There’s a big, hairy, and sweaty dude, possibly a bear, who claims you have to throw weights in the 6-12 repetition range to grow muscle.

There’s another folk scratching his armpits and roaring inappropriately for all the gym-folks to hear who swears by ‘to get bigger you need to get stronger’ approach. Therefore, you must focus on 1-5 repetitions.

And then we have this one dude claiming a soup-can-for-30-reps approach builds a helluva lot of muscle.

To put it simply, there seems to be fuck loads of opinions when it comes to training intensity. In this article, you’ll learn what’s the science take on the “best” repetition range for muscle growth. 

Training Intensity: What’s All That About?

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Many describe training intensity based on subjective feelings of muscle soreness, or how “hardcore” a workout was. However, when we talk about intensity, we’re referring to two things:

• The weight you lift relative to your 1 rep max: For example, if you have a maximal bench press of 100 lb (45.3 kg) and you perform a set with 80 lb (36.2 kg), then the intensity would be expressed as 80% of 1 rep max (1RM).
• How close to failure you train: If you can no longer physically move a barbell, you’re training more intense than keeping a rep or two in reserve (training to failure is a suboptimal way to train, believe it or not).

Now, the concept of the “perfect” rep range for muscle growth has come under scrutiny.

A 2017 meta-analysis¹ found that both high (>60% 1RM) and low (<60% 1RM) loads can cause comparable muscle growth if the volume (total work) is similar:

Lasevicius et al demonstrated² that when training to failure, 20% of 1RM produced less muscle growth than training in the 40–80% 1RM range:

Thus, it seems that using very high-rep ranges (40+ reps) is a kind of a…bunch of poop. It’s sub-optimal if muscle growth is your goal.

In another study³, a group doing 25–35 repetitions achieved similar muscle growth in comparison to a group doing 8–12 repetitions:

However, the chaps in the higher-rep group had a, hmmm…oh, I dunno, a hard time? Vomiting during training was reported… So using light weights and doing more reps comes at a cost of a bit of puking here and there.

So How Many Reps Should You Do?

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If there’s one thing every trainer knows about average gym-goers, it’s that they’re often wrong about weight lifting. They’re wrong about big things, and they’re wrong about small things, and they’re wrong about all the sizes of things in between.

You see, contrary to what you’ve been told by one of those gym-goers, you can build muscle performing 12–30 repetitions. However, it has to be done to failure and that sucks ballZ because you feel more discomfort than you are willing to tolerate. 

Ever tried doing 30 reps on exercises like squats, lunges, or barbell rows? It’s shit. You’d rather fight a pack of Direwolves than train that way. It’s just not worth it.

Training to failure also takes longer to recover from in subsequent days⁴. 

With that being said, does that mean you should never do 12-30 reps? Not at all.

In fact, when I design workout plans to my clients I always implement microcycles of lighter weights on isolation exercises like lateral raises and curls because they don’t generate the same level of fatigue. 

Similarly, like you’d get a great deal of discomfort doing lunges for 20-30 reps you’d also get joint pain doing isolation exercises in the 6-12 rep range (assuming that’s the only rep range you use).

What about a very low rep range? Like 1-5? Should you do a 180-degree turn on it? Again, not at all. 

Schoenfeld et al did a study⁵ where one group performed 10 repetitions and the other performed 3 repetitions. They found similar muscle growth between groups but greater strength in the 3 repetition group.

Inspired by that, you might say:

Again, very heavy training also comes at a cost. In that study, the 3 repetition group had more joint pain and more dropouts due to injury than the 10 repetition group. Basically, participants turned into you-shaped bags of pain.

As you can see using ONLY 1-5, 6-12, or 12-30 rep ranges don’t seem to be optimal for muscle growth. Or health. Very heavy training makes your joints and soft tissue to degenerate. Very light training invites you to a vomiting party. Medium load possibly gets you to miss out on strength gains.

That said, training across a wide spectrum of repetition ranges (1 to 30RM) is recommended to maximize muscle growth. However, we have enough evidence suggesting a medium-repetition range (6-12RM) being the most optimal. Which brings me to my recommendations.

Intensity Recommendations

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• ~70% of your training should have you training in the 6-12 rep range. There’s nothing magical about this range. It just happened to be a convenient range to protect your joints and soft tissue as well as accumulate sufficient training volume.
• ~20% of your training should have you training in the 12-30 rep range. While it can be fatiguing and workouts can take longer, it can help with joint and tissue health. And it’s not like you’re missing out on something either as it will induce muscle growth.
• ~10% of your training should have you lifting in the 1-5 rep range. Even though it mostly induces strength gain, it’s important for muscle growth too—when you’re stronger, you can use heavier weights which allows you to do more volume (total sets per muscle group per week). P.S. Volume is one of the key components of muscle growth.

Don’t be a militant shitnugget running around telling everyone to train only in 1-5 rep range because getting stronger sounds cool. By the same token, don’t be a militant shitnugget running around telling everyone to do only 12-30 repetitions because you’ll get toned AF.

Be that cool shitnugget (yea, you can be cool even if you’re a shitnugget) who utilizes all repetition zones ‘cuz, well, ‘cuz that’s not an idiotic way to train. 

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