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How Many Reps Per Set for Muscle Growth?

I’m going to start this article by asking a hypothetical question:  If you had to pick a single repetition range to train in for growth, what would it be?  That is, imagine some very strange situation where you could only train within a certain repetition range which I’ll limit to a 3 rep spread (i.e. 9-12).  What would you choose?  Put differently, is there an optimal number of reps per set for muscle growth?

I used to ask this of friends of mine in the field and, almost with exception, the answer was pretty much the same.  This was true regardless of whether or not they had arrived at that value from experimentation and experience or just looking at the research.  So I’m going to look at a variety of different topics to show you how I got to the answer I’m going to provide.

What Stimulates Muscle Growth?

I asked a job supervisor that question once once; he was a smart-ass like me and told me “It needs lots of sunlight and water.”  Close but not quite.

The mechanism of muscle growth has been under heavy scrutiny for years and a lot of theories and ideas have come and gone in terms of both the mechanism of growth as well as what stimulates it.  Semi-amusingly, about 98% of the actual answer was known back in the 70’s.

In an exceptional paper (which I recommend the reading of to any nerds in the field) titled “Mechanism of work induced hypertrophy of skeletal muscle” a researcher named Goldspink pretty much laid it out concluding that:

It is suggested that increased tension development (either passive or active) is the critical event in initiating compensatory growth.

Basically, the development of high levels of tension within the muscle is the key/primary factor in initiating the growth process.  I’d note that there are also some elements of fatigue that may be contributing to what “turns on” the growth response.  Finally, I’d note that in order to keep stimulating growth beyond an acute training bout, there has to be an increase in muscular tension.

Basically, over time you have to add weight to the bar.  This is called progressive tension overload.

Which as another great scientist in the field (Ronnie Coleman) summed up thusly:

Everybody wants to be a bodybuilder, but nobody wants to lift no heavy-ass weights.

Or as Dante Trudell, inventor of Doggcrapp training put it so simply

Growth is stimulated by increasing strength in a moderate repetition range.

The simple fact is that, outside of heavy drug users (steroids having the capacity to stimulate growth without even training), the biggest bodybuilders are the strongest.  They grow because they provide, over time, a progressive tension overload (of course there are more variables that go into this, total workload per workout, frequency of training and diet all interact here).   If you look at essentially all successful hypertrophy systems, they include a focus on adding weight over time.  It’s a fundamental component of growth.

But as I have been pointing out for years and years and years, if you’re not adding weight to the bar over time, you’re simply not growing. You can focus on the feel and the pump and the squeeze all you want; if you’re using the same weights 6 months from now that you’re using today, you won’t be any bigger.  You can prove this to yourself every day in the gym.

No, this doesn’t mean that you have to add weight at EVERY workout which is the fallacy of HIIT.  But over some time frame, which might be weeks or longer for advanced trainees, you have to be lifting heavier weights.

But that’s what stimulates growth in the most general sense.

Tension Overload + Some Fatigue/Volume -> Muscle Growth

With that background we move to the next topic.

How Does Muscle Generate Tension?

When you look at how muscles generate force (i.e. tension), you find that the body has essentially two methods to increase force output.  They are:

  1. Muscle fiber recruitment
  2. Rate coding

Muscle fiber recruitment is exactly what it sounds like, how many of the fibers within a muscle are actually being recruited.  Contrary to the exceptional silliness which is endlessly repeated in books and on the internet, even rank beginners can recruit 100% of the muscle fibers in their upper body.  It’s a little less, around 90% in the legs.  Rate coding refers to how quickly the body is sending electrical signals to the muscle.  As rate coding goes up, the muscle fires harder, generating more force and hence experiencing more tension.

In the muscles we’re interested in from a sports or bodybuilding standpoint, the body will generally use recruitment to increase force production up to about 80-85% of maximum force output.  In the lab, this is measured with Maximal Voluntary Isometric Contraction or MVIC, which is effectively 1 rep maximum weight.    Beyond about 80-85% of MVIC, fibers are maximally recruited and the body will use rate coding to generate further force.

