Hey guys, 

This week’s blog post is going to be a detailed guide to muscle memory. Muscle memory is an important part of weight lifting and fitness as it helps us maintain muscle during periods of detraining and rest. How does this process work exactly? What are the processes that our bodies and muscles undergo to maintain and facilitate muscle growth? 

This blog post will go over the definition of muscle memory, why we lose muscle, the theory behind muscle memory, the science behind muscle memory and how long until the muscle comes back. Why would we be interested to know about this concept? It affects our training in many ways. 

Learning more about this concept will help us optimize our rest periods and non-training periods knowing that we have this incredible structure holding our gains together. Let us find out more about muscle memory in this detailed guide!  

What Is Muscle Memory? 

Muscle memory refers to the body’s ability to maintain muscle after periods of detraining. As our bodies stop being trained to grow in size and strength, so do the adaptations that naturally follow. Our body’s ability to retain size and strength are a result of this process, it is often a combination of genetics, less time spent off training, training experience and food that will allow for the optimization of this natural process.

“When we stop lifting weights, muscle size and strength goes down over time. You’ve probably noticed that it’s much faster to get back your size and strength when you start training again, and this is what muscle memory refers to – it’s as if the muscles ‘remember’ what size they used to be (Tulloch, 2019).”

 Our body’s ability to remember its size and strength will come in handy to many who take multiple breaks during their training or sustain an injury. This concept also may have come in handy to those who had no gym access during the Corona pandemic. 

Why Is It Important? 

Our body’s intelligent way of remembering its previous size and strength adaptations can benefit any serious athlete or gym-goer who plans on taking time away from the gym. It also increases our awareness of how the body signals muscle growth and hypertrophy to further enhance our education on the subject. 

Why Do Our Bodies Lose Muscle? 

We lose the muscles that we are not working. Having muscle on is expensive for the body, it is taxing in both energy and amino acids. It requires consuming high amounts of protein for both growth and maintenance. Without training stimulus and food, our bodies will have no other choices but to get rid of it’s priciest currency which is our muscles. 

“This is because it’s expensive for the body to keep muscle around if it doesn’t need it. It costs energy and amino acids from protein to build and maintain large structures like muscle fibres, and if they’re not really being used to ensure survival the body recognises that resources are better spent elsewhere (Tulloch, 2019).”

The best way to retain our muscle is to keep them stimulated on a consistent basis, this does not have to be at a high frequency but the training should be intense enough that the muscle is challenged. If you have to go on vacation or are planning on being away from the gym for a long period of time, your best bet is to maintain your muscle through bodyweight workouts at home or even just perform a few Youtube videos in your hotel room. 

Make sure that you are still consuming your regular high-protein diet and you will ensure that your muscles have enough fuel for sustenance and growth. 

What are Myonuclei? 

Myonuclei are cells in our muscle fibers that are created from weight lifting. The function of Myonuclei helps us get stronger and increase the size of our muscle fibers.  

“When we achieve hypertrophy in the gym, our muscle fibers experience an increase in a type of cell known as myonuclei. These cells’ main job are to help us get stronger and increase our muscle fibers’ size (Legge, 2022).”

Myonuclei can remain in the system for up to three months of inactivity whereas our muscle fibers can decrease in size after we stop training and when our muscles are atrophied from long periods of inactivity. 

“Multiple studies suggest that while muscle fibers can decrease in size when we stop training, the number of myonuclei appears to stay stable even for extended periods of time and in atrophied muscles. For up to three months of inactivity (Legge, 2022).” 

For this reason, once we get back to the gym, these cells will allow us to synthesize proteins and merge muscle fibers quickly compared to untrained muscles. They will also come quicker than the first time they were created. 

Key findings from a 2020 Study by O’reilli on Myonuclei and Muscle Memory: 

Finding #1:

“Therefore, those cells are still there when we go back to the gym — ready to synthesize proteins and merge muscle fibers quicker than they did the first time around (O’reilli, 2020).”

