Is muscle-memory real? The answer is we don't really know
If you do any sort of exercising you will probably hear from some guy who took a long break from the gym who got back into reasonable shape start to talk about "muscle memory" and how that is the reason why he was able to get back into shape a lot faster than a person who has never worked out before.
It's a relatively common phrase that is thrown around in gyms all around the world. I've always kind of wondered whether it was real or not and started looking at research papers rather than just listening to a guy on YouTube who will insist that muscle memory is real but only if you buy these supplements..... This actually happens so once again, take anything you hear from an influencer online that is selling something with a pinch of salt, they are probably lying.
I find this image strangely disturbing
I know from my own experience that there must be something to the muscle memory theory because of my own body. When I was younger, in my years from say 10-25 years of age, I was involved in a bunch of team sports such as soccer and football. Even when i wasn't on a team it was common for me to be involved in these sports in pick up games many times a week. Therefore, I developed very strong legs and in particular quite profound calves.
Fast-forward a decade or so and the only exercise I was doing for the most part was lifting weights and just like most men who lift weights, I paid almost no attention to my legs. Once I started doing "leg day" once a week I became very strong with my legs and my definition, particularly in my calves, was back in no time at all. Given that I hadn't focused on this sort of exercise for years, how is it possible that I had calves that were the envy of other people who had only ever lifted, if muscle memory isn't real?
Therefore based on my own experience I feel as though it kind of has to be real but from a scientific point of view there is no consensus on this. We know that when you over exert a muscle group to the point of soreness, your body, especially if you are young, will generate new cells in order to compensate for this. This is why people who regularly lift of do some sort of exercise end up having definition of muscle mass that people who sit in an office chair or on the sofa watching movies all day do not have.
The brief article that I read regarding muscle memory talks about why muscles get bigger on a cellular level and it involves something called myonuclei. These tiny things replicate when muscle tissue tears from regular use in order to compensate for what the body perceives as a need to adapt for new stresses. Previously it was believed that the reverse would be true and that if you didn't continue to exercise that these cells would die off. However, some relatively recent research that has been done indicates that the "new" cells do NOT die off, but rather become dormant and shrink in size. This information is detailed in the above article and the boring scientific papers are referenced there as well in case you have difficulty falling asleep one night.
There is some dispute about whether or not this theory is actually true but this is based upon the fact that it is exceptionally difficult to track an individual cell so there "jury is still out" on whether or not these microscopic cells stick around even if you aren't using them. It would be wonderful if they do and you lived an active 20's and 30's though, because most research indicates that the body stops responding to this sort of stimulation in people's 40's or thereabouts.
The positive takeaway from this is that if the researchers who believe that you do retain the micronuclei are correct, then you effectively have a "bank" of sorts of cells that are just waiting to be reactivated. This is the science behind "muscle memory and I believe it to be true because there isn't much good other explanation for my own legs exploding back to their previous state when I rarely even worked them out.
There are some other factors that are difficult to quantify that contribute to someone who has a lapse in working out getting results faster as well though, and a lot of that isn't muscle memory, it is memory memory in that since you have already done all these exercises in the past, you already know how to do them properly and perhaps already have a system in place for how to develop and grow strength in the first place. A person who starts working out in their 40's is at a huge disadvantage here for a number of reasons and one of them is not knowing proper form in the first place.
Therefore, it is perfectly understandable that someone with experience in the gym is going to get gains a lot faster than someone that is just starting out.
For me, there is no other way to describe how my calves just "popped" in around a month of doing legs once or twice a week. The guys I work out with get a real kick out of how much I can do on calf raises in particular seeing as how this is a part of their own bodies that they struggle with. One of the guys is so frustrated about his lack of growth that he has pondered getting calf implants and yes, that is a real thing. We told him we would relentlessly pick on him if he did this.
The guy in question was never involved in team sports as a kid and didn't really start working out until he was in his mid-30's so there is some reasoning to the fact that while his upper body is impressive because he has been working that out for decades now, that developing his calves simply might not be an option. The cells simply aren't in his body and can't be grown.
Of course a lot of this is speculation on my part because I am not a researcher and i do not understand a bunch of the doctor lingo that is going on in peer-reviewed academic papers. The only thing I can really go by is the phenomenon that occurred in my own life.
What about you? Have you experienced and muscle memory moments in your own life? It seems as though there is no definitive answer in the scientific world about this but if you have experienced it I would like to hear about it.