When it’s game time for Al Horford, the Atlanta Hawks’ star center doesn’t hold back. “That used to be my approach to training, too,” he says. But recurring injuries have forced Mr. Horford, 28, to adjust his workouts and train smarter ahead of basketball season.

Mr. Horford took home two national championships in his three seasons at the University of Florida. He helped lead the Hawks to the playoffs in six of his first seven seasons. Coming off consecutive All-Star appearances in 2010 and 2011, Mr. Horford tore his left...