Training is a numbers game.
And today we’ll look at high reps vs low reps for building muscle.
Check out this email from website member Lucy:
My friends keep telling me to go higher in reps to gain size. I’ve always trained exclusively with lower reps, and it’s always worked for me, but am I missing something?”
So let’s get stuck in.
In fact, some of the startling research here will change the way a lot of folks train forever.
I’m a big fan of using both high reps and low reps to optimize muscle growth.
In fact, high rep training has been shown to build just as much lean muscle as low rep training, so sticking purely to one rep range means losing out on potential results.
The Battle Of Ego Mountain
Walk into any gym around the world and you’ll see guys making this classic mistake:
Hulking the biggest weight around with no care for form, pushing out an unconvincing 8 reps. Their ego will not let them train with a lighter weight.
As men, we all go through this bullshit.
We’d rather do 8 poor heavy reps with terrible form than 8 good ones if it means using a slightly lighter load. They aren’t training their muscles, they’re training their ego.
The “In Theory” Problem
There are three different rep ranges that we should be training in, each with their own primary goal.
These are things we are taught as trainers, and things we pick up from years of experience.
- 1-5 reps for strength
- 8-12 reps for muscle growth
- 15-25 reps for muscular endurance
So it makes sense that most guys see this quick analogy and stick mainly to the 8-12 zone, right? Given that most guys are trying to get a little bigger.
They sometimes go as low as 5 reps, or as high as 10, as this allows us to feel the most impressive with regards to the weights we’re throwing around.
But guess what – the information above is incorrect.
It is missing out some crucial information. It should read like this:
- 1-5 reps for strength and neuromuscular connection (mind/muscle connection)
- 8-12 reps for muscle growth and strength
- 15-25 reps for muscular endurance and muscle growth
High Reps Vs Low Reps – What Do Studies Say?
Several studies have found high rep training to be just as productive as low rep training (and in some cases more productive) for building lean muscle.
The first study to do a high reps vs low reps comparison was way back in 2010.
Researchers from Canada had a group of subjects perform 4 sets of leg extensions using their 4 rep max while another group performed the same exercise using their 25 rep max. (1)
The group who did the high reps increased muscle protein synthesis (muscle building) by an astonishing 60%!
This research opened many people’s eyes to the potential benefits of training in a high rep range, but one drawback of the study itself is that it used a 4 rep max.
Very few people train for this low number of reps, and given that it’s in the “strength” zone, it’s not a 100% accurate comparison of whether high rep ranges are as effective as low rep ranges for building lean muscle.
So two years later, researchers from McMaster University conducted a second study where they directly compared 8-12 rep sets to 25 rep sets to 8-12 rep sets.
One group performed three sets of leg extensions using their 8-12 rep max while another group performed three sets using their 20-30 rep max over a 10 week period.
The study was published in the Journal Of Applied Physiology and it noted that both groups increased muscle size by around 7% overall. (2)
This study was the first to conclusively prove high rep training was just as effective for building muscle as low rep training.
Why It Works
Our muscles are made up of two very different types of muscle fibers.
Weaker fibers with more endurance – known as slow twitch -and bigger, significantly more powerful fibers which have limited endurance – known as fast twitch.
When we perform heavy, explosive moves we tend to train our fast twitch fibers more.
Most guys want to hit those fast twitch fibers because, after all, they’re the ones which have the largest potential for growth.
But the real “secret” lies in hitting both types of fibers.
That’s because the human body tries to make every task as easy as possible. It tries to get away with doing the absolute minimum it can do, in order to keep you functioning at 100%.
So when we lift something heavy, our muscles are recruited from smallest to largest.
Curl a heavy bar, and your slow twitch – the small, weak fibers -are the first to be called into action.
Of course, they quickly realize they are no match for the weight involved and bail out on you, calling in some of the bigger fast twitch fibers instead.
If the weight is still too heavy, all of the remaining fast twitch fibers from the muscles being worked are called into action and you get the weight up.
So that’s exactly what’s happening inside your biceps when you do a set of curls for 8-12 reps.
The problem here is your fast twitch muscle fibers have been worked hard, but your slow twitch fibers have not been worked at all. Remember – they bailed on you the second the going got tough!
Let’s try it again, but this time we’ll use a weight which allows us to push out 20-25 reps…
Once again, our biceps are going to recruit the slow twitch fibers as we start the exercise.
The difference this time being that they can actually handle the stress for the time being. Once these slow twitch fibers fatigue, the cavalry is called and the bigger, fast twitch fibers take over again.
If you’re using a weight which causes you to “fail” after around 20 reps, you will have worked both types of muscle fibers extremely hard.
That’s the key difference between high reps vs low reps.
And that’s why high rep training is effective!
Another point worth noting here is that studies show our levels of growth hormone increase dramatically as a by-product of lactic acid.
By training in a higher rep range, you will feel “the burn” far more than a lower rep range, therefore kicking your growth hormone levels into over-drive.
Remember, ego is the enemy of success.
While the golden 8-12 rep range will still be your best friend for muscle growth, don’t be afraid to go lighter and aim for more reps per set from time to time. Forget “high reps vs low reps,” there are great benefits waiting to be had from doing both.
What About Girls?
If you’re a girl reading this, you’re probably panicking a little bit.
That’s because for years girls have been told to “stay away from heavy weights” to avoid bulking up and looking like a man in a dress.
Now, if high rep training can build just as much lean muscle, what the hell are you supposed to do?
Well, the main thing this should show you is that the whole “you’ll get bulky” thing is absolute bullshit.
Just like guys, girls should be training both types of muscle fibers for maximum results.
Here’s some more info on the whole high reps to tone up myth.
But Don’t Lift Light
Often, when people hear the words high reps they mistakenly think light weights.
That should not be the case.
It stems from the myth that “you should lift light weights and do high reps to tone up.”
I dislike the phrase “tone up.”
Here’s a post explaining why high reps and light weights won’t make you toned.
In terms of how much weight you lift, you should always be looking for a challenge.
It should never be easy.
Because training with weights which cause “failure” – i.e. being unable to perform another rep at the end of your set – will boost your results significantly.
In fact, there are several scientific studies out there which show training a muscle to failure leads to far superior results than training with a weight you can comfortably handle.
One of the most notable studies was mentioned earlier in this post! (1)
When researchers compared the effects of training with a 4 rep max versus a 25 rep max, there was actually a third group of participants included in the study.
They trained with a weight they could handle comfortably over 25 reps.
They found that the third group were obliterated by both other groups in terms of muscle growth.
While the 4 rep max group destroyed this third group in terms of muscle growth, what’s perhaps even more interesting is that the 25 rep max group were even further ahead.
This is due to the fact that training in a high rep range along isn’t enough – it still needs to be challenging.
Remember, we are not just looking to use higher rep range, we are also looking to create as much stress on the muscle as possible. And that means using a weight we need to work hard to move.
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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 5(8): e12033, 2010.
2. Mitchell, C. J., et al. “Resistance Exercise Load Does Not Determine Training-Mediated Hypertrophic Gains In Young Men”. J Appl Physiol. in press, 2012.
3. Burd, N. A., et al. “Enhanced Amino Acid Sensitivity Of Myofibrillar Protein Synthesis Persists For Up To 24 h After Resistance Exercise In Young Men”. J Nutr. 2011 Apr 1;141(4):568-73.