Trainers like to develop workouts that are so much fun, they flip you out. Jordan Shamir, who teaches AntiGravity Yoga, will flip you over.

Shamir, who owns The Hang Out in Kakaako, can get you upside down, hanging from your hips and thighs, in a matter of seconds. According to Shamir and his enthusiastic adherents, having your butt in a sling couldn’t be more fun, not to mention healthy and invigorating.

"It decompresses your spine," Shamir said. "It has many health benefits, including rehydrating the disks in your back, refreshing your circulatory system. It’s also a great supportive way to stretch your body."

The workouts are centered on "zero-compression inversions" in which one’s body is held upside down by a slinglike hammock made of semistretchy nylon. From that position, various stretches and poses are performed.

"In traditional yoga inversions, gravity is still acting the same way on your spine as it does when you’re right-side up. Gravity is still a compressant," Shamir said. "We’re hanging from your hips, so everything that’s hanging below your hips is actually decompressing. Your whole spine is actually opening up."

The results are visible, according to Shamir. "I’ll say ‘Take a deep breath into your belly, and as you exhale, let out a sigh.’ As people sigh, they go ‘aaah,’ and you’ll actually see their head get lower to the ground."

Unfortunately, the effect isn’t permanent. "I’d be 12 feet tall by now if it was," he said with a laugh.

During a session with Shamir, I found that flipping upside down might seem a bit odd, but with his expert coaching it’s not scary. Like the catcher in a trapeze act, your legs are entwined in the hammock so that you can lean back until you’re upside down, your arms hanging free. Fold your legs into a diamond shape, soles of your feet touching, and you’re in the Spider-Man position, head a few inches above the floor.

A bit trickier is the Vampire, in which you start on your back but eventually wind up flipped all the way over, face down, suspended only by your legs and shoulders. People with good core strength and flexibility can lower their abdomen so that their body is bowed backward, but I didn’t dare.

At other times, you might be in a jack-knife position, with the hammock supporting the waist. From that downward-facing dog position, you lift your legs into the air, forming the flying down dog position.

"There are modified yoga poses, so if someone’s coming here expecting a traditional yoga class, they’re not going to get what they’re thinking in their head," Shamir said. Every position he uses incorporates the hammock.

I found that in many positions, the hammock bunched up and created a burning sensation as my body pressed heavily against it. Shamir kept calling that "a deep-tissue massage," and while I had my doubts, the next day it did feel like I’d had a massage, with just a bit of soreness and a few chafing marks on my shoulders.

Shamir’s studio is part of a franchise called AntiGravity Fitness, which was started more than 20 years ago by aerial performance artist Christopher Harrison. Harrison developed his routines as a workout for his performance troupe and eventually started a chain of studios that now has locations around the world.

Two years ago, Shamir was toiling at a desk job. He was having back problems, and when he saw Harrison’s workouts on the "Good Morning America" show, he was immediately drawn to it.

"I knew I wanted to get upside down, and I actually tried going to the monkey bars at the park and tried hanging from the crook of my knees, but I wasn’t strong enough and I couldn’t keep myself there," he said. "What’s so great about this is the hammock does the work. You don’t have to be strong."

Shamir trained with Harrison and opened his studio last year, the first in Hawaii.

He’s already gained some faithful followers.

Brandee Faria, a 38-year-old attorney, goes to Shamir’s studio nearly every day and said it’s been especially helpful dealing with a herniated disk. Faria also did Bikram yoga but says AntiGravity Yoga is a lot more fun.

"At the end of class, there’s a pose called womb, and you get in (the hammock) and lay down. It’s very relaxing. At the end of my class, if he’s worked us hard, you feel like you can just go to sleep in there."

Klaire Dye, 28, started going to the studio because she recently quit smoking and "wanted something to replace it. You get a little bit of a head rush and you breathe easier."

Shamir offers three courses: fundamentals, slightly more advanced aerial yoga, and more intense suspension fitness. He incorporates meditation into his 75-minute sessions, which usually include two or three inversions of three to five minutes each. Yoga elements such as the opening sun salutation and the closing savasana are included.

James Otis, 42, a conventional yoga teacher for more than 20 years, has been working with Shamir for two months and said the workout is energizing.

"It mixes your blood up, like you’re a paint can," he said. "It evens your body out, that’s what it feels like."

"Good Fit" spotlights inspiring fitness stories of change, self-discovery and challenge, and other fitness-related topics. Tell us what motivates you and how you stay fit and healthy. Email features@staradvertiser.com