If you're looking to build muscle, you've probably heard that there are different rep ranges for different goals. Typically, it goes something like this:
- Low reps (1-5) for strength development
- Moderate reps (8-15) for hypertrophy (muscle growth)
- High reps (15+) for endurance
However, this doesn’t paint the entire picture. The truth is that the relationship between reps and performance outcomes is not so black and white. Different rep ranges for hypertrophy (muscle growth), strength, and endurance actually have a lot of overlap and can each contribute to any of these goals to some degree.
The goal of this article is to delve into the research on rep ranges and hypertrophy to provide a comprehensive understanding of how rep ranges can impact muscle growth. We'll be exploring the latest studies on rep ranges and their effects on muscle hypertrophy, as well as giving you some practical recommendations on how to select rep ranges when you train if you want to optimize muscle hypertrophy.
What is hypertrophy?
Hypertrophy is simply the growth of muscle. Hypertrophy is an adaptation that occurs as a result of you improving different physical capacities. For example, if you get stronger your muscles might potentially hypertrophy, if you run faster or longer, your muscles might potentially hypertrophy as well, which is why hypertrophy can actually occur as a result of many different training modalities across various different rep ranges. There are training variables that you can manipulate to make your training more effective for hypertrophy, but in general, any kind of strenuous training can cause hypertrophy.
What does the research show?
While it is certainly true that lifting heavy weight for low reps is optimal for improving strength and the opposite is true for endurance, there is pretty good evidence that hypertrophy can occur optimally in a very wide rep range. In fact, there are a number of meta-analysis showing that training at heavy or light loads results in similar hypertrophy as long as participants are taking sets near muscular failure and volume is equated.[1][2][3][4]
The most popular of these studies is a 2017 study published by Brad Schoenfeld that compared Strength and Hypertrophy Adaptations Between Low- vs. High-Load Resistance Training.[1] The studies included in this meta-analysis had to be a 1) clinical study involving both low- (≤60% 1 RM) and high- (>60% 1 RM) load training; 2) with all sets in the 7 training protocols being performed to momentary muscular failure; and 3) had to last for a minimum of 6 weeks.
Most of the studies included in the analysis were matched for total sets. In other words, independent of the weight or reps that participants used, most performed the same number of total sets. The results showed that heavy loads improved strength more than low loads, which is to be expected, but both heavy and low loads resulted in similar hypertrophy indicating that perhaps proximity to failure and total number of sets (volume) are better predictors of hypertrophy than the particular number of repetitions performed.
Again, these data have been replicated a number of times in various clinical trials. For example, Schoenfeld and colleagues showed that moderate loads (~10RM) and low loads (~30RM) resulted in similar growth of the biceps, triceps, and quads over an 8 week training period.[2] Similarly, Morton and colleagues found that training in the 8-12 rep range resulted in no better growth than training in the 20-25 rep range for the vastus lateralis (one of your quad muscles) over a 12-week training period.[5]
None of the studies that we have reviewed so far investigate the effects of training at very high loads on muscle hypertrophy (e.g., <5 reps per set). That being said there are some data that show that when volume is equated, really low repetitions can still lead to similar hypertrophy.[6] That being said, those who performed the low reps had to perform significantly more sets and displayed more signs of overtraining and joint discomfort indicating that while really heavy loads may, in theory, be useful for hypertrophy, they may not be the most optimal.
Overall, these results might lead you to think that rep ranges don’t matter for hypertrophy; and the truth is that in many ways, they don’t. That being said there are some practical considerations when deciding how many reps you should be performing if your goal is to maximize hypertrophy.
Practical Considerations for Rep Ranges
One of the main considerations when choosing a rep range is the nature of the exercise itself. Some exercises are better suited for higher rep ranges, while others may be more effective with lower rep ranges.
Compound Movements
Exercises that require a high degree of skill or coordination, such as squats, deadlifts, or any other free-weight compound movement may not be well-suited for high rep sets.
