What Is The Best Rep Range For Muscle Growth?

We know that 1-5 reps with heavier loads (85% or more of 1-rep max) produces greater gains in strength.

We also know over 15 reps with lighter loads (around 60% of 1-rep max) improves muscular endurance.

The rep range for muscle growth? Well, that’s not so clear.

Can you build muscle in the 1-5 rep range?

What about 15 or more reps?

Do you have to stay in the 6-12 rep range to build mass?

What is the best rep range for hypertrophy?

Let’s see what some of the top researchers have found.

The Rep Range for Muscle Growth Is Larger Than Expected

This meta-analysis involving 21 studies found that muscle protein synthesis and anabolic signaling were similar between heavier loads (5–12 reps) and lighter loads (12–40 reps) when sets were taken close to failure, or complete failure.

This would imply that muscle hypertrophy should be similar between heavy and light loads when sets are taken to failure or just short of failure. It’s believed that when sets are taken this far, you’ve maximally recruited all muscle fibers.

Greg Nuckols, strength expert and world record setting powerlifter, suggests sets of 4–40 reps are ideal for building muscle. According to others, such as Mike Israetel, sets of 5–30 reps are effective for muscle growth.

“The hypertrophic stimulus and fatigue generated by each set between roughly 5 and 30 reps are about the same. Volume and intensity cause growth and fatigue, and when one goes up per set, the other goes down to preserve a roughly even effect.” — Mike Israetel

We also have top researchers like James Krieger who also supports the idea that the rep range for muscle growth is far greater than 6-12 reps.

“As long as your sets are challenging (i.e., training to near failure) and volume is high enough, the rep range you use can be based on personal preference and injury risk/status.” — James Krieger

There’s nothing magical about the typical hypertrophy range of 6-12 reps. There’s nothing that makes it significantly better than other rep ranges when other training variables are controlled for. It’s that simply being able to do more hard training tends to produce better results, and most people tend to be able to do the most training with challenging weights when they stick with that rep range for the majority of their training.

In addition, using a variety of rep ranges for a single movement over the course of a week of training does not appear to negatively impact progress.

Brad Schoenfield conducted a study where 19 trained individuals were split into a constant rep group and a variety rep group. Both groups trained the same seven exercises for 3 sets to failure, three times per week, for eight weeks.

The constant rep group trained all movements with 3 sets of 8–12 reps. The variety rep group used 3 sets of 2–4 reps on day 1, 3 sets of 8–12 reps on day 2, and 3 sets of 20–30 reps on day 3.

Muscle thickness of the elbow flexors, triceps, and vastus lateralis (outside portion of the quads) were measured before and after the training period.

After 8 weeks, there were no significant differences in muscle thickness increases between the two groups. The results of this study suggest that hypertrophic, strength, and endurance adaptations are very similar whether you train in a fixed rep range of 8-12 reps, or train in a varied rep range, ranging from as little as 2 reps, to as many as 30 reps. This study supports what many other researchers have found as well— different rep ranges are equally effective for building muscle if the set is taken to failure, or very close to failure.

Besides taking sets to near failure, it’s also important to focus on progressive overload. Make sure you’re constantly pushing yourself, making the next workout more challenging than the last. This applies to your training no matter what rep range you’re working in.

Different Rep Ranges for Different Exercises

It’s very important to maintain proper form and execution on compound movements to avoid injury and effectively train the muscles being targeted. It’s much easier to focus on proper form and execution when performing less reps, especially for beginners.

With higher reps, form could break down as the set goes on and fatigue sets in. For this reason, it’s often recommended that compound movements, especially more complex ones like squats and deadlifts, be done in a lower or moderate rep range.

Being able to maintain proper form even when your body is spent takes practice. If you go too heavy and perform less reps, your form could still fall apart. The key is using a weight that allows you to use great form, but still challenges you.

Then there’s isolation exercises—movements that target one muscle group and joint. These don’t require as much skill and practice. With isolation exercises, you typically can’t go as heavy since not as many muscles are working together to move the weight.

It’s also easier to maintain proper form on isolation movements since they aren’t as complex as compound movements. Even if form does fall apart, the risk of injury is much lower compared to compound movements with heavier weights. Isolation movements are often done in a moderate to higher rep range. 

If you’re performing barbell back squats and on your first set you knock out 20 reps and nearly reach failure, you’ll be completely wiped out. There’s also a good chance your form will deteriorate later on in the set. If you’re already crushed at the beginning of your workout, you won’t be able to train with as much intensity and volume for the remainder of your workout. If you do 20 reps of leg extensions or leg curls, that’s not as taxing and it’s much more tolerable.

For these reasons, different rep ranges work better for different movements. It comes down to personal preference, injury prevention, and experience and skill level.

Muscle Fiber Types

Your muscles are made up of two primary types of muscle fibers—fast-twitch fibers and slow-twitch fibers.

If your goal is to increase muscle mass, you’ll want to maximize hypertrophy of both fiber types. Fast-twitch muscle fibers show greater hypertrophy with heavier loads (80-85% or more of your 1-rep max), and slow-twitch muscle fibers show greater hypertrophy with lighter loads (around 60% of your 1-rep max).

So, if you’re looking to maximize muscle growth, it’s best to work with both heavier and lighter loads in varying rep ranges.

A good way to go about varying your rep ranges to stimulate both muscle fiber types is to use heavier loads on compound lifts, and lighter loads on accessory exercises.

