It was Saturday night in South End, the room full of gyrating bodies and beats pulsing through the marrow, a laser projector beaming multicolored fireflies that danced on the ceiling and glow sticks whirling in the darkness.

You’ve seen this before. It’s what raves were 20 years ago. It’s what group exercise looks like now.

“OK, let’s open up the hip flexors,” called Beth Lange, who co-owns Moga Charlotte, a nearby yoga studio. She was leading a 20-minute yoga session during Moxy Madness at Midnight, a self-described “yoga rave gone mad” at – where else? – Fight Gone MAD, a high-intensity fitness club on South Boulevard. “OK, excellent!”

The DJ eased the Black Keys’ pounding “Gold On the Ceiling” into Bob Marley’s mellower “No Woman, No Cry.” The 80 or so participants contorted, sweated and smiled.

Yoga is usually a quiet, contemplative activity that emphasizes concentration and self-awareness. This, not so much. Folks laughed and chatted as they stretched and the music played.

Then the session switched, moving to another instructor and another 20-minute session, this one high-intensity interval training: 20 seconds of full-bore calisthenics and aerobic exercise followed by 10 seconds of rest, repeated again and again. Its practitioners claim interval training burns fat more effectively than the usual aerobic exercise. Then a brief break, then another yoga session, then more interval training. It lasted four hours.

This isn’t the traditional way to have a rockin’ good time on Saturday night, but it represents a trend that’s soaked deeply into fitness clubs and yoga studios around the country: bringing in DJs with playlists customized to specific workouts and classes.

Fitness companies are even co-licensing with music labels to market and sell workout compilations, as detailed in a recent Wall Street Journal article. The resulting sessions are commonly called “yoga raves,” and they’ve become quite popular in the last few years.

‘Our own twist on it’

In Charlotte, Coby Kraft and Brad Schamel, a pair of 29-year-old childhood friends, had recently founded Moxy Events, a fitness events company. Kraft works for his family’s lighting business, and Schamel is an Army Ranger captain on inactive duty and cycling out of the service. They’d always wanted to start some kind of venture together, and they incorporated Moxy Events in August.

Recently, the two friends were thinking about hosting an event that might bring together some of their friends in Charlotte’s fitness community who might not otherwise intermingle – yoga students and more high-intensity athletes. A yoga rave would be the foundation, but Kraft and Schamel wanted something with more variety and energy.

In chatting over beers with friends Brandon Cullen and Kirk Dewaele, former Charlotte Checkers who founded Fight Gone MAD in late 2011, they came up with it.

It would be a night session that incorporated interval training and high-intensity workouts led by Cullen and Dewaele – but also the owners of Moga Charlotte and Y2 Yoga in Cotswold, two well-respected yoga studios.

Moxy Madness was born. “We always try to take something and do it better, and also put our own twist on it,” Kraft said.

It started at 8 p.m. on March 9, lasting until midnight. People started trickling in at a little after 7. They cross-pollinated. “I’ve been to yoga raves before, with the DJ and black lights, but I’ve never been to one where you had a combination of yoga and cross-fit,” said Hannah Massey, 28, a yoga teacher at the Laughing Buddha studio in the SouthPark area.

One thing organizers stressed is that these kinds of events aren’t meant to take the place of regular workouts but complement them; the benefits are as much social and emotional as physical.

“Yoga can be very intense, with the concentration and breathing,” Massey said. “A yoga rave or something like this allows you to relax and not take things so seriously.”

‘Trancey, moody, kind of chilled-out’

As always at such events, the music was critical, and Moxy Events had that covered: Jason Herring, a local DJ, producer and owner of a label, 10 Millimeter Omega Recordings.

Herring has deejayed the Dharma Lounge’s weekly Tuesday-night yoga sessions for the past three years, and he said practitioners are looking for music a bit more sophisticated than the usual robotic technopop that provides the soundtrack for too many aerobics classes.

“The trend is more and more yoga studios with DJs, which I think is really cool,” Herring said. “People say there’s more of an emotional dimension with certain kinds of music, plus the beats can help with the breathing and concentration.”

As he spoke, the group was warming up, stretching and chatting over “Indus,” an instrumental track by the Australian world-music duo Dead Can Dance — “subdued, sort of trancey, moody, kind of chilled-out music,” Herring said.

The instructors from each of the three businesses helped put the playlists together. They submitted four or five tracks and let Herring branch out from there.

It was a fun and well-attended event that Moxy Events will not repeat – at least not in the same form, Kraft said. Moxy Events wants to try different ideas and combinations to keep things fresh, he said.

The combination of yoga and interval training turned out to be a blessing, said Noor Margaret Hannaney, a 25-year-old California native who’s trained with Kraft before.

Working out for four hours is a tall order, even for someone in peak physical condition, she said, so the yoga sessions were welcome respites from the intervals. In a way, the structure made for a kind of large-scale interval training, with alternating intense exercise and rest.

Either way, Hannaney said, Kraft was right — she got a good workout along with her enjoyable evening. “I thought it was a great event,” she said, “definitely something different from the usual Saturday night bar scene.”