"Muscle memory will allow people to gain significant amounts of muscle in short periods of time, if that muscle has been trained before." Then the book isn't t

"Muscle memory will allow people to gain significant amounts of muscle in short periods of time, if that muscle has been trained before." Then the book isn't telling how to "gain 35 pounds of muscle". It's telling how to restore 35 pounds of muscle you recently had. Which is significantly different from "add 35 new pounds of muscle".