On a recent Monday night in Memphis, Tenn., women were stomping, swaying and growling to a tribal drumbeat.
"Feel it through all your chakras," said Diane Sable, as she closed her eyes and pulled an invisible ball of energy up from her feet, over her silvery blond mane.
Under dimmed lights, women of all body types have been gathering to partake in a very different kind of fitness class.
"We never work our fingers, but in Nia we do," the instructor said.
Sable, 55, demonstrated from a deep crouch -- wiggling her fingers in front of her face in time with the drumming.
Nia, which stands for "neuromuscular integrative action," combines martial arts, dance and yoga.
"Nia is a dance of life," said Sable, who for roughly 20 years has been a certified personal fitness trainer and massage therapist.
Sable's classes are deceptively vigorous.
Starting with low lighting and calming music, the Nia movements are playful and childlike. But halfway through the one-hour session, her students are glistening with sweat.
"I hated lifting weights. That kind of thing is not for me," she said.
Despite being an energetic woman, Sable said she prefers gentle exercise instead of intense cardiovascular workouts.
Five years ago, after years of teaching Tai Chi Chuan, she became restless for something new.
As part of a circle of women who meditate together and help one another manifest their dreams, one of her "sister goddesses" told her about Nia.
Her friend badgered her until she finally ordered an introductory Nia DVD.
"It started to play, and I got the chills," Sable said. "It was so primal."
Six months later, she was in Houston, getting her training.
Every Nia class is done barefoot and includes 52 moves that correspond with the main areas of the body: the base, the core and the upper extremities.
Created in 1982 by Oregonian Debbie Rosas and Texan Carlos AyaRosas, the mind-body fitness classes took off on the East and West coasts.
Nia has also spread to more than 45 countries and is used for healing in hospitals and for spiritual rehabilitation in prisons.
Kym Franklin, 37, a singer and professor at the Visible Music College, moved this summer from Chicago to Memphis. She got hooked on Nia while in the Windy City, and her first priority was to find classes in Memphis.
"When I go, I feel like I'm going to have a spiritual experience," Franklin said. "I feel like I'm almost going to church."
Out of shape, she wanted something gentle and fun to ease her back into working out. Because she loves to dance, it seemed worth a try, she said.
But what has kept her interest in Nia is the unpredictable choreography of each session, she said.
"I don't like monotony," Franklin said.
Sometimes, they make wild-animal noises while doing high kicks, while other times they follow jazzy dance moves, Sable said.
Most important, however, she said, just have fun with it.
"It's about getting sweaty and making noises," she said.