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Ideal Number of Sets & Reps for Muscle Growth


Posted by Scott_Herman - May 27th, 2016

Here is a question that always seems to have a different answer no matter who you ask.

“How many sets and reps should I do to build muscle?”

The straight answer is that there is no “specific” set or rep range that will work for everyone.  There is no magical number and for those of you who are under the impression that you need to “lift big to get big”, well, that is just an old school mentality.  

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The truth is that the number of sets and reps that you should perform depends on how you are genetically built. In simple terms, you can fall into 3 categories:

  1. You have a higher ratio of fast-twitch muscle fibers
  2. You can have a higher ratio of slow-twitch muscle fibers
  3. You can have a balance of both types

Higher Ratio Of Fast-Twitch Muscle Fibers

In the first case, your muscles have a predominance of fast twitch muscle fibers. These fibers are responsible for short to moderate duration activities of high intensity. An easy way to understand this is to think about a runner. Olympic sprint runners, for example, tend to have a higher ratio of fast twitch muscle fibers: they run balls to the wall for a very short distance with maximum intensity.  Powerlifters are another example. They lift ridiculously high amounts of weight for one rep. So max intensity for a short amount of time.

If you fall into this category, you will get the maximum amount of growth by stimulating THESE fibers which equals very high intensity lifts with a low repetition range. This means doing the old school bodybuilder format with very heavy weights, 5 - 8 reps per set and 4 – 6 sets per exercise.

Higher Ratio Of Slow-Twitch Muscle Fibers

If you are the second case, you will have a higher ratio of slow-twitch muscle fibers. This type of fiber is responsible for long duration movements with moderate to low intensity. Now let us go back to the runner example. For this type of muscle fiber, you would be more like a marathon runner that has amazing endurance and does moderate intensity exercise for long periods of time and/or distances. With that being said, if you are this kind of person, performing heavy weights with low reps is not going to do much for you.  

Since you have a higher ratio of the slow twitch fibers, you have to structure your workouts to stimulate THOSE fibers. In this case, you will need to perform moderate intensity and more reps which means higher volume workouts. Now do not misunderstand this as claiming you have to lift with light weight. Your weights should still be challenging, but just not as close to your one rep max.  In fact, you would benefit more from shorter rest periods (30 to 60 seconds between sets), a repetition range of 10 – 15 reps per set and 4 – 5 sets per exercise.

Another thing you should know about slow twitch muscle fibers is that they have more limited growth ability so if you want to really maximize your size, you should focus on high volume workouts but still sprinkle some heavy weight low repetition sets to get the smaller percentage of fast twitch to grow and help with your overall size.  This is actually the basis for my SHREDDED 12 Week Transformation Challenge.

Balance Of Both Types

The third case should be easy to figure out by now. If you have a balance, you should incorporate both training strategies into your workout: high volume and heavy weights with low reps.

How Can I Figure Out My Ratio?

By now I am sure you are wondering how you can find out if you have a higher ratio of slow or fast twitch muscle fibers. Well, there are 3 ways to find out:

1. You can perform a six week test using each one of the protocols.  So train for 6 weeks with super heavy weights with 5 – 8 repetitions per set and then switch to 6 weeks of training with slightly lighter weights and a rep range of 10 – 15 reps per set and see which one causes the better response and more muscle growth.

2. Do a quick test. Now this is a rough test and will not be 100% accurate but should give you an idea. Here’s what you have to do:

  • Go to the gym, pick any exercise and find out what the maximum weight you can use is for one rep (also known as your one rep max).  Rest for 15 minutes, and then use 80% of your one rep max and see what the maximum number of reps you can perform is.  For example, if you chose to do a barbell bicep curl and your one rep max was 100 pounds, calculate 80% of that, which would be 80 pounds.  After resting 15 minutes, do as many reps as you can with the 80 pounds.
    • If you did less than 7 reps, you have a higher ratio of fast twitch.
    • If you did 7 to 12 reps, you have a balance of fast and slow twitch.
    • If you did more than 12 reps, you have a higher ratio of slow twitch.

3. The third way to find out, which is the most accurate, is to do a genetic test and that is how I figured out my genetic make-up of having a higher ratio of slow twitch muscle fibers.  If you would like to try the Fitness Genes test, CLICK HERE.

Hopefully you can now better understand how to structure your workouts and also, you should have a better idea on why certain guys are naturally bigger than others. If you have a higher ratio of fast twitch muscle fibers, you can grow bigger and you have a better chance at success practicing sports such as sprinting or powerlifting for example.

If you are predominantly slow twitch, you will have to work harder for growth and you will have a more limited potential for size. But that does not mean you cannot still look big and aesthetic. You can still be big, just not a natural monster. On the other hand, you will do much better at endurance type sports such as boxing, soccer and football.

Either way, you will still have to train hard to obtain the results you desire.  But at least now you will come better equipped with the knowledge you need to pick the right routine!

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So I did this with a bicep curl and got 13 reps . I guess this would lean towards the low side of slow or could I also be a combo since it was only one rep over 12?

aharmon22  Edit  Delete  Close

Thank you Scott !  Really useful information !!

Scott_Herman  Edit  Delete  Close

Looks more like you have a balance of slow vs. fast :-D