"Though Mac was revered for his unlikely victory, the documentary is unsympathetic toward the boxer, who was eventually embroiled in a number of scandals, including suspicion of using performance-enhancing drugs to gain health between the first and second rounds. Experts have claimed his workout regimen of merely jogging behind his bicycle-mounted coach would not have been sufficient to build the strength he displayed in the ring."
If this were real (and it should be...directors take note) it would be the greatest documentary ever