Before fighting Jack Sharkey on the comeback trail in 1927, Dempsey trained in the hills outside Ojai, Calif. He chopped trees, carried rocks, and did calisthenics to drop more than 20 pounds.

Two sports heroes captured the imagination of the public in the 1920s: Babe Ruth and Jack Dempsey. While Ruth could only be seen on newsreels, Dempsey appeared in Joplin as a boxer and referee ...