Written by Michael Matthews

Evidence Based

Key Takeaways Muscle memory describes the phenomenon of muscle fibers regaining size and strength faster than initially gaining them. This occurs because weightlifting permanently alters the physiology of muscle cells in a way that primes them for rapid regrowth. Taking too much time off training will result in muscle loss, but muscle memory helps you regain muscle quickly once you start training again.

Most guys and gals lift weights to look like this:

And think that taking even a short break results in this:

Or maybe this:

In other words, they think of a day without exercise as a step toward getting smaller, fatter, and weaker.

This mindset is particularly common among people who are new to lifting weights or who haven’t gained much muscle or strength to speak of, usually because they’re afraid to lose what little “aesthetics” they have.

Once they get more training time under their belt, though, which inevitably entails periods of less exercise than you’d like, they notice something curious:

Not only is it harder to lose muscle than they thought, they regain whatever they do lose much faster than the first time around.

In most cases, the losses are minimal and it only takes a few weeks to get right back to where they were before taking a break, even an extended break of a few weeks or more. And if they were out for many months, the losses are still limited and the rate of regain is remarkable.

If you’ve experienced this firsthand, you know what I’m talking about, and if you haven’t, you’re probably skeptical. And that’s okay. I’ve been there myself.

The good news, however, is your body, like mine, is hardwired to hold onto muscle, not lose it, and regain it quickly when it actually is lost.

In other words, “muscle memory” is a fundamental aspect of human physiology, not a perk for the genetic elite or #dedicated steroid users.

And in this article, you’re going to learn why, including how muscle memory works and how to use it to your advantage.

Table of Contents What Is Muscle Memory?

How Muscle Memory Helps You Regain Muscle Faster

Can Muscle Memory Help You Build New Muscle Faster?

The Bottom Line on Muscle Memory

Training

Diet

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What Is Muscle Memory?

Muscle memory describes the phenomenon of muscle fibers regaining size and strength faster than initially gaining them.

For instance, for an intermediate or advanced weightlifter, a few pounds of muscle gain per year is the norm, and eventually it slows to an almost imperceptible crawl. If they stop lifting for a bit and lose, let’s say, five pounds of muscle, however, it might only take a month or two to gain it right back.

The same principle of “hard to gain, easier to regain” holds true for many other skills and physical processes. For instance . . .

Regaining your aerobic capacity after a layoff is much easier than initially building it up.

Relearning to ride a bike is much easier than learning it newly, even decades later.

Relearning to play a song on the piano is significantly easier than the first time.

You can think of muscle memory as a lifelong reward for the hard work you put into building muscle and strength. Do it once and it’ll always be easier to do again.

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How Muscle Memory Helps You Regain Muscle Faster

Muscle cells are unique in that they can contain multiple nuclei—known as myonuclei—which carry the DNA that orchestrates the construction of new muscle proteins.

The nucleus of a cell is responsible for increasing or decreasing the production of various cellular chemicals and activities, regulating cellular replication and repair, and starting and stopping other vital functions.

You can think of the nucleus of a cell like its brain. This little brain can only handle so much information, though, and its limited computing capacity limits a cell’s ability to grow larger (and thus engage in more activities).

As muscle cells have multiple “brains,” they can grow significantly larger than most other cells in the body.

Each myonuclei can only manage so much cell, however, and this amount is referred to as its myonuclear domain. To continue getting bigger, then, a muscle cell must add more myonuclei.

The catch is muscle cells can’t produce myonuclei—they must take them from another kind of cell called a stem cell. Stem cells are special cells that can be developed into many different types of cells in the body.

There are many different kinds of stem cells in the body, but the kind most involved in muscle growth are referred to as satellite cells. These cells lie dormant near muscle cells and are recruited as needed to help heal and repair damaged muscle fibers.

Once called upon, satellite cells attach themselves to damaged muscle cells and donate their nuclei, which not only aids in repair but also increases the cells’ potential for more size and strength.

This is the body’s fundamental adaptation to resistance training that results in bigger and stronger muscles. It also helps explain why you have to progressively overload your muscles to get fitter:

The more you train, the more myonuclei your muscle cells accumulate, and this makes them more resistant to muscle damage, which means you have to work harder and harder to stimulate more satellite cell recruitment.

