It was the mid 90’s, I was a fresh-faced college graduate with a BS in kinesiology (ok, technically physiological sciences but they changed the name in my junior year) and therefore thought (no, KNEW) that I knew everything there was to know about everything. Hahahahaha.
At some point, I would go to take the USWF Olympic Lifting Level 1 Certification. Two oddities stand out from that. First was that the guy teaching it told me that his son had studied piano with my mother; and here I was, the son of two musicians taking a training certification. I have no idea what that means but it must mean something.
The second point, that is actually relevant was that Wes Barnett (then one of the US’s top lifters and hopefuls) was there to demonstrate. He was a big dude and I asked the coaches what he did for muscle growth. They told me that he would just do lots of sets of 5. This, of course, blew my all-knowing mind, I knew that the hypertrophy zone was higher than that. How could sets of 5 get it done? Clearly there was more to the topic than I then understood.
A Little History About the Hypertrophy Zone
For many years, it was generally asserted that 8-12 repetitions was the hypertrophy range. Shockingly, I never ever found an actual reference to support it. Usually it was one book citing a book by another author which would then cite a reference paper that they had written which would cite the first book; it was one big circle jerk of referencing. But bodybuilders of the day typically talked about working in that, or occasionally higher repetition ranges (because the pump is like coming and coming and coming). But that’s just broscience, amirite?
Now, I have a theory about where 8-12 reps actually came from. If you get way back into the history of the weight game, you see a lot of recommendations to do 3 sets of 10. This assuredly came out of some of the early work of DeLorme (look it up, folks) but it shows up a lot in earlier books. I suspect that what happened is that guys would sort of lose count during their sets; hell I can barely get past 8 without losing focus. So sometimes they would do 8 and sometimes they might do 12. Boom, the hypertrophy range became 8-12 going forwards.
In more recent years, the hypertrophy zone has been expanded to include anywhere from 6-15 repetitions or so with lower reps being more oriented towards strength (and a tension stimulus) and higher repetitions more oriented toward fatigue and the pump. My own generic bulking routine uses a mix of sets of 6-8 and 12-15 for exactly that reason (it combines a tension and a fatigue stimulus) and other approaches such as DUP and PhAT do the same across a week of training. I’ve written about various repetition ranges in the never to be completed Periodization for Bodybuilders series.
Is There a Hypertrophy Range?
Now, what stimulated this piece (other than the pressing need to get some good SEO for a current topic) was a recent interview with Brad Schoenfeld, titled (with no sense of hyperbole ha ha) “Everything We Know About Muscle Building is Wrong“. While the interview spanned a lot more than just the hypertrophy range, it started with that and that’s my main focus. In addressing the issue, Brad mentioned his own research (reviewed on my site) showing that both low repetitions and high repetitions can stimulate hypertrophy (at least in shortish term studies) just as well as moderate repetitions so long as the volume is matched. So 10 sets of 3 worked as well as 3 sets of 10 in the first study and long sets of 25-35 (which had been shown previously to stimulate gains, at least in beginners) had similar effects so long as they were to failure (this had been shown in beginners but Brad showed that it also worked in trained individuals).
And the general conclusion was that the idea that there is some specific hypertrophy range of 6-15 reps (or whatever) isn’t correct. So long as volume is matched, the effects are roughly the same (this has led to what I consider a silly idea which is that volume is the most important factor in growth but that’s something I’ll address in another piece). Certainly this idea has been presented before, even Charles Poliquin wrote years ago that low reps could build muscle so long as you did enough sets (and isn’t that what I was first told at the USWF certification?). I don’t know that very high repetition sets were ever really recommended for growth for the most part (although the idiocy of the 100 rep set would show up every few years in the muscle magazines).
The idea that low intensity work can build muscle was probably more debatable in my mind but the blood flow restriction/Kaatsu work suggested it and far be it from me to argue with the direct research on the topic (even if goes against my inherent confirmation bias that super high reps suck). Mind you, I saw leg growth during my time ice speed skating from low-intensity/high-repetitions along with only skating. But for reasons I’ll eventually write up, speed skating is sort of an inherent blood flow restriction type of activity.
A Practical Hypertrophy Zone
However, I am still going to argue that sets of 6-15 still represent a more or less optimal practical hypertrophy zone. That is, for most people under most circumstances, working in that range for the majority of their training is still the best approach. And here’s why I say that:
In Brad’s low repetition study, while the growth was the same between the 10 sets of 3 and 3 sets of 10 group, there were two other considerations. One is that the 10 sets of 3 took forever. With a 3 minute rest, that’s 30 minutes for the work sets on top of however long it takes to warm-up (and it takes longer to warm-up to lower rep sets than higher). Practically you’re looking at 40 minutes for one exercise. Three sets of 10 with a 3 minute rest takes 9 minutes plus one or two warmups; 4 sets of 8 with a 2-3′ rest is about 15′ with warmups tops. At most you could do 2 exercises in an hour with 10 sets of 3 while you can do at least 6 exercises with the higher repetitions. As well, many of the subjects reported joint pain and there were a couple of injuries. Constant low-repetition training beats people up and unless you have the joint structure to handle it, it’s usually a losing battle in the long-term.