For completeness, let me mention that smaller muscles in the body, the eyes and finger muscles work differently.  In general, they will use recruitment up to about 50-60% of MVIC and then rate coding handles the rest.  This allows for much finer motor control.  But it means that studies on these muscles (i.e. finger muscles) aren’t that relevant to what we do in the weight room.

Anyhow, now we have the next part of the picture, the body will recruit more fibers up to about 80-85% of maximum.  Essentially you will recruit 100% of your available muscle fibers from the first repetition of the set.

If you were to use a heavier load, 90%, you will not get any further muscle fiber recruitment.  If you use lower than 80%, you won’t get full fiber recruitment from repetition 1.  It will happen eventually, towards the end of the set approaching failure.

But only at a loading of 80-85% of maximum do you get full muscle fiber recruitment throughout the entire set.

How Many Reps Per Set for Muscle Growth?

So let’s sum up the above information.

  1. Growth is stimulated by a combination of high muscular tension and some amount of fatigue
  2. Full muscle fiber recruitment occurs at 80-85% of maximum (or near failure with lighter loads).

Because those two concepts lead us to the answer to the original question: If you had to pick a single repetition range for muscle growth to use for the rest of your career, what would it be?

The answer is 5-8 repetitions to or very near failure (1 rep in reserve maximum).

How did I reach that conclusion?

For most people 80-85% of maximum will allow about 5-8 repetitions per set to muscular failure.  This can vary slightly depending on the muscle and the movement.   Many find that they can do more repetitions in at least some leg exercises with this percentage for example.

If you were to put 90% of weight on the bar, you might only get 3 repetitions.  You wouldn’t increase fiber recruitment but you would decrease the amount of mechanical work done.  If you put 70% on the bar you might get 15 repetitions.  Taken to failure, you will actually get full recruitment near the very end.  Perhaps 3-4 of those 15 repetitions will occur under conditions of full recruitment.  Certainly you will have done more total mechanical work.  Again, all fibers will not experience high muscular tension until the end until the end.

Essentially, a near maximum set of 5-8 repetitions will allow you to perform the maximum amount of mechanical work under conditions of full fiber recruitment and muscular tension.  Heavier won’t increase recruitment but will decrease mechanical work and lighter will increase mechanical work but all fibers won’t experience it until the end.

Let me add that I am not advocating that trainees seeking maximum muscular growth only work in this range.  Rather, I am addressing a hypothetical question as a way to examine some basic physiological concepts.  Clearly other repetition ranges can be useful for hypertrophy  and there can be good reasons to use a variety of repetition ranges when training for maximal muscle growth.

But if you had to pick a single repetition range to use for the rest of your career for some reason, 5-8 would be the optimal number of reps per set for muscle growth.


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47 thoughts on “How Many Reps Per Set for Muscle Growth?

  1. sweet.

    that was my guess.

  2. Lyle,

    This was an excellent piece. As always you have a knack for perfectly blending the esoteric and the commonplace and leave people saying, “But of course!”

    While I am not doubting the fact that his methods likely work well, since the best workout is always the one you haven’t yet adapted to, does your comment about MU recruitment being maxed out (in most muscles) around 85% of maximum contraction and rate coding being responsible the rest of the way indicate that Chad Waterbury’s system of selecting total target rep ranges and not focusing on the number of sets but rather the speed of each rep is somewhat overrated compared with a more traditional approach of selecting a rep range like 4-6 or 6-8 and using a specific number of sets?

    Obviously you don’t want speed drastically slowing on multiple reps per set, but I’ve never found this to be an issue using a specific number of sets if proper loading and technique are respected.

    Thanks for the article!

  3. Ideally I would vary between 4-6 reps and 8-12 reps for 6-12 weeks at a time. But if I had to choose only one range – I would go with 5 to 8 reps like you.

  4. 8 was my guess.

