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June 24, 2022
Every gym-goer is familiar with the expression use it or lose it. Put the time in to lift heavy weights, and your muscles will grow. Stop working out, and your strength and muscle mass rapidly decline. Unfortunately, many of us will experience a time when getting to the gym isn't possible, whether from illness, injury, or a phase of life in which you’re just plain busy.
The bad news: If taking more than a few weeks off from the gym, losing strength and muscle size is inevitable. The good news is that when you resume your lifting routine, your previous hard work will not be for naught, thanks to muscle memory. This mechanism within the body helps you regain strength and muscle mass in about 1/10 of the time it took to originally get it. And that certainly beats starting from scratch.
In this post, we’ll discuss:
Before we get into muscle memory, let's first have a basic understanding of the muscle-building process. Weight lifting's goal is muscle hypertrophy, when your muscle cells increase in size, resulting in bigger muscles.
Achieving hypertrophy includes fatiguing your muscles, typically targeting a muscle with 10-20 sets each week, and during this process, the stress damages the fibers, creating micro-tears. The body rebuilds the damaged tissue through protein synthesis, growing them back thicker than ever, leading to visible muscle growth.
So, how does muscle memory play into this? A simple way to describe it is that if you lose the added muscle mass we just discussed, the fibers can retain a memory of the size and strength they once had. So if you strength train, stop, and eventually pick it up again, your muscle fibers can get bigger and stronger faster than they could the first time around.
Say you have been lifting weights for two years, fairly regularly, and have decent strength and visible muscle mass to show for it. If you stop working out, no matter why, you will experience muscle atrophy, resulting in a loss of muscle gains, strength, and mass previously made.
Fortunately, though, the myonuclei, which reside in your muscle fibers, don’t lose their memory of the size and strength they once were, making it easier for you to gain that muscle mass again. As you start to strength train again, the myonuclei stimulate protein synthesis, essential for building larger muscles, more quickly, which enables your muscles to gain strength and size faster the second time.
At a basic level, muscle memory is also responsible for your ability to do most everyday tasks without having to give them a second thought. Think about motor skills activities you do without thinking, including walking, running, riding a bike, and jumping.
Acquiring these skills resulted in motor skill learning, creating a new pathway between your central nervous system and the muscles used for your practiced skill. Once your nervous system creates this pathway, no conscious effort is required to accomplish them. Similarly, once you train your muscle fibers, their myonuclei will retain the memory of their previous size and strength.
The takeaway for muscle memory: It’s a great thing! Even the most dedicated gym-goer may hit a phase in their life - whether due to an injury or life commitments - that results in them not getting to the gym. And while previous beliefs followed the idea that if you stop going, you lose everything, muscle memory won’t allow that to happen.
Yes, you’ll lose muscle mass during your time off, but your muscles retain their ability to grow bigger and stronger. Start working them again, and you can re-build your muscles far faster than before. It's reassuring to know that if something halts your strength-training routine, all of your hard work won't be wasted. You trained your muscles to remember.
Much to our relief, muscle memory works. Multiple studies have proven that it exists. A study examining participants following seven weeks of training, followed by seven weeks of no weight lifting, and another seven weeks of resistance moves found their strength came back significantly faster in the second seven-week training interval1.
Separate research examined muscle adaptations between a group that followed continuous resistance training for 15 weeks and another that trained for six weeks, stopped training for three weeks, and then began re-training at week 10. At the end of the 15 weeks, both groups had similar muscle adaptations, showing comparable improvements to their 1-RM and added muscle mass2. The results showed that a 3-week training pause didn’t interfere with participant's muscle gain.
Separate research shows that despite muscle cells growing small due to detraining or disuse, the nuclei of a muscle fiber, referred to as myonuclei, can grow faster and larger than the first time you trained them3. Put in the work the first time, potentially take years off from the gym, and when you finally return, your myonuclei will reward you by increasing your muscle fibers far quicker than your first training experience.
Recent research shows that muscle hypertrophy causes changes at the cellular level that contribute to muscle memory. As you strength train, genes essentially get turned on in the muscle cell, helping to make RNA, which plays a role in protein synthesis and producing additional protein within the muscle cell. And while a period of detraining causes your muscle mass to decrease, the genes retain their ability to turn back on.
