What Is The Best Repetition Range For Building Muscle?


The best repetition range per set to generate an optimal hypertrophy response for muscle growth is one of the most widely debated subjects in the fitness community.

Visit any bodybuilding message board and inquire about what the best number of repetitions is. Immediately there will be dozens of numbers forcefully jousted in your direction with complete surety as to their correctness. You’ll honestly, probably just be left scratching your head and completely confused as to what is a truth is.

The amount of contradictory evidence supporting high repetitions and low repetitions is truly baffling.

So, what number of repetitions should you be training at to optimally promote muscle growth?

The question really is not very complicated, but unfortunately the answer is. Hopefully in this article we are able to clear up any questions that you may have.

Key Points [Video]

Intensity Zones

In reality, different from what you may have heard, there actually is no perfect rep range.
Between all numbers of repetitions there is massive overlap in their effect. It is possible to gain strength by using light weights for high repetitions, just as it is to gain endurance using heavy weights for low repetitions. One is just extremely more efficient in doing so than the other. So, you want to train in the range that is most effective at imparting your desired training effect.

After understanding that principle, we can dive into what generally will be the best rep range for most people.

perfect number of reps for muscle growth
Source: http://www.treinamentofuncionalrs.com.br

For the purposes of this article will create three weight zones. Intense, moderate, and light. In order for the zones to be accurate you must be working to all the way to failure. If you use a light weight you could do for 20 reps, and only do 5 reps, it does not count as intense repetition zone.


1-5 repetitions will be considered the intense zone. This section will generate hypertrophy as well as bolster your neurological adaptions.


6 to 12 repetitions will be considered the moderate zone. This section will give you a happy medium between the intense and light section. The results will be a blend of the two.


Over 12 repetitions will be considered the light zone. This section will mostly contribute to muscular fortitude for high rep sets.

Below is a visual representation illustrating the above.

As you can see, it’s very possible to put on size even while training in the light zone. And visa versa, you can add muscular endurance while training in a low repetition range.

chart showing the different effects of rep ranges
Source: Brainstay.com

Looking at the above chart you will see that training in the moderate zone leaves you with one dark and two medium-dark squares. Well the other two zones have one white square one medium square in one dark. For this reason, training in the medium zone is most advantageous for most trainees.

The Science

You may have heard that chasing the “burn” is what you should be doing by old school bodybuilders. Let’s go ahead and just throw that one out the door right now.

It also not efficient for you to only use weights near your maximum that nearly crush you and you can only do one rep with.

In order for your muscle to grow, it must be stimulated. Scientific experimentation has shown that there are three types of triggers. Mechanical tension, metabolic, and actual tissue damage.

The Best Repetition Range For Building Muscle
Source: http://www.coachmag.co.uk

Mechanical Tension

Do a repetition the weight causes tension to be placed upon your muscles. Researchers have coined a term called “mechanotransduction” to describe your body’s ability to recognize tension. With sufficient tension mechanotransduction promotes anabolism in the muscle.

The load multiplied by the time under tension is the equation that dictates the hypertrophy response.

Put simply the actual amount of weight that you are lifting is a key figure in the equation your body uses to determine how much muscle mass it would like to grow.

Getting back to the rep ranges. Selecting an intense load will limit the number of repetitions that you can do. On the flip side, selecting a very light weight will allow you to do a very high number of repetitions.

You may be scratching your head right now and wondering which is better. We just learned that both mechanical tension and the amount of time under tension are both factors your body uses to determine its hypertrophy.

As it turns out, the moderate weight allows you to achieve both a significant amount of mechanical tension and time under tension. An amount of each that using a heavyweight or lightweight does not allow for.

Before we go deeper into that conversation, let’s talk more about metabolic stress.

Metabolic Stress

Now that you understand basics of mechanical tension, let’s move on to metabolic stress. While mechanical tension relies solely on the load being used to generate a sufficient stimulus for muscle growth, metabolic stress is determined by the duration of the exercise.
Is very difficult degenerate much of, if any metabolic stress during low repetition sets.
This type of stress makes your cells literally swell with inflammation, subsequently up-regulating neural recruitment. These two things add together to enable hypertrophy of the muscle.

The aforementioned cellular expansion is caused by increased hydration of the muscle. It has been shown to increase the rate at which new protein is added to the muscle the muscle from having protein taken from it.

muscle fibers showing rep range for muscle building
Source: https://blog.thermoworks.com

Fiber Type & Repetitions

Muscles related to strength training or comprised of two different.

Type 1 are fibers that are more endurance-oriented and are called slow-twitch. They are best trained by using high repetitions.

Type 2 are fibers that fatigue very quickly and are power-oriented. They’re known as fast twitch fibers.

The average person has an even distribution of the two fiber types in their muscles. The legs generally tend to have more fiber type 1, while the upper body has more fiber type 2.
You may be thinking to yourself, “well this is obvious, I just need to train higher rep sets for my lower body and lower reps sets for my upper body”. And you are right. Some studies in the scientific literature have actually supported this theory.

What you should know though is that training to failure in the moderate-intensity zone will stimulate all types of muscle equally. This negates the need for training specific to fiber type.

1RM and Repetitions

It’s very simple.In order to put on muscular size you must be synthesizing more protein in your muscle than you are breaking down.

The greatest amount a protein production in the muscle has been shown to occur using somewhere between seventy to eighty-five percent of your one repetition maximum.
If you do not know your own one-rep maximum, there are several ways you can find out. Easiest is basically just to go max out on all of the relevant lifts. And if you do not want to go max out, you can simply use a 1rm calculator to give an estimation.

Just a backup what we’ve been saying, we’d like to mention a relevant study conducted in the Journal of Applied Physiology. It found that muscular response to training with weights that were 75% was greater than any other repetition range. The muscle building response was 30% better then the next best ranges, which were 60% and 90%.

The 90% range simply didn’t cause enough metabolic stress, and the 60% range did not caused enough mechanical tension stress.

The Bottom Line

By the end of this article I’m sure that you agree with us. Most general training unless you are specifically training for something like like a marathon, or peaking for a powerlifting meet, should be done at 75% of you 1RM.

The average person can do between 8 to 12 reps with 75% of their 1 rep max. So, it’s best for you to use a weight that you can only do 8 to 12 reps with.


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