    Say you do 5 sets and you are getting tired on set 4-5. Do you lower weight to stay in the range or reduce the amount of reps and stay at the higher weight?

  5. I didn’t really understand what you meant by ‘rate coding’.

    I tried to look around the net for clarification, but that only made me more confused.

    If all the muscle fibers are recruited, how does a greater frequency of electrical impulses to the muscle make it fire harder? I’m not even sure I understand what you mean by harder?

    Do you know any good links that explain this process in laymen terms?


  6. Great article. FWIW, my best gains in muscle mass have always been from 5-6 sets per muscle group within the 6-10 rep range. For upper day I would usually start out with 3 sets of 8-10 on dips, do the same with chins, then go to3x6-8 on flat bench and the same with rows.

    Leg days were similar with squats, RDL’s and leg presses.

    As Ronnie would say ‘Ain’t Nuthin but a Peanut!’

  7. I’m no expert, but I’ve been led to believe there are two types of muscle hypertrophy: sarcoplasmic (basically fluid, not much to do with strength) and myofibrillar (stronger fibers, but not much volume).

    So an athlete who wanted to be very strong, but in a certain weight class, he’d want to avoid sarcoplasmic muscle growth and do his best to gain myofibrillar muscle growth, which would mean using a weight very close to the 1RM to target maximal strength. But bodybuilders, who just want the biggest muscles, would be better served going to higher sets (more like 8-12) and be happy with not much strength gains but fluffy muscles.

    If this is the case (and my understanding of this stuff isn’t totally mangled), is the 5-8 rep range is how you’d target both types of hypertrophy in a set, and therefore maximize growth?

  8. Great article. If doing this 5-8 rep methodology, how many sets do you recommend, and also how much of a rest period between a set if the goal is hypertrophy?

  9. This goes for abs too?

  10. Thanks for this article–kind of explains to me some of the stuff you were talking about over at the forum.

  11. Joe: Chad Waterbury has never had a clue what he was talking about. Slowing of rep speed is irrelevant and you will only recruit more fibers as you fatigue. the idea that you must train fast to recruit the fastest fibers is simply nonsense.

    Ezekial: How to handle sets within a workout is one or two articles itself.

    Kira: Rate coding is literally the rate at which neural impulses travel from the brain to muscle. As rate coding increases (up to a point at least) so does force output. I can’t explain it any better than that.

    Jonny: Some sources say there are two types of hypertrophy, others do not. For sarcoplasmic hypertrophy, the primary stimulus is fatigue and energetic depletion so you’d use much higher reps.

    Ankit: Different article, I’ll talk about total workloads at a later date.

    Omar: Abs are a muscle like all the rest. Train them like any other muscle group.


  12. Your answer seems to be premised on gaining strength as the goal. But what if you want to gain strength and stimulate weight loss, or at least minimize fat gain? I was under the impression (and my anecdotal evidence seems to bear this out) that slightly higher reps can help stimulate the metabolic effect of the workout better. Put simply, even with no changes in diet, I seem to get fat off of low-rep routines.

  13. Jeremy

    The title of the article was:
    “Reps Per Set for Optimal Growth

    Not strength, not fat loss. Because if I had been writing about either of those, I probably would have called it something else.


  14. Lyle,

    In your old article ‘periodization for bodybuilders pt 2’, u mentioned, “Intensive bodybuilding method: 4-6 reps @ 80-85% 1RM. Extensive bodybuilding method: 6-12 reps @ 70-80% 1RM ” Have things changed slightly or am i worrying too much?

  15. Ok, I’m going to really try to not get screamy but I want you to go read the article again and the hypothetical question I posed at the start of it.

    Here, I’ll reiterate it

    “If you had to pick a single repetition range to train in for growth, what would it be?”

    Now I’ve bolded a key word in that sentence that explains the confusion you’re having.

    Put differently: in practice there’s no reason you’d limit yourself to a single rep range. Which is why I made sure to start this article by explaining my weird hypothetical question.

    In practice, you will use different rep ranges (either in the same day or different workouts).


