If you’re following one of the Kinobody courses or any other time tested muscle building program you probably already know that training in a medium rep range is the way to go.
But I thought you’d like to know why.
In this article we’ll see why the 5-8 (or even 4-12) rep range is ideal for building muscle. We’ll also discuss why you shouldn’t use the same rep range on all exercises and why training in the lower rep ranges (1-4) and higher rep ranges (10-15) can actually be a good thing to do sometimes.
Sounds good? Let’s start with the basics:
What makes Muscle Grow?
In this article we’re basically answering the question: How heavy should you be lifting?
The heavier the weight, the fewer the reps you’ll be able to do.
So before we explain how intensity affects muscle growth, I think it will be helpful to first address the causes of muscle growth.
Everybody who’s honest will be quick to tell you that the causes of muscle growth are not yet completely understood. But we do have about 90-95% of the picture. In my opinion the man that best explained the causes of muscle growth is dr Brad Schoenfeld. In one of his papers he concluded that the 3 main causes of muscle hypertrophy are:
- Progressive tension overload (lifting heavier and heavier weights over time)
- Muscle damage (micro-tears of muscle fibers that necessitate repair)
- Cellular fatigue (pushing a muscle to its metabolic limit through high reps)
Out of the three, progressive tension overload has the most profound effect (by far). But muscular damage and fatigue also stimulate growth so if we want to maximize our gains we must take those into account as well.
Does the rep range even matter as long as you get progressively stronger?
When we present progressive tension overload as the main driver of hypertrophy we’re tempted to believe that the rep range we use doesn’t matter.
Studies do show that you can make muscle gains training in any rep range as long as you’re progressing (low load, medium load, and high load). But results are not equal in all situations. The medium rep ranges still win out in the end.
Let’s see why:
1. The weight you use must be heavy enough to cause growth
Most people agree that there is a minimum intensity threshold for resistance training-induced hypertrophic adaptations. In simple terms, the weight you use must be heavy enough to cause growth.
How heavy? 60% of 1RM or above.
The reason it has to be above 60% of 1RM is to recruit the “fast-twitch” muscle fibers – the ones involved in explosiveness and high force production and the ones with the greatest potential for growth. These are the fibers you need to develop if you want big muscles.
Using a low load you primarily recruit the “slow-twitch” muscle fibers – the ones very resistant to fatigue and with a lower potential for growth and force output. These are not the muscle fibers we primarily target, these are best for muscular endurance.
So the main reason low loads are not optimal for growth is that they don’t provide enough tension to recruit all muscle fibers.
With one exception. Of course there’s an exception, right? Low loads can recruit the “fast-twitch” muscle fibers too but only if a set is taken to failure. As the slow-twitch muscle fibers get fatigued, fast-twitch fibers will have to be used in their place.
So you can recruit all muscle fibers with low loads too but you’d have to train to failure in every set. And doing sets of 20-30 reps until failure with a low load is grueling. I haven’t tried it myself but so I’ve heard. Apparently about half the people who do this end up throwing up because of the effort.
Why would you train like that on purpose? You can just train with medium load instead. You’d get the same effect with much less work.
Alright so low loads are out but what about high loads? Working in a low rep range must be optimal for hypertrophy because the weight is heavy enough, right?
Well, sort of… but medium rep ranges are still better. Here’s why:
2. You need to accumulate a certain amount of volume
Remember that optimal growth doesn’t all come down to high tension on the muscle fibers, it also requires muscle damage and metabolic fatigue.
That means you need a certain amount of time under tension to create muscle damage and a certain amount of reps to fatigue the muscle fibers. You need to do enough volume too.
You’ll say: Aha! I see. So I can get optimal growth training in a low rep range. I just need to do enough sets to get the required volume.
That’s exactly right… but as I said you’d still do better if you trained in a medium rep range.
Brad Schoenfeld showed us why. He studies what would happen if you did the same amount of volume with two different loads: a weight you can only do 3 reps with or a weight you can do 10 reps with (both loads being heavy enough to cause growth).