In other words, your body won’t fire up its muscle-building machinery unless it has to—unless you force it to.

And here’s where muscle memory enters the picture: Once a satellite cell has donated a nucleus to a muscle cell, it stays there for good.

While scientists aren’t sure exactly how long myonuclei remain in muscle cells once donated, estimates range from several months to forever, with most evidence supporting the latter conclusion.

Now, it’s important to remember that satellite cell activation is just one mechanism that contributes to muscle growth. Muscle fibers can grow to a point before requiring additional myonuclei, but once they reach that limit, the only way to keep growing is to add myonuclei.

So, if you’ve built a significant amount of muscle—20 or more pounds as a man and 10 or more pounds as a woman—your muscles contain a lot more myonuclei than when you started training them.

Furthermore, if you stop training your muscles for at least a few weeks, you’ll lose strength and eventually muscle size, but the additional myonuclei you worked so hard for will remain in your muscle cells for some time (and maybe forever).

This is why you can regain muscle you’ve lost much quicker than you can gain muscle you never had—your muscle cells don’t need to recruit new satellite cells to grow back to their former glory and instead can simply work with the hardware they’ve already got, which is mechanically simpler and more efficient.

So, to recap what we just covered, here’s how muscle memory works:

When you lift weights, you damage muscle fibers. This causes nearby satellite cells to flock to damaged muscle cells and donate nuclei for repair and recovery. These additional myonuclei increase the muscle cells’ ability to grow bigger and stronger. Once inside a muscle cell, myonuclei stick around for a very long time, possibly forever. If you’ve gained a considerable amount of muscle and then lose a considerable amount for whatever reason, your body is primed for rapid muscle regrowth when you start training again.

So, that describes how muscle memory helps you regain muscle faster.

Some people believe you can use muscle memory accelerate new muscle growth as well. Let’s review this theory and see how it holds up to scientific scrutiny.

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Can Muscle Memory Help You Build New Muscle Faster?

Part of the reason people new to weightlifting build muscle so quickly (“newbie gains”) is their bodies are highly highly sensitive to muscle damage.

Specifically, during the first six to twelve months of lifting, satellite cells are easily activated after workouts, resulting in large infusions of myonuclei into muscle cells.

The more muscle you gain, however, and the closer you approach your genetic potential for muscle growth, the more difficult it is to keep adding new nuclei to muscle cells.

The reason for this basically boils down to a phenomenon known as the repeated bout effect, which states that the more you do a certain kind of exercise, the more your body becomes accustomed to it and the less adaptation is stimulated by it.

In other words, as you accumulate more training experience, you get less and less muscle and strength gain per unit of training effort.

The mechanism of satellite cell activation is the primary culprit behind this unfortunate reality. As you build more muscle. . .

The total amount of satellite cells available for recruitment decreases. You must do harder and harder workouts to produce enough muscle damage to convince satellite cells to donate their nuclei to muscle cells. The muscle damage that does occur results in less satellite cell activity.

Some people believe there’s a way to “hack” this system, though.

It takes around three to four weeks without training for a muscle to begin atrophying, but as you know, the additional myonuclei gained through training stick around significantly longer (possibly forever).

Additionally, the bigger and more trained your muscles are, the less satellite cells are recruited in response to training and the less muscle you build over time.

The sixty-four thousand-dollar question, then, is this:

What if you included training breaks in your plan that were long enough to “resensitize” satellite cells to muscle damage but not so long as to result in muscle loss?

Could that allow you to build muscle faster?

Maybe.

While there’s little research looking at how this strategy might influence satellite cell activity per se, there is some information on how it might influence your overall rate of muscle growth.

For instance, a study conducted by scientists at the University of Tokyo divided 14 young men into two groups:

Group one lifted weights every week for 24 weeks. Group two lifted weights for six weeks, stopped lifting weights for three weeks, and then repeated this cycle twice more for a total of 24 weeks.

Both groups followed a weightlifting routine that involved bench pressing three days per week for 3 sets of 10 reps at 75% of their one-rep max.

