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Research

In Ultimate Bodybuilding: The Master Blaster's Principles of Training and Nutrition Joe Weider says the following:

I learned that the best repetition range for building muscle mass is 5-8.

In the Wikipedia article on muscle hypertrophy, the recommended rep range is 8-12 reps:

Strength training typically produces a combination of the two different types of hypertrophy: contraction against 80 to 90% of the one-repetition maximum for 2–6 repetitions (reps) causes myofibrillated hypertrophy to dominate (as in powerlifters, Olympic lifters and strength athletes), whereas several repetitions (generally 8–12 for bodybuilding or 12 or more for muscular endurance) against a submaximal load facilitates mainly sarcoplasmic hypertrophy (professional bodybuilders and endurance athletes).

In contrast, the training program Shortcut to Size by Jim Stoppani on bodybuilding.com uses reps in the 12-15 range:

Barbell Bench Press - Medium Grip
4 sets of 12-15 reps
Rest-pause on final set

On stackexchange itself, this post links to a chart that recommends 6-12 reps for muscle growth. The confusion here is that the Wikipedia article above mentions 2-6 reps for strength improvements.

Feeling

It feels as though trainers, bodybuilders, and sport scientists cannot agree on the ideal rep range for muscle growth. This could be attributed to the mantra that "every body is different", but that's not very scientific.

Questions

  • Is there an ideal rep range for increasing muscle mass, and if so, what is it?
  • How much difference does the rep range make?
  • Why is there so much contradiction between sources?

Update 1

I don't remember the name, but I read a book a couple of years back that contradicts the mantra that "every body is different" using the premise that human physiology is for the most part the same for all people, which feels plausible.

Update 2

One of the comments got me thinking about another mantra: "You gotta lift big to get big." It follows that by increasing the reps you decrease the weight, which eventually will mean you break that mantra. I suppose the truth of that mantra is for another question, but my feeling in this question is that Joe Stoppani's plan breaks it.

Update 3

An answer has caused me to question why rep ranges get so much focus. I started thinking about training intensity, which is often cited as needing to be high. I've started wondering if the reason rep ranges get so much focus is because it's easy to understand and measure when compared to intensity.

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The post you linked to answers your question perfectly. There is no confusion, both that post and wikipedia recommend ~6-12 for hypertrophy, and ~1-5 for strength. Looks like you have confused yourself, comparing hypertrophy recommendation from the post against strength recommendation from wikipedia. –  hamstergene Jul 13 at 18:55
    
Why does Joe Weider recommend 5-8 reps and not 6-12? Why does Joe Stoppani's "Shortcut to Size" go above 12 reps if 6-12 is ideal, especially if the programme is supposed to be a shortcut? –  Jon Jul 14 at 7:04
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Rep schemes aren't everything. Different schools of thought propagate different concepts to gain size. For starters there's time-under-tension (superslow reps come to mind), intensity (high % of 1RM), and work density (lbs per min) and don't even get me started on frequency vs. volume. All those are more or less important to a certain extent, so there's really much more than one variable to consider. –  LarissaGodzilla Jul 14 at 13:48
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In all honesty, there isn't that much contradiction. The rep ranges are all over 6 reps and more. Volume is a big component of improving size, rep ranges are only a part of the solution. We are still learning more about hypertrophy and the best ways to improve it. The go to guy for hypertrophy research would be Dr. Brad Schoenfeld, who both lifts and studies. –  Berin Loritsch Jul 15 at 13:28
    
Thanks for the name. His website has a wealth of information. The articles page links to another website, with this page standing out: t-nation.com/free_online_article/most_recent/…. –  Jon Jul 15 at 13:41

5 Answers 5

A research paper entitled Resistance exercise load does not determine training-mediated hypertrophic gains in young men written in 2012 showed that a weight as low as 30% of 1RM can contribute to muscle growth, as long as you work to failure, which is around +30 reps and for >2 sets:

There was no correlation between phosphorylation of any signaling protein and hypertrophy. In accordance with our previous acute measurements of muscle protein synthetic rates a lower load lifted to failure resulted in similar hypertrophy as a heavy load lifted to failure

It is hard to provide any hard guide-lines as you can see from this.

