High rep sets can be very effective for building muscle.

High Reps Vs Low Reps For Muscle Growth

Written by Russ Howe PTI, and most recently updated 1 day ago.

9 min read

When I was a gym newbie I was advised to avoid high rep training.

Meanwhile, women who go to the gym are often told the complete opposite – to do lots of high reps with light weights in order to tone up and avoid big, bulky muscles.

You know what?

It was all bullshit.

It turns out high reps are just as good as low reps when it comes to building muscle. Furthermore, the key to unlocking the absolute best results is NOT to choose between them, but rather to combine the two approaches, because they each offer unique subsidiary benefits which play an important role in helping you to build your best body.

Table of Contents

Our Old Beliefs About High Rep Training Are Wrong

should you do high reps or low reps to build muscle

These old beliefs stem from a piece of missing information.

If you asked ten “experts” what the goal of each rep range is, I guarantee nine of them would say this:

  • 1-5 reps is for strength
  • 8-12 reps is for hypertrophy
  • 15+ reps is for muscular endurance

So what would the one in ten expert say?

I’ll tell you, because I am him. You see, each rep range has more than one benefit. That means the information above is not necessarily wrong, it’s just missing some crucial details, and it could impact the way you train forever:

  • 1-5 reps is for strength and neuromuscular development
  • 8-12 reps is for hypertrophy and strength
  • 15+ reps is for muscular endurance and hypertrophy


This changes things, doesn’t it?

It means you no longer need to avoid 15+ reps for fear of not making any gains! And ladies, you do not need to worry about going heavy and turning into The Hulk, because the high rep work you’ve already been doing is tapping into your muscle building capabilities anyway!

What The Studies Say

high reps vs low reps

The first study to stir interest in this topic arrived in 2010 from researchers at McMaster University, Canada.

The team were looking at the neurological differences between having a group of trainees go to failure with a heavy weight for 4-5 reps, and then go to failure with a light weight for 20-25 reps, when they noticed something interesting… the high rep group managed to boost muscle protein synthesis 60% more than the low rep group. (1)

Muscle protein synthesis is the anabolic response to training, which has a direct link to how much muscle you’re going to build, so this study made a lot of people sit up and take notice of the potential benefits of high rep work.

However, it also left us with some unanswered questions.

Was it the high rep set which caused the spike? Was it the fact they went to failure? Was it that 4-5 reps just isn’t very good at creating hypertrophy (it’s in the strength range, after all)?

We would need more studies to find out.

high reps vs low reps

Twelve months later, researchers from the same university set about answering those questions with a couple of follow-up studies..

Their first port of call was to find out if the results of the first study were simply a fluke. Using a similar setup to the original trial, they were able to successfully replicate their earlier findings. (2)

Holy flaps!

Eyebrows were being raised at this point, but there was still more work to be done. If we were going to get a true reflection of the muscle building capabilities of high rep sets, we would need a trial which compared them directly against 8-12 rep sets (the so-called “sweet spot” for muscle growth).

That study arrived the following year.

In a detailed paper published in the Journal of Applied Physiology, the researchers compared the results of one group of trainees who were performing sets with a weight which caused failure at 8-12 reps, and another group of trainees who performed sets with a weight which caused failure at 20-30 reps. Amazingly, the high rep group were able to create a near identical spike in MPS (muscle protein synthesis), and both groups recorded a 7% improvement in muscle mass. (3)

This is the study which quite literally changed the game.

high reps vs low reps to build muscle

And here’s where things get even more interesting.

Considering that high rep sets force you to use lighter weights, many people make the deadly mistake of going too light, and this causes them to miss out on results. You see, the caveat with using high reps for muscle growth is that you must train to failure – in fact, there has NEVER been an effective study on high rep training where participants did not go to failure!

That’s because high rep sets rely on something called The Size Principle, which I explain in this post, but right now, to demonstrate how important it is that you take at least one of your high rep sets to failure, let’s go back to two of the studies I mentioned above, and look at some information which I didn’t show you first time around.

In each of these studies there was actually a third group of participants, so alongside the trainees who were doing sets of 4-5 reps which a weight which caused failure and 20-25 reps with a weight which caused failure, there was also a group of trainees performing sets of 20-25 reps with a weight which did not cause failure. In both studies it was those participants who saw (by far) the worst results.

So put those pink fluffy dumbbells away and choose a weight which challenges you.

high reps vs low reps for building muscle

So This Applies To Women Too?

should women do high reps and light weights to tone up

Oh, you guys thought there was too much conflicting fitness information out there?

Try being a woman.

