I’m sure you’ve witnessed the talk around rest periods for muscle growth.
Basically, it goes something like this:
“Bro! If you want to grow muscle you should train with high reps using short rest in between. It’s the pump that leads to the growth!”
This has long been the belief, but we have during recent years learned that taking longer rest between sets is actually better for muscle growth.
Let’s look at why:
The Hormone Hypothesis And Short Rest Intervals
Studies have shown that shorter rest intervals between sets leads to acute spikes in hormones such as testosterone and human growth hormone (HGH) during, and for a while after the training session.
This has led to the thought that shorter rest periods must produce more muscle growth since testosterone and HGH is highly anabolic.
However, that is not the case, and here’s why:
1. The body is smart and will always strive for balance:
When any of these hormones is increased in the body, the body senses this through something called a feedback loop.
What this feedback loop does is signaling the glands that produces these hormones to stop producing them because there’s enough of them in the body already.
2. The anabolic hormones that are acutely released by shorter rest intervals (or any type of training) will still be within the natural physiological range:
But, for these drugs to work they need to be taken in supra-physiological doses, meaning intakes that are far above what the body could ever produce naturally, even with the most optimal rest interval ever created…
So, even though these hormones do get increased from low rest training, they’re still within the “natural” range and won’t help push extra muscle growth.
3. It’s not only anabolic hormones that’s increased acutely after training:
Cortisol increases (which is a catabolic hormone), heart rate, cardiac output and sympathetic activity increases, all things that are known to be acutely counterproductive to muscle growth.
Not only that, protein degradation is something that occurs as well. Training causes damage to the muscle cells, meaning that we must build those cells up before we can build any new muscle tissue. These are all completely natural things that happen in the body after a workout.
So, what’s important to know about low rest training is that the increases in various hormones is just an effect to the training, and not a cause of muscle growth. The body simply must make this kind of hormonal response in order to start the recovery processes.
Okay, so what makes longer rest periods better then?
Why Longer Rest Periods is Better For Muscle Growth
First of all, thanks to the work of Brad Schoenfeld, we know that longer rest periods is better for muscle growth. He carried out an extremely solid study on well-trained lifters comparing 1 minute rest to 3 minutes rest on compound lifts done for 3 sets of 8-12 RM.
The group doing 3 minute rest between sets nearly doubled the gains in muscle mass compared to the 1 minute group.
So, what causes longer rest periods to be better?
I mean, it seems counter-intuitive that chilling around for 3 minutes would cause more growth than hammer set after set using 1 minute rest and getting a good pump, right?
Well it’s not, and here’s why:
Volume: The Main Driver of Muscle Growth
And the reason why longer rest periods beats out shorter rest periods, is because more training volume can be achieved with longer rest between sets.
Here’s an example of this in action:
Let’s say you were to do 3 sets of 10 reps with 225 lbs on a certain exercise. By doing long rest periods of 3 minutes or more, you successfully complete all 30 reps with 225 lbs.
Now, let’s say that instead of taking 3 minutes of rest between the sets, you take 1 minute. By resting shorter you get 10 reps on your first set, 8 reps on your second, and only 6 reps on third sets.
By taking 1 minute of rest, you get a total of 6 reps less than what you did with 3 minutes of rest. Sure you got a good pump, but the fact that you lost out on training volume, will lead to less muscle growth.
Essentially what you’re doing when utilizing shorter rest periods is trading volume for metabolic fatigue. You get a good pump, but at the expense of volume.
Is Shorter Rest Intervals Completely Useless?
No, in fact, shorter rest intervals can still be very useful during certain circumstances.
James Krieger wrote a fantastic article discussing all the research behind rest intervals for muscle growth, he basically concluded that:
So, if you for some reason are training with higher rep ranges, then it looks like shorter rest periods, below 30 sec, is a very viable way to train. At least for smaller upper body muscles.
This is perfect for muscle groups that may be hard to hit effectively and safely with heavier weights, such as your medial delts. In this case you could use a technique called:
One very effective method that utilizes short rest periods is Myo-Reps, which was invented by Børge Fagerli.
This is a very good technique for individuals that are time pressed and want a way to get a good training stimulus in less time. In fact, Myo-reps give you the same training stimulus in around two thirds of the time it would normally take you, and it also leaves you with an incredible pump.
Not only that, it’s also a very good technique for muscle groups that can’t be hit safely with heavy weight, standard training. And it’s certainly a cool way to add extra volume for certain msucle groups that might need it.
The reason why Myo-reps works so well for muscle growth is because you’re taking advantage of short rest intervals. What this does is making all your reps effective, from the get go of each miniset.
Think of it this way, if you were to do 12 to 15 reps the standard way, meaning with ~2-3 min rest in between. Then the first 8-10 reps of the exercise are going to be so easy that you would just go through the motion and not actually get any productive work from the time and movement invested.
As displayed under high reps/low load in this image:
With Myo-reps on the other hand, since you’re utilizing shorter rest periods, each miniset would be like starting on rep 8-10, meaning that immediately from the first rep you do effective work that causes muscle growth.
Conclusion Rest Periods For Muscle Growth
Full rest periods of around 3 minutes are shown to be superior for muscle growth and strength. By using longer rest periods, you can accumulate higher levels of volume since you don’t lose reps because of fatigue.
Short rest periods of around 1-2 minutes seems like the worse thing to do, since you’re compromising volume too much.
Very short rest periods of around 15-30 sec can be very valuable with some training techniques such as Myo-reps, since you can still accumulate efficient volume this way.
Okay, so even though it can be important to train with the correct rest periods, as doing so would lead to more muscle growth in less time. What’s most important is still the total training volume, intenisty and frequency. You can learn more about these concepts here: