Should you do high reps or low reps to build muscle?
This is one question I get asked on a regular basis in the gym, and today I want to delve into the latest sports science to give you a definitive answer to your question…
… and it’s an answer which might just surprise you.
In fact, the information you see here today could well change the way you train forever.
You see, have you ever heard this old saying:
“Low reps are for building muscle, and high reps are for toning up.”
It’s a common belief, but it’s bulls**t.
People are often surprised to find out that I do a fair amount of training in the higher rep ranges (20+ reps per set), and so do many of my clients.
And that’s because high reps will build just as much muscle as low reps.
Yeah, I said it.
If somebody is sticking purely to the so-called “golden 8-12 rep range”, they are missing out on results across the board.
Poor Form Charlie
Before we get stuck into the real science, I can pinpoint one specific individual who would benefit from higher reps and lighter weights.
I call him Poor Form Charlie.
He’s a character in every gym, and he’ll swing heavy dumbbells over his head with death-defying speed in his quest to build more muscle.
Suggesting he goes lighter and performs reps with better form is almost like an insult.
But, as I like to say, “Ego is the enemy of success.”
Because this is one instance where it would yield instant results; suddenly his target muscle would be able to work properly against the weight it was handling.
High Reps Vs Low Reps: The Key Info To Know
We have 3 rep ranges to choose from depending upon our training goal.
These are so ingrained into fitness folklore, I was even taught them on personal training courses.
- 1-5 reps for overall strength
- 8-12 reps for hypertrophy (muscle growth)
- 15-25 reps for muscular endurance
Given that most guys want to get bigger, it makes sense that we gravitate towards that 8-12 rep range and stay there until we die, right?
Sure, we might occasionally throw in a super heavy set of 5 rep deadlifts, or a high rep burnout for our biceps, but that’s about as adventurous as we get…
But guess what…
The table above is missing some crucial information.
It should read like this:
- 1-5 reps for overall strength and neuromuscular connection
- 8-12 reps for hypertrophy and strength
- 15-25 reps for muscular endurance and hypertrophy
That’s right, each rep range has multiple benefits!
So while training in a higher rep range will certainly give you more muscular endurance, it will also create more muscle growth. But how much? How effective can it be, if muscle growth is the secondary benefit?
Turns out, it’s pretty sizable.
High Reps Or Low Reps: The Studies
There are several studies out there which compare the effects of high reps and low reps for muscle growth, and we’ll get stuck into some below.
But this is all still relatively new information.
In fact, the first study only emerged in 2010.
Researchers from Canada compared the effects of maxing out with as much weight as possible for 4 reps, versus maxing out with as much weight as possible for 25 reps.
They discovered that the group who did the higher rep sets increased muscle protein synthesis by a whopping 60%! (1)
This study opened up a whole new world of possibilities for researchers to delve into, as it had previously simply been taken at face value that heavier weights would equate to more muscle growth.
The one caveat with this study is that one of the groups trained in a very low rep range (4 rep max), which is primarily touted as a strength training zone, not a hypertrophy zone.
So we’d need to repeat this study with a group training in the 8-12 rep range for a true reflection of high reps vs low reps for muscle growth…
Thankfully, 2 years later, researchers from McMaster University gave us that answer.
This time around, one group performed leg extensions with their 8-12 rep max weight while another group performed the same exercise with their 20-30 rep max weight.
Published in the Journal of Applied Physiology, this trial was the first of its kind to show that high reps can be just as effective as low reps for building muscle. (2)
At the end of the study, both groups increased muscle size by 7%.
Like a last-minute twist in an action movie, if everything we thought we knew was wrong, what else could they discover?
Well, we were given another answer almost immediately, because one of the aforementioned studies managed to unearth another golden nugget of training know-how; training to failure.
You see, during the first trial shown above (4 rep max vs 25 rep max), there was a third group of trainees taking part.
These people were training with a weight they could comfortably lift over 25 reps, while the other two groups were using weights which took them to muscle failure (i.e. struggling to perform the final rep because the weight was challenging).
Both groups who used challenging weights stimulated much more hypertrophy than the group who took it easy. (1)
So remember; high reps doesn’t mean “light” weights.
You should be churning out those last few reps with a face that makes Freddy Krueger have nightmares.
Why It All Works
So you’ve seen the research, and it stacks up well.
But now, let’s science this s**t out of this b**ch by taking a look at what’s occurring inside the muscle cells when you workout.
This will explain exactly why higher rep work can be so beneficial to muscle growth, so if you’ve previously been stuck in the 8-12 rep range, listen up.
Our muscles consist of two types of fibers:
- Slow twitch fibers
- Fast twitch fibers
Slow twitch fibers are weaker, but have more endurance. Fast twitch fibers are the opposite (bigger and stronger, but very limited endurance).