In the high-repetition study, while the results were also the same (even using a relatively low resistance), the subjects reported severe discomfort and nausea and I believe a few threw up. High repetition sets like that are grueling from a metabolic standpoint (even with blood flow restriction, people report enormous pain) as lactate levels climb and climb and climb. One of the worst sets I have personally ever done (while I was ice speed skating) was a set of 25 repetitions in the single leg leg-press with a 2 second hold in the bottom position. The set took about 2 minutes and two of them would wipe me out. I’d rather do repeat sets of 8 any day of the week (towards the end of my skating career I’d do sets of 5 for weight work and save high repetitions for bodyweight stuff like properly done skater squats).
Basically, working in a 6-15 repetition range avoids both extremes and has multiple practical benefits. It’s more time efficient for one. Say you’re trying to hit the roughly 40-70 repetitions per body part suggested in the Wernbom review as providing optimal growth. Repeat triples means anywhere from 12 to 25 sets. Good luck with that. Certainly 25-35 repetitions only means 2 sets but it will be 2 of the worst sets you will ever do. Especially the second when lactate is already high and you want to throw up.
In contrast, working in a 6-15 repetition range means somewhere between 4X15 (which still hurts) up to 8 sets of 6-8 (which the great Lee Haney used to recommend, funnily enough). Or you could use a more realistic combination of 4 sets of 6-8 (24-32 reps) followed by 3 sets of 12-15 (24-45 reps) to get the total (48-77 reps). You get tension, fatigue and a nice growth response without blowing out your joints, taking forever in the gym or having to suffer with the puke bucket. And for most people under most circumstances, I think that will be better for the majority of training.
In some cases, it might be someone’s preference to do all lower reps (8 sets of 6-8) or higher (3-5 sets of 12-15) and body structure and psychology can impact on this. Not everyone has the joint structure or even psychological drive to push heavy weights (even in the 6 repetition range) and higher repetition ranges (12-15) may be better.
There is arguably more variability in women both in terms of psychology and body structure. I’ve never met a man who didn’t want to push big weights to impress his buddies but not all of them have the joints to handle that kind of heavy loading. And in contrast to all of the joyous riot grrlll nonsense online, not all women have that mental orientation to push heavy 5’s in the back squat. Many also simply don’t have the joint structures to do it safely.
There is a selection process for women who like to push big weights and it typically comes from a more androgenized brain and/or elevated testosterone levels along with a more linear body type with narrower hips. This doesn’t describe even a majority of women however. Women also don’t suffer as much in higher repetition ranges since, below a certain intensity (about 80% of 1RM or about 8 reps to failure) ,they show better endurance and lower lactate levels. Above 80%, 8 reps or lower, the difference disappears despite some simplistic statments that women always have better endurance by people who don’t like to think in terms of context. If anybody is going to tolerate sets of 25-35, it’s women and not men (and women LOVE training legs in the same way men LOVE training upper body).
Certainly low reps have their place, I wrote years ago that using them to bump up maximum strength and neural factors can be useful for bodybuilders as it will allow them to use heavier weights in a higher repetition range. High repetition sets (even my own Ultimate Diet 2.0 uses repeat sets of 15-20) can improve work capacity, muscular buffering capacity and may have some nice benefits for connective tissue health if for no other reason than it removes some of the heavy loading (the GH response may also have benefits for connective tissue health). I just wouldn’t use them a majority of the time.
There is also the potential that different repetition ranges may be targeting different fiber types (Brad and I have discussed this privately and the science is pretty sparse here but there is some first principle physiology that would support the idea). From a maximal/optimal growth response, a variety of repetition ranges might be superior in this regard (again, I wrote about this in the Periodization series).
I’d note for completeness that Brad makes the same actual comment about the topic, stating that:
Maybe having a theoretically, I would say having more of the 6 to 12 rep is using that as your base, and adding in your higher and lower repetition during training would ultimately maximize the hypertrophic response.
Eric Helms, in his Muscle Building Pyramid, makes the same basic recommendation:
If your goal is hypertrophy, 2/3rds-3/4ths should be in the 6-12 rep max range, with the rest being both above and below this load level.
And irrespective of the exact percentages, I think you get the idea: if your goal is muscular size, do the majority of your work in the traditional hypertrophy range with a little bit of extra work above and below that. And I think it’s worth putting in those terms as I suspect a lot of very stupid idea are going to come out of this.
I’ve already seen one article saying that it doesn’t matter how you train for growth so long as you just work hard and while this is technically true, I think it misses the point entirely (it’s more amusingly ironic as the author has a penchant for writing detailed turgid analyses of topics but is now going with “don’t worry about the details” but I digress).
So no, there is no singular hypertrophy zone in a purely physiological sense. But practically, spending most of one’s training time in what has traditionally been considered the hypertrophy zone probably still makes the most sense for most people under most circumstances.