How heavy can you go for hypertrophy?

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“3 sets of 10 repetitions” is arguably the most common set/rep range recommendation for how to build size. In fact, many programs apply this recommendation to every single exercise in the routine. The origin of this recommendation isn’t too hard to trace. To this day, most personal training textbooks clearly outline rep ranges for strength vs size vs muscle endurance. For strength, stick to sets of 3-5 reps. If you bump that to 8-12, you’re in the muscle-building rep range. Go beyond that – say above 15 reps – and you’ll mostly be targeting muscle endurance improvements.

That consensus has slowly started to shift. We wrote about this topic years ago. In the article, we review the evidence showing that provided a set is taken close to failure, a rep range of around 6 to 50 appears similarly effective for muscle growth. A similar conclusion was reached in a review paper shortly thereafter. Practically, lower rep ranges can be beneficial for training for hypertrophy: high-rep training is miserable, and a review study suggests most people tend to be more accurate at gauging proximity to failure when training heavier, below 12 reps per set.

However, it’s important to note how those boundaries were established. Why 6 reps as a minimum? Why 50 as a maximum?

Let’s take the bottom end as an example. To determine how few repetitions can be performed per set while still maximizing hypertrophy, this review looked at studies that compared low reps (say >6 reps) to rep ranges that we know tend to elicit maximum hypertrophy per set (8-12 reps, frequently).

Notably, though, while we can have plenty of faith that sets of around 6-15 reps are similarly effective, there aren’t as many studies looking at 5 or fewer reps as you might think. In this post, we’ll review some new research on the topic and provide recommendations on the minimum number of reps per set that is likely to maximize hypertrophy.

There are now 12 studies that have examined this concept. We’ll briefly summarize the results of each.

1. A study by Masuda et al compared 5×2 at 90% 1RM to 3 drop-sets, performed with lower loads. Both types of training resulted in similar growth of type I, IIa, and IIb muscle fibers.

2. A study by Chestnut and Docherty found similar growth from 6 sets of 4RM vs 3 sets of 10RM.

3. A study by Weiss et al found similar growth from 3 sets of 3-5RM vs 3×11-13RM vs 3×23-25RM. 

4. A study by Campos et al compared 4×3-5RM vs 3×9-11RM vs 2×20-28RM. While the 3-5RM and 9-11RM groups saw greater hypertrophy in type I, IIa, and IIx fiber size, these findings should be interpreted cautiously, as the number of sets was greater with higher intensities.

5. A study by Tanimoto and colleagues compared 3×80-90% 1RM to 3×55-60% 1RM. No significant differences were found for upper- or lower-body muscle thicknesses.

6. Another study by Tanimoto and colleagues compared 3 sets at around 60% 1RM (with a more controlled tempo) to 3 sets at around 88%1RM (with a less controlled tempo). Both groups saw increases in anterior and posterior thigh muscle thickness with no significant differences.

7. A study by Schoenfeld and colleagues compared performing 3x10RM with 90 seconds rest to performing 7x3RM with 3 minutes of rest. Note that neither set numbers nor rest times were equated, reducing our ability to draw conclusions as to the effect of rep target. That said, both rest times and set numbers predisposed the 3RM group to see greater gains in size. And yet, both groups saw similar hypertrophy, suggesting that 3RM training was less effective for growth, on a per-set basis.

8. A study by Mangine et al compared 4×3-5 with 90%1RM and 3-minute rest intervals to 4×10-12 with 70%1RM and 1-minute rest intervals. The higher intensity group saw slightly greater growth, though this may have been due to greater rest intervals.

9. A study by Klemp et al compared one group doing 4×12, 4×10, and 5×8, to group 2 doing 8×5, 9×4, 10×2 for group 2. Both groups saw similar growth, despite the substantially greater number of sets in group 2.

10. Another study by Schoenfeld and colleagues compared 3 sets of either 8-12 reps or 2-4 reps per set. Muscle growth was similar in the elbow flexors and extensors, but substantially greater in the higher rep group for the lateral thigh.

11.  A study by Mattocks and colleagues compared 3-5x1RM attempts to 4×8-12RM in untrained participants. While the 8-12RM group saw appreciable increases in upper leg and upper arm thicknesses, the 1RM group either maintained or actually lost muscle thickness. This is particularly notable given their training status.

12. Finally, we have the most recent study by Cumming et al, published as of September 1. The authors compared 3×3-5RM to 3×20-25RM using a within-participant design. Muscle thickness of the quadriceps increased similarly between groups, with no statistically significant differences.

These studies can be slightly tricky to interpret, mostly on account of variability in design. In trying to remain ecologically valid, many studies (i.e. Schoenfeld, Campos, etc.) don’t equate for rest times or volume, both of which can influence hypertrophy directly.

However, when interpreted collectively, as a tentative takeaway, it looks like the breakpoint for effectiveness might be around 3 reps per set. For a set to be maximally effective for hypertrophy, you likely want to do at least 4 reps per set. 3 or fewer appears to compromise effectiveness.

Because lower rep sets tend to be less uncomfortable and make it easier to push close to failure, doing most of your training in the 4-12 rep range is likely a good bet. That being said, some variety might be a good thing, and you might find that you simply prefer a different rep range.

More than arguing for a specific breakpoint, though, the aim of this post is to showcase just how difficult to interpret a heterogeneous body of research can be. The original claim that the hypertrophy rep range was limited to 6-12 was based on extremely limited research; likewise, it’s important not to assume that we have the boundaries of the actual hypertrophy rep range firmly figured out.

The post How heavy can you go for hypertrophy? appeared first on Stronger by Science.

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