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Excellent link. My first thought is that a study of just 18 men is rather small - the title of the study is a wild claim based on such a small sample. Studies like this complicate matters. It's very difficult for most people to understand. Moreover, it's extreme in its message, dismissing the entire idea that there is an ideal rep range. –  Jon Jul 14 at 7:37
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I agree, 18 is close to nothing, however thats sadly the way most physiological studies are done. With a very little sample. I've talked to researches and they say it is both because of logistics and due to expenses. So you have to remember a healthy dose of skepticism when reading these kind of studies. And I for one would not schedule my training program around 30 reps, but just to show how wildly conflicting the advice is in this area. –  Soccerman Jul 14 at 7:57
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I agree that the advice is indeed conflicting, and I also wouldn't change my training. It's about making informed decisions, and so far, I don't feel well-informed. This discussion is making me think that training intensity (which is hard to measure) plays a bigger role than rep range (which is easy to measure). –  Jon Jul 14 at 8:02
    
Just wanted to add, the subjects didn't have any weightlifting experience over the last year. So all gains are basically newb-gains, which really only need consistency (provided by the study) to happen. This study was a waste of money... –  LarissaGodzilla Jul 14 at 13:58

Strength Endurance Continuum

The strength endurance continuum shows that strength and endurance are at opposing ends of a spectrum. Focusing on one end of the spectrum (for example strength) sacrifices the other (endurance).

strength endurance continuum

People tend to view this scale as being a trade-off between strength and size, but as you'll see in a bit, this isn't entirely true.

Low Repetitions vs High Repetitions

In a paper entitled Muscular adaptations in response to three different resistance-training regimens: specificity of repetition maximum training zones, the authors concluded that only low-repetition (3-5 reps) and intermediate-repetition (9-11 reps) groups hypertrophied, with no significant increases shown in the high-repetition (20-28) group:

All three major fiber types (types I, IIA, and IIB) hypertrophied for the Low Rep and Int Rep groups, whereas no significant increases were demonstrated for either the High Rep or Con groups.

Moreover, the high-repetition group were shown to improve aerobic power and stamina:

The High Rep group, however, appeared better adapted for submaximal, prolonged contractions, with significant increases after training in aerobic power and time to exhaustion. Thus, low and intermediate RM training appears to induce similar muscular adaptations, at least after short-term training in previously untrained subjects.

Resistance Training Load

The paper shown in another answer entitled Resistance exercise load does not determine training-mediated hypertrophic gains in young men came to the conclusion that training load (percentage of 1RM, from 30% to 80%) in combination with training volume (1 or 3 repetitions) had no affect on hypertrophic gains.

In accordance with our previous acute measurements of muscle protein synthetic rates a lower load lifted to failure resulted in similar hypertrophy as a heavy load lifted to failure.

High vs Low Intensity

Update: This section is removed in response to comments as it's not related to the discussion and only misleads.

In Muscular adaptations to combinations of high- and low-intensity resistance exercises, the authors performed the following experiment:

Acute and long-term effects of resistance-training regimens with varied combinations of high- and low-intensity exercises were studied. Acute changes in the serum growth hormone (GH) concentration were initially measured after 3 types of regimens for knee extension exercise: a medium intensity (approximately 10 repetition maximum [RM]) short interset rest period (30 s) with progressively decreasing load ("hypertrophy type"); 5 sets of a high-intensity (90% of 1RM) and low-repetition exercise ("strength type"); and a single set of low-intensity and high-repetition exercise added immediately after the strength-type regimen ("combi-type").

They concluded that a combination of high and low intensity was more effective for optimizing the strength adaptation.

Answers to Questions

Is there an ideal rep range for increasing muscle mass, and if so, what is it?

Low to intermediate rep ranges (3-11 repetitions) have been shown to be more effective than high repetition ranges (20-28 repetitions). What happens between 11-20 repetitions isn't covered in the papers I was able to find, but I suspect that going as high as the 15 repetitions in Joe Stoppani's program will not be detrimental to gaining muscle.

I think it's important to get out of the mindset that rep range alone is the only factor to consider to increase muscle mass.

How much difference does the rep range make?

A big difference. Regardless of the rep range your body will change, be it for strength/mass or endurance.

Why is there so much contradiction between sources?

The biggest contradiction for me is that 8-12 repetitions is "best". This falls within the low to intermediate range, but there is no evidence (that I could find) to suggest that 8-12 is better than 5-8. Likewise, I suspect that same for Joe Stoppani's 12-15 rep range.

I can only imagine that, as in Joe Weider's case, people have anecdotally reported better results, and they have been taken as fact. This is a huge assumption of course.

Other Considerations

There are other variables that aren't covered in this answer. For example, the age and sex of the person training, and the amount of training experience someone has.

I only read the abstracts of the papers, because I'm not qualified to understand a lot of what's in the paper, so take it with a pinch of salt.

