There’s no way to tell till you start using one of the programs (there are a number of different workouts in the book, some of which take less than 30 minutes). How much muscle you gain depends on everything from your genetics—including recovery ability, muscle lengths, fiber makeup, neuromuscular efficiency—to your persistence to your experience to your diet to your ability to generate intensity on any given set (which can be a reflection of your genetics or personality).
We can say this, however: We collectively have more than 40 years of training experience under our belts, and we made faster gains in one month with X Reps than we have with anything else we can remember. It was very exciting—and somewhat shocking considering our training experience—to see weekly and often daily changes in our muscle size and strength. It was especially impressive in Steve’s case, as he’s a 44-year-old hardgainer who has to fight for every ounce of muscle. After one month with X Reps, he looked better than he ever has. Even Jonathan was beginning to think he was at his genetic limit, but X Reps helped push him to a new level of muscularity. (Check out the photos in our gallery section.)