  16. @KIra:
    In order to make a muscle contract you nervouse system sends pulses to your muscle. A single pulse leads only to a very short contraction. In order to get what looks like a constant contraction you nervouse system sends a lot of pulses (something about 50 pulses per seconds).
    So a contraction of a muscle fiber actually consists of a lot of mini contractions. The next contraction starts before the muscle completely relaxed from the previous contraction.

    In order to generate more force the frequency of these pulses can be increased to – I think – about 120 pulses per seconds. The mini contractions overlap even more and as a result more force is produced.

  17. Is the ideal rep range assuming a single set? The reason I ask is that if my 8 rep max is 80%, my three sets of 8 max is probably less than 75% which would fall out of the ideal growth percent. If you are looking for a volume of more than 8 reps, wouldn’t the ideal rep range be more like 3-6? What kind of volume do you generally recommend in the 5-8 rep range?

  18. IIRC the IART (Bryan Johnston (sp?)) idea is to test each exercise at 85% of 1RM and use that rep range for most sets as opposed to a cookie cutter 5-8 rep average. Seems to work well for me; I can do @5 reps with 85% for pecs but about 10 for tris, for example. Quads are higher still…

  19. How would that translate to TUT instead of reps? When talking about time under tension, we’d have to test 1 RM with the same rep tempo we wish to use for training, right?

  20. I am simply wondering about this and the thought of muscle confusion, do they correlate?

  21. I’m not very expert but I like training a lot!
    I think your article is very interesting and well written.
    Thank you!

  22. Hi Lyle,

    I hope linking to websites is allowed in your comments, as I am certainly not self-promoting or anything, but just wondering what your thoughts are on this particular article (Link:, which states:

    2-3: strength with little size gain

    4-5: strength and size gains, but more strength than size

    6-8: strength and size gains, almost equally

    9-12: strength and size gains, but more size than strength

    13-15: size gains, and some muscle endurance gains

    16-20: muscle endurance gains, and some size gains.

    How much of that is factual?
    Eagerly awaiting your response!

  23. Jono,

    An element of truth, an element of gibberish.

    You can grow on low reps if you do enough sets and Ol’ers rarely go above 5 reps per set and get pretty decent legs (and sometimes upper bodies). And you can gain some strength with high reps.


  24. I’m afraid Joe has misinterpreted Chad. Chad recommends that on each rep you attempt to accelerate the bar as fast as possible in the concentric phase – maximal voluntary muscle contraction! and by doing so you can recuit near 100% muscle fibre even at sub 80-85% loads. It doesn’t matter about the speed the bar is travelling at, what matters is the attempt to move the bar as fast as possible on each rep in order to get the most out of each rep. Why recruit 100% of muscle fibres only at the end of the set when you begin to fatigue when you can do it from rep one by applying as much force as you possibly can regardless of the loading?

    What Chad actually recommends is stopping the set when you lose the ability to perform a maximum voluntary contraction – nothing to do with speed, and this is were Chad differs from other coaches.

    There are alot of olympic lifters, powerlifters, bodybuilders and coaches all of whom recommend performing the concentric as fast as possibe and with good reason – muscles like it be it for increasing size and or strength

  25. Beside this tab on my browser i’m reading another article mentioning something that the author calls post-activation potentiation – where by some neurological adaption, you’re able to perform reps more easily if beforehand, you lift heavily for one or two reps (over 85% of your 1RM). I guess this is true… a lot of people must know what it’s like to perform pushups after a heavy set of bench pressing, or dips.

    What i’m wondering/asking is whether this is a good way to ‘enhance’ muscle growth outside that 5-8 rep range with every workout?

    Such as (after warm-ups) performing 1 rep at 95% of your max, resting a minute or two, lifting within 5-8 reps, rest, then repeat until fatigued? Could it hinder results?

    After reading about it I figured that since the CNS is responsible for the number of motor units recruited when activated, this might be a smart way to train muscle groups.