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The Goto et al. article is completely unrelated to your question about muscle mass. Citation: “No significant changes were observed in body mass or percentage of body fat at any time points over the training period in HC and HS groups.” –  hamstergene Jul 15 at 9:41
    
I included that paper to highlight how intensity can change results. My conclusion also mentions strength adaptation and not muscle gains, though I can see how that can be misleading. This does highlight the limits of being able to read only the abstract. Do you think this affects the overall message of the answer? Do you think I should remove the intensity section from the answer? –  Jon Jul 15 at 10:01
    
There are no comparison of different intensities either. One group did 5x90% and another did the same 5x90% plus one extra set of 1x50%. –  hamstergene Jul 15 at 11:13
    
I've updated the post to remove it (by strikethrough, so people can understand our discussion in the comments). Thanks for your feedback. –  Jon Jul 15 at 11:25
up vote 0 down vote accepted

A comment pointer me to the website of Dr. Brad Schoenfeld, an apparent expert in the effects of training on muscle hypertrophy. He wrote an article for T-Nation in 2012 entitled Four Reasons You're Not Gaining Muscle which provides a much better answer to this question:

Mistake #1: You're not varying your rep range.

The optimal number of repetitions for hypertrophy-oriented training is a source of ongoing debate in the fitness field. Although the research is by no means conclusive, evidence indicates that a moderate rep range (approximately 6-12 reps per set) is generally best for maximizing muscle growth.(1)

This is often referred to as "bodybuilding-style training" as it seems to provide the ideal combination of mechanical tension, muscle damage, and metabolic stress – the three primary factors involved in hypertrophic gains.(2) The problem is, most lifters seem to think this means all training should be carried out in this rep range and thus they rigidly adhere to the same loading patterns. Wrong assumption.

Understand that maximal muscular development is built on a foundation of strength. This mandates that at least some of your sets need to be carried out in the lower rep ranges (1-5 reps per set).

Stronger muscles allow you to use heavier weights, and thus generate greater muscular tension in the moderate repetition ranges that optimally stimulate hypertrophy. By increasing muscle tension without compromising metabolic stress, you're setting the stage for enhanced growth.

On the other end of the spectrum, high rep sets (in the range of 15 to 20 reps per set) also have a place in a hypertrophy-oriented routine. Provided that training is carried out at or near your sub-rep max, lower intensity sets help to increase your lactate threshold, the point at which lactic acid rapidly begins to accumulate in working muscles.

The problem with lactic acid is that beyond a certain point its accumulation interferes with muscle contraction, reducing the number of reps you can perform.(3) (Technical note: it's actually the H+ component of lactic acid that hastens the onset of muscular fatigue.)

Here's the good news: Higher rep training increases capillary density and improves muscle buffering capacity, both of which help to delay lactic buildup. The upshot is, you're able to maintain a greater time under tension at a given hypertrophy-oriented workload. In addition, you develop a greater tolerance for higher volumes of work–an important component for maximizing hypertrophy (see Mistake #2).

Take home message: Optimal muscle development is achieved by varying your rep range over time. This is best carried out in a structured, periodized program. Both undulating and linear periodized approaches can work, depending on your goals. Whatever scheme you employ, though, make sure you include the full spectrum of loading ranges.

Sure, hypertrophy training is probably best achieved with moderate rep sets, but higher and lower intensities are nevertheless important for optimizing muscular development.

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Very short answer : Low reps with high weights build muscle mass. High reps with low weights build endurance/stamina. Ideal reps ~ 8.

But you must try it with heavier weights and keep increasing the weight little by little over time. If you don't increase weight, you will not get results. When you keep on doing the same weights you get into maintenance zone. So be daring and believe that you can indeed lift more than you can imagine. :-)

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Is there an ideal rep range for increasing muscle mass, and if so, what is it?

There isn't ideal, but generally there is wide range, like 4-15. You must understand that everybody is different, for one low rep training will be the best and for other high reps will be good even on those complex exercises like bench presses and squats. Anyway for most people it's best to do less reps on multi-part complex exercises (presses, squats etc) and more reps on isolated exercises.

How much difference does the rep range make?

Depends on your body.

Why is there so much contradiction between sources?

Understanding your own body is the answer for many fitness questions :)

I'm not native English speaker, so if I wrote something wrong, please,let me know in comments :)

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Can you provide sources for your answer? Also, I don't remember the name, but I read a book a couple of years back that contradicts the mantra that "every body is different" under the premise that human physiology is for the most part the same for all people. That is, that the muscle growth process is the same for everyone. I've added this point to the question. –  Jon Jul 13 at 11:16

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