This is because these types of movements are extremely taxing when performing high repetitions and your cardiovascular system may become the limiting factor instead of the muscles you’re trying to target. Have you ever done a set of 20 on squats and realized how hard you’re breathing? Furthermore, these kinds of exercises require a high amount of coordination and as reps increase, your technique may begin to breakdown making the exercise less effective and increasing risk of injury.
For free-weight compound movements, 6-12 reps per set is a more practical target than 15+ reps per set.
Now, you may be thinking, what about machine-based compound movements like a leg press or cable row? Since these kinds of exercises do not require as much coordination as a free weight movement, they are likely more suitable for higher reps. That being said, your cardiovascular system may be a limiting factor if you’re trying to perform 20+ repetitions on a leg press, which is why a moderate rep range may still be ideal for these kinds of exercises.
Single-Joint Movements
On the other hand, we have single-joint movements like a bicep curl, which is way less complex of a movement. For these kinds of movements, it may be more effective to use a higher rep range, such as 12-15 reps per set, or even more, with a lighter weight. From a practical standpoint, it just doesn’t make sense to perform extremely heavy sets of five reps on a bicep curl. You’ll likely put a ton of stress on the single joint that's working - the elbow in the case of bicep curls - which could lead to discomfort and injury.
Workout Structure
In general, a good strategy for a hypertrophy-focused workout is to start your workout with 1 heavy compound movement in the moderate rep range of perhaps 6-12 repetitions. After your heavy movements, you can perform 1-2 additional movements in a slightly higher rep range (e.g., 10-15 reps). Lastly, you can finish your workouts with some isolation movements in a high rep range of 15+ reps per set. This way you get the benefits of various different rep ranges in the same workout, and you are choosing your reps based on the nature of the exercise. Again, this is not an “exact science,” but is a general workout structure that should favor hypertrophy.
It's important to note, however, that while optimal rep ranges may vary for different exercises, the key to hypertrophy remains the same: training near failure and the total number of sets performed. Regardless of the specific rep range used, the intensity (i.e. proximity to failure) and volume (i.e. total number of sets) of your workout is what drives muscle growth. So, regardless of the rep range you choose, make sure you're training hard enough to get close to failure on each set.
Conclusion
You can achieve muscle growth with low reps and high loads, as well as high reps using low loads. What matters most is intensity and volume. That being said, certain exercises lend themselves to different rep ranges. Choosing an appropriate rep range for each exercise can help you maximize the benefits of your workout, minimize the risk of injury, and improve your overall results to optimize muscle growth.
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References
1. Schoenfeld, Brad J et al. “Strength and Hypertrophy Adaptations Between Low- vs. High-Load Resistance Training: A Systematic Review and Meta-analysis.” Journal of strength and conditioning research vol. 31,12 (2017): 3508-3523. doi:10.1519/JSC.0000000000002200
2. Schoenfeld, Brad J et al. “Effects of Low- vs. High-Load Resistance Training on Muscle Strength and Hypertrophy in Well-Trained Men.” Journal of strength and conditioning research vol. 29,10 (2015): 2954-63. doi:10.1519/JSC.0000000000000958
3. Carvalho, Leonardo et al. “Muscle hypertrophy and strength gains after resistance training with different volume-matched loads: a systematic review and meta-analysis.” Applied physiology, nutrition, and metabolism = Physiologie appliquee, nutrition et metabolisme vol. 47,4 (2022): 357-368. doi:10.1139/apnm-2021-0515
4. “Resistance Training Load Effects on Muscle Hypertrophy and Strength Gain: Systematic Review and Network Meta-analysis-Corrigendum.” Medicine and science in sports and exercise vol. 54,2 (2022): 370. doi:10.1249/MSS.0000000000002838
5. Morton, Robert W et al. “Neither load nor systemic hormones determine resistance training-mediated hypertrophy or strength gains in resistance-trained young men.” Journal of applied physiology (Bethesda, Md. : 1985) vol. 121,1 (2016): 129-38. doi:10.1152/japplphysiol.00154.2016
6. Schoenfeld, Brad J et al. “Effects of different volume-equated resistance training loading strategies on muscular adaptations in well-trained men.” Journal of strength and conditioning research vol. 28,10 (2014): 2909-18. doi:10.1519/JSC.0000000000000480
