It's all in the bounce when it comes to rebounding, the group fitness class that uses mini-trampolines to pump up the cardio without slamming the knees and joints. And if the equipment will always resemble a low, round coffee table, the workout can be as versatile as the instructor's imagination. “In my class we do sprints, running, jump rope style, lateral ski, and boxing moves, like jabs and hooks,” said Terrell Pruitt, a rebounding instructor for Crunch, the national fitness chain. “What I love is that it's less shock for your knees and joints,” Pruitt said. “Your workout is actually pushing down, not going up. You bounce, you don't jump. You're pushing down, fighting gravity, abs engaged, knees bent in a power stance.” And it's fun. “Once you get used to it it's hard to let it go,” Pruitt said. “When you can get 80- year-old women and 20-year-old girls in the same class, you know people get addicted to it.” The name trampoline comes from the Spanish “trampolin,” or diving board. But while the mini may share a name with its full-sized progenitor, when it comes to trampolines, size matters. The mini-trampoline is used for physical fitness, whereas the full-sized trampoline was designed by gymnasts for gymnastics and acrobatics. On a full-sized trampoline a skilled athlete can bounce up to 10 meters (yards) high while executing somersaults, flips and twists. It has been part of the Olympic Games since 2000. Pete McCall, an exercise physiologist with the American Council on Exercise, says it's important to understand, and respect, the difference. “The large trampoline is used for tumbling, acrobatics, while the mini-trampoline is used to train aerobically,” McCall said, adding either while recovering from injury or for general fitness, health and weight loss. “Walking and running on the ground you get what we call a ground reaction force. About half one's bodyweight is sent back up the body as a reaction,” he explained. McCall said using the mini-trampoline in place of running is a relatively safe way to reduce that force, but the full-sized version should always be treated with respect. “Proper supervision, proper location, proper education of instructor,” he advises. “Use (large trampolines) as part of acrobatic/gymnastic program for air awareness, for practicing the flips and tumbles, drills and body shapes, and to aid body awareness and timing and strength.” That accords with the thinking at Chelsea Piers, a sports and recreation center in Manhattan that offers gymnastics classes to all ages and abilities. The 23,000-foot gymnastics center has two full-size in-ground trampolines, as well as a tumble track, which is a long strip for forward and backward movements. “We don't offer specific trampoline classes but everything that we do incorporates some amount of trampoline work,” said Kim Rich, director of gymnastics for the center. “And while we have all ages, we use judgment about which trampolines are appropriate for which clients,” she said. Rich said trampolines should always be used with caution. “They're very specific in the way they will work, and if you're not using them with the right body position and awareness, there's a danger,” she said. “I'm not a big fan of backyard trampolines,” she added.