When we perform heavy exercises, we are using our fast twitch fibers.
Given that they have the largest potential for growth, it makes sense to perform heavy movements on a regular basis.
But the real “trick” is to hit both types of muscle fibers…
See, your body’s primary goal (in everyday life) is to keep you alive. It doesn’t care what you want to look like, etc. It only cares about maintaining a status quo and sustaining life.
So it will try to perform tasks with as little effort as it can “get away with”, so to speak.
Let’s transfer that into the gym…
You grab a heavy weight, and the body recruits muscle fibers from smallest to biggest. It won’t involve the bigger muscle fibers unless it has to, because that requires more effort.
If that dumbbell is too heavy, your slow twitch muscle fibers will quickly realize they are no match, and let the fast twitch fibers handle it.
If the weight is still too heavy, all of the remaining fast twitch fibers from the muscles in the surrounding area will be called up on to help, and you’ll get that weight up.
Take that set to failure, and you’ve just exhausted your fast twitch muscle fibers.
Of course, all of this takes place in a split second as we train, but this gives you a snapshot of what’s going on inside your biceps while you pound them into submission.
But while our fast twitch muscle fibers have enjoyed a good workout, our slow twitch fibers remain relatively untrained.
Remember, they ran out on you the second it got too hard!
So let’s try this experiment again, only this time we’ll use a 25 rep max weight instead…
Once more, our body recruits muscle fibers from smallest to biggest, so a bunch of slow twitch fibers in the working area are called up to lift weight weight.
The key difference is that now they can.
Once they reach fatigue, the “cavalry” is called and your bigger muscle fibers take over until you reach the end of your set.
If you’re using a weight which causes muscle failure, you have now taken both types of muscle fibers to hell and back – and that’s why high rep training is so effective.
Mix It Up
Although I love high rep training, I want to make one thing clear;
You shouldn’t be training exclusively in any one rep range.
Obviously, if your goal is to gain strength at all costs, then it makes sense to base a large chunk of your work in the strength training rep ranges (1-5). But if your goal is to simply look great naked, you should be mixing up your rep ranges for maximum results.
You see, aside from muscle growth, there are many crossover benefits waiting to be unlocked…
Refer back to the rep range tables above.
The 8-12 rep range has a secondary benefit of increased strength.
If we can unlock those strength benefits, it will help us lift heavier weights in future, which is great.
Higher rep ranges will improve muscular endurance, which means you’ll be able to keep on forcing out those reps when “the burn” kicks in. Again, this is great.
Another benefit of higher rep work is a slight boost in growth hormone release, as a by-product of training in rep ranges which induce lactic acid build-up (“the burn”).
And one last thing I’d like to address here is the myth of “toning”.
“Do high reps to tone up” really p**es me off.
Your muscles know how to grow (hypertrophy) and shrink (atrophy). That’s literally all they can do. They do not know what “tone” means, and how “toned” you look depends on how much body fat you are carrying at the time, which has 100% more to do with your nutrition anyway.
What About Women?
To all the girls reading this, I apologize.
I apologize for going against everything you’ve likely been told about weight training in the past.
But hey, at least I brought you the science.
Because for years now, women have been told they need to do high reps with light weights, or run the risk of looking like The Incredible Hulk in a prom dress.
But now I’ve shown you that those higher rep ranges will build just as much muscle anyway, so what the f**k are you supposed to do?!
There are two areas I want to address regarding rep ranges for women.
First, women release much less testosterone than men.
You’d find it much harder to “get huge” than a guy, and it isn’t exactly “easy” for guys (otherwise they’d all be running around like Rambo), so you have nothing to fear.
(Not unless you start injecting good old “vitamin S”.)
What this should really do is remove the fear (if you had one) of training with heavier weights in lower rep ranges.
After all, if you’ve been going higher in reps you have already seen the type of muscle you are able to build. Lower reps won’t do any more than that; you can see that in the studies above.
About 80% of the women I train at the gym go between low reps and high reps on a regular basis.
Squats, deadlifts, rows, overhead press, they do them all.
The goal is simple; whatever the target rep range, use a challenging weight which takes you to (or close to) muscle failure.
The next time someone tells you to grab those pink fluffy dumbbells and do endless triceps kickbacks, tell them to suck it.
So now you know why I like to mix high reps with low reps, and why I include this style of training in so many of my online workout plans.
Give it a try, report back to me with your results.
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- 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)
- Mitchell C. J., et al. Resistance Exercise Load Does Not Determine Training-Mediated Hypertrophic Gains In Young Men. J Appl Physiol. (2012)