So when you get back to the gym, your genes can quickly switch on, enabling you to grow and strengthen your muscle faster than the first time. Essentially, strength training alters your muscle cell’s DNA. This modification to your genes remains even when you’re not weight lifting, so that when you can get back to your training, the DNA alterations kick in, helping your muscles remember their previous, much larger size and strength.
It may sound too good to be true, but we promise it's not. Research examining muscle memory had a group of participants strength train three days a week for seven weeks1. The participants then avoided strength training for seven weeks. The third portion of the study had the participants return to their previous routine for an additional seven weeks. The results? Drumroll, please.
In the first seven weeks, the participants improved their lean muscle mass, and muscle biopsies proved that their DNA, over 17,000, had changed significantly. During the seven weeks of no training, everyone lost muscle mass (no surprise there).
Despite this, the muscle biopsies revealed that the DNA remained modified, showing that the muscles remembered their previous mass and strength. Now, for the best part: The participants returned to their workout program for another seven weeks.
They gained back their muscle mass and then some, almost doubling gains made in the first seven weeks. A third muscle biopsy after this period revealed that even more DNA was modified, setting the group up for even more muscle memory. Not only were the participants able to regain their previously achieved strength, but they gained even more muscle mass, and altered more DNA to help in the future.
To our surprise (and relief!), not long at all. If you look at the research, one study we discussed above saw muscle memory kick in after only six weeks of training. A separate one saw muscle memory exist after seven weeks of training, showing that after a month and a half of training, you’re most certainly going to reap some muscle memory benefits.
But it may not even take that long. When you first start strength training, neural adaptations occur between 2 and 4 weeks4. Considering these adaptations involve the nervous system building stronger connections to your muscle cells and fibers, leading to more significant strength gains, it’s plausible that muscle memory may begin kicking in at this time as well.
Our suggestion: Unless illness or injury prevents you from maintaining your gym routine, stay consistent with your fitness regimen for the first six weeks of training to ensure muscle memory will kick in if you need it down the road. The longer you can train, the larger your muscles will grow, and the more DNA will modify. If the time comes, you've ensured you can bounce back faster following a deloading period.
Muscle memory provides reassurances that in a worst-case scenario in which you injure yourself and can't continue your fitness regimen, your hard work isn't wasted. The next question to tackle: How long does muscle memory last?
First, more research on this subject is needed as guidelines have yet to be researched and released in an exact number of weeks, months, or years.
But existing studies at least gives us an idea of the length of time. The study that reviewed a group of participants following seven weeks of training, seven weeks off, and seven weeks on again yielded great results, meaning that muscle memory exists for at least seven weeks.
Another study states that muscle memory lasts for at least 15 years, possibly even forever2. This holds more true if you start weight lifting at an earlier age. So the sooner you begin weight lifting, the more likely you retain muscle memory for longer.
More recently, another study examined the longevity of muscle memory. Examining a group of people training and detraining over several years is a time commitment, so the researchers used mice who age much faster than humans3.
Researchers required the mice to train for eight weeks and then had them do nothing for 12 weeks, a time period that equates to about 10% of their lifespan and years for us. After 12 weeks, the mice began training again, and despite three months of inactivity, the mice got stronger, much more quickly than the first time.
The difference here is the study looks at mice instead of people. But the researchers looked at the same genes that are studied when using humans in muscle research, suggesting that we may be able to go years without training and still keep our muscle memory intact.
The adage practice makes perfect rings particularly true for jogging your muscle memory. After years of not riding a bike, you wouldn’t hop on and go full throttle, right? Instead, to ride a bike, you’d start slowly, being mindful of keeping your balance before increasing your speed.
Similarly, after many months or years away from the gym, it’s not in your best interest to head to the gym, rack a barbell with your previous 1-RM bench press record, and get to work. Your strength is not going to be close to what it once was (only at first!), and hitting the ground running may cause one of two scenarios: the best case being overly sore and worst case, injury.
Use your body weight for your first few training sessions. This strategy will help jog your muscle memory as your muscles re-acclimate with strength training movements, such as squats, lunges, push-ups, and dips. Using your weight is a gentle way to push yourself and engage your muscles without risking injury.
Get a week or two of bodyweight exercises under your belt, and then you can start to throw weights into your exercise routines. But go slow. Thanks to muscle memory, you will regain your strength quickly, but only if you don’t push too hard and injure yourself. To start, reduce the volume, weight, and number of training sessions.
