When it comes to knowing how many repetitions to build muscle, this is the most important factor of your exercise routine when it comes to meeting your own personal fitness goals. To understand this you have to be cognizant of the fact that repetition range is directly related to the type of growth muscles will do. It does not matter what your exact goals are, for example, getting bigger, getting stronger or more solid or frankly a mixture of any of these, the range of repetitions is the most important factor.
Let's just get this huge misunderstanding cleared up now
Low repetitions and heavy weights make you bigger and lower weights and higher repetitions make you more defined. I bet this sounds familiar. This is as about as incorrect as it gets. In fact, it’s almost the exact opposite.
In order to build the most mass, how many reps to build muscle? You must trigger sarcoplasmic hypertrophy in order to build mass. Only by doing higher repetitions will you be able to increase the muscle cell size and in effect trigger this sort of hypertrophy. If your main goal is to pack on size, then going against the common theory of lifting heavy with low reps is the way to go.
Lower repetitions trigger what kind of growth? The only benefit from training with lower repetitions and heavy weights is strength increases. Building muscle size is not effected by training with low repetitions and heavy weights. But it might make you look more solid and increase muscle density.
How many repetitions are needed exactly to build muscle mass, density and strength?
4-6 Strength and Density
7-10 Size, Strength, and Density (x)
You have to now set your goals based off of your understanding of repetition range if you are going to build muscle mass, strength and density. You can mix things up by training different repetition ranges during different phases. In 6 weeks I trained 11-15 reps in order to pack as much mass on myself as possible. Consequently, I was able to switch to 4-6 repetitions for 6 weeks and it allowed me to mold the look I wanted while getting stronger and more solid.