Muscle memory, a truth or a myth?
You may have witnessed people acquiring muscle mass, losing it after a period of time when they stop exercising, and then regaining muscle mass in a much shorter period of time than before. This is achieved through the phenomena of muscle memory, and it is not just restricted to muscle mass; this phenomenon may be applied to any other physical training that you perform. Muscle, made up of cells called myocytes, is a contractile tissue whose function is to produce movement or locomotion and is organized in a regular pattern to produce a force through contraction. We obviously don't have brains in our limbs, so we can't recall things in our arms and legs, so how is that done? What exactly is the purpose of muscle memory?
Muscle memory refers to the process of repeatedly putting a motor task to memory. While your muscles do not have the ability to recall anything, they do contain neurons that are connected to your neurological system and play a part in motor learning. When you repeat an action enough times, even if it's difficult, your brain develops identifiable patterns in the areas of your brain that control motor abilities. As a result, a taught action will take less mental effort in the future. Your myocytes and myonuclei divide and then develop and repeat anytime you begin training or simply doing things for bodybuilding. The more pressure you put on them, the more likely they are to multiply in order to satisfy the demand. However, When you stop training, your existing myocytes shrink and grow smaller in size, which is known as muscular atrophy, but the good news is that their myonuclei don't disappear. Even in atrophied muscles, the number of myonuclei appears to remain constant over long periods of time. As a result, those cells are still present, ready to manufacture proteins and fuse muscle fibres at a faster rate than before.
Only one research in humans has attempted to directly test the notion of muscle memory through myonuclear persistence. Healthy young males participated in Psilander's study, which included 10 weeks of unilateral resistance exercise training, 20 weeks of detraining, and 5 weeks of bilateral retraining. The first exercise training phase resulted in considerable increases in skeletal muscle thickness and strength, which were mainly lost during the subsequent 20 weeks of detraining. However, no changes in muscle thickness or strength increases were found between the previously trained limb and the untrained limb after retraining. During the first 10 weeks of exercise training, the size of muscle fibres expanded considerably. During 5 weeks of bilateral retraining, however, no changes in muscle fibre size or myonuclear content were detected. The degree of muscle fibre development observed during the first 10 weeks of exercise training may have been insufficient to trigger a group mean increase in myonuclear content, which is necessary to prove that muscle memory through myonuclear retention occurs in humans.
Muscle memory has been proposed to have origins at the epigenetic level, in addition to the presence of muscle memory due to myonuclear retention. Researchers from Keele University, along with Liverpool John Moores University, Northumbria University, and Manchester Metropolitan University, studied over 850,000 sites on human DNA and discovered the genes ‘ marked' or 'unmarked' with special chemical 'tags' when muscle grows following exercise, then gets back to normal, and then regrows following exercise in later life, using the most up-to-date genome-wide techniques. These markers or 'tags,' also known as epigenetic modifications,' inform the gene whether it should be active or inactive, giving the gene instructions to switch on or off without altering the DNA itself. Dr. Sharples elaborated that if an athlete's muscle increases and then they are injured and lose some muscle, knowing the genes involved for muscle 'memory' may aid their rehabilitation. It will need further research to figure out how different workout programmes can assist activate these muscle memory genes.
Seaborne found that 7 weeks of resistance exercise training resulted in DNA hypomethylation and muscle fibre hypertrophy. Furthermore, this hypomethylation was sustained during a subsequent 7-week period of resistance exercise retraining, during which muscle mass and strength developments were considerably higher than during the original 7-week exercise training phase. This suggests that exercise training causes genes to become more hypomethylated, which is subsequently retained during detraining, allowing for more transcription of these genes during retraining and, as a result, allowing for a higher muscle fibre growth response. Indeed, epigenetics might be a plausible method for explaining muscle memory.
The phrase “use it or lose it” is might be more accurately articulated as ‘use it or lose it, until you work at it again’.”
References
1. Human Skeletal Muscle Possesses an Epigenetic Memory of Hypertrophy. Scientific Reports, 2018.
2. Gundersen K, Bruusgaard JC. Nuclear domains during muscle atrophy: nuclei lost or paradigm lost? J Physiol. 2008;586(11):2675‐2681.
3. Dirks AJ, Leeuwenburgh C. The role of apoptosis in age‐related skeletal muscle atrophy.
4. Keele University. Study proves ‘muscle memory’ exists at a DNA level. ScienceDaily, 30 January 2018.
5. Muscle memory discovery ends ‘use it or lose it’ dogma: Posted on January 28, 2019 in Featured News, Life Science.
6. Stephanie J. Valberg. Muscle anatomy, physiology, and adaptations to exercise and training: The Athletic Horse (Second Edition), 2014.
7. Sara Chadosh. Muscle memory is real, but it’s probably not what you think: July 25, 2021.
8. Anthony O’Reilly. Muscle Memory: What is it & How to Use it: June 27, 2020.
Very well written..and the concept well explained..you guys are really picking up v good topics...that need to be pondered at...keep writing and spread the knowledge.Kudos to you.