HAVANA — Softball has been a passion for Michael Eizenberg since he was a child, but the 63-year-old has never been as excited about a game as the one played Monday on a children’s ball field at a faded sports complex under Havana’s warm Caribbean sun.

Eizenberg is one 56 Americans — all at least 55 years old — who are in Cuba this week for friendly games of slow-pitch softball against their Cuban counterparts, part of an effort to use sports to bridge decades of official mistrust between America and its southern island neighbor.