“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.” w/ photos