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.       NYT