Sons of Cuba

Sons of Cuba is a 2009 documentary film set in the Havana Boxing Academy, a school at the heart of Cuba's Olympic success in the ring. It follows the stories of three young hopefuls through eight months of training and schooling as they prepare for Cuba's National Boxing Championship for Under-12's. Sons of Cuba was directed by Andrew Lang and is distributed by Cinetic Rights Management for the US and Canada and Ro*co Films for the rest of the world.

Synopsis from Wikipedia, CC BY-SA 4.0. Everything below written here.