Optimum range of reps proved by science

Let’s get one thing straight – feeling the “burn” in your muscle from very high rep training does not cause growth. Muscles grow from a combination of tension overload and fatigue. Maximum protein synthesis occurs between 70-85% of your 1RM (one rep max).

A study in 2009 conducted by Kumar et al. (Journal of Applied Physiology) measured the fluctuations in muscle protein synthesis after weight training. They found that the anabolic response (muscle building) increased by:

30% after training with weights that were 20% of 1RM*
40% after training with weights that were 40% of 1RM
100% after training with weights that were 60% of 1RM
130% after training with weights that were 75% of 1RM
100% after training with weights that were 90% of 1RM

(1RM – One repetition maximum, is the maximum amount of weight a person is able to lift for a single repetition*)

As we can see from this information, the peak of muscle growth occurs when training with a weight that is around 75% of our 1RM. The reason that the muscle building response is lower at 90% of 1RM is because the weight is just too heavy. This weight causes the nervous system to fatigue first, not the muscle fibres. This means that the muscles are not receiving enough time under tension to trigger the adaptive growth response.

So how many reps is 75% of your 1 RM? Take a look at the chart below to see how 1RM percentages relate to repetitions:

100% of 1RM = 1 rep
95% of 1RM = 2 reps
93% of 1RM = 3 reps
90% of 1RM = 4 reps
87% of 1RM = 5 reps
85% of 1RM = 6 reps
83% of 1RM = 7 reps
80% of 1RM = 8 reps
77% of 1RM = 9 reps
75% of 1RM = 10 reps
67% of 1RM = 12 reps
65% of 1RM = 15 reps

As you can see, 75% of your one rep max works out at around 10 reps. So, training anywhere between 8 – 12 reps to failure is the optimum rep range for muscle growth.

So why does training in this rep range produce greater gains in muscle size?

Skeletal muscles are made up of a mixture of three different types of muscle fibers. Type 1, Type 2a and Type 2b. The back, legs and neck have a higher number of Type 1 muscle fibers while the shoulders, chest and arms have more Type 2b fibers.

Type 2b fibers come into play when fast of heavy tension is required, such as with heavy weight training around 75% of 1RM. The only way to really stimulate these kinds of fibers is through this heavy weight training. These Type 2b fibers are the most responsive to growth. They will get much bigger and stronger compared to Type 1 muscle fibers.

When you max out/fail between 8 – 12 reps you will recruit ALL muscle fibers, (Type 1, Type 2a and Type 2b) so this is the rep range where you get maximum muscle fiber recruitment which leads to greater increase in size. This rep range gives the best combination of muscle fiber recruitment, metabolic fatigue and good nervous system activation. From the first rep you will get full recruitment and enough time under tension to produce muscle hypertrophy.

Heavy low rep training in the 6 – 8 range does produce great muscle hypertrophy, but slightly higher 8 – 12 reps produces a greater increase in muscle mass.

I would have to disagree in part to some of what you state.

First, typically the accumulation of lactate or the "burn," causes the muscle to fatigue before any type of neurological or "central Fatigue," is experienced.

Secondly, the accumulation of blood lactate has a direct relationship with the amount of GH that is released which stimulates in part increased protein synthesis.

Third, post exercise protein synthesis is not the be all end all measure of muscular growth. It is one of a number of factors exercise physiologist use to measure acute changes during exercise but in and of its self, maynot translate in measurable muscle hypertrophy.

Fourth, I do agree that higher percentages of 1rm seem to suggest that it's greater for strength. The literature does not always definitively support lower rep higher wieght as being superior for muscle hypertrophy.

Thus, whatever is working for you. Go with it. Lol

Effects of Low- vs. High-Load Resistance Training on Muscle Strength and Hypertrophy in Well-Trained Men. - PubMed - NCBI

Comparison of two resistance training protocols, 6RM versus 12RM, to increase the 1RM in healthy young adults. A single-blind, randomized controlled ... - PubMed - NCBI

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Originally Posted by Tovarasu

Let’s get one thing straight – feeling the “burn” in your muscle from very high rep training does not cause growth. Muscles grow from a combination of tension overload and fatigue. Maximum protein synthesis occurs between 70-85% of your 1RM (one rep max).

