"Power flow yoga" performance by Shiva Rea, a Californian in low-cut white trousers shocked the traditionalists. By the time Shiva Rea, famed for inventing the high-energy Yoga Trance Dance, had completed her demonstration at a yoga festival in northern India, some 20 people had left the room.
"This is not yoga, it's just a show, but to succeed in California, this is what they have to do," griped Austrian yoga teacher Florian Palzinsky, 42, as he watched the Santa Monican.
For thousands of years, yoga has been expressed through gradual control of the body, breath and mind.
Rishikesh, nestled in the Himalayan foothills, shot to world prominence when the Beatles visited in 1968 to learn about transcendental meditation from Maharishi Mahesh Yogi, helping to popularise ideas about Indian spirituality.
Now hundreds of visitors, most of them foreigners, come each year to the festival from dozens of countries, bringing their yoga mats to learn about breathing, posture, chanting and nutrition from experts in all types of yoga.
The classes start at 4:00 am and go on until sunset.
"Yoga doesn't flow in our veins like it does in Indians so I came here to go back to basics," said French yoga teacher Juliette Allard, 38, who has been coming to the festival for the past three years.
German nutritionist Daniela Wolff, 50, said that she felt happiest with the festival's tradition-minded Indian teachers, such as the spry 103-year-old Indian guru Swami Yogananda who gave his course every morning at 6:00 am sharp.
"They are genuine, do not use fancy words, there is no music. Most importantly, they don't need to prove anything to anyone," Wolff said.
For Japanese yoga teacher Hikaru Hashimoto, the Americans "are very gifted at making yoga evolve -- at changing and inventing new styles that will spread throughout the world".
"But India is the first country of yoga. The basis of yoga is here," he insisted.
Nevertheless, the more unconventional practitioners succeeded in drawing the spotlight at the festival, such as white-robed American Gurmukh Kaur Khalsa -- born May Mary Gibson but now a devout Sikh.
Khalsa has given private lessons to stars such as Madonna, Cindy Crawford and Courtney Love, teaching Kundalini Yoga -- a meditative form of stretching -- and urging people to find the sunshine "in your hearts".
What really matters is that people "want to feel better, be closer to ourselves", she said. "That's what yoga is."
But Khalsa scandalised some festival-goers when her group held hands and chanted the word "Hallelujah" for 10 minutes, waving their bodies.
Tears poured down some faces of the group and others looked ecstatic after the session, but their emotional response did not impress critics.
"I've practised yoga for 20 years. To me, it's superficial, there's no depth -- it's like playing sports," said Indian yoga teacher Kamal Deep Ohlan, 35.
"Today, yoga has become a business when it should be a discovery of one's inner self, a philosophy."