Finding #2:

“Note that there was no loss of the elevated number of myonuclei induced by previous resistance training after 20 weeks of detraining (O’reilli, 2020).”  

Finding #3:

“Together, the previously trained muscles showed a significantly greater muscle size increase when re‐trained compared to muscle without a pre‐training history (O’reilli, 2020).” 

Finding #4:

“Studies have shown that, once hypertrophy occurs, the muscle tends to regain muscle mass relatively quickly toward the largest size that it ever has, even after a prolonged lay‐off period (O’reilli, 2020).”  

Finding #5:

“The most prominent finding of the present study is that previously trained muscles confer greater mitochondrial adaptations when subjected to resistance exercise training at a later time (O’reilli, 2020).”   

Finding #6:

“Furthermore, the data showed that the acquired myonuclei may assist with muscle hypertrophy and mitochondrial biogenesis following subsequent re‐training. Taken together, the results of the present study suggest a potential cellular mechanism supporting the notion that exposing young muscles to resistance exercise training may have benefits with respect to regaining metabolically active muscles in later life (O’reilli, 2020).”  

These findings all suggest that myonuclei creation allows muscles to retain size after longer periods of detraining and inactivity. 

What is the Myonuclear Domain Theory?  

The myonuclear domain theory stipulates that the above-mentioned myonuclei remain largely intact after long periods of detraining. This is the primary reason that muscle memory is an effective process. 

“And although we lose muscle size fairly quickly after ceasing training, we retain any additional myonuclei we’ve accrued for a much longer period and this gives us a huge advantage when we get back to training again. It means instead of having only one command center overseeing muscle growth, we have several that can all work together at the same time (Tulloch, 2019).”

The Link Between Satellite Cells and Muscle Memory

Satellite cells are important to understand because they end up creating a lot of the muscle that we work for at the gym. They allow muscles to regenerate. Having built the original amount of satellite cells after the initial hypertrophy period of 16 sessions, they then can convert into muscle stem cells and eventually give its nucleus to the muscle fiber. 

“Satellite cells are activated by exercise and can help repair muscle damage, but most importantly they can change into muscle stem cells, which then donate their nucleus to the muscle fibre (Tulloch, 2019).”

This then might imprint itself as cellular memory, allowing recall as hypertrophy re-starts in a previously trained individual. 

“In summary, our own interpretation of the preponderance of the best evidence currently available suggests that de novo muscle hypertrophy in mature mammals is dependent on myonuclear accretion, and that nuclei are subsequently not lost from intact fibers (Tulloch, 2019).”  

However, this could also be caused by epigenetic imprinting instead of the myonuclear domain theory. 

“The elevated number of nuclei might serve as a substrate for a cellular memory, but we are not excluding that additional mechanisms such as long lasting epigenetic imprinting might influence the level of protein synthesis governed by each nucleus. (Petzigner & Fisher,2022). ”

How Long Does it Take to Build Satellite Cells?

It can take years for full adaptations to take place. Hypertrophy of the muscles takes longer than our first training session and can take up to 16 workout sessions in an untrained individual. 

“It can take years for your musculoskeletal adaptations to fully take place, but for hypertrophy to really begin, it takes about sixteen sessions to really see lasting change for an untrained person (the pump you feel after a workout is called transient hypertrophy, it goes away) (Loews,2016).”

How is This Related to Gaining Muscle Back via Using our Muscle Memory?

“When you engage in detraining or take an extended break from working out, your muscles lose their strength—a process known as muscle atrophy or muscle loss. Myonuclei (muscle fiber nuclei), however, remain in your muscle tissues, and when you work out again, those myonuclei engage in protein synthesis, helping your muscles regrow and regain their strength. Retraining muscles will build muscles faster than working with untrained muscles for the first time (Holder,2022).”

How Long Until We Can Get our Muscles Back from a Long Period of Detraining? 

This all depends on how long you have spent away from training, your starting fitness level and other factors like nutrition and current activity level. 