At the end of the study both groups showed the same amount of muscle growth. So if you did the same volume with a heavy enough weight, the results were the same. But again the amount of work the groups had to do was very, very different.
As you can imagine doing a lot of reps with a weight you can barely lift is not fun. The high load group had a very bad time because they had to do 10 sets of 3 compared with the other group who did 3 sets of 10. They reported feeling exhausted and some of the guys inevitably got injured and had to drop out.
On the other hand, the guys doing 3 sets of 10 reported feeling energized and willing to do more. Their workout only took about 20 minutes compared to other guys who stayed in the gym more than one hour.
The conclusion here is this: Although you can get optimal growth with low reps, it’s probably not worth it. As in the case of low load training you’d have to do more work to get the same results.
The medium rep range is the way to go (most of the time)
If you workout in the 5-8 rep range (or even 4-12) you use a heavy enough load to recruit all muscle fibers, you get enough time under tension to produce muscle damage, and you do enough reps to fatigue the muscle.
Basically, training in a medium rep range is the easiest way to accumulate volume with a heavy enough weight.
(That’s actually a quote by Eric Helms. I could’ve stayed up all night and not think of that.)
If you’re a beginner my recommendation is to do all your work in the 4-10 rep range. If you’re an intermediate it’s probably best to do 70% of your work in that range and leave some room for pump training as well.
If you’re an advanced lifter it’s probably best to do 50-60% of your work in the 6-12 rep range and also do both heavy low rep training and pump training as part of your routine. You probably need to do this to maximize muscle growth.
Why train with Low Reps sometimes (as an advanced lifter)
In natural lifters strength is very closely linked with muscle development. If working in a lower rep range allows you to get stronger that will probably lead to some muscle gains.
The reason for that is because once you’ve made your neurological strength gains, your bones, ligaments and tendons have improved and your form is efficient, the ONLY way for you to get stronger is by increasing the size of your muscle fibers. That’s it. So if you are getting stronger, and you’re past the intermediate level…you are by default getting bigger. You have to be.
Also, if you get stronger in a lower rep range you’ll probably be able to lift heavier weights when you return to lifting in a medium rep range. Progressive overload = muscle growth.
Why train with High Reps sometimes (as an intermediate and advanced lifter)
First of all there are some movements that simply can’t be trained efficiently with low or medium reps.
For example try doing sets of 5 on lateral raises. You’ll feel all the pressure in your joints instead of actually feeling the muscle working. The same goes for rear delt flyes, chest flyes, rope pushdowns, calf raises, leg raises, etc, etc.
A good rule of thumb is to work isolation movements in a slightly higher rep range than you use for your compound movements. For example I do biceps curls and skull-crushers in the 6-10 rep range, and lateral raises, rear delt flyes and abs in the 10-15 rep range. That works great.
Another reason to incorporate higher rep training is to get more sarcoplasmic growth – increase the fluid inside the muscle. When you repeatedly deplete glycogen from a certain muscle group our body will respond by super compensating glycogen stores in that muscle group. That’s the main purpose of pump training.
Pumping your muscles up from time to time may also lead to an increase of the actual muscle fibers. Here’s what brad Schoenfeld wrote about pump training in the Max Muscle Plan:
“People often dismiss the pump as a temporary cosmetic phenomenon, but this dismissal is short sighted. Recall that the body perceives cell swelling as a threat to the integrity of the affected muscle fibers. The body responds by increasing protein synthesis and decreasing protein breakdown—the basis of muscle development.”
As I said in the beginning, if you’re following any of the Kinobody courses or other solid training programs you are probably already training in a medium rep range. And now you know why.
As you get more advanced the need to change things up and add in elements of periodization increases. That’s when it’s useful to lift in a lower rep range and add in more pump training.
Let me know what you think about this article in the comments below. Questions are always welcomed. I read and answer every comment.
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This is the program I used to build my physique and I still use it today.
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