Muscle Memory Is The Real Thing

6 Aug

fitness-dipsStrength training is an essential component of a well-balanced fitness program. By performing squats, push-ups, dips, chins, deadlifts, and other multi joint exercises on a regular basis you can build a leaner, stronger body, correct muscle imbalance patterns such as lower crossed syndrome, and prevent and slow down chronic disease processes.

Another potential, often forgotten, benefit of resistance training is that it may provide you with muscle memory, in the sense that some of the adaptations that occur in your body as a result of pulling, pressing, and pushing heavy objects don’t disappear completely when you take a break from training, but rather stay with you. These changes, which are encoded and “stored”, allow you to build muscle at an accelerated speed when you, at a later time in your life, start exercising again.

Not just gym talk

Some people are under the impression that the whole muscle memory thing is nothing more than a myth. This isn’t necessarily surprising, as the idea that the process of gaining muscle is slower when you first hit the gym as a scrawny teen, than when you start exercising again after a lengthy training break, may sound a bit far-fetched at first. After all, it’s a well-established fact that novice lifters gain muscle and strength at a rapid pace, pretty much regardless of what kind of training program they adhere to. As long as they lift something, and hence, put more stress on their body than it’s used to, “noob gains” occur.

Also, it doesn’t help that the term muscle memory is something that is routinely heard in the men’s locker room, often as part of discussions that include plenty of anecdotal experiences and “broscience”. When you hear a guy make outrageous, non-scientific statements that revolve around the conversion of muscle to fat, post-exercise anabolic windows, and protein needs for bodybuilders, before he goes on to say that he was able to gain 12 pounds of lean muscle in 5 days, all thanks to muscle memory, you may quickly be led to believe that everything is just complete bullshit.

It’s certainly true that there is a lot of folklore, broscience, and myths circulating in the bodybuilding & fitness community. But not everything is nonsense… Some of the beliefs that gym enthusiasts cling to do rest on a scientific foundation, one of which is the belief that muscle memory is a real thing.

Muscle memory obviously won’t be able to provide you with 12 pounds of lean muscle in 10 days. That said, it can be very powerful. This statement is both based on my own experience as a lifter and strength coach, as well as what I’ve read about this phenomenon.

Losing muscle may not be as bad as you think

When I was younger, I did a lot of resistance exercise. I did heavy bodybuilding-type training at least 3 times every week, mostly 4-5, and during virtually every training session I pushed my body close to the limit of what it could handle.

In retrospect, I realise that the training program I was following back then was not doing my body any good. I was pushing myself too hard, doing way too many sets to failure, and stressing my system in ways it was not prepared for. If I had paid more attention to the hormonal and inflammatory status of my body, things I unfortunately knew little about at the time, I certainly would have recovered faster between training sessions, made better progress in the gym, and been able to maintain my health despite adhering to an imprudent exercise program.

Nevertheless, I did gain some muscle and strength. Actually, I gained a lot of muscle. I wasn’t healthy, but I was big.

For many years I stuck with a heavy resistance training program, but after a while, as my interest in strength training and muscle started to decline and my body could no longer take the endless punches, I started to slow down. In the years that have passed since these early days of my strength training endeavors, there have been periods where I’ve barely been doing any resistance exercise at all.

The reason I’m telling you this story is to show that I have some experience with the whole muscle memory thing.

I’m not as obsessed with lifting and gaining muscle as I was, so it’s not that big of a deal if I’m not able to lift for some time, and hence, lose some lean mass. That said, I still like to include some resistance training in my fitness routine; largely because it helps enhance my health, but also because it provides me with a stronger, more muscular body. It’s therefore good to know that I don’t have to start all over again when I start training after a lengthy break.

This is to say that my personal experience is that muscle memory is a very real, powerful thing. The observations I made when I worked as a personal trainer also suggest that this is true. I particularly remember one male client I had many years ago. He definitely wasn’t the most punctual client I’ve ever had, and sometimes he skipped entire personal training sessions without giving notice (I still got paid though). However, when he first met up, it was an absolute joy to coach him through his workouts.

He pushed himself harder than pretty much any client I’ve ever had and usually followed instructions to the letter. He mostly did squats, deadlifts, advanced push-up variations, and other similar resistance exercises when he was with me, while he did mostly sprints and aerobic training during his own, personal sessions.

He got quite strong and muscular; however, since he was so busy with work and family stuff, he often ended up taking long, unplanned breaks from training. It wasn’t that big of a problem though, because when he got back in the gym, it didn’t take much time for him to regain the strength and muscle he had lost. Muscle memory in action!

Muscle memory may be explained by the recruitment and retention of myonuclei

I obviously realise that the information in the previous section is all based on anecdotal experiences, which by no means prove that muscle memory is a real thing. If you’ve read about this phenomenon on other health and/or fitness websites, you’ve probably come across stories and anecdotes from other people that have somewhat the same experience as me. A pile of anecdotal reports don’t necessarily prove anything either, but it obviously shouldn’t be ignored.

