What rep range is best for muscle growth (hypertrophy)?
I normally don’t get too “tech-y” or “science-y” on this blog. I like to keep all that jargon in publications I write for. But I can’t talk about rep ranges without a little science to back it up.
Traditionally, we’ve been told by media and gym bros that the 8-12 rep range is ideal. Not too heavy (which has been believed to be more for strength gains) and not too light (for muscular endurance). And that’s actually not bad advice. It’s neither right nor wrong.
But what if what we’ve been told 8-12 is only half true? What if there are many more options? In a way, what if almost all of the options are correct?
The mechanism for more muscle gain
A recent meta-analysis found that the hypertrophy window is actually quite wide–3 to 30 reps wide. But here’s the catch: all sets, no matter the rep count, have to be taken to muscular failure.
It seems as though muscular failure was the overarching commonality for achieving hypertrophy gains.
Other studies looked at low reps (1-5), moderate reps (6-15), and high reps (15+) and all comparably built muscle when taken to failure.
More effort is the name of the game.
Mechanical tension–the force placed on muscle fiber near failure–is the primary driver of hypertrophy. For example, one 2021 review found 30% 1RM (Rep Max) loads to failure produce hypertrophy similar to 8–12 reps at heavier loads. Effort reigns, making the actual rep range secondary.
What rep range should you use?
If you’ve been a reader of this blog for any period of time, you know that I normally write for the older crowd (not old, just a little older).
With a few miles on our joints, heavier loads can become a bit of a hassle, to say the least. Not only will heavy loads create more joint stress and potential injury, but many times it’ll also slow or even stifle gains for hypertrophy. More injury equals less opportunity to build muscle.
I would never tell anyone directly what to do. Barking orders isn’t my wheelhouse. But I will say that ever since I’ve switched to higher rep ranges (with the added confidence that I will still add muscle with plenty of effort), I’ve been less injury-prone and have built more muscle tissue.
I’ll loiter anywhere between the 10 to 20 rep range with an occasional visit to eight reps.
Healthier joints, more muscle, and a renewed motivation. You can’t beat that.
Happy lifting!
What about you? What’s been your experience with rep ranges as you’ve gotten older?
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Brad Borland 
I love this. The groove I’m getting into is to climb into that first exercise like I’m a juiced up psychopath, and go for broke. This amuses me because it’s a challenge to maintain form while going as heavy as I can. I typically achieve mechanical failure at 6-7 reps in my third of four sets. The first is always a compound that uses a number of different muscle groups to complete a rep.
After that first hit, I’ll dial it back a notch and aim for 10-12. These exercises all tend to involve one or two muscle groups to complete a rep.
By the time I’m 25 minutes into an average 45 min workout, I’m starting to flag, so I’ll look to introduce a pause of a second or two at the contraction phase of the rep. If I’m not failing at 10-12 reps, I add more, ensuring the pause is at 2 seconds.
If I read you right Brad, the aim is mechanical failure on every set? If so, I’ll start targeting that from tomorrow!
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Thanks! It sounds like you know your body and how it functions very well.
Yes, mechanical failure. And recent research even suggests that you can stop a rep or two short of failure and still get similar gains. That’s good news for when you are feeling gassed and need to back off just a bit.
Let me know how you do!
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Well sir, will be backing off a rep or two before mechanical failure. I went for my badge this morning, and was gassed halfway through my routine. I know where my limit is though. Was a fun day in the gym!
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Good luck!
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