Repranges have been the subject of discussion in the changing rooms for decades. In 2021, however, there is no longer any need for discussion: there is an ideal reprange for hypertrophy!
THE REPRANGE ISSUE
The dogma used to be: with sets of 1-6 repetitions you mainly train strength, with sets of 6-15 repetitions muscle growth (hypertrophy) and sets of more than 15 repetitions strength endurance.
Over the past decade, it has become clear that this theory is not quite right. For muscle growth, you can achieve maximum results in all rep ranges, as long as you train those sets to (near) muscle failure and as long as the training weight is greater than 30% of your 1 rep max (1RM) .
It remains true that with lower rep ranges you simultaneously train more for strength and with higher rep ranges more for strength endurance. But that is basically independent of muscle growth.
Is that the end of the matter and the discussion closed? Not quite.
THEORY VERSUS PRACTICE
In theory it is established that relative load is decisive, in other words the degree of effort (how far you reach muscle failure) is decisive, not the number of repetitions (the absolute load). But that’s purely theoretical, viewed on a set basis.
In practice, seen over an entire training program, not all rep ranges appear to be ideal if muscle growth is your (main) training goal.
For example, with very light weights (30-50%1RM) it is much more difficult to create a sufficient growth stimulus, because the cardiovascular fatigue often leaves you stranded well before you have reached the point of muscle failure. Doing very long sets is simply not an efficient and pleasant way of training, and also causes a lot of central fatigue. Plus it takes more time.
On the other hand with very heavy weights (>85%1RM) you get very short sets which leaves you with few effective reps. You’ll have to compensate by doing more sets – also not very efficiently. In addition, with heavy weights it is more difficult to make a good mind-muscle connection, your tendons and joints have to endure more, and you have a higher risk of injuries.
For muscle growth it is therefore best to be in the middle of the spectrum, between 6 and 15 repetitions. Not that you can’t do sets that contain more or fewer repetitions, but as a rule you operate in the middle range of reps. Within that reprange, it is best to do compound exercises in the range of 6-10 repetitions, and isolation exercises with 10-15 repetitions or possibly a little more.
That is also the conclusion of a scientific publication by, among others, hypertrophy specialist Brad Schoenfeld.
Isn’t muscle growth your main goal and do you also or mainly train for strength? Then you can indeed gain some advantage in the range of 1-5 reps. If you are more focused on endurance sports, higher rap ranges (> 15RM) offer a solution, although the positive influence on strength endurance seems to mainly take place in the lower body.
The figure below summarizes all this nicely.
In retrospect, you can say that the bro’s were right with their 6-15 or 8-12 reps after all, albeit for different reasons. There’s nothing “magic” about the moderate rep range for muscle growth — it’s purely for practicality that this rep spectrum is preferable.