DENVER — It was evening at one of this city’s most popular yoga centers, and teacher training was about to begin. Students wore flowing genie pants. Votive candles lit a classroom. Annie Prasad Freedom, the studio’s founder, greeted arriving yogis.

“Hello,” she cooed to a man with dreadlocks. “Nice to see you.”

Bubbling beneath the evening’s placid veneer, however, was a debate that has roiled Colorado’s growing yoga world, pitting studio owners like Ms. Freedom against a government agency that says programs that train yoga teachers must be certified, just like schools that prepare barbers, cosmetologists and truck drivers.

“I get pretty fired up about this new thing with the government,” said Ms. Freedom, 45, sitting outside her studio, Samadhi Center for Yoga and Meditation. “How can you have people who know nothing about yoga regulating yoga schools?”

Studio owners say the rules — which involve paying hundreds of dollars in fees and submitting curriculums for approval — will cut into their into tiny profits and limit their yogic creativity. But officials of the state agency, the Division of Private Occupational Schools, say they are trying to protect aspiring teachers from fraudulent and unsafe programs. And they point to the case of Bikram Choudhury, a well-known yoga teacher accused of sexually assaulting students, as evidence that schools need government supervision.