Strangely, both groups gained almost the same amount of muscle and strength at the end of the study, despite group two doing 25% less training.

The researchers didn’t measure satellite cell activity, so it’s impossible to say if that might have contributed to the surprisingly positive results in group two, but it’s possible.

Another similar study conducted by the same team of scientists produced almost identical results. In this case, the researchers divided 15 young men into the following two groups:

Group one lifted weights continuously for 15 weeks. Group two lifted weights for 6 weeks, stopped lifting for 3 weeks, then lifted weights for another 6 weeks for a total of 15 weeks.

Both groups gained the same amount of strength and muscle, but there was an interesting disparity in the rates of strength and muscle gain.

Group one’s strength and muscle gains started to slow down in the last 6 weeks of the study, which is to be expected due to the repeated bout effect.

In group two, however, although they didn’t gain any muscle during their 3-week break (natch), they gained muscle quickly and consistently enough during their two 6-week bouts of training that they ended up gaining the same amount of strength and muscle after 15 weeks as group one.

As interesting is all that is, it doesn’t necessarily mean inserting longer breaks into your training is going to help you get jacked faster.

First of all, it’s possible that in both of these studies the people who took training breaks were simply benefitting from feeling more rested and enthusiastic for their workouts, which can make a huge difference in muscle and strength gain.

Second, the people in these studies were beginners, so you’d expect them to gain muscle quickly and easily regardless of whether they took breaks. More advanced lifters have to work much harder to make gains, however, so you wouldn’t necessarily expect training breaks to produce the same results for them.

Third, in both studies the people who took breaks didn’t build more muscle than those who trained continuously—they just built the same amount of muscle with fewer workouts. This doesn’t indicate that taking breaks increases muscle gain, then, just that it can be equally effective as continuous training.

Finally, neither of these studies tells us how things might play out over time.

Sure, both groups gained about the same amount of muscle over four to six months, but how would this strategy work if continued for several years?

Considering that volume and intensity are the two most important training factors in muscle growth, common sense dictates that dramatically reducing these (by taking several-week breaks every so often) over longer periods of time would result in less muscle gain, not more.

And while taking breaks now and then can increase your enthusiasm for training and make it more enjoyable, you can accomplish the same thing with regular deloads.

So, a more plausible yet still comforting conclusion from this research is you can be out of the gym for weeks at a time without having to worry much about losing gains.

That means you can enjoy that vacation with a guilt-free conscience. Or recover from that injury patiently. Or play some sports for a bit instead of lifting. Don’t worry. Your muscles will be ready for a quick and triumphant return.

The Bottom Line on Muscle Memory

Muscle memory describes the phenomenon of muscle fibers regaining size and strength faster than initially gaining them.

And it’s true: you’ll regain muscle in less time than it took to gain it initially.

This is largely thanks to two facts:

The rate at which you gain muscle and the amount you gain are largely governed by the amount of new nuclei that are added to muscle cells. Intense and frequent resistance training appears to more or less permanently increase the amount of nuclei in muscle cells.

In other words, when you train your muscles hard enough, you’re not only increasing their size and strength, you’re also upgrading their muscle-building machinery for the long-term, possibly forever.

If you then stop training for whatever reason, you eventually start to lose size and strength but not the upgrades to the machinery.

Thus, when you start training again, the enhanced muscle cells regain muscle and strength quicker than the first time around, when they were powered by lower-horsepower equipment.

While this phenomenon allows you to quickly regain muscle you’ve lost, it doesn’t help you build muscle you’ve never had before faster.

There’s no shortcut for that, there’s just lots of heavy, compound weightlifting, high-protein dieting, and thoughtful management of your calories and macros.

If you want to learn more about how to set up a weightlifting and diet plan for gaining muscle and strength, check out these articles:

Training

The Definitive Guide on How to Build a Workout Routine

The 12 Best Science-Based Strength Training Programs for Gaining Muscle and Strength

How to Create the Ultimate Muscle Building Workout

Diet

The Ultimate Guide to Bulking Up (Without Just Getting Fat)

How Much Protein You Should Eat to Build Muscle

This Is the Best TDEE Calculator on the Web (2019)

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