Training Intensity and Why Rep Ranges Don’t Matter for Hypertrophy

What is this article about?

• How much training intensity you need when training for hypertrophy
• Why there are no ‘hypertrophy rep ranges’ as previously believed
• Practical applications for prescribing training intensity for hypertrophy

In many traditional strength training paradigms, there is a dose-response relationship ascribed to different rep ranges. They say 1–5 reps are for building strength, 6–10 for functional hypertrophy, 10–15 for non-functional hypertrophy, and 15+ for muscular endurance. However, when you dissect the current body of training literature, this concept doesn’t seem to hold up.

Training with very light loads to failure can produce similar muscle gains than training with heavier loads. The only real difference between a set of each of these is the number of reps you’ll be able to hit before you reach failure. Based on the current body of research, it looks like repetitions range isn’t all that important for hypertrophy as long as you take your sets with 3–5 reps of true muscular failure.

Somewhere along the lines, every bro and brah reading muscle and fitness came to believe and espouse the fact that there is an optimal rep range for hypertrophy. Which, happens to fall perfectly between 8–12 reps. If you train lower than that you’re building strength and if you go higher you’ll build muscle endurance. Why would a heavier load than you can only do for 4–5 reps, that puts more tension on the muscle fiber, create less of a stimulus for growth than a lighter weight you can do for 8–12 reps ? Simply put, it wouldn’t assuming volume is equated. There is even evidence that low rep / high load strength training will results in better strength development and equally as good hypertrophy development as high rep/ lower load training. This leads to the next point. If reps under the mystical 8–12 range are equally useful for eliciting hypertrophy what about reps over that range? Say, to the tune of 20+? According to some studies you can rep it out until Pukie the Clown rolls up in his creepy clown car with as low as 30% of your 1RM, and it will be equally as effective as working weight of 80% of your 1RM assuming both loads are taken to near failure.

So, does intensity not matter for muscle growth as long as sets are taken to, or near, volitional failure? Eh, not so fast.

It does appear that there is a minimum and maximum intensity threshold that is ‘optimal’ for hypertrophy training (~30% and ~90% respectively). Though, I tend to hedge my bets and err between 40–85% in most cases. Within that intensity range total sets taken to near failure will be one of the biggest drivers of muscle gain.

Since repetitions per set aren’t all that important as long as the set is done within the aforementioned intensity range, and taken to a near failure point, it leaves you with some wiggle room of how to divy up your volume in different intensity ranges.

There are certainly some issues with doing all your sets at the upper end of the range including stress on the connective tissues and a higher fatigue cost per set, but living in the lower end of that range isn’t a great idea either.

I personally like to perform the bulk of my volume in the middle of the range, and then 20–30% will be done on the lower/ upper ends. This is partly due to psychological reasons. If I’m performing heavier training and I get 4 reps this week, then in order to hit 5 next week I would need a 25% improvement in strength. Doable, but probably not for extended durations. While it may not matter that I’m only adding reps or load every 2–3 weeks from a physiological standpoint, it’s tough to train hard day in and out when you do not see some form of acute progress.

While I love the process of training as much as any other meathead, I also enjoy the little hit of dopamine I get from ‘winning’ in my workouts. When I’m training in the light to the moderately challenging range, there’s more opportunity to win frequently. If I’m hitting 10–20 reps in a set, then a 1 rep improvement is a 5–10% gain, which is a lot more manageable on a week to week basis.

This raises a really important point for coaches to consider. Creating long term adaptation, whether that’s building muscle, improving performance, or weight loss is about habit change. I’d rather a client do a program that isn’t ‘optimal’ by my arbitrary standards and stick to it week after week because they enjoy it than write a perfectly dialed-in program that they hate doing and won’t commit to. I’m personally not above that either. You can scoff at that while wearing your ‘HTFU’ or ‘beast mode’ shirt, or you can realize that progress is about consistent behaviors. As a coach, I like to know what the research says and what appears to be optimal based on our current evidence, but at the end of the day, we need to make it work for the individual.