Luckily for us, we don’t have to rely exclusively on observations and personal experiences, as scientists have looked into the muscle memory phenomenon (1, 2, 3, 4, 5, 6). I’m not going to dig into and break down all the research in this area in this article, because it would make the post way too long. Also, I don’t think it’s that important or interesting to know all the nit-picky details regarding which receptors, hormones, and cells that are involved in the build-up of muscle memory, in part because we today don’t have a clear picture of exactly how muscle memory is encoded.

Instead, I thought I would focus on one of the most recent research papers on muscle memory that have been published. The article, entitled Muscle memory and a new cellular model for muscle atrophy and hypertrophy, had the following to say about muscle memory:

Memory is a process in which information is encoded, stored, and retrieved. For vertebrates, the modern view has been that it occurs only in the brain. This review describes a cellular memory in skeletal muscle in which hypertrophy is ‘remembered’ such that a fibre that has previously been large, but subsequently lost its mass, can regain mass faster than naive fibres. A new cell biological model based on the literature, with the most reliable methods for identifying myonuclei, can explain this phenomenon. According to this model, previously untrained fibres recruit myonuclei from activated satellite cells before hypertrophic growth. Even if subsequently subjected to grave atrophy, the higher number of myonuclei is retained, and the myonuclei seem to be protected against the elevated apoptotic activity observed in atrophying muscle tissue. Fibres that have acquired a higher number of myonuclei grow faster when subjected to overload exercise, thus the nuclei represent a functionally important ‘memory’ of previous strength. This memory might be very long lasting in humans, as myonuclei are stable for at least 15 years and might even be permanent. However, myonuclei are harder to recruit in the elderly, and if the long-lasting muscle memory also exists in humans, one should consider early strength training as a public health advice. In addition, myonuclei are recruited during steroid use and encode a muscle memory, at least in rodents. Thus, extending the exclusion time for doping offenders should be considered. (3)

The author also includes a small segment called Evolutionary considerations, which may be particularly interesting to ancestral health enthusiasts. Here’s a part of this segment:

… the muscle memory might represent an adaptive mechanism to allow individuals from whom strength has been demanded in the past to more quickly rebuild muscle mass in the future, as an individual adaption or specialization. In this way, maintaining a constant high muscle mass is avoided, for example, during less labour-intensive seasons. As for the classical learning and memory of the brain, ‘experience’ becomes useful if the same task arises again. (3)

As you can gather from the first quote above, the author makes the case that muscle memory primarily develops as a result of the recruitment and retention of myonuclei – the nuclei of muscle cells. Other research supports this theory (1, 2, 4). The higher number of nuclei in a muscle cell likely contributes to an increase in protein synthesis because total protein synthesis is the product of synthesis per nucleus and the number of nuclei.

That being said, it’s important to note that there’s still a way to go in terms of establishing which mechanisms that are involved in the development of training-induced muscle memory. It may be that we have some of the mechanisms wrong, or that other processes have to be considered. For example, the author of the article above mentions at the end that several other mechanisms, including DNA and histone modifications, may be important for the accumulation of muscle memory. Also, it should be noted that more controlled exercise trials are needed to firmly demonstrate that muscle memory can be encoded by strength exercise without steroids.

That said, the weight of the evidence clearly suggest that muscle memory is a real thing.

Last words

So, what does this mean for you? It’s certainly interesting that it’s possible to “save” some of the progress that you’ve made in the gym in the past. Also, there’s no doubt that the observations that myonuclei may essentially be permanent, and that more nuclei translate into greater capacity for regrowth, have important implications for sport and public health. But does it have any implications for you personally, for example in terms of how you should plan your training or eating? It may…

First of all, it should make you less concerned about losing muscle during training breaks, as you know the lost mass can “quickly” be regained. Secondly, it suggests that it may be important to start training early in life, as myonuclei get harder to recruit as you get older. Resistance training early in life can help prevent degenerative loss of skeletal muscle mass quality. Thirdly, it may change how you plan your training program and diet. One of the things I’ve noticed is that when I start doing resistance exercise again after a long break from training, I get extremely hungry, particularly during the first week or so, which is not surprising, as the protein synthesis is ramped up and muscle mass is regained. I’m sure others have experienced the same.

This is something I take into consideration when I plan my diet and training program. During these periods I pretty much have to increase the caloric density of my diet (above what I normally would during periods where I regularly perform strength exercises) and eat more meals throughout the day. I also try to keep the training volume at a low-moderate level, so as to avoid extreme hunger and muscle soreness.

Picture: Creative Commons picture by A&A Photography. Some rights reserved.