They call it their "Vitamin J."

For the women in Cara Mierl's Jazzercise class, a music-blasting, heart-pumping hour of exercise a few times a week tones the mood as well as the muscle.

They swirl, groove, gyrate and rotate away the blahs at the McBeth Recreation Center, a low-frills, city-owned facility tucked in a woodsy corner of Zilker Park. They use this exercise class to cope with everything life throws at them: kids, illness, divorce, change and, for some, depression.

It's no wonder they feel better after sweating to the beat. Studies have shown that all kinds of aerobic exercise, from running to biking, can ease the effects of depression. Even those who aren't clinically depressed can gain benefits beyond stronger hearts and muscles from revving up their body's engine.

Jazzercise is one way to do that. With 11 classes a week at McBeth, anyone can pop in for an hour-long pick-me-up, touch base with a close-knit circle of exercisers — and even get in a workout.

Let's get moving

The students in Mierl's 9:30 a.m. Monday class flood through the door of the recreation center, towing gym bags, sweat towels and water bottles emblazoned with the Jazzercise logo.

Class begins when Mierl, 42, climbs on top of the small wooden stage. She cranks up the music, and begins a neck-rolling, body-swaying series of stretches.

"Are you feeling funky?" she calls out through her headset. "Plant your hips and let your body move forward!"

About 40 women (men are also welcome) mimic her moves, marching in place, jabbing their fists out in mock punches, swiveling their hips. Not everyone can keep up. Some don't even try. It doesn't matter. When the first song fades into the second, everyone cheers.

"Give me some attitude!" Mierl yells. She's not even breathless. The women whoop. Ricky Martin croons. Before the class is finished, they've grooved to the Funky Green Dogs, Usher and Nelly Furtado. As they move, Mierl keeps up a steady banter, announcing one student's recent engagement and her own sister's new diet.

After 40 minutes of high-energy dance action, the women pull out hand weights and shift to the toning and strengthening portion of the routine. As class winds down, they stretch again. Before the students scatter, Mierl announces a few milestones: One student has earned her Jazzercise towel by attending classes and doing extra-credit activities; another has logged her 50th class of the year.

This class has spawned Bible studies, play groups and close friendships. When one student died of melanoma, another Jazzerciser gave the eulogy at her funeral.

"A lot of people know people in the class and what they go through," Mierl says afterward. "I think that encourages them."

"I think it is more than just exercising that makes people feel better. It is the positive, encouraging and loving atmosphere that we nurture in Jazzercise that makes people feel better mentally, besides just the physical."

Jazzercise an upper

Research shows that it might be more than just a supportive atmosphere that makes exercisers feel better.

We've heard of runners' high. Some folks work out their aggression pumping iron at the gym. A brisk swim makes you sleep better at night.

Now a study published in January by the University of Texas Southwestern Medical Center at Dallas shows that for some people, aerobic exercise can reduce symptoms of mild to moderate depression. And it works as well as antidepressants for some. (Although a few of the women in Mierl's class have been diagnosed with depression, most have not.)

The Dallas study of adults ages 20 to 45 who were clinically depressed showed that symptoms were cut nearly in half for those who exercised moderately on treadmills or stationary bicycles for half an hour, three to five times a week.

So what message we can glean from that? "Physical activity may have benefits if you have depression," says study co-author Dr. Madhukar Trivedi, professor of psychiatry and head of the mood disorders research program at UT-Southwestern.

Still, he warns, those with depression shouldn't simply rely on exercise for treatment. They should see a physician and include a discussion of exercise in that visit. "And no treatment, including exercise, is a panacea," Trivedi says.

Not every patient in the study got better, he notes.

Depression is a difficult and sometimes fatal disease that can sometimes lead to suicide, Trivedi said. Yet for patients who do not get fully well with antidepressants, there is a growing body of research that shows exercise can help.

Feeling better

Melanie S. Uribe, 48, used to take Jazzercise, but fell out of the routine when her children were born. Then her infant daughter was diagnosed with brain cancer and was in and out of the hospital.

"The past 10 years have been extremely hard," Uribe says. "I almost lost her several times."

Marisa, now 10, has been in remission since 2000, and Uribe went back to Jazzercise a year ago at a girlfriend's invitation. She says returning to the class "is like coming out of darkness."

"Depression can do so much damage to your mind and body . . . I didn't feel like a woman any more," Uribe says. "Thank God for the swivels of Jazzercise — it gave me back the feeling of 'Hey, I still got it.' "

The energy of the group and the music, as well as the physical movement, provides a boost. "In this room for an hour, you can be free, so the outside wall goes away — you just release. Exercise lets you lift all that stress out," Uribe says.

Another student has battled depression for decades. Last year, she signed up for Jazzercise, knowing she would feel better if she could just get out the door and to the classes. Still, sometimes she has to struggle to make herself go. There are times she has gone to the bathroom and cried during class because she is so depressed.

But she returns because she knows the music and movement will make it better. She's among women of all ages who enjoy the same thing. Jazzercise takes her mind off of what is bothering her. Besides, she likes to dance.

Other exercisers — including those with physical problems — have their own stories to tell.

Jenny Meadows, 58, was immobilized for six weeks last year with back spasms.

"There were times when it seemed so hopeless — the doctors weren't sure what was wrong or even how to treat me, and I ended up overmedicated — that I just cried myself to sleep," Meadows says. "I was almost suicidal because I thought it was going to be forever."

After three months of physical therapy, though, her doctor gave her permission to do Pilates. A few months later she added Jazzercise to the mix.

"When I started moving, hope came back," Meadows says. "I went from being immobile, to walking with a cane, to walking gingerly sans cane, to mild exercise to feeling terrific."

For April Burge, 34, a 13-year Jazzercise veteran who works as a life coach, exercise builds self-confidence. "Especially in here — I can do things I never thought I could do," she says. "There's no judgment, no competition, it's just be here and have fun."

It's a support group for people in different stages of life. And missing it, for them, is like forgetting to take your vitamin.

pleblanc@statesman.com; 445-3994