    PS. I’m no sport scientist, you could probably say that my gappy knowledge is recycled from months of googling and ebooks. When I started reading your articles i’ve seemed to straight out a lot of my problems with training and diet though.

  26. The Warming Up for the Weight Room series talks specifically about using a heavy single above the day’s work weight for essentially this purpose. Certainly there is something to the idea of PAP.

  27. 1. How much strength can be gained without hypertrophy? as in with purely neural adaptions? and i read that low reps with heavy weight is the way to go to achieve this?

    2. Is it the neural firing rate you refer to what is becoming more efficient when people talk about neural adaptions? say there is evidence to show two types of hypertrophy and also evidence against it? surely we must know this by now? do you side with this theory?

    thanks dan

  28. Lyle,

    Great article, as (almost!) always.

    I picked 5-7 reps at the beginning of the article. Glad to hear most experienced lifters would agree (my first choice was 6 RM, but since you asked for a range, I went for 5-7).

    What do you think of the good ‘ol 8-12 rep? Most training books say it’s the best rep range to build muscle… and it’s even backed by some research by Kraemer and friends who found that sets of 10 with 1:00 in between triggered the most anabolic response.

    Curious to know your thoughts on the 8-12 range.



  29. Lyle

    Great article!
    I get so tires of having this age-old argument with everyone I run into. I feel 5-8 reps is ideal for maximal muscle growth along with strength gains.
    I personally experiment with a 4-month phase of high reps per set (12+) for 5-6 sets. It gave me crazy pumps and that sick Greek god look… BUT 1hr after lifting I deflated!!! Lots of sarcoplasmic growth and very little strength gain.

    My advice to all fitness enthusiasts looking for solid hypertrophy:
    – Lift hard and heavy
    – Majority of lifts should be less than 10reps per set
    – Focus on slowly loading the eccentric phase (ex// lowering the bar during a chest press)
    – Explode through the concentric phase (ex// pressing the bar during a chest press)

    I’ve seen a lot of guys become bogged down in the “science” of body building and their routines suffer from overthinking ideal rep/set, total reps per group, time under tension, etc.

    Keep up the great work!

  30. As I get older injuries have increased to tendons / ligaments and joints as i am very small boned. is there any way of appreciably strengthing tendons? my understanding is due to lack of blood supply tendon injuries take ages to heal. for the same reason i doubt much can be done to strengthen them. your thoughts???

  31. For the most part, it’s probably an issue of time. Connective tissues are very slow to adapt but they do adapt. The idea that isometrics preferentially strengthen tendons has been bandied about in the strength training literature for decades; I can’t recall having seen anything to support that but I can’t honestly say I’ve looked exhaustively. Folks with lighter frames often do better staying at the higher end of the repetition ranges (lower rep work simply being too much) or need to cycle intensity more to avoid causing problems.

  32. Lift heavy weights fast…..or try to lift them fast. Slow and controlled lowering of the weight. I love 4-6 or 6-10 rep ranges. Good article!

  33. Thanks Lyle. Been a personal Trainer for 4 years and just questioned the logic of the 12×4 formula for hypertrophy for the first time tonight…shame, shame, shame. I hate that 12 – 15 rep shit! bring on the heavy!

  34. Very nice article! But how many sets are we talking about? 5×5, 6×4, 8×3, for example?

  35. At last! Practical fitness advice backed by sound science. I’ve learned more in the last 5 articles than in 2 years of reading “The latest study suggests…” articles. If I hear the words “whole grain” one more time I’m going to stick a fork in my eye! Excellent work Mr. McDonald. Passing along this info to others as well. Thank you so much.

  36. 1.I used very high rep training (25 per set) at 135 pounds-all that was available to me at the time,and became extremely strong and 1 rep max when done for the bench ,later on,was 305 pounds.2 As far as protein the rda is spot on.

  37. Nice article Lyle. Informative. Many folks here have raised a question again and again..on the optimal set/rep numbers. I would say 5 by 5. I would also direct them to a website which is ALL about this.
    I have been into this program for sometime and i would want people to know more about it.