“A 2015 Danish study, for example, found that young, physically fit people who became immobile lost one-third of their muscular strength while older people only lost one-fourth (O’reilli, 2020).”

What are Type 1 and Type 2 Fibers? 

Check out this post on muscle fibers to learn more about the Type 1 and Type 2 fibers in our bodies. 

“Your body has two types of muscle, type I (oxidative, which is used for endurance activities), and type II (glycolytic, which is used for intense activities). Type II have greater mass potential, while type I is improved upon, mostly the same way that cardiovascular training improves your body, through improved pathways to get blood and gas to your muscles (Loews,2016).“

What are the Roles of the Cerebellum and Basal Ganglia in Improving Muscle Memory?  

The basal ganglia is the part of the brain where new actions activate growth of new neural pathways. It is generally responsible for functions like motor learning, executive functions, behaviors and emotions. 

On the other hand, the cerebullum is important for making postural adjustments in order to maintain balance. It modulates commands to motor neurons to compensate for shifts in body position or changes in load upon muscles.

“Performing an action repeatedly activates neurons in certain parts of the brain, particularly the cerebellum and basal ganglia, and creates a new neural pathway between the central nervous system and the muscles you’re moving. Once you’ve established muscle memory, you can accomplish the task without consciously thinking about it (Holder,2022).” 

These newly created pathways in the basal ganglia and cerebellum allow for re-activation when training continues after periods of rest. This access in turn, serves as muscle memory and allows us to regain more size over time. 

“In addition, muscle memory allows athletes to take a break from training and competing. During that time, their muscles and the neural pathways will weaken because of disuse, but when they resume training, they can return to their previous athletic state and gradually regain muscle size without having to start from square one (Holder,2022).”

Finally, a 2022 study performed by Petzigner & Fisher found that exercise directly improves performance of the basal ganglia and cerebellum. This in turn strengthens the adaptive abilities of our brains to access these newly formed pathways when exercise resumes. 

“While controlled clinical trials have been limited, they do show that exercise provides motor benefits to patients with PD and in aged subjects, and exercise provides cognitive benefits including improved executive function, memory and learning (Petzigner & Fisher, 2022).”

What is the Link between Detraining Duration and Muscle Memory?  

The importance of knowing about muscle memory is for when we plan to take time off of training. Our bodies’ ability to access our muscle memory largely depends on factors like training experience, age and time off of training. 

“Altogether, our results indicate that some of the molecular hallmarks of strength-trained muscle can be preserved after 20 wk of detraining (Loews,2016). “ 

“Your body will also start shifting more attention to type I fibers away from the high burning Type II muscles. At this point, it really depends on who you are and how well you’re trained:

• Some athletes see a loss of about 6% muscle density after three weeks.
• Some power lifters see losses of as much as 35% after seven months.
• Young women who trained for seven weeks and gained two pounds of muscle mass, lost nearly all of it after detraining for seven weeks (Loews,2016).” 

In essence, the longer that you have spent without training, the more that you would have lost. 

In conclusion, muscle memory is an important concept to understand as it helps us understand our bodies’ muscular intelligence in maintaining our hard-earned muscles. You want to try to limit the amount of time detraining in order to hold on to the muscle that you have. Do not fret as your body is able to remember the new neural pathways that you built when you started training. 

I hope that you enjoyed this detailed guide to muscle memory, please let me know what you thought about it in the comments section below! 

 Sources: 

https://journals.physiology.org/doi/full/10.1152/japplphysiol.00761.2019

https://legionathletics.com/muscle-memory/:

https://www.luketulloch.com/blog/how-does-muscle-memory-work-for-bodybuilding

https://www.masterclass.com/articles/what-is-muscle-memory

​​https://medium.com/oxford-university/the-amazing-phenomenon-of-muscle-memory-fb1cc4c4726 

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3691073/

https://www.trifectanutrition.com/blog/muscle-memory-what-is-it-how-to-use-it