IT was a classic father-son moment, reversed: The 2-year-old sat and watched patiently as his parent hung upside down from the monkey bars. A few feet away, a white-haired man skipped across an S-shaped metal beam. Another man squeezed his six-foot frame onto a metal rack for situps, and two others hoisted themselves up chin-up bars.


Never mind the punishing diets, the gym dates and the doctors’ warnings, the quest to live a healthier, more active lifestyle has come to this: playgrounds for adults.


New York City is testing its first such playground in Macombs Dam Park in the Bronx, and plans to bring as many as two dozen more to neighborhoods across the five boroughs in the next 18 months, park officials said.


The goal is to lure people off their couches and into the outdoors with specially designed playground equipment — in grown-up shades like forest green and beige — that recall the joy of childhood play while tightening up flabby abs, thighs and triceps.


Though there are no swings or slides — these are essentially outdoor gyms — such playgrounds not only have the look of traditional children’s play spaces, but they are also built in some cases by the same manufacturers.


The adult playground concept is borrowed from China and parts of Europe, where outdoor fitness areas for adults have become as routine as high-fiber diets or vitamin D supplements in preventive care, particularly for older people.


Now a growing number of city and park officials, health experts and community leaders throughout the country are praising the health and social benefits of adult playgrounds. They say that the playgrounds will succeed where treadmills have failed in combating rising rates of obesity and related illnesses by enticing the grown-ups out for play dates.


“Let’s face it, most of us dread going to the gym,” said Dr. David Ludwig, a Harvard Medical School professor who directs the Obesity Prevention Center at Boston Children’s Hospital. “The point is to make physical activity fun, easy and accessible, so it’s the normal thing to do.”


Adult playgrounds have spread across the nation, including to Miami-Dade County in Florida, where four fitness zones with advanced strength-training equipment opened this year in neighborhoods with high rates of cardiovascular diseases. San Antonio has added outdoor fitness stations to 30 parks since 2010. Los Angeles has 30, with 15 more on the way, after park officials found, to their surprise, there were “lines of people waiting to use the equipment.”


And two mothers in Washington State, Paige Dunn and Kelly Singer, started a grass-roots campaign last year to build “Momentum” sites to help new mothers shed their baby weight; each site would face a children’s play area and hold seven pieces of equipment that specifically target problem areas. The women raised $30,000 to open the first one in Auburn, Wash; a second will be dedicated in Redmond, Wash., next month.


In New York City, where adults are banned from playgrounds unless accompanied by a child, the $200,000 Bronx playground with 15 pieces of equipment opened two years ago as part of an effort to get more people out to the parks to exercise and slim down. Parks officials said it had been popular enough that the city was now planning a rapid expansion.


“This represents a continuing evolution of both parks and playgrounds,” said Adrian Benepe, the parks commissioner.


This fall, the city will build a second adult playground with upgraded amenities — river view, exercise mats, chess tables, a sign that says, “Adult Space” — at John Jay Park on the Upper East Side. Councilwoman Jessica Lappin, who represents the neighborhood, said she had secured $250,000 in city money for the project after some of her older constituents pointed out, “There are tot lots, but there’s no place for us.”


“A lot of these people live alone,” she said. “So going outside to the park, and being part of the activity of the park, is important to them.”