DETROIT — About 40 women line up in rows of about 10 each. They watch as teacher Thomasenia Johnson demonstrates a few steps of a hustle called “Vanilla Swirl.” But they don’t stand and watch long. Johnson turns on the Luther Vandross song “Shine,” and every student attempts the moves.

“Up on the left foot; cha, cha, cha. Up on the right foot. Cha, cha,” Johnson calls out the steps. “Now when I say twirl, act like you have an imaginary lasso, and twirl it high and round.”

Before the dance is over, most of the students have caught on and are stepping, cha-cha-cha-ing and twirling to the beat in a hustle class at the Charles H. Wright Museum of African-American History in Detroit.

A group of women make similar moves to some saucy salsa numbers in a Zumba class at Henry Ford Hospital West Bloomfield in Michigan.

“You’re exercising, but unlike running on a treadmill, you’re having fun,” says Mary Fischioni, 58, of Farmington Hills, Mich., after the one-hour class.

They’ve discovered what growing numbers of people are finding: Dance is a fun way to step, shake, sway and shimmy your way to fitness.

Not only does dancing improve physical well-being, it delivers a three-pronged fitness punch — a mind, body and spirit boost. It helps with everything from cardiovascular fitness to memory, say proponents and participants.

The benefits of dancing for fitness are becoming more evident in the scientific community as well.

The American Osteopathic Academy of Sports Medicine this year became the first American medical academy to dedicate an entire conference to performing arts, which includes dance.

“This is significant because it shows the increased importance of performing arts medicine,” says the organization’s president-elect, Dr. Steven Karageanes, sports medicine physician and director of Performing Arts Medicine at the Detroit Medical Center.

“There’s a ton of evidence on the benefits of dance,” Karageanes says. “Dance helps increase muscle tone, flexibility and, in some types of dance, aerobic capacity. It’s also easier on the joints than something like running or jumping. And almost anyone can do it.”

Interest in dancing for fitness jumped 26 percent from 2002 to 2010, according to a survey on exercise trends from the IDEA Health and Fitness Association based in San Diego.

There are anecdotal indications of growing interest, too.

“I’m always getting calls and e-mails asking me to teach more classes,” says exercise physiologist Shawnita VanHook-Williams, who teaches Zumba at Henry Ford West Bloomfield, and at parks and recreation programs for Lathrup Village and West Bloomfield.

“People get such a euphoric feeling from dancing,” she says. “You feel good from accomplishing the class, but it also releases endorphins that help reduce stress and relieve tensions in your body.”

Some people say the classes have helped them with serious health challenges.

Lasandra Ross, 51, of Ferndale, Mich., is diabetic and says her doctors were on the verge of putting her on an insulin regimen because her blood-sugar levels were too high. She started dancing — at least twice a week — about three years ago and now her blood-sugar levels are normal.

“My doctors told me my next step was insulin, but I could avoid it if I ate right and exercised,” she said after a two-hour hustle class at the Wright Museum. “I like to dance, and this doesn’t feel like exercise.”

Toure Finley, 47, of Southfield, Mich., dances five times a week — attending Zumba and hustle classes all over metro Detroit.

“Since I started in March, I’ve lost 10 pounds,” she says.

Hustle instructor Thomasenia Johnson, who teaches classes at the Wright Museum three to four times a week, says she dropped from a size 22 dress to a size 12 in six months. “Once I realized I was losing weight, I stopped eating potato chips, and potato chips are my thing. Now, I eat whatever I want when I want.”

Denise McLaren, 48, of Detroit, says going to hustle classes has eased her arthritis pain. She dances about four days a week at various locations. “When I work out it doesn’t hurt as much. Dancing strengthens your muscles. If I miss coming here today, my whole body knows it tomorrow.”

Another benefit is that dancing has no age limits.

Just ask Josie Gentry-Huyghe, 84, of Detroit. She’s a regular at the Sunday evening hustle classes where she knows routines people a third of her age struggle to learn. She also enjoys square dancing.

“When I was growing up my parents didn’t allow us to dance, so I guess I’m making up for it,” she says with a laugh.

She says she likes it because it keeps her moving. “Dancing is something that age doesn’t define you. If you’re able to do it, you do it. And with hustling, I don’t have to sit and wait on a man to dance. When a good hustle song comes on, you get up and dance.”

Terry Klenczar, 65, of Farmington Hills, believes dancing helps with memory as well.

“You can’t let your mind wander. You have to focus on what you’re doing to keep up,” she says after Zumba at Henry Ford West Bloomfield.

Her contention is backed by scientific research, says the DMC’s Karageanes.

“For instance, a 2003 study published in the New England Journal of Medicine found that ballroom dancing at least twice a week made people less likely to develop dementia,” he says. “Research also has shown that some people with Alzheimer’s disease are able to recall forgotten memories when they dance to music they used to know.”

Others find it’s just a good stress reliever.

“If you had any stress, it’s gone by the time you leave here,” says Mary Fischioni after an hour of Zumba.