Women have been told so much bullshit over the years regarding weight training, cardio, supplements, and nutrition that it would probably take me a 5000 word essay to debunk all of the fucking nonsense, but here’s what we’ll focus on today:

There are three reasons why this is total nonsense.

  1. If it was this easy to look like Rambo, every guy in your gym would, and let’s face it, they don’t. Interestingly, Sylvester Stallone was one of the pioneers of high rep training, so you’re possibly already training like Rambo right now.
  2. I’ve just shown you that high rep training builds the same amount of muscle mass as low rep training, and you’re already doing high rep training, so you have nothing to worry about – and you’ve got even less to worry about if you venture into the strength range (1-5 reps).
  3. Testosterone is the key hormone responsible for muscle growth, and women produce considerably less of it than men. So when we look at this on a scientific level it’s actually harder for women to build muscle than men (yes, ladies, if you’ve ever felt frustrated that your husband seems to get results faster than you, you’re not going crazy, this is a real thing!). (4)

I hope this erases any fears you may have had about training in different rep ranges. I felt like I needed to include this section, because unfortunately the fitness world is still behind the times when it comes to educating women on how to train properly.

How To Get Maximum Results From These Findings


Now let’s discuss periodization.

If you watch how professional athletes train you’ll see that they work through several different phases on the way to achieving their goal (i.e. they don’t just exclusively stick to one rep range the whole time). This is because each training zone brings a desirable set of subsidiary benefits, and if we tap into those then it enables you to increase results even higher. (5)

So we know 1-5 reps will primarily increase strength, and we know 8-12 reps will primarily build muscle, and we know 15+ reps will primarily boost endurance, but now we’ve also seen that 15+ reps is very useful for building muscle, and it turns out that the other rep ranges have their own unique side-benefits as well:

A graph showing the different adaptations made with different rep ranges
H: hypertrophy, S: strength, E: endurance, N: neuromuscular connection

By combining a couple of training styles (or even all three) you will see significantly better results in the long-term.

For example:

Picture a guy who always trains in the 8-12 rep range. His quest to build muscle hinges on his ability to create progressive overload (increasing the weight). Unfortunately, he will eventually reach a ceiling in terms of how heavy he can go, which causes results to stagnate, but we are guys and we don’t listen to anyone, so we just keep trying to get heavier and battering away at ourselves, until eventually the injuries begin to rack up as years of heavy lifting start taking their toll.

It’s a story as old as time itself.

If we restructured his training program so that he’s spending 3-weeks in the 15+ rep range, 3-weeks in the 8-12 rep range, and 3-weeks in the 1-5 rep range, there are a number of reasons why he’d see much better results:

  1. Training is no longer boring.
  2. He is kept safe from injury because he’s not lifting heavy all the time.
  3. The 1-5 rep range will improve his strength, which helps him to achieve that all-important progressive overload when he returns to the 8-12 rep range.
  4. The 15+ rep range will boost endurance, improving his conditioning and making it easier for him to push through “the burn”, triggering a greater anabolic response.
  5. The 1-5 rep range will improve his neuromuscular development, making it easier for his body to handle heavy phases.
  6. High rep training places far less stress on the central nervous system, so he can recover from session very quickly and perhaps even increase the number of workouts he does each week.

I hope you enjoyed this read on high reps vs low reps, now go lift something! If you’d like to start a good high rep program, or one which mixes all three styles into one system, you’ll find some below.


  1. Burd N. A., et al. Low-Load High Volume Resistance Exercise Stimulates Muscle Protein Synthesis More Than High-Load Low Volume Resistance Exercise In Young Men. PLoS ONE (2010).
  2. Burd N. A., et al. Enhanced Amino Acid Sensitivity Of Myofibrillar Protein Synthesis Persists For Up To 24 Hours After Resistance Exercise In Young Men. J Nutr (2011).
  3. Mitchell C. J., et al. Resistance exercise load does not determine training-mediated hypertrophic gains in young men. J Appl Physiol (2012).
  4. Handelsman D. J., et al. Circulating Testosterone as the Hormonal Basis of Sex Differences in Athletic Performance. Endocr Rev (2018).
  5. Rhea M. R., et al. A meta-analysis of periodized versus nonperiodized strength and power training programs. Res Q Exerc Sport (2004).

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I’m Russ. I’ve been a personal trainer since 2002, and I own russhowepti.com.

My job is to simplify fitness for my readers.

I send out free fitness tips to over 100,000 men and women every week, all in the same no-nonsense style as the article you’ve just read, so if you enjoyed reading it be sure to jump on my email list below.

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