For example, you might do 5 sets of 5 reps on barbell back squats, then 4 sets of 12 reps on leg extensions.

Not only is varying your rep range beneficial for building muscle, but it can be a great way to add variety to your training to prevent becoming bored with your training program.

Heavier Loads vs. Lighter Loads

Training with heavier loads is best for improving strength due to greater neural adaptations (nervous system adaptations that allow you to generate more force, with little to no muscle hypertrophy). Greater strength gains can result in more training volume over time. Training volume is one of the primary drivers of muscle growth. However, training with lighter loads and performing 20 reps or more typically results in greater training volume over time compared to training with heavier loads.

Below is the equation for calculating training volume. As you can see, both the amount of weight lifted and the number of sets and reps performed can result in more training volume.

Sets x Reps x Weight Lifted = Training Volume

Not all studies agree with the idea of using lighter loads (higher reps) for slow-twitch muscle fiber growth and heavier loads (lower reps) for fast-twitch muscle fiber growth.

These three studies (study, study, study) found no significant changes in slow-twitch and fast-twitch muscle fiber hypertrophy when training with lighter loads and heavier loads.

As mentioned earlier, less reps with heavier loads (1-5 reps) is great for neuromuscular adaptations which promotes increases in strength. We know that getting stronger also helps build muscle. This is why heavier training in a lower rep range should not be neglected.  The biggest drawback of low rep training is the lack of volume. If you end up performing less than 5 repetitions per set, then you will be required to do more sets to get in enough volume for muscle hypertrophy. Another downside is that with heavier weights you run the risk of excessive CNS (central nervous system) fatigue and sore joints. Low rep, high load training is likely to be more difficult to recover from compared to training a more moderate rep range. It’s also not as time efficient since you require more sets to increase total training volume and you’ll be taking longer rest periods between heavy sets.

When using lighter loads and more reps (15+ reps), muscle activation will be low early on during the set, and increase as the set progresses and you get closer to failure. One downside to high rep training is that as the set progresses and fatigue sets in, your form could diminish which can increase your chance of injury and be ineffective for training a targeted muscle group. For this reason, high reps on many of the compound lifts are often not recommended for beginners who are still developing the skill of lifting challenging weights with good form and technique. High reps on compounds can also sometimes even be painful or cause people to throw up. With how taxing high reps can be, you run the risk of being so fatigued and worn out early on in your workout, resulting in an overall reduction in the quality and volume of your training. Volume causes much more fatigue than the amount of weight you’re lifting. Higher reps with challenging weights causes an immense amount of muscle damage that requires more recovery. People often stick with a low to moderate rep range for compound lifts, and go for more reps on accessory movements like bicep curls, tricep pushdowns, lateral raises, cable flyes, rear deltoid flyes, leg extensions, and calf raises. 

Using moderate rep ranges (6-12 reps) is safer, more efficient, and easier to recover from. Recovery is key for muscle growth and if you’re recovering quicker, you can train the muscle or muscle groups again sooner. In this rep range, the weight being used is manageable enough that you can maintain good form and technique throughout the entire set. You’re also using a load that won’t burn out your CNS and cause sore joints, at least not as quickly. Taking sets to near failure in a moderate rep range can stimulate the muscles enough to promote growth, but without the added CNS fatigue from using very heavy loads, or the extreme metabolic exhaustion from performing very high reps. 

In the end, all rep ranges have their place in a training program. 

Conclusion

The rep range you work in is not as important as many people make it out to be. The rep range for muscle hypertrophy is much broader than you’d expect. As long as your sets are taken to failure or just short of failure, and training volume is sufficient, muscle fiber recruitment and hypertrophy is likely similar between lower reps (heavier loads) and higher reps (lighter loads). Also be sure to focus on progressive overload, no matter what rep range you’re training in.

It’s a good idea to do most of your training in the rep range that allows you to get in the most challenging sets per training session and per week for each exercise you use and each muscle you train. You also want to work in a rep range that you can recover from and does not cause excessive amounts of wear and tear. More often than not, a moderate intensity and rep range for most exercises will work well for most people.  

Since different rep ranges trigger slightly different signaling pathways to produce a muscle hypertrophy response, you’re probably better off training with a variety of rep ranges instead of staying in a single rep range. Different rep ranges trigger slightly different signaling pathways to produce a muscle growth response. In addition, having a variety of rep ranges can make your training a bit more fun, which could be very beneficial if you tend to get bored with training programs easily.

If your form starts to break down on a certain lift when you perform high reps, then stick with low to moderate reps. As you get better at performing that exercise, you can throw in more reps over time to find out if you’ve improved enough to handle more reps while maintaining good form.

If you find that higher reps on a certain lift completely wipes you out and negatively impacts the remainder of your workout and your ability to recover, then stick with lower reps until your body can handle that much stress and volume.

If performing lower reps with much heavier loads quickly results in achy joints and CNS burn out, then reduce the load and stick with a more moderate rep range.

Some people and some exercises seem to do better with higher reps or lower reps. As long as you are taking sets close to failure with sufficient volume, rep range may be more a matter of personal preference and what works best for you.

Here are some important takeaways: 

• Different rep ranges are equally effective for building muscle if the set is taken to failure and there is sufficient volume in the training session.
• If you’re looking to maximize muscle growth, it may best to work with both heavier and lighter loads in varying rep ranges. It could help, but it won’t hurt.
• Whichever rep range you decide to work in for a specific exercise, be sure to focus on progressive overload.