What is the best repetition range for building muscle?

The conventional view that fewer reps in each set equates to more muscle gain is a bit too simplistic. In reality, when someone performs sets with very high weight and low reps, the main physiological change is a strengthening of neuromuscular pattern. In other words, high weight/low reps strengthen the brains ability to activate muscle. However, if we bump up the reps slightly while decreasing the weight as necessary, the muscle tissue will perform more total work, And thus more muscle growth occur. However, if the reps are increased too high, the main effect will be an increase in muscle endurance.

Through research, it has been determined that the best range for hypertrophy (muscle gain) is roughly between 8-12 reps, and then the reps are decreased from this range. In contrast, more than 12 reps mainly allows for increases in muscular endurance.