31 DoB: 27: Muscle Memory - Science Fact or Science Fiction?

Much like riding a bike, getting back into fitness is far easier than starting from scratch.

Rebuilding muscle, performing old skills, getting back up to a level of strength near to where you were before, it’s all chalked up to muscle memory. The idea that our muscles “remember” familiar movements and weights, making it easier to get back to where we were before a long break.

Reading that, it might look like a lot of mumbojumbo or broscience.

Our muscles are muscles, not brains. They have one job - to contract. Fast, slow, for a short or long period of time, why would they remember one contraction more than the other?

Muscles remembering stuff, how ridiculous.

If these are your thoughts on the matter, then you better grab a knife and fork to eat those words - because it turns out they do.


Well, not strictly remember in the sense that they have a scrapbook of movements - ahh I remember that squat session, burned like hell. Those were the days… - but the work we put in does more than grow or make the muscle more efficient.

By completing successively harder workouts and stimulating progress, we start to affect more than just the nerves and muscle fibres. We start to alter the cells themselves, adding more nuclei.

The muscle cells are a special kind of cell, in that they have more than one nucleus (aka they are multinuclear). In our cells, the nucleus is where all our genetic material is stored (our DNA), housing the blueprints for making proteins, enzymes and other cell products.

By having more than one nucleus, the muscle cells are able to create more proteins and building blocks - like having a team where everyone has the building instructions, instead of just one person.

This means our muscles have the potential to grow faster and adapt quicker than other parts of our body - most likely because faster adapting muscles means a greater chance at surviving in our environment (our muscles carrying our bodies away from danger and getting to food - not much of a problem in modern day Earth, but our bodies are still of the animal kingdom and built to survive).

By being able to add more nuclei to the cell, the muscle cells are able to build more and create bigger muscles. This lifts the limit for muscle size, as there are more nuclei to work on the project, and we get bigger and more efficient muscles that are able to handle more stimulus.

This means we can progressively overload each week, forcing the muscles to create more nuclei and better muscles to handle the greater strain.

That’s great, but what happens when we stop training? Doesn’t the body break down the nuclei in the muscle cells - we’re not using them so why let the resources go to waste?


While that would make sense, the answer is no. All the nuclei remain.

Even if we don’t train, the muscles will break down somewhat (as the protein degradation rates exceed protein synthesis - no stimulus means no need to build bigger structures) but the nuclei will stick around.

Maybe indefinitely, according to one study.

These means that when we do get back into training, our muscles can skip the process of creating new nuclei as they’re already there. Instead, the cells can focus working on building the muscle up again, which is a much quicker process thanks to the extra nuclei available.

This is the way that the muscles “remember” your old workouts, strength and muscle size - we still have all the nuclei from that time. All we need to do now is build up training to gradually stimulate the muscle growth to the same point is was before.

This can be a slower process as we age (metabolism slowing down and chemical processes becoming less efficient) and pick up injuries/wear and tear, but the ultimate potential is there if we can overcome these factors. Even if we don’t reach the same level of performance/size, we’ll still be doing a hell of a lot better than someone the same age but new to the game.


While it gets hard to add muscle as we age, the presence of extra nuclei can only help us preserve a decent amount of it - as long as we use it.

Without stimulus in the form of exercise, resistance or non resistance, our muscles will begin to break down and get recycled for nutrients elsewhere. But with an active life, we can add a tonne of nuclei and keep everything in working order as we age.

This gives progressively harder exercise the added benefit of being a long term investment. By putting in the work now, we can help preserve our muscles for when we get older.

Even in the short term, if you’re off from training for an extended amount of time you don’t have to worry. The gainZ are not lost, they’re just broken down and need to be rebuilt.

So if you want to take a holiday, focus on a project or spend time elsewhere, that’s all good.

We can even maintain a decent level of fitness with 1-2 sessions a week. Because the effort required to maintain is much lower than what’s needed to progress to the next level we don’t need to spend as many hours exercising to stay at the same level. By exercising or practising the movements you want to maintain 1-2 times a week, we can hold on to a lot of our fitness. It’ll still be tough moving up a level, but we’ll not have set ourselves back so much.

Just get back into it when you can, build back up to where you were and keep crushing it.

We’d obviously be progressing more if we don’t stop in the first place, but unless you live in a bubble or training is your only priority in life, this is unrealistic. Just put in the work when you can, challenging yourself to progressively harder things, and enjoy the lifelong rewards for your efforts.

Start now, work hard, and make it count.


Bruusgaard JC, Johansen IB, Egner IM, Rana ZA, Gunderson K. 2010. Myonuclei acquired by overload exercise precede hypertrophy and are not lost on detraining. [online]. PNAS. Aug 107 (34) pp 15111-15116. Available from: http://www.pnas.org/content/107/34/15111 [Accessed on 27/1/2018].

Gunderson K, Bruusgaard JC. 2008. Nuclear domains during muscle atrophy: nuclear lost or paradigm lost? [online]. Journal of Physiology. Jun 586(11). Pp 2675-2681. Available from: https://www.ncbi.nlm.nih.gov/pubmed/18440990 [Accessed on 27/1/2018].

Staron RS, Leonardi MJ, Karapondo DL, Malicky ES, Falkel JE, Hagerman FC, Hikida RS. 1991. Strength and skeletal muscle adaptations in heavy-resistance-trained women after detraining and retraining. [online]. J Appl Physiol. Feb 70(2) pp631-640. Available from: https://www.ncbi.nlm.nih.gov/pubmed/1827108 [Accessed on 27/1/2018].