    Thanks Lyle..good job on your part on explaning things which would have otherwise been considered as arcane by laymen like me 🙂

    Ramesh EMV

  38. Protein synthesis is maximally spiked from 75-80% of the 1rm. It doesn’t matter if the you engage all fiber from rep one vs 2 reps into the set…the overall volume greater with a 10rm load vs a 6 or 8rm.

    Protein synthesis is what builds muscle, not fiber recruitment from rep 1.

  39. Hi Lyle, great article.
    I’ve been looking for the article you mentioned: “Mechanism of work induced hypertrophy of skeletal muscle” by Goldspink, but I can’t seem to find it.
    Do you know where I could find it? Thank you.

  40. I always enjoy reading your ideas Lyle.

    As an Olympic lifter, who purportedly doesn’t spend much TUT due to the nature of the quick lifts, I have found that the greatest hypertrophy has been with those exercises which required the use of heavy weights, relatively high TUT and relatively high reps for the development of strength (5-8). Basically full squats, presses, rows and cleans (sets of 3-5 reps for cleans), on top of the competition lifts.

    What you bring out in your article is very similar to what I have found in real life and I don’t train for hypertrophy so my muscle gains are just a side effect of my training.

    All the best.

  41. Hello, this is a very interesting article. I guess I agree, but I have to note I made very good gains in strength and visual size with doing the heaviest I could lift (with 5 lbs. Increments as I grew stronger, i.e.: generally many sets of 1-3). I’m trying out less sets of 8-12 reps now and to be honest, it doesn’t seem as effective for strength gaining. But I do need to lose weight now because of some unrelated bizarre muscle loss and weight gain. After losing fat, I think I might go heavy again to gain strength, my main goal, which seems like more fun. 🙂

  42. Hi I was just wondering what if You were mainly going for size but you occasionally went for really low repage would that help you lift more weight when training for size and then did high reapage occasionally to help you squeeze out an extra 1 or 2 rep on your days you go for size?

  43. The 5-8 rep range is the range I choose for 2 of my 4 workouts per week. I find that working in two different rep ranges works for me, but just about anything works for me in terms of mass. I am a mesomorph and doing anything physical will make me gain muscle mass rapidly.

    I am on a standard u/l type workout with two workouts for the upper and two for the lower. I have a heavier workout in the 5-8 rep per set range, and a lighter workout in the 8-12 rep per set range.

    The question is, since I gain with the above pattern, is there any benefit in going to straight sets of 5-8 reps for all workouts?

  44. I have also felt the same.
    About 5 reps is what led to progression with the load, and that is exactly what led to growth in muscles.

    I have tried quite a few different rep set schemes.

    However, there is something more that I observed: whenever I did a movement where I “felt” the muscle working (perhaps because I felt some burn), I could never make progression on it. (this happened at rep range greater than 8-9 if I remember correctly)

    Whenever I felt pumped after the workout, I kind of retained the pump for about a week (very mild edema sort of) – however again I could never make progression on such. (this happened with high volume like multiple exercises for same body parts + multiple sets for each exercises)

    Anyway I have come to a conclusion that the volume (for me) needs to be ultra low (or I don’t progress and feel sick quite often), the load needs to be high, and the reps need to be low enough so that I can push myself mentally and “not feel the muscle working” but rather the whole body working to move the load (imagine you need to push a large rock on the road – you won’t really feel your legs, abs and back working – just the whole body + mental effort). This usually happens in rep range lower than 8!

    Also another thing I felt (not experimented yet) is that standing press and squat “feel” much heavier than doing the bench press. Perhaps it is because the bar path length and time is drastically less in case of bench press as compared to press and squat (I guess about 1/3rd less).

  45. Years later and this post is still rockin’ it.

    When I first read it I still thought sets of 8-12 reps were the way to go most of the time.

    Now I’d have to agree sets of 5-8 seem dead on.

    Well done Lyle. Way ahead of your time.



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