So you want to gain muscle and aren’t sure where to start with your rep range. It seems to be a well started rumor that in order to build massive muscle you should lift heavy with low reps, and to tone lift light weight with high reps. Well it’s a myth. There is no proven research to show that there is any difference between the two, at least for when starting out.
To be most effective you want to use microcycles and macrocycles. This is where for a period of 4 weeks (a macrocycle) you change each week (microcycle) up. Ideally start with high reps the first week, then each week for the next four weeks drop the reps and increase the weight, and at the end of the four weeks start over.
This causes muscle confusion, which allows your muscles to grow more because their is muscle confusion and they are forced to change up their routine.
Looking for more? Check out Bones to Bulk