Your first week using weights should include two sessions, one upper body, and one lower body. Use a light weight that enables you to perform 12-15 repetitions and still have some fuel left in the tank, and only target 2 to 3 sets. Move through your exercises slowly as your muscles re-engage with the movements and added weight. If you aren't overly sore after week one, you can increase the difficulty in several ways - but not all at once.
Options include adding a third training session during week two, following a split of the upper body, lower body, and full body, or sticking with two sessions but bumping up your weight. You can also leave the sessions and weight as is and add a set. Continue checking in with yourself to gauge how you're feeling. If you’re still feeling good, plan to increase one of the three training variables for your next lifting session. As your muscle memory kicks in, progressions will be pretty significant in the beginning. Walk that fine line between progressing week-to-week and not overextending yourself.
Re-familiarize your muscles by triggering their memory with your go-to exercises and routines. If lunges were consistently a staple in your lower-body day, by all means, make sure they have a place in your strength training 2.0 plan. If the bench press is an exercise you did religiously, add that one into your upper body day (with far less weight, to start.)
If you can, remember your favorite routines for upper and lower body days, maybe parse it down to avoid overdoing it. Stick with it as much as possible, as the familiar movements will help kick your muscles back into gear.
The mind-muscle connection is when you concentrate on an activated muscle while performing an exercise and is a great way to get communication back up and running between the nervous system and motor units.
Motor units stimulate your muscle fibers, ultimately leading to a contraction. A strong and rapid connection between your nervous system and muscles is ideal for powerful contractions, and a mind-muscle connection can help kick-start this. Use slightly lighter weights, go through the movements slowly, and concentrate on the contracting muscle. Your muscle memory and motor units will start firing, and you’ll be back to breaking deadlift PRs before you know it.
First, and foremost: A proper warm-up and cool-down are essential for everyone, even bodybuilding bros in the gym six days a week. Warming up activates your muscles, getting them ready to put in some serious work.
Skipping it and heading right to the dumbbells may lead to injury - if not today, then soon. Similarly, cooling off is crucial for everyone and increases your flexibility, lowering your injury risk, reducing inflammation, and keeping oxygenated blood pumping through your body. You can also use a dynamic warm-up to trigger your muscle memory.
Dynamic warm-up movements such as bodyweight squats or forward lunges with a twist will gear your muscles up for the workout ahead. In addition, those once familiar movements will gently remind your body of exercises it was once used to while activating and engaging your muscles. Dynamic warm-ups are also a great time to practice the mind-muscle connection we just discussed.
Everyone, even the most experienced weight lifters, needs rest days because this is where your muscles put in the most work. During rest, muscle fibers repair, which is when they rebuild bigger and stronger than before.
The goal of triggering your muscle memory is for your myonuclei to remind the muscle fibers about how big and strong they once were, so when they repair themselves, they kick into overdrive and begin re-building your muscles quickly to achieve their previous size. But this isn't possible if your muscles don't have the time to recover, which is why rest days are essential.
Upon your return to the gym, you should have more rest days than you do strength training days, and after a week or two, you can start to add longer weight lifting sessions or increase the frequency in which you train.
Creatine monohydrate reigns supreme in the supplement world. The reason is that the strength-building superstar increases creatine and phosphocreatine concentrations within the muscle, improving its environment for anaerobic energy production.
Increased energy leads to more powerful contractions, improving your muscular strength, body composition, and strength, power, and volume per training session5. Now, if we take a step back, the hope with muscle memory is that it will kick in so we can return to and then exceed our former strength, power, and training volumes.
See where we’re going with this? While it won’t get you there overnight, creatine monohydrate will contribute to your muscle-building goals and help with quicker gains.
This won’t necessarily trigger your muscle memory, but if you’re going through all the work to get back into a strength training routine and return to your previous training volume and muscle mass, you have to eat for those goals. We could write a whole series of posts on how crucial nutrition is for hitting your goals, but for now, we’ll leave you with a few key pieces of advice:
It can be discouraging to start over. But remember, thanks to muscle memory, your previous hard work isn’t for nothing! You’ve put in the time before, and once you get back into it, your muscle fibers will reward you for your previous work by quickly returning to their former strength and size.
Start slow, not allowing your current physical state to bum you out. Focus on our new motto: If you don’t use it, you’ll lose it, but that’s only the case until you start to use it again.
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