It felt like the 1980s all over again. The aerobic moves, the knee-high socks, the high-ponytailed instructor. But most of all, it was the trampoline. All the rage back in the era of sweatbands and spandex, this mini trampoline at BounceLimit, a new fitness studio in Sheung Wan, seemed a lot bigger when I was a child. In recent years, it's bounced back in popularity and has become one of the hottest fitness trends. Exercising on a mini trampoline, also known as "rebounding", has won over fans for its low-impact yet highly efficient calorie-zapping abilities: it's said to take up to 85 per cent of the stress off weight-bearing joints and burn up to 1,000 calories an hour. It's reportedly part of Madonna's conditioning routine, and how Gwyneth Paltrow shed her post-baby weight. Besides, bouncing on one always seems like fun and never hard work. That is, until you've tried a mini trampoline exercise class, as I did at BounceLimit. The 3,000 sq ft space, which opened two weeks ago at The Pemberton, is Asia's first trampoline fitness studio. Embedded in the studio's raised flooring are 30 mini trampolines that were made in China according to the specifications of the gym's senior instructor, Lucia Tam. Hexagonal rather than circular, Tam's trampolines are held up by bungee cords instead of the traditional steel-coil springs. Not only does this prevent nasty scrapes and injuries, but also creates a bounce that is smooth and silent rather than jarring and squeaky. The trampoline surface has also been made at Tam's desired density. "If it's too soft, your ankle will roll over, and if it's too hard, there's no shock absorption," she says. Drawing on her experience as a former professional ballroom dancer and exercise instructor at a leading Hong Kong gym, Tam has designed various programmes to cater to different fitness levels and goals. They range from pure rebounding for cardio ("AirBounce") to sculpting and toning with exercise bands and weighted balls ("MaxBounce"). At BounceLimit, the trampolines are permanently in place - with the option of capping these "hot pods" with hard flooring to transform the space into a regular fitness studio. In other words, trampolines are the bread and butter of Tam's sessions. "Basically, you can transfer any floor exercise to a trampoline for a safer workout," she says. Developed in 1934, trampolines - the room-sized type - were originally used to train tumblers and astronauts, and to develop and hone acrobatic skills for other sports such as diving, gymnastics and freestyle skiing. Soon, they became popular among the masses for their sheer fun. In 1977, professional trampolinist Al Carter published the book Rebound To Better Health based on his research into the exercise, which he credited for his children's exceptionally good health and improvements in endurance, coordination and mental development. He also developed the first home-sized rebounder, the Dyna-Bound. Carter's second book, The Miracles of Rebound Exercise, published in 1979, sold 1.3 million copies in the US. He suggests that rebounding is one of the best forms of exercise, and claims that it stimulates the lymphatic system and boosts immune system response, without trauma to the musculoskeletal system. Rebounding may be up to 68 per cent more efficient than running on a treadmill Nasa researchers A study by researchers from US space agency Nasa supports the benefits of rebounding exercises. Published in the Journal of Applied Physiology in 1980, the study found that "the magnitude of the biomechanical stimuli is greater with jumping on a trampoline than with running". The researchers showed that rebounding may be up to 68 per cent more efficient than running on a treadmill, since the instability created by the trampoline surface requires the exerciser to engage more muscle groups, including the core. This increases oxygen capacity, energy exertion and calorie expenditure. Rebounding, says Tam, is not unlike working with a balance ball. Instability is a full-body workout's best friend. "The core muscles work involuntarily when you're jumping on a trampoline, so people don't realise they're working their core - until they come back stronger," she says. Tam is quick to note that rebounding is vastly different from trampoline parks, which are huge arenas that consist of many interconnected large trampolines that allow you to bounce from wall to wall. "These are more like theme parks," she says. I was curious about how tough a workout could be and soon learned that rebounding is not the same as the playful jumping on a trampoline I'd done as a child. Rather than trying to jump high, rebounding is about keeping low. "The right technique is to make use of the rebounding and push into the mini-trampoline," says Tam. "The push down requires the body to contract muscles as it resists the bounce up. As you try to stabilise your body, your muscles are involuntarily working, particularly in the core, back and legs." I felt it in my legs all right, specifically the calves. And it was just a 30-minute sample of Tam's programmes - a typical class ranges from 45-55 minutes. We started off with AirBounce. Basic jumping was a breeze, but the hard work began as the music tempo increased and we had to match the beat. Resisting the body's acceleration upwards took a lot more effort and focus than I'd thought. Within a few minutes I had perspiration trickling down my forehead. Then it became a full-blown sweat shower as we progressed to more challenging moves that involved high-knee lifts, kicking, punching and quick direction changes. We had a taste of BouncePilates, performing crunches, leg lifts and other core exercises while lying on the trampoline. These were just marginally tougher than doing them on a hard surface. Then we tried MaxBounce. Tam set up a circuit of exercise stations. Among other things, we sped through an agility ladder and finished off with three jumps on a trampoline, and did star jumps with arms pulling up against resistance bands. I found this the most enjoyable as I got to move around. Tam says the classes will be tailored according to individuals' fitness levels and physical abilities. She is also planning programmes incorporating other fitness equipment or philosophies with rebounding. A class is HK$375 for members and HK$550 for non-members; annual membership is HK$2,000.