Pilgrimage To the Heart Of Yoga Devotees from around the world head for Mysore, India, home of the vigorous form called Ashtanga

At 5 p.m. on a breezy Saturday, the Ashtanga Yoga Research Institute in the southern Indian city of Mysore is buzzing. Students from around the globe are thronging the steps of the three-story, light-gray concrete building. Clad in light-colored cotton pants and T-shirts, their backs ramrod straight, their eyes and skin aglow, they are queuing up to greet Sharath Ranga-swamy, 35, a master of Ashtanga yoga, and his grandfather, Guruji K. Pattabhi Jois, the institute's founder. Some are there to inquire about their classes, which start at 5 a.m. the next day, and some are still hoping to enroll.

While there are numerous yoga centers in Mysore, a two-hour trip by car or train from Bangalore, Ashtanga Yoga Research Institute is the most well-known and the one that attracts the greatest number of visitors from overseas. Ashtanga, which means "eight limbs" in Sanskrit, is an extremely active form of yoga. It combines "vinyasa," or flowing breath, with "asanas," or poses. The rigorous mix heats the body in an intense workout that some say is equal to a grueling session at the gym.Russell Smith, a New York entertainment lawyer, says part of the attraction of Ashtanga yoga is the physical rigor. When he first took classes in New York, "I couldn't do any of the poses, and I felt awful," he recalls. "Even so, I was on a cloud. The class really opened me up—the combination of movement and breathing was amazing. I'm hooked." Since 2004, Smith has spent at least three months a year studying in Mysore.Perhaps because of the physical challenge, Ashtanga appeals to "type-A, overachiever kind of people," says Andrea Varalli, a freelance graphic designer from Maui and student at the Institute. Yet even people who push themselves, he says, soon realize that, as in all yoga practices, "the physical part is just an entry" into enhanced mental well-being.Classes start at 5 a.m., but many students arrive earlier to find choice spots for their mats. Five days a week, sessions are "Mysore-style"—that is, students work at their own pace while Sharath, who goes only by his first name, and his mother, Saraswati, move around the room, correcting students' poses and demonstrating new ones. On Fridays and Sundays, classes are taught to the group as a whole. Beginners get separate instruction for part of the day. Class ends at 8:30 a.m., after which many students adjourn to nearby cafés. Whatever they order must be vegetarian. Alcohol, too, is off-limits.The strict regimen doesn't seem to be a problem for the students, according to Marcus Fontoura, a senior research scientist at Yahoo! Research in Sunnyvale, Calif., who is on his first pilgrimage to Mysore. "I practice at 5 a.m. in California, too. I'm used to it. Everyone is."A month's tuition is 26,900 rupees (about $600), with additional months 17,900 rupees (about $400) each. There's no weekly rate since the school requires a one-month commitment—no refunds if you leave early, either, and some students do. The Institute is open from January through March and June through December, except for a short break around yearend.When the school is closed, Sharath travels abroad. His workshops in New York, London, Sydney, and elsewhere have been attended by a host of celebrities, including Gwyneth Paltrow, Madonna, Willem Dafoe, Sting and his wife, Trudie Styler, and Mike D., drummer for the Beastie Boys. Sonya Jones, wife of hedge-fund magnate Paul Tudor Jones and a close friend of Guruji and Sharath, has made a few low-profile visits to Mysore, too.While yoga beckons many tourists, it's not the only reason to visit. Mysore and its 1.5 million residents are still somewhat sheltered from the wave of modernity that has swept through India over the past decade. An ancient city, Mysore gained sovereignty as a kingdom near the end of the 18th century. The main palace, built in the Indo-Saracenic style that incorporates Hindu, Muslim, Gothic, and Rajput styles, was commissioned in the late 19th century and completed in 1912. It remains one of the city's most popular tourist attractions.Mysore is also close to some of South India's finest wildlife sanctuaries. Two national parks, Bandipur and Nagarhole, draw visitors for jeep safaris into the jungle and stays at eco-friendly resorts. The area also boasts renowned health-and-beauty spas, such as Indus Valley Ayurvedic Centre, and the regal Brindavan Gardens, which has served as the colorful backdrop of countless Bollywood movies.Residents have adapted enterprisingly to the stream of yoga adherents. Locals rent rooms, apartments, and even houses to visiting students, and they will arrange for phone and Internet service.For travelers who prefer something more upscale, there are several good hotels in the area, including Hotel Regaalis, Royal Orchid Metropole, and Lalitha Mahal Palace Hotel. Rates run from around $100 to $170 a night for a double room. Dinner at a high-end restaurant, such as the Tiger Trail at the Royal Orchid Metropole, costs about $40 to $60.The best times to visit are winter, fall, and—if you don't mind the monsoons—summer. The Institute is closed in April and May because it's just too hot, even for those who seek to transcend the physical.