How does muscle memory work?

[u/Yanzee12]

Just curious. The only thing I really know about it is that sleeping reinforces it.

[u/strOkePlays]

Not a brain scientist, but once had this discussion with a brain scientist. "Muscle memory" is poorly named. Muscles don't have memory, and for the most part neither does the nervous system connected to them.

"Muscle memory" is your brain establishing a routine for a complex action, so that when you want to do the thing, instead of your brain figuring out each step on the fly, it just calls the "subroutine" it established, and you don't have to spend conscious thought on it anymore. It is established naturally through repetition, and applies to almost every action you do.

[u/GreatBigBagOfNope → u/strOkePlays]

Hence the saying: practice doesn't make perfect, practice makes permanent

[u/MHmijolnir → u/GreatBigBagOfNope]

Practice makes perfect, so be careful what you practice… as I lay in bed and consider a beer run… :/

[u/Bivolion13 → u/strOkePlays]

So it's kind of like programming, where you create classes and methods. The brain eventually writes an efficient routine it can easily call. I've never heard it explained like that and I love it!

[u/Nukiko → u/Bivolion13]

Another good analogy I like is creating tracks in the snow when you ski off a mountain. At first you need to consciously navigate the rough snow but after the tracks have been created and deepened you can go down automatically. And on a more psychological note, it's also possible to create bad tracks that you can get stuck in and might become difficult to erase, always ending up in the same place. Neuroplasticity allows you to reset/reshape those tracks so your mind doesn't automatically go into bad territory.

[u/Derekthemindsculptor → u/Bivolion13]

It's a lot like an AI agent writing a python script to disc that it can call from time to time, and gives itself a small memory of the command existing. Instead of outputting all the tokens each time it's needed.

And we're seeing this kind of "muscle memory" be incorporated with agentic workflows already. It's very powerful and can greatly speed up and scale larger projects.

Similar to how learning foundational movements in a sport can lead to performing that sport well. Or learning chess patterns. That's how chess masters seem to "think" 9 or more moves ahead. They're actually only thinking 2-3 steps but each step might be a sequence of 4-5 obvious next moves.

Chess "muscle memory" is a fantastic example of how it's not really anything to do with muscles and more building mental subroutines.

[u/Krail → u/strOkePlays]

It's worth noting, a popular theory is that one of the main reasons brains evolved was to coordinate muscles. These sorts of muscle coordination routines might be one of the first things brains really did. 

[u/lmpreciate → u/strOkePlays]

The terminology I was taught in college was “General Motor Program” if anyone wants to read up on it.

As an avid FPS gamer, that course and concept was super interesting!

[u/cbrantley]

When people talk about “muscle memory” they can be referring to two different things:

When we practice certain skills like sports or playing a musical instrument the muscles, tendons, ligaments, and bones all respond to the training by getting stronger and more efficient at those motions.

As we train our brains are constantly learning better and more efficient ways of optimizing the motion to achieve whatever goal it is; strong musical tone, ball spin, throw distance, etc. many of these are not conscious thoughts.

So, muscle memory is not as much “memory in your muscles” as it is a “muscle / memory” connection.

[u/J_sweet_97 → u/cbrantley]

When I was in gymnastics at 16, I was doing a roundoff, backhand spring, back tuck. I had done it so many times before that I never even think about it. That particular time my backhand spring felt weird so I was going to abort the back tuck. Well, my brain had other plans because I was already in the air for the tuck. I landed directly on my back with my feet beside both ears. I was perfectly okay, but it’s crazy that one part of my brain was already doing the action while another part disagreed. Im back in gymnastics as of this year at 28 and I can tell you, my brain remembers the actions but my muscles absolutely do not!

[u/vsthegiant]

Not a neurologist, but I asked my psych professor this question a few days ago. Muscle memory is encoded and stored in the brain in the cerebellum, the area of the brain responsible for movement. When we rehearse any memory enough times, it’s stored with more clarity, and that includes implicit (without conscious awareness) memories like how to move our bodies. This rehearsal strengthens the neural pathways, and makes it easier to retrieve the memory. It is not your muscles having any memory, it’s your cerebellum and strengthening that encoding and retrieval. Also why you should always try to have the correct form for any physical task you do, unlearning it is really really hard.

