga.

Nor has local yoga instructor and yoga therapist Theresa Conroy. "I have been deeply involved in the yoga world for more than a decade and, aside from once in a while hearing a reference to naked yoga - like, in a joke - I have never encountered it," said Conroy, owner of Yoga on the Ridge. "I mean, really, in any yoga class, you wouldn't be doing any of that partner stuff. That just seemed to be, well, naked, sexually inspired stuff. Although, I have to say, those were outstanding yogis," Conroy said of the practitioners in the "Yoga Undressed" video.

"I've never been in a yoga class where people - clothed or naked - got all twisted up all over each other like that."

The Associated Press

contributed to this report.