A study in 2009 conducted by Kumar et al. (Journal of Applied Physiology) measured the fluctuations in muscle protein synthesis after weight training. They found that the anabolic response (muscle building) increased by:

30% after training with weights that were 20% of 1RM*
40% after training with weights that were 40% of 1RM
100% after training with weights that were 60% of 1RM
130% after training with weights that were 75% of 1RM
100% after training with weights that were 90% of 1RM

(1RM – One repetition maximum, is the maximum amount of weight a person is able to lift for a single repetition*)

As we can see from this information, the peak of muscle growth occurs when training with a weight that is around 75% of our 1RM. The reason that the muscle building response is lower at 90% of 1RM is because the weight is just too heavy. This weight causes the nervous system to fatigue first, not the muscle fibres. This means that the muscles are not receiving enough time under tension to trigger the adaptive growth response.

So how many reps is 75% of your 1 RM? Take a look at the chart below to see how 1RM percentages relate to repetitions:

100% of 1RM = 1 rep
95% of 1RM = 2 reps
93% of 1RM = 3 reps
90% of 1RM = 4 reps
87% of 1RM = 5 reps
85% of 1RM = 6 reps
83% of 1RM = 7 reps
80% of 1RM = 8 reps
77% of 1RM = 9 reps
75% of 1RM = 10 reps
67% of 1RM = 12 reps
65% of 1RM = 15 reps

As you can see, 75% of your one rep max works out at around 10 reps. So, training anywhere between 8 – 12 reps to failure is the optimum rep range for muscle growth.

So why does training in this rep range produce greater gains in muscle size?

Skeletal muscles are made up of a mixture of three different types of muscle fibers. Type 1, Type 2a and Type 2b. The back, legs and neck have a higher number of Type 1 muscle fibers while the shoulders, chest and arms have more Type 2b fibers.

Type 2b fibers come into play when fast of heavy tension is required, such as with heavy weight training around 75% of 1RM. The only way to really stimulate these kinds of fibers is through this heavy weight training. These Type 2b fibers are the most responsive to growth. They will get much bigger and stronger compared to Type 1 muscle fibers.

When you max out/fail between 8 – 12 reps you will recruit ALL muscle fibers, (Type 1, Type 2a and Type 2b) so this is the rep range where you get maximum muscle fiber recruitment which leads to greater increase in size. This rep range gives the best combination of muscle fiber recruitment, metabolic fatigue and good nervous system activation. From the first rep you will get full recruitment and enough time under tension to produce muscle hypertrophy.

Heavy low rep training in the 6 – 8 range does produce great muscle hypertrophy, but slightly higher 8 – 12 reps produces a greater increase in muscle mass.

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Got to lift big to get big. Simple as that. Got to give them muscles a challenge and stress them. 10-12 reps usually I say for growth. But I like 8 -10 usually cuz i want power and not just size or strength. I want balance.
like the calvs. You walk on them every day and they lift your body with one calv each step. So even Arnold said that in order to grow them that you have to at least double your body weight or something significant for reps to grow them. And you shouldn't do less them 5 reps because any amount of reps less then that is not reasonable because it lacks number of reps. Etc and doesn't break the muscle down enough. I like 8-10 reps. 12 if I'm doing isolation maybe or post exhausting.
Plus I've heard of steng men competitors doing super high reps with low weight to get the lactic acid built up. Unsure if this is good for mass but who knows unless you try and test it out.

But I am always set on random mode for the shock factor. Like some drop sets. If I want a 10 rep range total. Sometimes I will lift weight I can only do 3 reps, then drop and lift a lighter weight again for another 3-4. Then repeat with that heavy weight until i reach my desired rep,range. So I'm doing the higher reps But with heavy weights...so many different combos i can do and it keeps it exciting

Muscle hypertrophy is much more complicated than just doing a certain number of reps with a certain percentage of weight. However good job with the cut and paste.

I was watching. A Dorian yaites clip and he mentioned that if you want size. 6-8 reps. Beyond the details of why because everyone is different that's what I do mainly ( not because he says so. First time seeing the clip lol) especially to challenge them muscles and get a decent amount of reps in as well.