Stephen Chernin for The New York Times The Men 'n Sync team rehearses its competitive synchronized skating routines to music at Wollman Rink in Central Park. Early on a recent Friday morning, as they do every Friday at 6:45, the slender, graceful men in black took to the ice at Wollman Rink in Central Park. Overseen by their coach, Nina Newby, and buoyed by the winter-turns-to-spring weather that had thawed all the ice in the park that is not manufactured, they set about practicing their sport, a combination chorus line and ice dance. Traveling the ice linked in various arm...