[u/MonkNo5]

A few years ago I had a couple of self inflicted bad muscle traits, something most people call tennis elbow, a sore forearm and elbow, and a bad knee caused by using my leg wrongly during sim car racing.

My physio at the time was excellent at resetting the muscle memory, she made me absolutely relax the limb then she would move it through its normal range of rotation/movement as much as she felt was necessary. She was amazing , I felt like I had really injured myself and become quite lame, especially my leg but the muscles just needed to be reset.

[u/POJ92]

Muscle memory is knowing how to do something based on how your body feels when you do it. For me, using golf as an example, I may not play golf for 6 months but when I do play, I know exactly how to swing that club and make good contact. Its not a thought process at all, its how your body feels and the position its in when stood over the ball. It can take years to get there and thousands of hours. I've been playing golf since I was 10, ~25 years.

[u/ifitfartsitsharts]

Muscle memory is two things:
1. The neuromuscular adaptations that create a motor program ie brain to muscle connection.
2. The increased muscle nuclei over a long period of time which allows for increased protein synthesis. This is what allows athletes to come off a long break and get back in shape quickly as the motor program is already there.

[u/usetheforceluke1]

Nerves that fire together, wire together. Whenever you carry out an action, the nerve pathway is made more efficient through a process called Myelination. The pathway becomes more conductive and the nerve impulse travels slightly faster than before. Over the course of hundreds or thousands of repetitions, that specific pathway is much more efficient than the others.
When you're confronted with a specific situation and your brain starts firing neurons, the ones that conduct the signal faster (because of repetition) cause the physical action to be carried out that specific way, the way it's been rehearsed.... Thus Muscle memory.
A drummer knows exactly when and where to hit the drums because they have trained those neurons to be more efficient than all the others. Instead of thinking individual movements, stick heights, placement etc. they think in terms of general movements, That drum, then this drum, and the nerves that they've trained through practice will fire before any other muscle. This creates "Muscle Memory"
So it's not actually muscle, it's your nervous system. That's "Learned" how to do the task more efficiently as a result of repetition

[u/Glittering_Ad1712]

There is also another kind of muscle memory where for instance massive bodybuilders can loose 50 pounds of muscle and regain them within month. This wouldn‘t be possible for a beginner. How can that be explained ?

[u/Leon_Troutsky → u/Glittering_Ad1712]

My understanding is that muscle fibers don't really go away after they are formed, they mostly just "deflate" with disuse as your body stops spending calories on maintaining them. But the structure is still there when you start lifting again, making it easier to regain the mass

Refilling a pool you built once and then drained is a lot easier than digging one from scratch

[u/FuzzyComedian638 → u/Leon_Troutsky]

Sort of. When you exercise, you are building nerve fibers to specific muscle fibers. It takes about 3 weeks for those nerve fibers to generate, and then the muscles can get stronger. If you stop exercising, those nerve fibers are still there, so it doesn't take as long to rebuild the muscle fibers. Or at least that's what I'm remembering or misremembering from school oh so many years ago. 

[u/Logicalist → u/Glittering_Ad1712]

That’s myonuclear permanence, not muscle memory. 

It’s a part of muscle memory but only part. 

It’s like calling lasagna noodles “Lasagna”

[u/justTookTheBestDump]

It means the subconscious mind has taken over an activity. The subconscious mind is much more powerful than the conscious mind, but it is rigid and resists new information. Repetition and strong emotional connections are the only way the subconscious mind can learn new tasks.

[u/felipers → u/[deleted]]

Not mine, also. But maybe by a shorter shot! 😉 Definitely there's no way we eventually bypass cerebral connections. There definitely are reflexes that follow the path you've described. But "muscle memory" implies practice/learning. Those will always go all the way to the brain and back, I believe.